1,516 research outputs found
Automated Meter Reading and SCADA Application for Wireless Sensor Network
Currently, there are many technologies available to automate
public utilities services (water, gas and electricity). AMR, Automated
Meter Reading, and SCADA, Supervisory Control and Data Acquisition,
are the main functions that these technologies must support. In
this paper, we propose a low cost network with a similar architecture to
a static ad-hoc sensor network based on low power and unlicensed radio.
Topological parameters for this network are analyzed to obtain optimal
performances and to derive a pseudo-range criterion to create an
application-specific spanning tree for polling optimization purposes. In
application layer services, we analytically study different polling schemes
Digital Signal Processing on FPGA for Short-Range Optical Communications Systems over Plastic Optical Fiber
Nowadays bandwidth requirements are increasing vertiginously. As new ways and concepts of how to share information emerge, new ways of how to access the web enter the market. Computers and mobile devices are only the beginning, the spectrum of web products and services such as IPTV, VoIP, on-line gaming, etc has been augmented by the possibility to share, store data, interact and work on the Cloud. The rush for bandwidth has led researchers from all over the world to enquire themselves on how to achieve higher data rates, and it is thanks to their efforts, that both long-haul and short-range communications systems have experienced a huge development during the last few years. However, as the demand for higher information throughput increases traditional short-range solutions reach their lim- its. As a result, optical solutions are now migrating from long-haul to short-range communication systems. As part of this trend, plastic optical fiber (POF) systems have arisen as promising candidates for applications where traditional glass optical fibers (GOF) are unsuitable. POF systems feature a series of characteristics that make them very suitable for the market requirements. More in detail, these systems are low cost, robust, easy to handle and to install, flexible and yet tolerant to bendings. Nonetheless, these features come at the expense of a considerable higher bandwidth limitation when compared to GOF systems. This thesis is aimed to the investigate the use of digital signal processing (DSP) algorithms to overcome the bandwidth limitation in short-range optical communications system based on POF. In particular, this dissertation presents the design and development of DSP algorithms on field programmable gate arrays (FPGAs) with the ultimate purpose of implementing a fully engineered 1Gbit/s Ethernet Media Converter capable of establishing data links over 50+ meters of PMMA-SI POF using an RC-LED as transmitte
Tailored particle current in an optical lattice by a weak time-symmetric harmonic potential
Quantum ratchets exhibit asymptotic currents when driven by a time-periodic
potential of zero mean if the proper spatio-temporal symmetries are broken.
There has been recent debate on whether directed currents may arise for
potentials which do not break these symmetries. We show here that, in the
presence of degeneracies in the quasienergy spectrum, long-lasting directed
currents can be induced, even if the time reversal symmetry is not broken. Our
model can be realized with ultracold atoms in optical lattices in the
tight-binding regime, and we show that the time scale of the average current
can be controlled by extremely weak fields.Comment: 4 pages, 4 figure
Torque pulsations in a three phase induction motor subject to sinusoidal voltage fluctuations associated to light flicker effect | Pulsaciones de par en un motor de inducción trifásico sujeto a fluctuaciones de tensión sinusoidales asociadas al efecto lumínico flicker
A statistical indicator used to measure human visual perception of light flicker is the short term flicker severity index (Pst). A value equal to one indicates visual annoyance, thus becoming a limit to the flicker phenomenon of lamps and, indirectly, to the voltage fluctuation that causes it. Limits of voltage fluctuations are only based on its effects on lamps; consequently, it is important to investigate the effects on other electrical equipment. With this purpose, torque response of a three phase induction motor subject to sinusoidal voltage fluctuations was evaluated in this study. For each voltage fluctuation, the associated flicker index Pst was determined. A wide range in the index, including flicker limits, was considered. Through simulations, pulsating torques in steady state were observed which could give rise to vibration problems. Given that Pst is not suitable to establish limits of voltage fluctuations in the case of induction motor, other parameters were proposed in this respect. Results are supported by means of analytical methods. Key words: Power quality, induction machine, pulsating torques. RESUMEN Un indicador estadístico utilizado para medir la percepción visual humana del efecto lumínico flicker es el índice de severidad de flicker de corta duración (Pst). Un valor igual a uno implica molestia visual, convirtiéndose así en el valor límite para el fenómeno flicker de las lámparas y, de manera indirecta, para la fluctuación de tensión que lo origina. Los límites a las fluctuaciones de tensión se basan únicamente en sus efectos sobre las lámparas; en consecuencia, es importante investigar los efectos sobre otros equipos eléctricos. Con este propósito, en este artículo se estudia la respuesta del par de un motor de inducción trifásico sujeto a fluctuaciones de tensión sinusoidales. Para cada fluctuación de tensión, se determinó el índice de flicker Pst asociado. Se consideró un amplio rango del índice, incluyendo límites de flicker. A través de simulaciones, se observaron pares pulsantes en estado estacionario que podrían dar lugar a problemas de vibraciones. Dado que el índice Pst no es apropiado para establecer límites a las fluctuaciones de tensión en el caso del motor de inducción, se propusieron otros parámetros en este sentido. Los resultados son respaldados por medio de métodos analíticos. Palabras clave: Calidad del servicio eléctrico, máquina de inducción, pares pulsantes
