On the Complex Inversion Formula and Admissibility for a Class of Volterra Systems

This paper studies Volterra integral evolution equations of convolution type from the point of view of complex inversion formula and the admissibility in the Salamon-Weiss sens. We first present results on the validity of the inverse formula of the Laplace transform for the resolvent families associated with scalar Volterra integral equations of convolution type in Banach spaces, which extends and improves the results in Hille and Philllips (1957) and Cioranescu and Lizama (2003, Lemma 5), respectively, including the stronger version for a class of scalar Volterra integrodifferential equations of convolution type on unconditional martingale differences UMD spaces, provided that the leading operator generates a C0-semigroup. Next, a necessary and sufficient condition for Lp-admissibility p∈1,∞ of the system's control operator is given in terms of the UMD-property of its underlying control space for a wider class of Volterra integrodifferential equations when the leading operator is not necessarily a generator, which provides a generalization of a result known to hold for the standard Cauchy problem (Bounit et al., 2010, Proposition 3.2)

Etude hydrogéologique et géophysique de l’extension de l’intrusion marine dans le sahel de l’Oualidia (Maroc) : Analyse statistique, hydrochimie et prospection électrique

The Sahel of Oualidia is located on the Moroccan Atlantic coast. In this area, aquifers are suffering from intensive pumping mainly in the coastal fringe, where the agricultural activities are significant. This study aims, firstly, to determine the origin and the processes responsible for water mineralization and, secondly, to define seawater intrusion extension in this coastal area. To meet these objectives, five approaches were adopted along this thesis: Climatic, piezometric, hydrochemical, hydrodynamic and geophysical approaches. Statistical analysis of climatic data results (temperature and precipitation) obtained from four meteorological stations, located on the Sahel Doukkala Abda, showed an increasing trend of temperature and a decreasing trend of rainfall during some months. The piezometric investigation enabled to determine groundwater flow direction, which is toward the ocean. In addition, historical piezometric data showed that water table level is mainly influenced by precipitation changes. The hydrochemical analysis of major elements allowed to determine groundwater salinity origin. The most mineralized part was limited to the morphological unit called Oulja (at 1km from the coastal fringe), where water mineralization is mainly due to seawater intrusion. Moreover, hydrodynamic data interpretation, obtained from ocean-aquifer interaction study, helped to highlight general hydrodynamic characteristics of groundwater and oceanic tide effect on water table mineralization changes. The geophysical approach, using apparent resistivity maps and electrical resistivity tomography enabled to determine the mineralization extension, showing the presence of two main areas. The first one, near the coastal fringe, was characterized by low electrical resistivities, and the second one, located beyond $1\,km$ from the sea, was characterized by variable resistivities, generally high.Le Sahel de l'Oualidia est situé sur le littoral atlantique marocain, les aquifères de cette zone connaissent un pompage intensif principalement dans les deux premiers kilomètres de l'océan où les activités maraichères sont plus importantes. L'objectif de cette étude est de déterminer l'origine et les processus responsables de la minéralisation de ces aquifères côtiers, ainsi que déterminer l'ampleur et l'extension de l'intrusion marine dans ce secteur. Pour répondre à cet objectif, cinq approches ont été menées: climatique, piézométrique, hydrochimique, hydrodynamique et géophysique. A la suite de l'analyse statistique des données climatiques (température et précipitations) de quatre stations météorologiques localisées sur le sahel des Doukkala Abda, nous avons constaté une tendance à l'augmentation des températures, et une diminution des hauteurs des précipitations annuelles et mensuelles pour quelque mois. L'étude piézométrique a permis de déterminer la direction de l'écoulement de la nappe qui s'effectue vers l'océan, la variation du niveau de la nappe est influencée par les variations des précipitations, alors la nappe est principalement alimentée par les précipitations. L'analyse hydrochimique des éléments majeurs a permis de déterminer l'origine de la salinité de l'aquifère, en mettant en évidence que la partie proche (1 km) de la côte connait une minéralisation principalement due à l'intrusion de l'eau de mer. L'interprétation des données hydrodynamiques a permis de mettre en évidence les caractéristiques hydrodynamiques générales de l'aquifère tenant compte de la relation qui existe entre la marée océanique et le niveau de la nappe. L'approche géophysique, par les cartes des résistivités apparentes et par la tomographie de résistivité électrique a permis de déterminer l'extension de la minéralisation, en montrant la présence de deux zones principales, une proche du littoral essentiellement caractérisée par des faibles résistivités électriques, une deuxième localisée à plus de 1 km de la mer, caractérisée par des résistivités variables, généralement élevées

