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The power amplifier (PA) is the most critical subsystem in terms of linearity and power efficiency. Digital predistortion (DPD) is commonly used to mitigate nonlinearities while the PA operates at levels close to saturation, where the device presents its highest power efficiency. Since the DPD is generally based on Volterra series models, its number of coefficients is high, producing ill- conditioned and over-fitted estimations. Recently, a plethora of techniques have been independently proposed for reducing their dimensionality. This paper is devoted to presenting a fair benchmark of the most relevant order reduction techniques present in the literature categorized by the following: (i) greedy pursuits, including Orthogonal Matching Pursuit (OMP), Doubly Orthogonal Matching Pursuit (DOMP), Subspace Pursuit (SP) and Random Forest (RF); (ii) regularization techniques, including ridge regression and least absolute shrinkage and selection operator (LASSO); (iii) heuristic local search methods, including hill climbing (HC) and dynamic model sizing (DMS); and (iv) global probabilistic optimization algorithms, including simulated annealing (SA), genetic algorithms (GA) and adaptive Lipschitz optimization (adaLIPO). The comparison is carried out with modeling and linearization performance and in terms of runtime. The results show that greedy pursuits, particularly the DOMP, provide the best trade-off between execution time and linearization robustness against dimensionality reduction. Ministerio de Ciencia, Innovación y Universidades TEC2017-83343-C4-2-R Unión Europea TEC2017-83343-C4-2-R Ministerio de Ciencia e Innovación PID2020-113832RB-C21 Generalitat de Catalunya 2017-SGR-813 Unión Europea 2017-SGR-813 Generalitat de Catalunya 2021-FI-B-137 Unión Europea 2021-FI-B-137

Over the past half century, the improvements in spacecraft technology have been primarily in the areas of microelectronics for on-board processing, high frequency electronic devices, and integrated circuits for communications and navigation, solar cells and batteries for on-board power generation and storage among many others. Despite the fact that energy-storage technologies have advanced dramatically over the past years, the power consumption of on-board communications, sensors and digital signal processing systems is of paramount importance in battery or solar powered systems such as small satellites, HAPs or UAVs (drones). There is multiple applications that involves the use of these systems, e.g., Earth observation applications, surveillance, broadcast communications, scientific research, etc. In wireless communications, the power amplifier is a critical subsystem in the transmitter chain. Not only because it is one of the most power hungry devices that accounts for most of the direct current power consumption, but also because it is the main source of nonlinear distortion in the transmitter. Amplitude and phase modulated communications signals presenting high peak-to-average power ratio have a negative impact in the transmitter's power efficiency, because the PA has to be operated at high power back-off levels to avoid introducing nonlinear distortion. Digital predistortion (DPD) linearization is the most common and spread solution to cope with power amplifiers (PA) inherent linearity versus efficiency trade-off. When considering wide bandwidth signals, such as Doherty PAs, envelope tracking PAs or outphasing transmitters, the number of parameters required in the DPD model to compensate for both nonlinearities and memory effects can be very high. This has a negative impact in the DPD ceofficients extraction, because increases the computational complexity and drives to over-fitting and uncertainty. However, by applying dimensionality reduction techniques we can both avoid the numerical ill-conditioning of the estimation and reduce the number of coefficients of the DPD function, which ultimately impacts the baseband processing computational complexity and power consumption. In this Project, several dimensionality reduction techniques will be described and compared in terms of model order reduction capabilities and evaluation performance. In particular, some of the machine learning techniques for dimensionality reduction will be studied.

This paper uses a search-and-matching model to examine the effects of labor regulations that influence the cost of formal labor (notably minimum wages and payroll taxes) on labor market outcomes in Morocco. The model assumes that the informal sector is unregulated and thus not directly affected by these labor policies. However, the model takes into consideration that although labor policies apply only to the formal sector, they may influence the size and the composition of employment in the informal sector, as well as the size and composition of unemployment and self-employment. The results indicate that these regulations, especially minimum wage policy, contribute to higher unemployment rates and constraint formalization in Morocco, especially for youth and women.

