Hardware-software integration platform for a WSN testbed based on cookies nodes

In this work a complete hardware-software support platform for a WSN testbed focused on developing wireless sensor applications in a simple and intuitive way is presented, as an alternative of commercial-motes-based testbeds that can be found in the state of the art. The main target of this hardware-software platform is to provide the highest abstraction level on the management of WSNs but in the simplest way in order to achieve a fast profiling mechanism for reliable prototyping based on the Cookies platform as well as helping users to develop, test and validate Cookie-Based WSN applications.

Low-speed longitudinal controllers for mass-produced cars: A comparative study

Four longitudinal control techniques are compared: a classical Proportional-Integral (PI) control; an advanced technique-called the i-PI-that adds an intelligent component to the PI; a fuzzy controller based on human experience; and an adaptive-network-based fuzzy inference system. The controllers were designed to tackle one of the challenging topics as yet unsolved by the automotive sector: managing autonomously a gasoline-propelled vehicle at very low speeds. The dynamics involved are highly nonlinear and constitute an excellent test-bed for newly designed controllers. A Citroën C3 Pluriel car was modified to permit autonomous action on the accelerator and the brake pedals-i.e., longitudinal control. The controllers were tested in two stages. First, the vehicle was modeled to check the controllers' feasibility. Second, the controllers were then implemented in the Citroën, and their behavior under the same conditions on an identical real circuit was compared.

Cattle-powered nodes experience in a heterogeneous network for localization of herds

A heterogeneous network, mainly based on nodes that use harvested energy to self-energize is presented and its use demonstrated. The network, mostly kinetically powered, has been used for the localization of herds in grazing areas under extreme climate conditions. The network consists of secondary and primary nodes. The former, powered by a kinetic generator, take advantage of animal movements to broadcast a unique identifier. The latter are battery-powered and gather secondarynode transmitted information to provide it, along with position and time data, to a final base station in charge of the animal monitoring. Because a limited human interaction is desirable, the aim of this network is to reduce the battery count of the system.

On-the-fly dynamic reprogramming mechanism for increasing the energy efficiency and supporting multi-experimental capabilities in WSNs

Remote reprogramming capabilities are one of the major concerns in WSN platforms due to the limitations and constraints that low power wireless nodes poses, especially when energy efficiency during the reprogramming process is a critical factor for extending the battery life of the devices. Moreover, WSNs are based on low-rate protocols in which as greater the amount of data is sent, the more the possibility to lose packets during the transmitting process is. In order to overcome these limitations, in this work a novel on-the-fly reprogramming technique for modifying and updating the application running on the wireless sensor nodes is designed and implemented, based on a partial reprogramming mechanism that significantly reduces the size of the files to be downloaded to the nodes, therefore diminishing their power/time consumption. This powerful mechanism also addresses multi-experimental capabilities because it provides the possibility to download, manage, test and debug multiple applications into the wireless nodes, based on a memory map segmentation of the core. Being an on-the-fly reprogramming process, no additional resources to store and download the configuration file are needed.

A 3D multi-objective optimization planning algorithm for wireless sensor networks

The complexity of planning a wireless sensor network is dependent on the aspects of optimization and on the application requirements. Even though Murphy's Law is applied everywhere in reality, a good planning algorithm will assist the designers to be aware of the short plates of their design and to improve them before the problems being exposed at the real deployment. A 3D multi-objective planning algorithm is proposed in this paper to provide solutions on the locations of nodes and their properties. It employs a developed ray-tracing scheme for sensing signal and radio propagation modelling. Therefore it is sensitive to the obstacles and makes the models of sensing coverage and link quality more practical compared with other heuristics that use ideal unit-disk models. The proposed algorithm aims at reaching an overall optimization on hardware cost, coverage, link quality and lifetime. Thus each of those metrics are modelled and normalized to compose a desirability function. Evolutionary algorithm is designed to efficiently tackle this NP-hard multi-objective optimization problem. The proposed algorithm is applicable for both indoor and outdoor 3D scenarios. Different parameters that affect the performance are analyzed through extensive experiments; two state-of-the-art algorithms are rebuilt and tested with the same configuration as that of the proposed algorithm. The results indicate that the proposed algorithm converges efficiently within 600 iterations and performs better than the compared heuristics.

