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Justinas Janulevicius, Lauryna Siaudinyte, Antanas Cenys, Nikolak Goranin
Detection and measurement of information system risks through adaptive management diagnostic expert systems

Current growth of usage of lT systems in almost every field of industry causes rapid optimization of production and maintenance of goods and processes. Nevertheless, wider usage of automated lT systems has it's drawbacks as well: while most of the lT solutions fully exist in an online environment, certain risks for assets stored within the systems exist. Diagnosing and measuring damages, generated by harmful events can have a strong impact on further evolution of the owners, therefore it is very important to assess the possible risks and requiring much expertise and estimating every possible event and it's possibility. Since this process can easily be described as a complex decision-tree, a rule-based expert system can be facilitated to generate the needed expertise on risk assessment. The precision of risk measurement can be increased by using continuous reasoning instead of discrete. Fuzzy-logic based reasoning is proposed instead of Boolean. Possible IT risks vary depending on the technologies popular at given time, so this type of data is considered as sensitive. Therefore it must have a possibility to be updated at any time to provide the end-user with the most actual data. This leads to proposition of an adaptive hybrid fuzzy-logic and rule-based expert system for preventive early diagnostics of threats and measurement of risk of IT assets.

B. Aubert, J. Regnier, S. Caux, D. Alejo
Stator Winding Fault Diagnosis in Permanent Magnet Synchronous Generators Based on Short-Circuited Turns Identification Using Extended Kalman Filter

This paper deals with an Extended Kalman Filter (EKF) based fault detection for inter-turn shortcircuit in Permanent Magnet Synchronous Generators (PMSG). A specific faulty model in d-q frame is developed to estimate the number of short-circuited turns which are used to a fault indicator setting up. Simulation results demonstrate the sensitivity and the robustness of the chosen indicator against various operation points on an electrical network.

Giovanni Bucci, Fabrizio Ciancetta, Edoardo Fiorucci
A Testing System for the Performance Evaluation of Fault-Tolerant Electromechanical Drives for Aircraft Applications

In this paper, a testing system for the evaluation of the performance of innovative electromechanical drives for aircraft flaps is presented; it has been developed as a cooperation with the Umbra Group Aerospace. The research activity is focused on the design of the measurement system and on the development of the software for the measurement and the monitoring of mechanical, hydraulic and electrical parameters as well as the managing of the control system for the emulation of the load force opposing to the actuators movement. Innovative solutions based on the multithreading technique has been implemented, to guarantee the correct execution of the required tasks and the system synchronization.
The obtained results shows that the different sections of the system are able to communicate and cooperate successfully, according to the required performance.

Wenyu Zhao, Edzel Lapira, Lodovico Menozzi
Trends in Asset Monitoring and Prognostics

This presentation introduces signal processing techniques as applied to specific machine components with a focus on the output and use with prognostics technologies. With properly organized outputs, prognostics algorithms transform the fleet condition and health management challenge into a deployable fleet health management solution. This approach includes data and model driven failure patterns, sensory data connectivity from deployed assets, prognostics analytical applications, and advisory generation outputs which guide the asset owners and maintainers. To illustrate the concepts, a Wind power asset monitoring case study is presented.
A data-driven approach is applied to model power curve continuously, which is entailed within a two-tier framework that employs Prognostics and Health Management (PHM) techniques for wind turbine monitoring. A set of measurements during a known good condition is utilized to setup a baseline model. Regular power curve measurements arc then coinpared while taking into account the multi-regime dynamics of the turbine.
The approach was implemented using NI LabVIEW's Watchdog Agent (R) Toolkit and was successfully validated using actual SCADA data collected from an on-shore wind turbine.

Diego Galar, Uday Kumar
SMART bearings: From sensing to actuation

A Centre has been created within Lulea University of Technology (LTU), with support from SKF, to examine the opportunities presented by developments in sensing and communication technologies in adding sensing and analysis functionality to rolling element bearings. One of the goals is the development of an artefact which closes the loop from sensing to actuation and taking advantage of all existing IT, mechanical and maintenance technologies.

