In this paper we present a versatile and easy-to-assemble measurement system for structural health monitoring (SHM) based on the electromechanical impedance (EMI) technique. The hardware of the proposed system consists only of a common data acquisition (DAQ) device with external resistors and allows real-time data acquisition from multiple sensors. Besides the low-cost compared to conventional impedance analyzers, the hardware and the software are simple and easier to implement than other measurement systems that have been recently proposed.

A voltage reference with low sensibility to temperature and power-supply that can generate flexible reference values (from milivolts to several volts) is proposed. Designed for AMS 0.35 μm CMOS process, the circuit provides a stable output voltage working in the temperature range of -40-150°C. The proposed reference provides a nominal output voltage of 1.358 V with a power-supply of 3.3 V.

We have carried out 31P-NMR (nuclear magnetic resonance) studies on Sm-based filled skutterudite compounds SmRu4P12. The measurements of NMR spectrum at various fields (H's) give evidence that spontaneous internal field occurs below the metal–insulator transition temperature TMI∼16.5K. Concomitantly H-induced local field was observed between two successive transition temperatures, T*(∼14K)<T<TMI, suggesting that some multipole ordering coexists with dipole ordering in this compound.

An analog synthesizer of orthogonal signals for digital CMOS technology and 3V supply voltage is presented. The adaptive architecture accomplishes the synthesis of mutually orthogonal signals, such as trigonometric and polynomial basis. Experimental results using 0.35 /spl mu/m AMS CMOS process are presented for generation of the cosine and Legendre basis.

Fatigue is an important problem to be considered if a ferroelectric film is used for non-volatile memory devices. In this phenomena, the remanent polarization and coercive field properties degrades in cycles which increase in hysteresis loops. The reasons have been attributed to different mechanisms such as a large voltage applied on ferroelectric film in every reading process in Ferroelectric Random Access Memory (FeRAM) or memories for digital storage in computer, grain size effects and others. The aim of this work is to investigate the influence of the crystallization kinetics on dielectric and ferroelectric properties of the Pb(Zr 0.53 Ti 0.47 )O 3 thin films prepared by an alternative chemical method. Films were crystallized in air on Pt/Ti/SiO 2 /Si substrates at 700°C for 1 hour, in conventional thermal annealing (CTA), and at 700°C for 1 min and 700°C 5 min, using a rapid thermal annealing (RTA) process. Final films were crack free and presented an average of 750 nm in thickness. Dielectric properties were studied in the frequency range of 100 Hz–1 MHz. All films showed a dielectric dispersion at low frequency. Ferroelectric properties were measured from hysteresis loops at 10 kHz. The obtained remanent polarization (P r ) and coercive field (E c ) were 3.7 μC/cm 2 and 71.9 kV/cm respectively for film crystallized by CTA while in films crystallized by RTA these parameters were essentially the same. In the fatigue process, the P r value decreased to 14% from the initial value after 1.3 × 10 9 switching cycles, for film by CTA, while for film crystallized by RTA for 5 min, P r decreased to 47% from initial value after 1.7 × 10 9 switching cycles.

It is very important for the building of the SAW devices to study dielectric and ferroelectrics properties because every SAW device is based in piezoelectric effect that it is made up to transform an electric sign in the mechanical or acoustic sign and a mechanical or acoustic sign in an electric sign. Thus, the purpose of the present work is to prepare PbZr 0,53 Ti 0,47 O 3 (PZT) and PbTiO 3 (PT) thin films on the Si (100) substrates across spin-coating using a chemical method based in polymeric precursors. After conventional treatment in the furnace, the films were characterized by impedance spectroscopy and hysteresis loops to know its dielectric and ferroelectric properties.

An analog synthesizer of orthogonal signals for digital CMOS technology and 3 V supply voltage is presented. The adaptive architecture accomplishes the synthesis of mutually orthogonal signal, such as trigonometric and polynomial basis. Simulation results using 0.35 /spl mu/m AMS CMOS process are presented for generation of the cosine and Legendre basis.

This paper describes a mathematical study about chaotic system and about the unified approach of chaos control via fuzzy control system based in linear matrix inequality to design a controller which synchronizes the transmission/reception system. This system, that was based in Lorenz chaotic circuit, can be used for transmit signals in secure way

This paper describes an analog implementation of radial basis neural networks (RBNN) in BiCMOS technology. The RBNN uses a Gaussian function obtained through the characteristic of the bipolar differential pair. The Gaussian parameters (gain, center and width) are changed with a programmable current source. Results obtained with PSPICE software are shown.