During the past 20 years, Morocco has implemented a wide range of macroeconomic, social and labor market reforms that have delivered in terms of GDP growth and household welfare. Yet, these positive developments are not reflected by the main labor market indicators, a phenomenon observed elsewhere in developed and developing economies alike and labeled as ‘jobless growth’. For the first time in Morocco, this paper investigates the question of labor mobility using quarterly panel data in an effort to determine whether people have moved to better sectors and jobs. Results point to significant labor mobility between labor statuses with quite distinct features across population groups. All groups experience some form of labor market mobility every quarter and women are as mobile as men. However, the transitions that women experience are very different from the transitions that men experience and women's performance is worse than men's performance in almost all aspects of labor mobility.

A aquesta tesi, les dades diàries de temperatures màximes i mínimes i precipitació de 12 estacions meteorològiques guineanes han segut sotmeses a controls de qualitat utilitzant les rutines RClimdex-ExtraQC. Les quals contenen eines per una sèrie temporal única. Els valors identificats com potencialment erronis han segut examinats mitjançant decisió subjectiva, han segut validats, corregits o eliminats. Aquestes dades lliures de qualsevol registre sospitós han segut homogeneïtzades utilitzant l’arxiu de sortida HOMER de dades mensuals. Els índexs escollits d’ETCCDI i ET-CRSCI s’han calculat per a les dades de temperatura i precipitació anuals i estacionals utilitzant ET-CRSCI del paquet RClimPact. A més, les mitjanes anuals de Tx, Tn i precipitació nacional junt amb vuit índexs d’extrem han segut utilitzats per detectar teleconexions entre els índexs climàtics i l’índex SOI. Un anàlisis de tendències no paramètric s’ha dut a terme sobre tres períodes superposats que comencen al 1941, 1961 i 1971 i tots acaben al 2010. Els resultats indiquen diversos patrons espacials coherents amb l’escalfament, significatius identificats tant amb els índexs extrems de Tx com de Tn per a tots els períodes i estacions. Els índexs basats en dades de precipitació diària mostren patrons menys coherents però, en general, existeixen patrons de sequera significatius per a la majoria d’índexs relacionats amb la precipitació diària per als períodes 1941-2010 i 1961-2010, mentre que per al període 1971-2010 l’anàlisi suggereix canvis no significatius cap a condicions més humides. En general, no s’han produït canvis espacialment coherents amb esdeveniments extrems de precipitació per al conjunt de Guinea i període d’estudi, ja que aquests, s’han produït a escala local. Hi ha indicis de que les condicions humides estan relacionades amb la Niña. Les precipitacions durant el període 1971-2010 han segut entre un 13.6 % i un 27.75 % menors que durant el període 1941-1970., En esta tesis, datos diarios de temperaturas máximas y mínimas y precipitación de 12 estaciones guineanas han sido sometidos a controles de calidad utilizando las rutinas RClimdex-ExtraQC. Estas rutinas contienen herramientas para una serie temporal única. Los valores identificados como potencialmente erróneos han sido examinados y mediante decisión subjetiva, han sido validados, corregidos o eliminados. Estos datos libres de cualquier tipo de registro sospechoso han sido homogeneizados utilizando el archivo de salida HOMER de datos mensuales. Índices elegidos de ETCCDI y ET-CRSCI se han calculado para las temperaturas y precipitaciones anuales y estacionales utilizando ET-CRSCI del paquete R ClimPact. Además, promedios anuales de Tx, Tn y precipitación nacional y ocho índices de extremos han sido usados para detectar teleconexiones entre los índices climáticos y el índice SOI. Un análisis de tendencias no paramétrica se ha realizado sobre tres períodos superpuestos que empiezan en 1941, 1961 y 1971, y terminan todos en 2010. Los resultados indican diversos patrones espaciales coherentes con el calentamiento, significativos, identificados tanto en los índices de extremos de Tx como de Tn para todos los periodos y estaciones. Los índices basados en datos de precipitación diaria mostraron patrones menos coherentes pero, en general, existen patrones de sequía significativos en la mayoría de los índices relacionados con la precipitación diaria para los períodos 1941-2010 i 1961-2010, mientras que para el período 1971-2010 el análisis sugiere cambios no significativos hacia condiciones más húmedas. En general, no se han producido cambios espacialmente coherentes con eventos extremos de precipitación para el conjunto de Guinea y el período de estudio, ya que estos, se han producido a escala local. Hay indicios de que las condiciones más húmedas están asociadas con La Niña. Las precipitaciones durante el periodo 1971-2010 han sido entre un 13.6% y un 27.75% menores que durante el período 1941-1970., In this thesis, Guinea's 12 weather stations daily minimum and daily maximum temperatures and daily precipitation data have been carefully quality controlled using the RClimdex-ExtraQC routines. These routines contain suitable tools to quality control single time series. The values identified as potentially erroneous have been carefully scrutinized and a subjective decision has been made to validate, correct or set them to missing. The resulted dataset free of any kind of suspicious data record has been homogenized using HOMER monthly output file. Chosen indices from ETCCDI and ET-CRSCI indices have been calculated using ET-CRSCI ClimPact R package. Annual and seasonal temperatures and precipitations indices have also been computed. Additionally, eight nationwide averaged climate extremes indices, the nationwide averaged annual Tx mean and Tn mean and total precipitation indices have been use to detect teleconnection between climate indices and SOI indices. A nonparametric trend analysis is then performed for three overlapping periods, with different starting years 1941, 1961 and 1971 but all ending the same 2010 year. The result suggested that coherent spatial patterns of significant warming changes have emerged from both Tx and Tn related extremes indices for all periods and season. Indices based on daily precipitation data showed more mixed patterns of change but, in general, significant drying patterns have been seen in most of the 1941-2010 and 1961-2010 periods' daily precipitation related indices while over the period 1971-2010 analyses suggested non-significant changes towards wetter conditions. Overall, there have been no spatially coherent changes in extreme rainfall events across Guinea for the study period, but changes in extreme precipitation events have occurred on local scales. There are signs that wetter conditions are associated with the La Niña years. Rainfall during the 1971-2010 is on average some 13.6 % to 27.75 % lower than during the period 1941–1970.

