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The paper analyzed Volterra and its territory between the centuries first BC-fifth. AD to show the effectiveness of a comparative, diachronic, multidisciplinary methodological approach applied to ancient landscapes. All available sources were considered, integrating data from the most recent archaeological research and unpublished contexts and combining them with the new theories on Roman elites. Thanks to a detailed investigation of Volterran marginal areas, the paper suggested solutions for the different evolutive dynamics between the inland areas and the coast. The reassessment of information within a broader social, economic, and cultural frame explained why the main changes in settlement distribution occurred in the marginal areas. In conclusion, the detailed analysis of the frontier regions and the integrated approach prompted a complete reconsideration of the Volterran settlement pattern evolution providing further insights to reconsider the historical complexity of the district and its landscapes.

The optoelectronic reservoir computing (RC) is considered as a promising optical signal processing technique for nonlinear channel equalization. In this paper, a parallel optoelectronic RC scheme with a dual-polarization Mach- Zehnder modulator (DPol-MZM) is proposed and demonstrated numerically. The nonlinear channel equalization performance is greatly enhanced compared with the traditional optoelectronic RC scheme and Volterra-based DSP scheme, since the nonlinear dynamics of RC are enriched from the dual-polarization methodology. Besides, the system efficiency is improved with a single DPol-MZM., Part of proceedings: ISBN 978-1-6654-3194-1QC 20220816

[EN] The recovery of the “mastio” and the surrounding courtyard of the new fortress of Volterra (1472-1474) has as its objective the opening to the public of this fortified work, after 542 years from its construction, with the possibility of being enjoyed without interposing with the prison function of the complex, it also represents the possibility of knowledge and study of a constructive typology in the context of the Renaissance fortified architecture of the Italian school called “transition” with the use of the first artillery. The fortress was born as a military garrison and at the time of Lorenzo the magnificent only a part was used as a prison, it will be definitively transformed into a House of Imprisonment during the Grand Duchy of Lorraine in the middle of the eighteenth century. It is the first work by Francesco di Giovanni di Matteo called the Francione (1428-1495), it has an almost square shape with large cylindrical towers at the corners (rondelle) and at the center of the inner courtyard, a large cylindrical tower like of “mastio” (donjon) and inserted the artillery in the walls. The “mastio” consists of a basement and five floors above ground with a domed roof and connected by a narrow spiral staircase. After the cognitive essays carried out on the internal domes of the “mastio”, placed in the first three floors including the cistern, the presence of “hemispherical domes” emerged, made by workers of the Opera del Duomo in Florence, built entirely in bricks without the carpentry of “centina” (self-supporting), with the system called “alla fiorentina”, as well as the dome of Santa Maria del Fiore in Florence by Filippo Brunelleschi. This construction system is also applied in the fortified structures of Pietrasanta, Poggibonsi, Sarzanello, Castrocaro, Pisa and Terra del Sole.

Considering landscaping in the past, increased attention is now given to the perception of changes, the concept of resilience and methods of power ostentation. In this sense, the role played by urban centres as a local arena for competition, ostentation, and negotiation is fundamental. The continued use or the abandonment of ancient urban areas or hinterland settlement was determined by a complex mix of religious feelings, political attitudes, and cultural influences and tied to the ruled space organization determined by representatives of the civic community. An approach considering landscaping as strongly connected to the role of local elites is fundamental to finding a general model, especially reflecting the question: did social and cultural conditions influence landscaping more than environmental contingencies? In this context, the urban status, both on civic and religious levels, of Volterra represents an example of extraordinary resilience to the macro events of Tuscany between the 3rd and the 5th centuries AD. Studies on Volterra territory are extremely varied, and there is a lack of integration of archaeological and literary data and results of previous research. Analyzing the 3rd-century Roman city, the 5th-century bishopric and the Lombard centre, this research tries to explain the great resilience by examining how the Volaterran elite organized and controlled the urban and rural landscape. The emerging idea is that certain environmental conditions are fundamental for settlement. Still, local elites' cultural, social, and economic interests had a very important and often much stronger impact on landscaping spaces of power.

