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The study of ladder networks made by sequences of directly coupled inductor&ndash, capacitor single cells has led us to discover a new property, which may be of certain interest in the sensor field. In the case of n cells, the n-frequencies vector characterizing each node may allow for the identification of that capacitor (sensor), which has experienced a variation of its nominal value. This localization is possible independently from the observable node of the ladder network as proven by the application of the following multivariate data analysis techniques: principal component analysis and partial least square discriminant analysis. This property can be applied on a large scale down to micrometric dimensions in agreement with the technologic ability to shrink the capacitive sensor dimensions.

This paper deals with an analysis of the different behaviors existing between ladder networks (LN) terminated and not Phi terminated by the characteristic impedance Z0. The main purpose of this work is to find, in both cases, links with the golden ratio and, as a consequence, with Fibonacci numbers. Results of some simulations related to the determination of impedances, node voltages and branch currents are given in order to underline approximation effects on the node voltages and branch currents related to both the presence and absence of Z0.This study has been firstly applied to R-R ladder networks but it is here extended to consider other kinds of LNs, having other types of single cells such as C-C ; L-L whose characteristic impedances have also been determined. Double resistive LN have also been investigated for which impedances in any cell, currents in any branch and voltages in any node have been determined in the two cases of presence and absence of the characteristic impedance and with different ratio between longitudinal and transversal impedances. This study has another not less relevant aim: find one of the possible platform for the modelization of biosystems like DNA and RNA, because these structures even if much more complex look like a LN

The UMTS appear to be the communication system of the next future. In this system all the communication services will be included. This means that the Quality of Service (QoS) will have a great importance. So is envisaged that the management of the system will take in account the momentary system capabilities continually determined in real time. Until now, the quality of the links is determined by end-to-end in line procedures based on Bit Error Rate (BER) measurements. It is clear that an end-to-end procedure cannot detect the worse section of the link. To overcome this inconvenient the more recent trend of QoS management is to realise a distributed monitoring of the whole system. Following this last trend this paper proposes a distributed off-line monitoring of the system based on the analysis of the Quality of Analog Signal (QoAS). This proposed analysis implies a high-speed analog to digital conversion of the Intermediate Frequency signal and a very complex processing. In this paper, the state-of-the-art researches performed in this perspective are described.

The paper presents a first implementation of a novel tool to assist radiologists in analyzing screening mammographic images. The software named Assisted Breast Cancer Diagnosis Environment (ABCDE) is able to acquire DICOM images (also in presence of Grayscale Softcopy Presentation State). It is designed to assist the doctor, as a second reader, during the various phases of the diagnosis. The program uses some public libraries and implements many new algorithms developed in the last years by the research group.

The paper deals with noise power variation that occurs when Discrete Dyadic Wavelet Transform (DDWT) is applied to signals affected by Wide Sense Stationary (WSS) additive white noise owing to the use of a non orthonormal expansion. An exact relationship between the noise variance in the original signal and the noise variance in the wavelet coefficients at a generic level is derived. This relationship is crucial in the application of wavelet thresholding for signal denoising to properly select the threshold in each subband.

Breast cancer is the most common cause of death among women and the most effective method for its diagnosis is mammography. However, this kind of analysis is very difficult to interpret and for this reason radiologists miss 20-30% of tumors. We propose a module for the segmentation of masses that can be implemented in a complete CADx (Computer Aided Diagnosis) system. In particular, we implement a new version of the region growing algorithm specific for this kind of images and for the constraints on computation time of this application.

Mammography is the most effective method for early detection of breast diseases. However, the typical diagnostic signs, such as masses and macrocalcfications, are difficult to be detected because mammograms are low contrast and noisy images. In this paper, we present an algorithm for mammographic images enhancement and denoising based on the wavelet transform. In particular, we develop an adaptive procedure to perform an optimal denoising using a local iterative fuzzy noise variance estimation. Moreover, the degree of enhancement is adaptively tuned at each scale. The proposed algorithm has been tested on clinical images.

The passive intermodulation (PIM) is a well known inconvenience in satellite links. It consists in an unwanted generation of harmonics and resulting intermodulation products in weak nonlinear components crossed by RF currents or in irradiation of these unwanted signals by external materials exposed to a strong RF electromagnetic field. Several studies have been carried out to reduce this negative effect and particular measurement techniques have been employed in pre-launch testing of the whole components of the required payload. The extension of the satellite links to mobile communications, which require more transmitted power and increased receiver sensitivity, renders more and more important the reduction of the PIM effects on the downlinks to obtain a satisfactory level of quality of service (QoS). This paper reports the simulation results of effects of the third order PIM products in a multichannel transmitting system. The simulations are carried out by using time-frequency representations of the unwanted combinations of spurious signals generated by third order PIM products. The results of the above simulations are interpreted and a first attempt of design guidelines is given.

The paper faces the problem of designing a compact processor devoted to the evaluation of a time-frequency transformation for space applications. The guidelines to save circuitry and power consumption are searched. Starting from the simple Gabor transformation, the effects of the Weyl-Heisenberg indetermination principle are examined in connection with the effects induced by the use of a short wordlength. A simple criterion to choose the optimal wavelet is given and applied to improve the transformations performed using a reduced wordlength.

The scaled Chinese remainder theorem (CRT) is a very useful tool in residue arithmetic. Its properties can be exploited for the simplification and speeding-up of the conversion process. The main drawback presented by this methodology, when it is used for the output conversion, is the need of long wordlength look-up tables (LUTs) storing the correspondence among the modular numbers and the corresponding scaled terms of the CRT. This fact limits the maximum speed obtainable by this approach. In this brief, a new method for the computation of the scaled terms is presented. It has been implemented by using very small wordlength LUTs and simple arithmetic operators. The only proviso is that the moduli must be odd. The obtained architecture is very fast and due to the local interconnections is suitable for an efficient VLSI implementation.

A residue number system (RNS) method to implement fast recursive digital filters is considered. The speed improvement is obtained as a better performance of the elementary arithmetic blocks, given by the RNS. In the past the RNS double moduli method has been applied as a scaling procedure. In the present work a technique which uses this method partially is presented to improve the performance of recursive filters. This technique is based on the Chinese remainder theorem (CRT). Using CRT a partially parallelized structure can be realized which reduces the computational time and improves the speed performance. The effectiveness of this method has been tested numerically and by a 1.5- mu m CMOS implementation of a second order infinite impulse response (IIR) filter cell. >

The residue number system (RNS) digital circuit is defined as a circuit constituted by delays, modular adders, and multipliers. The synthesis of RNS digital circuits is considered starting from a given impulse response. The key requirement of the proposed synthesis procedures is the length of the sequence, which depends on the modulus, the type of the poles, and their multiplicity. The definitions of the different types of poles require the use of suitable extensions of the basic field corresponding to the modulus. >