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Page 503 of 977 Results 5021 - 5030 of 9762

Filippo Attivissimo, Nicola Giaquinto, Mario Savino
SOME THOUGHTS ABOUT THE FREQUENTIST AND THE BAYESIAN APPROACH TO UNCERTAINTY

The paper presents ideas about the use of the frequentist and the Bayesian approach to estimation and uncertainty. The merits and the pitfalls of the Bayesian approach, compared with the frequentist one, are illustrated using a simple example (of electrical measurement), which gives rise to an instructive paradox. The implicit presence of the same paradox in the GUM is highlighted and discussed. The final suggestion is to keep in the GUM the approaches, the frequentist and the Bayesian one.

Hélder R. Florentino, Raimundo C. S. Freire, Dimitri Galayko, Caio S. Florentino
OPTIMIZATION OF CONTROL SWITCH FOR ENERGY HARVEST CIRCUIT USING A VARIABLE CAPACITOR

This work presents an analysis of a harvesting system of vibratory energy through a variable capacitor and a DC-CD Buck converter circuit. A switch circuit architecture of the Buck converter is presented. The performance of the switch in relation to the wasted energy due to the size of the used transistor as well as the work tension over the switch was verified. The circuit was developed in the cadence scheme and it used components with 0.35 μm technology of high voltage in order to support tension up to 50 V. This circuit presents a loss smaller than 4% of the transferred energy.

Bruno Cabral de Oliveira Dutra
ROBOTIC MAIPULATORS FOR ATTITUDE SESORS CALIBRATIO: MEASUREMET MODEL AD UCERTAITY CALCULATION

Recent works have proposed the use of industrial robots as a standard for intermediary calibrat sensors such as accelerometers and magnetometers. In this paper it is developed the (mathematical) measurement model to be used for the determination of the measurement result and the uncertainty in multiple links robot manipulators. This model relates many random such as the linear and angular positions of theffector, and correction factors for the determination the mean and the measurement uncertainty for a simple three link manipulator case using both the law of uncertainty propagation (LDU) technique and the Monte and the results are compared.

Hélder R. Florentino, Raimundo C. S. Freire, P. Basset, Caio Florentino, Dimitri Galayko
CAPACITIVE ENERGY HARVESTER WITH ACTIVE CHARGE LEAKAGE COMPENSATION AND PIEZOELECTRIC GENERATOR

The search for compact autonomous devices has been increasing in the microelectronics industry. These devices have the capacity to generate their own energy in order to be charged. One of the ways of harvesting environmental energy for charging such devices is by using mechanical vibrations through the use of variable capacitor. Taking this principle into account, this work presents a behavioral analysis of a system model of harvesting vibratory energy for low power, made up of a circuit which includes a variable capacitor. An architecture of a circuit which improves the relation concerning the amount of harvested energy/circuit area in relation to conventional architectures is also presented as well as a comparison between the circuit with the proposed architecture and the circuit. The conventional circuit harvested a maximum power of 4.5 μW whereas the circuit with the new architecture harvested a 6.25 μW power. A piezoelectric generator to provide initial power and to supply the circuit losses is still used.

S. A. Rodrigues, R. C. S. Freire, H. Aboushady, M. M. Louërat, J. I. C. Accioly
DESIGN OF A DIFFERENTIAL OPERATIONAL AMPLIFIER IN A CLOCKLESS A/D CONVERTER

This paper presents a differential operational amplifier used in a continuous-time 8-bit folding analog-todigital converter. The clock-less architecture is composed of 8 identical stages with 1 bit/stage. The circuit is designed in a 350nm CMOS process with a supply voltage of 3.3 V. Simulation results show that, with this operational amplifier, the 8-bit clock-less ADC can achieve a Signal-to-Noise and Distortion Ratio of 53 dB. The ADC has a power consumption of 5.51 mW.

Thiago B. P. de Souza, Marcelo M. da Costa, Oswaldo G. dos S. Filho, Ipojucan L. de Carvalho, Julio S. do Nascimento
DEVELOPMENT OF ELECTRIC AND MAGNETIC FIELD STANDARDS AND CALIBRATION SERVICE TO MEET THE ANEEL RESOLUTION Nº 398/2010

This article aims to show the development of instrumentation for measuring electric field and development of standards for calibration of electric and magnetic field in the Centro de Tecnologia da Eletrobras Eletronorte (CCT) in Belém, Brazil to meet the ANEEL Resolution 398/2010.

Tomasz R. Woliński, Piotr Lesiak, Robert Plaga, Mateusz Szeląg, Daniel Budaszewski Andrzej W. Domański, Anna Boczkowska, Ginu Rajan, Yuliya Semenova, Gerald Farrell
STRESS INDUCED IN OPTICAL FIBER SENSORS EMBEDDED IN COMPOSITE MATERIALS BY THE LAMINATION PROCESS

The influence of the lamination process on stress sensitivities of the composite structure incorporating optical fiber sensors with fiber Bragg gratings (FBGs) and polarimetric highly birefringent (HB) fibers has been investigated. Coating layers of the HB fibers are found to be responsible for performance of the embedded polarimetric sensors while the angular orientation of embedded FBGs written in HB fibers is responsible for the observed optical wavelengths shifts.

Robert Rice Brandt, Benedito Guimarães Aguiar Neto, Raimundo Carlos Silvério Freire, Joseana Macedo Fechine, Silvana Luciene do Nascimento Cunha Costa
CHARACTERIZATION OF PATHOLOGICAL VOICE SIGNALS BASED ON CLASSICAL ACOUSTIC ANALYSIS

This work describes a method used to classify voice signals as normal or pathological. Voices were chosen from the KAY ELEMETRICS CORP Voice Disorders Database. The process of characterization of the voices as normal or pathological was done using classical acoustic analysis characteristics. Individual features gave false positive and false negative rates ranging from 15% up. By using three features simultaneously false positive and false negative rates of 13% and 15%, respectively, were obtained.

Octavian Postolache, Artur Lopes Ribeiro,Helena Ramos
UNIFORM EDDY CURRENT PROBE IMPLEMENTATION USING PLANAR EXCITATION COIL AND GMR SENSOR ARRAY

Defect detection in conductive plates represents an important issue. This work presents designed and implemented uniform eddy current probe architecture (UECP) that includes a planar excitation coil and a GMR magnetometer sensor array as part of a non-destructive testing (NDT) system developed using a virtual instrument system technology. The usage of GMR sensors provides frequency independent sensitivity to the UECP, assuring speed, depth, and higher resolution in eddy-current testing, while the usage of a set of GMR sensors allows rapid scanning of an area for defects in a single pass.
A practical approach concerning the UECP design, implementation and experimental results obtained on cracks detection machined in aluminum plates for a single or multiple GMR sensor usage as main parts of UECP are presented. Experimental results regarding the usage of the novel eddy current probe to detect induced flaws in aluminum plates are included in the paper.

Ricardo García, Lucas Di Lillo, Andrés Torán, Jorge Cioffi
SIMULTANEOUS DC VOLTAGE CALIBRATION OF MULTIMETERS AND CALIBRATORS

This paper describes an automatic method for simultaneous calibration of digital multimeters (DMM) and multifunction calibrators in the 100 DCV range. This method can be also used in other ranges by connecting zeners in series.

Page 503 of 977 Results 5021 - 5030 of 9762