Este trabajo de Fin de Grado aborda el problema de la linealización de amplificadores de potencia. En particular, se centra en los problemas numéricos que resultan de la inversión de matrices necesaria para la determinación de los parámetros de predistorsionadores digitales y posibles alternativas al cálculo de la matriz inversa, común en problemas de regresión. Se comienza planteando el contexto en el que estamos trabajando y se definen los objetivos que se esperan alcanzar. A continuación, se presentan las técnicas de linealización existentes, haciendo especial énfasis en la predistorsión digital. El tercer capítulo analiza el algoritmo más extendido en el cálculo de los coeficientes del predistorsionador, el algoritmo Least Square (LS). Una vez analizado, se discuten los problemas asociados al condicionamiento de las matrices de regresión y se plantean estrategias que intentan solventar las limitaciones de éste, manteniendo su exactitud en la estima. El cuarto capítulo presenta la plataforma sobre la que se ha trabajado y realiza ciertas aclaraciones sobre el código generado. Las pruebas y resultados obtenidos al aplicar la predistorsión digital con los diferentes algoritmos de cálculo serán expuestos en el quinto capítulo. El capítulo final recoge las conclusiones obtenidas en base a las pruebas realizadas y las líneas futuras de investigación. En él queda reflejado que los métodos analizados constituyen una alternativa eficiente para la resolución de los problemas identificados, así como la importancia de tener en cuenta la memoria, para una mejor linealización, a la hora de diseñar un predistorsionador.

This article presents the Stockholm Volterra Project and its developments since 2013. This project, run by Stockholm University and the Department of Archaeology and Classical Studies, has carried out geophysical prospections in Volterra in collaboration with Soprintendenza Archeologia, Belle Arti e Paesaggio per le province di Pisa e Livorno. The aims and methods of the project are outlined together with a closer presentation of key sites from 2014 and 2015: the ‘Football Pitch’, the area in front of the church of San Giusto, the ruined church of Santo Stefano, the amphitheatre and Ortino sites., The Stockholm Volterra Project

Este trabajo presenta una comparativa de técnicas de selección de componentes para modelos basados en series de Volterra destinado a la predistorsión digital de amplificadores de potencia. En primer lugar, se ha introducido teóricamente la distorsión no lineal presente en los dispositivos activos, concretando en el amplificador de potencia, y la serie de Volterra, herramienta matemática en la que se basan los modelos de comportamiento de amplificadores de potencia contemplados en este documento. Seguidamente, las técnicas Orthogonal Matching Pursuit (OMP), Iterated Ridge Regression (IRR) y Análisisde Componentes Principales (PCA) han sido analizados y comparados desde un punto de vista teórico. La parte experimental consiste en el modelado de la salida esperada de un amplificador de potencia GaN bajo prueba cuando se le excita con una señal de entrada según el estándar long term evolution(LTE) a 15 MHz. Las señales medidas han sido adquiridas usando un analizador vectorial de señal y postprocesadas para obtener alineamiento temporal entre la señal medida y la de referencia. Los resultados experimentales enriquecen esta comparativa y resaltan los beneficios de cada uno de los algoritmos.

This paper presents a multiple-input multipleoutput (MIMO) nonlinear mitigation technique for closely spaced concurrent aggregated carrier systems. The transmitter architecture considers band-limited sources, where the predistorter and signal bandwidth are the same, thus reducing transmitter hardware cost and power consumption. The technique relies on multirate processing and linear filtering and uses the carrier frequencies to isolate the contribution of linear and nonlinear basis functions to the desired bands. This approach can be used with any MIMO model structure. In particular, models are linear in the parameters of low computational complexity. The technique was evaluated using three concurrent carriers of 50 MHz each fed to a Doherty amplifier. The results show significant reduction in the error vector magnitude and improvements for the transmitter efficiency using the proposed compensation technique., QC 20170330