Impact of hemodialysis on P-wave amplitude, duration, and dispersion

Atrial fibrillation (AF) is a frequent arrhythmia in patients undergoing hemodialysis (HD). P wave duration (PWdu) and P wave dispersion (PWdi) have been shown to be predictors of emerging AF in different clinical conditions. We sought to study the impact of HD on PWdu, PWdi, and P wave amplitude in a cohort of patients undergoing HD. Seventeen patients (8 men, 31±10 years) were studied. Echocardiography parameters, the sum of the amplitude of P waves in all 12 ECG leads (SP), mean PWdu, and PWdi, along with a host of other parameters (body weight, heart rate, electrolytes and hemoglobin/hematochrit) were measured 1/2h, before and after, HD. SP increased (11.8±3.9 vs 15.3±4.0 mm, p = 0.004), mean PWdu remained stable (82.7±11.1 vs 81.6±10.5 ms, p = 0.606), PWdi decreased (51.7±19.1 vs 41.7±19.1 ms, p = 0.03), and left atrial dimension decreased (37.96±3.90 vs 30.62±3.38 mm, p = 0.0001), after HD. The change in PWdi correlated with fluid removed by HD (r = -0.55, p = 0.022). Re-measurements of P-wave parameters in a random group of 11 of the 17 patients revealed augmented SP (p = 0.01), and stable mean PWdu (p = 0.36), and PWdi (p = 0.31), after HD. Fluid removed by HD leads to an increase in SP, a stable mean PWdu, and decrease (or stability on re-measurement in a subgroup of patients) in PWdi. Stability of PWdu may be due to the effects of augmentation of the P-wave amplitude and the reduction of the left atrial volume, cancelling each other. Variability of PWdi may stem from the occasional impossibility to measure PWdu (or measure it correctly) in minute P-waves in certain ECG leads, which in turn profoundly affects the PWdi

Hydrogeological and geophysical study of the extension of seawater intrusion in the Sahel of Oualidia (Morocco): Statistical analysis, hydrochemistry and geoelectrical survey

Le Sahel de l'Oualidia est situé sur le littoral atlantique marocain, les aquifères de cette zone connaissent un pompage intensif principalement dans les deux premiers kilomètres de l'océan où les activités maraichères sont plus importantes. L'objectif de cette étude est de déterminer l'origine et les processus responsables de la minéralisation de ces aquifères côtiers, ainsi que déterminer l'ampleur et l'extension de l'intrusion marine dans ce secteur. Pour répondre à cet objectif, cinq approches ont été menées: climatique, piézométrique, hydrochimique, hydrodynamique et géophysique. A la suite de l'analyse statistique des données climatiques (température et précipitations) de quatre stations météorologiques localisées sur le sahel des Doukkala Abda, nous avons constaté une tendance à l'augmentation des températures, et une diminution des hauteurs des précipitations annuelles et mensuelles pour quelque mois. L'étude piézométrique a permis de déterminer la direction de l'écoulement de la nappe qui s'effectue vers l'océan, la variation du niveau de la nappe est influencée par les variations des précipitations, alors la nappe est principalement alimentée par les précipitations. L'analyse hydrochimique des éléments majeurs a permis de déterminer l'origine de la salinité de l'aquifère, en mettant en évidence que la partie proche (1 km) de la côte connait une minéralisation principalement due à l'intrusion de l'eau de mer. L'interprétation des données hydrodynamiques a permis de mettre en évidence les caractéristiques hydrodynamiques générales de l'aquifère tenant compte de la relation qui existe entre la marée océanique et le niveau de la nappe. L'approche géophysique, par les cartes des résistivités apparentes et par la tomographie de résistivité électrique a permis de déterminer l'extension de la minéralisation, en montrant la présence de deux zones principales, une proche du littoral essentiellement caractérisée par des faibles résistivités électriques, une deuxième localisée à plus de 1 km de la mer, caractérisée par des résistivités variables, généralement élevées.The Sahel of Oualidia is located on the Moroccan Atlantic coast. In this area, aquifers are suffering from intensive pumping mainly in the coastal fringe, where the agricultural activities are significant. This study aims, firstly, to determine the origin and the processes responsible for water mineralization and, secondly, to define seawater intrusion extension in this coastal area. To meet these objectives, five approaches were adopted along this thesis: Climatic, piezometric, hydrochemical, hydrodynamic and geophysical approaches. Statistical analysis of climatic data results (temperature and precipitation) obtained from four meteorological stations, located on the Sahel Doukkala Abda, showed an increasing trend of temperature and a decreasing trend of rainfall during some months. The piezometric investigation enabled to determine groundwater flow direction, which is toward the ocean. In addition, historical piezometric data showed that water table level is mainly influenced by precipitation changes. The hydrochemical analysis of major elements allowed to determine groundwater salinity origin. The most mineralized part was limited to the morphological unit called Oulja (at 1km from the coastal fringe), where water mineralization is mainly due to seawater intrusion. Moreover, hydrodynamic data interpretation, obtained from ocean-aquifer interaction study, helped to highlight general hydrodynamic characteristics of groundwater and oceanic tide effect on water table mineralization changes. The geophysical approach, using apparent resistivity maps and electrical resistivity tomography enabled to determine the mineralization extension, showing the presence of two main areas. The first one, near the coastal fringe, was characterized by low electrical resistivities, and the second one, located beyond $1\,km$ from the sea, was characterized by variable resistivities, generally high