Female labor participation in the Arab world is low compared with the level of economic development of Arab countries. Beyond anecdotal evidence and cross-country studies, there is little evidence on what could explain this phenomenon. This paper uses the richest set of panel data available for any Arab country to date to model female labor participation in Morocco. The paper finds marriage, household inactivity rates, secondary education, and gross domestic product per capita to lower female labor participation rates. It also finds that the category urban educated women with secondary education explains better than others the low level of female labor participation. These surprising findings are robust to different estimators, endogeneity tests, different specifications of the female labor participation equations, and different sources of data. The findings are also consistent with previous studies on the Middle East and North Africa region and on Morocco. The explanation seems to reside in the nature of economic growth and gender norms. Economic growth has not been labor intensive, has generated few jobs, and has not been in female-friendly sectors, resulting in weak demand for women, especially urban educated women with secondary education. And when men and women compete for scarce jobs, men may have priority access because of employers'and households'preferences.

Beginning in 1981, the government of Mali undertook several policy reforms to allow participation of private traders in cereal marketing, which up to that date was officially controlled by a parastatal. These reforms can be expected to have an impact on the working of the cereals market. One of the main objectives of this study is to assess the performance of the cereal marketing system. The task is to study how different markets are interrelated in terms of price formation, by using wholesale and retail price data and different techniques of analysis. These methods of analysis include bivariate correlations, calculation of margins, and multiple regression techniques. Not only is the research aimed at showing the differences and similarities of the different methods of analysis, but also at showing the strength and weaknesses of different data sets on cereal prices in Mali. Another objective of this paper is to study the price interrelationships across commodities in order to determine the degree of substitutability between the cereals involved.