Yongping Han, Shahin Mehdizad Taleie, Tino Copani, Bertan Bakkaloglu, Sayfe Kiaei
A CMOS 1.5-Bit ΣΔ DIGITAL IF TO RF TRANSMITTER FOR WCDMA APPLICATION

A digital intermediate frequency (IF) to RF transmitter targeted for 2 GHz wideband code division multiple access (WCDMA) is presented. The proposed transmitter integrates a 3-level digital IF current-steering cell, an up-conversion mixer with a tuned load and an RF variable gain amplifier (RF VGA) with an embedded semidigital finite impulse response (FIR) reconstruction filter. A 4th-order 1.5-b IF bandpass sigma delta modulator (BP ΣΔM) is designed to guarantee in-band signal-to-noise ratio (SNR) and error vector magnitude (EVM) performances while the out-of-band quantization noise due to noise shaping is suppressed by the embedded FIR reconstruction filter to meet spectrum emission mask and ACPR requirements. The on-chip RF VGA provides 50 dB power scaling in 10-dB steps with less than 1 dB gain error. Together with the power control at the ΣΔM stage, the 74-dB dynamic range at RF frequency is achieved. The design is fabricated in a 4-metal 0.18-µm CMOS technology with a total core area of 0.8 × 1.6 mm². The IC delivers 0 dBm output power to the 50 Ω load at 2 GHz and it draws approximately 120 mA from a 1.8 V DC supply at the maximum output power.

A. Baccigalupi, D. L. Carnì, D. Grimaldi, A. Liccardo
EXPERIMENTAL SETUP FOR THE CHARACTERIZATION OF THE OUTPUT SECTION OF ARBITRARY WAVEFORM GENERATOR

An experimental setup is pointed for the characterization of the output section of Arbitrary Waveform Generator (AWG). It is based on test method pointed out for high resolution Digital to Analog Converter. The output signal of the AWG under test is reconstructed by the zero crossing time sequence detected into the resulting signal obtained by subtracting the sinusoidal signal fed by reference AWG. The characterization of the output section of the AWG is carried out by analyzing this signal in time and frequency domain. Proper procedure is pointed out to evaluate the transfer characteristic of the output section to overcome the difficulties arising from the functionality modality of the AWG.

Mario Luca Fravolini, Simone Fiani, Antonio Moschitta
COMPONENT-WISE BOUNDS FOR MIMO CONTROL SYSTEMS USING FINITE RESOLUTION QUANTIZERS

This work presents a methodology that guarantees component-wise stability bounds for the states of a disturbed linear Multiple Input Multiple Output (MIMO) feedback control systems, featuring bounded uncertainties and bounded quantization errors both in the measurements and in the controls. The controller synthesis is based on the design of a robust invariant ellipsoidal set, which assumes that all the uncertainties sources introduce upper bounded signals. We show that the component-wise boundedness requirements for the states and controls of the closed loop uncertain system can be expressed as a Linear Matrix Inequality (LMI) problem. Thus, feasibility and optimal controller design can be effectively and advantageously computed solving a convex linear optimization problem. The approach is validated by means of a meaningful numerical example.

Pasquale Napolitano, Antonio Moschitta, Paolo Carbone
MODELING NOISE EFFECTS IN TIME-TO-DIGITAL CONVERTERS

In this work, the main sources of error affecting time interval measurements are analyzed and modeled. Time interpolation techniques utilizing both synchronous and asynchronous strategies to perform time measurements have been considered. Jitter on start and stop timing signals, interpolator nonlinearities, quantization error and jitter affecting the system clock driving the counter have been recognized as the main contributors to measurement uncertainty and their effects are analytically described. A deeper investigation on the cumulative effect of the clock jitter is discussed in order to determine mean values, variances and probability density functions of quantizer output and quantization error sequences. Simulations showing mean values and variances of the quantizer output are also presented, in order to validate theoretical results. The obtained model is useful both for design and testing purposes.

Andrea Pugliese, Domenico L. Carni, Domenico Grimaldi
EFFECT OF THE RESONATOR SETTLING BEHAVIOUR ON SC BAND-PASS ΣΔ MODULATOR PERFORMANCE AND CARRIER FREQUENCY ERROR MEASUREMENT

The impact of the settling behaviour of operational amplifiers (op-amps) used to implement switched-capacitor resonators on band-pass sigma-delta (BPΣΔ) modulator performance is investigated. Behavioural simulations of a second-order BPΣΔ modulator are performed by means of numerical models which allow the designer to well-describe high-order dynamics occurring in real op-amp circuit implementations. The results show that high-order poles and zeros in the resonator frequency response affect significantly the overall BPΣΔ modulator performances. In the paper, the effects of the resonator settling behaviour on the dynamic parameters and the carrier frequency error measurement for a Single Quantizer Loop (SQL) BPΣΔ Analog to Digital Converter architecture are also investigated.

Page 544 of 977 Results 5431 - 5440 of 9762