Tuscany is for Cassola, who was born and had long been living in Rome, a land of choice where he moved after his Twenties and set almost all his works. The paper explores, both from a biographical and a literary point of view, the writer’s attachment to places whose importance and inspirational value were such that he even thought of them as possible principles of thematic organization in cycles for his entire literary production, that is Cecina, Volterra, and the inland of Maremma. The literary transposition of these beloved places is informed by the astonishment he felt when he discovered them as an adolescent on holiday. The beauty of landscapes is described with the lyricism of his writing’s existential realism., La Toscana è per Cassola, nato e vissuto a lungo a Roma, terra elettiva: scelta come luogo di residenza dopo i vent’anni, diventa lo scenario di ambientazione di quasi tutti i suoi lavori. Si esamina qui, sui due fronti biografico e letterario, il legame dello scrittore con i luoghi che più hanno contato per lui e dai quali trae ispirazione: Cecina e Volterra, che insieme all’entroterra maremmano sono i luoghi più legati alle sue esperienze, vengono da lui assunti a categorie per raggruppare in cicli di differente tematica i propri testi, in una sua ipotesi di ordinamento dell’intera produzione. Nella trasposizione letteraria, i luoghi amati, recuperati con lo sguardo stupefatto con cui li scopriva in vacanza da adolescente, sono descritti anche nella loro bellezza paesaggistica, cui resta affidato il lirismo del realismo esistenziale della sua scrittura.

Since they appeared, wireless technologies have deeply transformed our society. Today, wireless internet access and other wireless applications demandincreasingly more traffic. However, the continuous traffic increase can be unbearableand requires rethinking and redesigning the wireless technologies inmany different aspects. Aiming to respond to the increasing needs of wirelesstraffic, we are witnessing a rapidly evolving wireless technology scenario.This thesis addresses various aspects of the transmitters used in wireless communications.Transmitters present several hardware (HW) impairments thatcreate distortions, polluting the radio spectrum and decreasing the achievabletraffic in the network. Digital platforms are now flexible, robust and cheapenough to enable compensation of HW impairments at the digital base-bandsignal. This has been coined as ’dirty radio’. Dirty radio is expected in future transmitters where HW impairments may arise to reduce transmitter cost or to enhance power efficiency. This thesis covers the software (SW) compensation schemes of dirty radio developed for wireless transmitters. As describedin the thesis, these schemes can be further enhanced with knowledge of thespecific signal transmission or scenarios, e.g., developing cognitive digital compensationschemes. This can be valuable in today’s rapidly evolving scenarioswhere multiple signals may co-exist, sharing the resources at the same radiofrequency (RF) front-end. In the first part, this thesis focuses on the instrumentation challenges andHWimpairments encountered at the transmitter. A synthetic instrument (SI)that performs network analysis is designed to suit the instrumentation needs.Furthermore, how to perform nonlinear network analysis using the developedinstrument is discussed. Two transmitter HW impairments are studied: themeasurement noise and the load impedance mismatch at the transmitter, asis their coupling with the state-of-the-art digital compensation techniques.These two s, QC 20150526

Efficient power amplification is inherently a non linear operation that introduces unwanted interference in the amplified signal. Strong inter-symbol interference is generated when the amplifier non linearity is combined with channel memory effects. Further, signals with very high peak to average power ratio, typical of multiple carrier systems, are even more sensitive to the non linearities resulting in severe distortion effects. Signal pre-clipping (crest factor reduction) and predistortion are conventional countermeasure techniques to reduce the generated non linear distortion and improve power and spectral efficiency. In this work, novel optimization methods for predistortion and pre-clipping are analytically derived for a general non-linear communication channel with memory. A combined architecture in which crest factor reduction is followed by signal predistortion is proposed and the parameters are estimated resorting to iterative algorithms based on least squares method. Performance evaluation of the estimation techniques shows the effectiveness of the derived algorithms and significant gain compared to previously known methods. © 2015 IEEE.