Smart meter privacy by suprression of low power frequency components

This paper focuses on the problems associated with privacy protection in smart grid. We will give an overview of a possible realization of a privacy-preserving approach that encompasses privacy-utility tradeoff into a single model. This approach proposes suppression of low power frequency components as a solution to reduce the amount of information leakage from smart meter readings. We will consider the applicability of the procedure to hide the appliance usage with respect to the type of home devices.

Cooperative Learning Model based on Multi-Agent Architecture for Embedded Intelligent Systems

Cooperative systems are suitable for many types of applications and nowadays these system are vastly used to improve a previously defined system or to coordinate multiple devices working together. This paper provides an alternative to improve the reliability of a previous intelligent identification system. The proposed approach implements a cooperative model based on multi-agent architecture. This new system is composed of several radar-based systems which identify a detected object and transmit its own partial result by implementing several agents and by using a wireless network to transfer data. The proposed topology is a centralized architecture where the coordinator device is in charge of providing the final identification result depending on the group behavior. In order to find the final outcome, three different mechanisms are introduced. The simplest one is based on majority voting whereas the others use two different weighting voting procedures, both providing the system with learning capabilities. Using an appropriate network configuration, the success rate can be improved from the initial 80% up to more than 90%.

New Fault-Resistance Estimation Algorithm for Rotor-Winding Ground-Fault Online Location in Synchronous Machines With Static Excitation

New Fault-Resistance Estimation Algorithm for Rotor-Winding Ground-Fault Online Location in Synchronous Machines With Static Excitation

USCG group control and communications system study /

Final report; January 1979.

CONTRIBUIÇÃO DOS CURSOS SUPERIORES DE TECNOLOGIA NA EDUCAÇÃO PROFISSIONAL DO TRABALHADOR BRASILEIRO

Os Cursos Superiores de Tecnologia são um tipo específico de graduação (tecnólogo), com características próprias, entre as quais, a focalização na especialização dos seus currículos e duração mais curta objetivando uma formação mais rápida. A graduação tecnológica vem sendo amplamente difundida no país desde a segunda metade da década de 1990, após a promulgação da lei no 9.394/96 LDB, e por uma série de decretos, portarias e pareceres do MEC/CNE. Entre as principais metas e objetivos do PNE para a educação superior, se destacam: diversificação do sistema superior de ensino para atender clientelas com demandas específicas de formação; articulação entre currículo e mercado de trabalho; financiamento e gestão; criação de políticas de acesso à educação superior que facilitem o ingresso de alunos provenientes de grupos de maior vulnerabilidade educacional; crescimento da oferta de educação superior para a faixa etária de 18 a 24 anos. O presente estudo tem por objetivo refletir e debater a contribuição dos CSTs na educação profissional do trabalhador brasileiro dentro das perspectivas do PNE. O estudo se fundamenta no método qualitativo, com base numa pesquisa exploratória e descritiva, caracterizada como estudo de caso único, através da pesquisa de campo realizada com alunos em formação e com egressos do Curso de Eletrônica Industrial da Faculdade de Tecnologia Senai Anchieta, na cidade de São Paulo. Para alcançar seus objetivos, o estudo foi dividido em duas etapas: a primeira faz uma análise das variáveis que caracterizam o perfil do aluno em formação buscando identificar sua percepção quanto à escolha pelo CST, conhecimento sobre essa modalidade de ensino e as expectativas futuras da profissão. Na segunda parte, o estudo faz uma análise da percepção do egresso acerca das habilidades e competências adquiridas durante a formação, o grau de satisfação com salário e plano de carreira, e a aceitação profissional do tecnólogo pelo mercado de trabalho. No estudo realizado com alunos em formação constatou-se que os índices de evasão escolar das primeiras turmas do curso foram elevados, sendo apontadas como principais causas as dificuldades de conciliação entre o horário de estudo com a do trabalho e as dificuldades econômicas familiares. O perfil do aluno em formação na IES em estudo é majoritariamente da faixa etária entre 18 e 24 anos; do gênero masculino; egresso do ensino médio feito em escola pública; morador em bairro periférico e natural de cidade da RMSP; o próprio aluno é responsável pelo pagamento das mensalidades; não houve interferência de terceiros na sua escolha pelo CST; tem percepção favorável quanto à empregabilidade futura como tecnólogo. A pesquisa com egressos apontou que os mesmos tem percepção favorável quanto à formação profissional recebida, exceto o fato de não terem atendido disciplinas que desenvolvessem competências gerenciais e de negócios; quanto à empregabilidade e perspectivas de carreira mostraram preocupação na valorização profissional do tecnólogo pelo mercado de trabalho; declararam estar insatisfeitos quanto ao salário recebido; quanto à educação continuada reconheceram ser esse o processo que os manterão atualizados profissionalmente. Como conclusão da pesquisa, há recomendação para estudos futuros na sondagem de outras possíveis causas da evasão escolar com alunos dos cursos com outros eixos temáticos e de IES públicas. Igualmente, aponta-se para a necessidade da proposta curricular da IES em estudo oferecer, além das disciplinas técnicas, outras que desenvolvam competências e habilidade em gestão de pessoas e negócios.