This paper presents a high speed current mode CMOS comparator. The comparator was optimized for allows wide range input current 1mA, /spl plusmn/0.5uA resolution and has fast response. This circuit was implemented with 0.8 /spl mu/m CMOS n-well process with area of 120 /spl mu/m /spl times/ 105 /spl mu/m and operates with 3.3V (/spl plusmn/1.65V).

A circuit for transducer linearizer tasks has been designed and built using discrete components. It is implemented by a Radial Basis Function Network (RBFN) with three basis functions. The application in a linearized thermistor showed that the network has good approximation capabilities. The circuit advantages are the amplitude, width and center.

A radial basis function network (RBFN) circuit for function approximation is presented. Simulation and experimental results show that the network has good approximation capabilities. The RBFN was a squared hyperbolic secant with three adjustable parameters-amplitude, width and center. To test the network a sinusoidal and sinc function was approximated

This paper presents a new approach to develop Field Programmable Analog Arrays (FPAAs),^1 which avoids excessive number of programming elements in the signal path, thus enhancing the performance. The paper also introduces a novel FPAA architecture, devoid of the conventional switching and connection modules. The proposed FPAA is based on simple current mode sub-circuits. An uncompounded methodology has been employed for the programming of the Configurable Analog Cell (CAC). Current mode approach has enabled the operation of the FPAA presented here, over almost three decades of frequency range. We have demonstrated the feasibility of the FPAA by implementing some signal processing functions.

This paper presents a new approach to develop Field Programmable Analog Arrays (FPAAs). It is based on a simple current-mode primitive which allows easy adaptability to implement the fundamental analog functions such as integration, attenuation and amplification. A novel solution to avoid the use of excessive number of programming devices in the signal path is proposed. The paper also introduces an architecture for the FPAA, which is devoid of the conventional switching and connection modules used in Field Programmable Gate Arrays (FPGAs). High frequency operation, a simple programming methodology, operation over almost three decades of frequency (30 kHz to 10 MHz), and use of a standard digital CMOS fabrication process are the salient features of the proposed FPAA. We have demonstrated the feasibility of the FPAA by implementing some signal processing functions.

Temperature and magnetic field dependence of surface acoustic wave (SAW) velocity has been measured for Y1-xPrxBa2Cu3Oy films with x = 0.3 and x = 1. SAW velocity shows step-like anomaly at the superconducting transition Tc and a remarkable softening at low temperatures. The amount of the anomaly at Tc is 4.5 × 10−5, which is the same order as bulk samples. SAW velocity below Tc is enhanced by applying the magnetic field, which is caused by interaction between the vortices and SAW.

Elastic anomalies have been observed as a function of temperature in ZrN sputtered films. Both metallic and insulating samples show a broad minimum at high temperature. A remarkable elastic softening is found in the insulating sample at low temperature. The latter softening is characterized by T−1 dependence above 1K. Low temperature data below 2.5K are also fitted by logT. The origin of the elastic anomalies is discussed from viewpoints of Two-Level System and electronic localization.

AbstractDie durch Cyclodehydratisierung der Aryloxybutanone (Ia) bzw. (Ib) mit Polyphosphorsäure (PPA) und anschließende Demethylierung erhältlichen Hydroxybenzofurane (IIa) bzw. (IIb) werden mit den Säuren (III) in Gegenwart von PPA zu den 6‐Acy1‐Derivaten (IVa) (15‐39% Ausbeute) bzw. (IVb) (36‐49%) acyliert.

The action of acetic acid, phenylacetic acid, or β-phenylpropionic acid and polyphosphoric acid on 5-, 7-, and 6-hydroxy-2,3-dimethylbenzofurans afforded 6-acyl-5-hydroxy-, 6-acyl-7-hydroxy-, and 5-acyl-6-hydroxybenzofurans, some of which were also obtained by the Friedel-Crafts acylation of the corresponding methoxybenzofurans. The hydroxyketones thus obtained were converted to dimethylfuro derivatives of 4-hydroxycoumarins and isoflavones, and 3-benzyl-4-hydroxyfurocoumarins were also prepared by the thermal condensation of the hydroxybenzofurans and diethyl benzylmalonate.

This paper describes the implementation of a radial basis neural networks using the BICMOS process. In the neural network training was used a evolutionary computation. The radial basis function used in this neural network was a sech 2 x function. The sech 2 x function has three parameters (gain, center and width) that are changed with programmable current source in binary way. In this work was also described the evolutionary algorithm to training this neural network. Two examples are presented to illustrate the application of this neural network: the triangular to sinc function converter and the thermistor characteristic linearization. The software was developed in C language and the experimental results from the prototype fabricate using the 0.8µm AMS BiCMOS process are also presented.