Since they appeared, wireless technologies have deeply transformed our society. Today, wireless internet access and other wireless applications demandincreasingly more traffic. However, the continuous traffic increase can be unbearableand requires rethinking and redesigning the wireless technologies inmany different aspects. Aiming to respond to the increasing needs of wirelesstraffic, we are witnessing a rapidly evolving wireless technology scenario.This thesis addresses various aspects of the transmitters used in wireless communications.Transmitters present several hardware (HW) impairments thatcreate distortions, polluting the radio spectrum and decreasing the achievabletraffic in the network. Digital platforms are now flexible, robust and cheapenough to enable compensation of HW impairments at the digital base-bandsignal. This has been coined as ’dirty radio’. Dirty radio is expected in future transmitters where HW impairments may arise to reduce transmitter cost or to enhance power efficiency. This thesis covers the software (SW) compensation schemes of dirty radio developed for wireless transmitters. As describedin the thesis, these schemes can be further enhanced with knowledge of thespecific signal transmission or scenarios, e.g., developing cognitive digital compensationschemes. This can be valuable in today’s rapidly evolving scenarioswhere multiple signals may co-exist, sharing the resources at the same radiofrequency (RF) front-end. In the first part, this thesis focuses on the instrumentation challenges andHWimpairments encountered at the transmitter. A synthetic instrument (SI)that performs network analysis is designed to suit the instrumentation needs.Furthermore, how to perform nonlinear network analysis using the developedinstrument is discussed. Two transmitter HW impairments are studied: themeasurement noise and the load impedance mismatch at the transmitter, asis their coupling with the state-of-the-art digital compensation techniques.These two s

Tectonic faults are commonly modeled as Volterra or Somigliana dislocations in an elastic medium. Over the years, many practical solutionmethods have been developed for problems of this type. This work presents a concise overview in consistent mathematical notation of the most prominent of these methods, emphasizing what the various methods have in common and in what aspects they are different. No models other than that of elastic dislocations are considered. Special attention is given to underlying assumptions and range of applicability., Geoscience & Remote Sensing, Civil Engineering and Geosciences

It is shown that the absolute value of a complex-valued function can be expressed as a polynomial in the square of the absolute value of the function. A series expansion is given and related to the Volterra-series. The results find application in explaining and improving the understanding of the “even” order memory polynomial models.

Acoustic echo cancelation (AEC) composes a fundamental property of speech processing to enable a pleasant telecommunication conversation. Without this property of the telephone the communicator would hear an annoying echo of his own voice along with the speech from the other communicator. This would make a conversation through any telecommunication device an unpleasant experience. AEC has been subject of interest since 1950s in the telecom industry and very efficient solutions were devised to cancel linear echo. With the advent of low cost hands free communication devices the issue of non linear echo became prominent because these devices use cheap loudspeakers that produce artifacts in addition to the desired sound which will cause non linear echo that cannot be cancelled by linear echo cancellers. In this thesis a Harmonic Distortion Residual Echo Cancelation algorithm has been chosen for further investigations (HDRES). HDRES has many of those features that are desirable for an algorithm which is dealing with nonlinear acoustic echo cancelation, such as low computational complexity and fast convergence. The algorithm was first implemented in Matlab where it was tested and modified. The final result of the modified algorithm was then implemented in C and integrated with a complete AEC system. Before the implementation a number of measurements were done to distinguish the nonlinearities that were cause by the mobile phone loudspeaker. The measurements were performed on three different mobile pones which were documented to have problems with nonlinear acoustic echo. The result of this thesis has shown that it might be possible to use an adaptive filter, which has both low complexity and fast convergence, in an operating AEC system. However, the request for such a system to work would be that a doubletalk detector is implemented along with the adaptive algorithm. That way the doubletalk situation could be found and the adaptation of the algorithm could be stopped. Thu

As the demand for higher data rates increases, commercial analog-to-digital converters (ADCs) are more commonly being implemented with multiple on-chip converters whose outputs are time-interleaved. The distortion generated by time-interleaved ADCs is now not only a function of the nonlinear behavior of the constituent circuitry, but also mismatches associated with interleaving multiple output streams. To mitigate distortion generated by time-interleaved ADCs, we have developed a polyphase NonLinear EQualizer (pNLEQ) which is capable of simultaneously mitigating distortion generated by both the on-chip circuitry and mismatches due to time interleaving. In this paper, we describe the pNLEQ architecture and present measurements of its performance., Defense Advanced Research Projects Agency (Air Force Contract FA8721-05-C-0002)