El Dialogus in donatione laureae Baraballis. Pasquillus et Marphorius. Estudio, edición y traducción
Presentamos un breve diálogo neolatino anotado y traducido, precedido de un estudio que lo sitúa en su medio y momento: Roma, 1514. En él hablan Pasquín y Marforio, estatuas transformadas en personajes satíricos, que se burlan de Baraballo, poetastro coronado por el papa León X para reírse y lucir en la ocasión a Hannón, elefante indio, su mascota preferida. El texto se sitúa en el marco de la literatura de pasquines y de los diálogos lucianescos, y pudo servir para ejercicios docentes en colegios o universidades por profesores como Decio en Valencia.We present a brief Neo Latin dialogue, annotated and translated to Spanish, preceded by a study that situates it in his place and moment: Rome, 1514. In it Pasquin and Marforio, statues transformed into satirical characters, mock Baraballo, a crowned poet by pope Leo X, just for laughs and present Hanno, an Indian elephant, his most beloved pet. We set the text in the frame of Pasquinate literature and satiric dialogues; it could be used for teaching exercises in colleges and universities by professors like Decius in Valencia
A new QoS routing algorithm based on self-organizing maps for wireless sensor networks
For the past ten years, many authors have focused
their investigations in wireless sensor networks. Different
researching issues have been extensively developed: power
consumption, MAC protocols, self-organizing network algorithms,
data-aggregation schemes, routing protocols, QoS
management, etc. Due to the constraints on data processing
and power consumption, the use of artificial intelligence
has been historically discarded. However, in some special
scenarios the features of neural networks are appropriate to
develop complex tasks such as path discovery. In this paper,
we explore and compare the performance of two very well
known routing paradigms, directed diffusion and Energy-
Aware Routing, with our routing algorithm, named SIR,
which has the novelty of being based on the introduction of
neural networks in every sensor node. Extensive simulations
over our wireless sensor network simulator, OLIMPO, have
been carried out to study the efficiency of the introduction
of neural networks. A comparison of the results obtained
with every routing protocol is analyzed. This paper attempts
to encourage the use of artificial intelligence techniques in
wireless sensor nodes
Using Artificial Intelligence in Wireless Sensor Routing Protocols
This paper represents a dissertation about how an artificial
intelligence technique can be applied to wireless sensor networks. Due
to the constraints on data processing and power consumption, the use
of artificial intelligence has been historically discarded in these kind of
networks. However, in some special scenarios the features of neural networks
are appropriate to develop complex tasks such as path discovery.
In this paper, we explore the performance of two very well known routing
paradigms, directed diffusion and Energy-Aware Routing, and our
routing algorithm, named SIR, which has the novelty of being based
on the introduction of neural networks in every sensor node. Extensive
simulations over our wireless sensor network simulator, OLIMPO, have
been carried out to study the efficiency of the introduction of neural networks.
A comparison of the results obtained with every routing protocol
is analyzed
Giving Neurons to Sensors: An Approach to QoS Management Through Artificial Intelligence in Wireless Networks
For the latest ten years, many authors have focused their investigations
in wireless sensor networks. Different researching issues have
been extensively developed: power consumption, MAC protocols, selforganizing
network algorithms, data-aggregation schemes, routing protocols,
QoS management, etc. Due to the constraints on data processing
and power consumption, the use of artificial intelligence has been historically
discarded. However, in some special scenarios the features of
neural networks are appropriate to develop complex tasks such as path
discovery. In this paper, we explore the performance of two very well
known routing paradigms, directed diffusion and Energy-Aware Routing,
and our routing algorithm, named SIR, which has the novelty of being
based on the introduction of neural networks in every sensor node. Extensive
simulations over our wireless sensor network simulator, OLIMPO,
have been carried out to study the efficiency of the introduction of neural
networks. A comparison of the results obtained with every routing protocol
is analyzed. This paper attempts to encourage the use of artificial
intelligence techniques in wireless sensor nodes
Using artificial intelligence in routing schemes for wireless networks
For the latest 10 years, many authors have focused their investigations in wireless sensor networks. Different researching issues have
been extensively developed: power consumption, MAC protocols, self-organizing network algorithms, data-aggregation schemes, routing
protocols, QoS management, etc. Due to the constraints on data processing and power consumption, the use of artificial intelligence has
been historically discarded. However, in some special scenarios the features of neural networks are appropriate to develop complex tasks
such as path discovery. In this paper, we explore the performance of two very well-known routing paradigms, directed diffusion and
Energy-Aware Routing, and our routing algorithm, named SIR, which has the novelty of being based on the introduction of neural networks
in every sensor node. Extensive simulations over our wireless sensor network simulator, OLIMPO, have been carried out to study
the efficiency of the introduction of neural networks. A comparison of the results obtained with every routing protocol is analyzed. This
paper attempts to encourage the use of artificial intelligence techniques in wireless sensor nodes
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