Favard spaces and admissibility for Volterra systems with scalar kernel

We introduce the Favard spaces for resolvent families, extending some well-known theorems for semigroups. Furthermore, we show the relationship between these Favard spaces and the $L^p$-admissibility of control operators for scalar Volterra linear systems in Banach spaces, extending some results in [22]. Assuming that the kernel a(t) is a creep function which satisfies $a(0^+)>0$, we prove an analogue version of the Weiss conjecture for scalar Volterra linear systems when p=1. To this end, we also show that the finite-time and infinite-time (resp. finite-time and uniform finite-time) $L^{1}$-admissibility coincide for exponentially stable resolvent families (reps. for reflexive state space), extending well-known results for semigroups

Some physical parameters of CuInGaS2 thin films deposited by spray pyrolysis for solar cells

International audienceCopper–indium–gallium–disulphide (CuInGaS2) is a promising absorber material for thin film photovoltaic. In this paper, CuInGaS2 (CIGS) thin films have been prepared by chemical spray pyrolysis method onto glass substrates at ambient atmosphere. Structural, morphological, optical and electrical properties of CuInGaS2 films were analysed by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–Vis spectrophotometer and Hall Effect measurement, respectively. The films exhibited single phase chalcopyrite structure. The strain and dislocation density decreased with increase of spray time. The grain size of the films increased from 4.45 to 9.01 nm with increase of spray time. The Raman spectrum indicated the presence of the principal chalcopyrite peak at 295 cm- 1. The optical properties of the synthesized films have been carried out through the measurement of the absorbance spectrum. The optical band gap was estimated by the absorption spectrum fitting (ASF) method. For each sample, the width of the band tail (ETail) of CuInGaS2 thin films was determined. The resistivity (ρ), conductivity (σ), mobility (μ), carrier concentration and conduction type of the films were determined using Hall Effect measurements. The interesting optical properties of CuInGaS2 make them an attractive material for photovoltaic devices. © 2017, Springer-Verlag Berlin Heidelberg

Copper indium gallium disulphide (CuInGaS 2) thin films deposited by spray pyrolysis for solar cells: Influence of deposition time in controlling properties of sprayed CuInGaS 2 absorbers

International audienceCuInGaS2 (CIGS) multi-component semiconductors thin films were elaborated by spray pyrolysis on glass substrates using different spray times. The structural, optical and electrical properties of CuInGaS2 thin films were investigated. The obtained films were characterized using X-ray diffraction, Raman spectroscopy (RS), UV–Vis spectrophotometer and Hall Effect measurement. Thin films were formed by varying deposition time in the range, 30–50 min, keeping other deposition parameters as constant. The X-ray spectra revealed that the CuInGaS2 thin films have chalcopyrite structures with a highly (112) preferential orientation. The best crystallinity is obtained for HK-50 the maximum (112) peak intensity. RS also confirmed this structure. Optical constants such as band gap (Eg), extinction coefficient (k), refractive index (n), dielectric constants (εr) and (εi) and optical conductivity (σo p t) were calculated from the measured transmittance and absorption spectra in the wavelength range between 550 and 900 nm. The bulk concentration, mobility (μ), conductivity (σ), resistivity (ρ) and conduction type of thin films obtained at different deposition times were determined using Hall Effect measurements. It has been observed that the optimum time of spray was 50 min for best performed CuInGaS2 thin films with low resistivity and high mobility. Deposition time has been discussed to obtain the high quality thin film absorbers for solar cell applications. Here, we report a study on structural, optical and electrical properties of CuInGaS2 films grown by chemical spray pyrolysis in view of its application as an absorber in thin film solar cells. © 2016, Springer Science+Business Media New York

Evaluation of geoelectrical models efficiency for coastal seawater intrusion by applying uncertainty analysis

Seawater intrusion (SWI) is one of the most important phenomena which occurs in shorelines and islands and affects groundwater storage in the region. This study aims to investigate how far seawater has intruded in a coastal area and what is its extent variation. The results can lead to different management plans. To achieve these goals, a geoelectrical method is applied in the coastal aquifer of Chaouia, Morocco. In order to choose the best inversion process, different settings are applied in two different software packages namely RES2DINV and BERT and the results are compared using the Taylor diagram. Also, to determine the minimum and maximum SWI extent in the region, a new approach of uncertainty analysis is applied in the inversion process by the Monte Carlo method. The general results indicate that the seawater has intruded about 2 km into the shore. The obtained results show that by considering uncertainty, there is a sensible difference between the maximum and minimum extent of SWI (maximum 9% variation in the area of SWI) which should be noted when doing water research management studies. The methodology procedure in this study can be applied to different coastal areas around the world