Im Rahmen dieser Arbeit werden die Volterra-Reihen zur Analyse der Nichtlinearität in RF Schaltungen verwendet, um den Designprozess für RF Systeme zu optimieren. Die auf Volterra-Reihen basierende Nichtlinearitätsanalyse wurde in eine Matlab-Toolbox implementiert. Diese Toolbox kann mittels Volterra-Reihen die symbolische Berechnung der Nichtlinearitätsparameter (harmonische Verzerrungen und Intermodulationsverzerrungen) eines RF Blocks für eine gegebene Architektur und Technologie durchführen. Danach können die symbolische Ausdrücke der Nichtlinearitätsparameter in Abhängigkeit von den Architekturparametern und Technologieparametern erhalten werden. Dies ermöglicht die Beschränkung der Wertebereiche der Architekturparameter und die Überprüfung auf die Erfüllung der Nichtlinearitätsspezifikationen für unterschiedliche Kombinationen von Architekturen und Technologien. Somit ist eine Beschränkung der Klassen der Architekturen und Technologien möglich. Die Toolbox wurde zur Verdeutlichung auf einen Low Noise Amplifier (LNA) der Inductive Source Degeneration (ISD) Architektur angewandt. Zur Verifikation wurde diese LNA-Schaltung auch in Cadence SpectreRF Design Tool simuliert.

The present work is dedicated to the development of high performance integrated circuits for wireless communications, by acting of three different levels: technologies, devices, and circuits. Silicon-on-Insulator (SOI) CMOS technology is used in the frame of this work. Micromachining technologies are also investigated for the fabrication of three-dimensional tunable capacitors. The reliability of micromachined thin-film devices is improved by the coating of silanes in both liquid- and vapor-phases. Since in telecommunication applications, distortion is responsible for the generation of spurious frequency bands, the linearity behavior of different SOI transistors is analyzed. The validity range of the existing low-frequency nonlinear characterization methods is discussed. New simple techniques valid at both low- and high-frequencies, are provided, based on the integral function method and on the Volterra series. Finally, the design of a crucial nonlinear circuit, the voltage-controlled oscillator, is introduced. The describing function formalism is used to evaluate the oscillation amplitude and is embedded in a design methodology. The frequency tuning by SOI varactors is analyzed in both small- and large-signal regimes., (FSA 3)--UCL, 2004

Total pressure non-uniformities in an axial flow compressor can contribute to losses in aerodynamic operability through a reduction in stall margin, pressure rise and mass flow, and to loss of structural integrity through means of high cycle fatigue (HCF). HCF is a primary mechanism of blade failure caused by vibrations at levels exceeding material endurance limits. Previous research has shown total pressure distortions to be the dominant HCF driver in aero engines, and has demonstrated the damaging results of total pressure distortion induced HCF on first stage fan and compressor blade rows [Manwaring et al., 1997]. It is, however, also of interest to know how these distortion patterns propagate through a rotor stage and impact subsequent downstream stages and engine components. With current modeling techniques, total pressure distortion magnitudes can be directly correlated to induced blade vibratory levels and modes. The ability to predict downstream distortion patterns then allows for the inference of blade vibratory response of downstream blades to inlet distortion patterns. Given a total pressure distortion excitation entering a blade row, the nonlinear Volterra series can serve as a predictor of the downstream total pressure profile and therefore provide insight into the potential for HCF in downstream blade rows. This report presents the adaption of nonlinear Volterra theory to the prediction of the transport of non-uniform total pressure distortions through an axial flow compressor. The use of Volterra theory in nonlinear system modeling relies on the knowledge of Volterra kernels, which capture the behavior of a system's response characteristics. Here an empirical method is illustrated for identifying these kernels based on total pressure distortion patterns measured both upstream and downstream of a transonic rotor of modern design. A Volterra model based on these kernels has been applied to the prediction of distortion transfer at new operating points of

This work is a numerical study of a class of weakly singular neutral equations. The motivation for this study is an aeroelastic system. Numerical techniques are developed to approximate the singular integral equation component appearing in the complete dynamical model for the elastic motions of a three degree of freedom structure, an airfoil with trailing edge flap, in a two dimensional unsteady flow. The flap can be viewed as an active control surface to dampen vibrations that contribute to flutter. The goal of this work is to provide accurate approximations for weakly singular neutral equations using finite elements as basis functions for the initial function space. Several examples are presented in order to validate the numerical scheme.