Short-circuit and ground fault analyses and location in VSC-based DC network cables

The application of high-power voltage-source converters (VSCs) to multiterminal dc networks is attracting research interest. The development of VSC-based dc networks is constrained by the lack of operational experience, the immaturity of appropriate protective devices, and the lack of appropriate fault analysis techniques. VSCs are vulnerable to dc-cable short-circuit and ground faults due to the high discharge current from the dc-link capacitance. However, faults occurring along the interconnecting dc cables are most likely to threaten system operation. In this paper, cable faults in VSC-based dc networks are analyzed in detail with the identification and definition of the most serious stages of the fault that need to be avoided. A fault location method is proposed because this is a prerequisite for an effective design of a fault protection scheme. It is demonstrated that it is relatively easy to evaluate the distance to a short-circuit fault using voltage reference comparison. For the more difficult challenge of locating ground faults, a method of estimating both the ground resistance and the distance to the fault is proposed by analyzing the initial stage of the fault transient. Analysis of the proposed method is provided and is based on simulation results, with a range of fault resistances, distances, and operational conditions considered.

A learning feed-forward current controller for linear reciprocating vapor compressors

Direct-drive linear reciprocating compressors offer numerous advantages over conventional counterparts which are usually driven by a rotary induction motor via a crank shaft. However, to ensure efficient and reliable operation under all conditions, it is essential that motor current of a linear compressor follows a sinusoidal current command with a frequency which matches the system resonant frequency. The design of a high-performance current controller for linear compressor drive presents a challenge since the system is highly nonlinear, and an effective solution must be low cost. In this paper, a learning feed-forward current controller for the linear compressors is proposed. It comprises a conventional feedback proportional-integral controller and a feed-forward B-spline neural network (BSNN). The feed-forward BSNN is trained online and in real time in order to minimize the current tracking error. Extensive simulation and experiment results with a prototype linear compressor show that the proposed current controller exhibits high steady state and transient performance. © 2009 IEEE.

Experimental measurement of switched reluctance motor non-linear characteristics

For a Switched Reluctance Motor (SRM), the flux linkage characteristic is the most basic magnetic characteristic, and many other quantities, including the incremental inductance, back emf, and electromagnetic torque can be determined indirectly from it. In this paper, two methods of measuring the flux linkage profile of an SRM from the phase winding voltage and current measurements, with and without rotor locking devices, are presented. Torque, incremental inductance and back emf characteristics of the SRM are then obtained from the flux linkage measurements. The torque of the SRM is also measured directly as a comparison, and the closeness of the calculated and directly measured torque curves suggests the validity of the method to obtain the SRM torque, incremental inductance and back emf profiles from the flux linkage measurements. © 2013 IEEE.

Design optimization of short-stroke single-phase tubular permanent-magnet motor for refrigeration applications

This paper describes a design methodology to achieve optimal performance for a short-stroke single-phase tubular permanent-magnet motor which drives a reciprocating vapor compressor. The steady-state characteristic of the direct-drive linear-motor compressor system is analyzed, an analytical formula for predicting iron loss is presented, and a motor-design procedure which takes into account the effect of compressor loads under nominal operating condition is formulated. It is shown that the motor efficiency can be optimized with respect to two leading dimensional ratios. Experimental results validate the proposed design methodology. Copyright © 2010 IEEE.