Binding energy of excitons in parabolic quantum wells in uniform electric and magnetic fields

Parameterized equations have been derived using variational calculation for energy levels of Wannier excitons in 2D-parabolic quantum wells in uniform electric and magnetic fields. The formulation has been performed in the framework of the effective mass approximation and two-band model. Illustrations have been given for GaAlAsGaAs-GaAlAs and CdMnTe-CdTe-CdMnTe parabolic quantum wells. The comparison with existing data displays good agreement

A theoretical model for exciton binding energies in rectangular and parabolic spherical finite quantum dots

. Using the variational method in real space and the effective-mass theory, we present quite an advanced semi-analytic approach susceptible for calculating the binding energy Eb of Wannier excitons in semiconductor quantum dot structures with rectangular and parabolic shapes of the confining potential in the so-called strong-confinement regime. Illustration is given for CdS, ZnSe, CdSe, GaAs structures of crystallites for both rectangular and parabolic quantum dots, and it displays a very good agreement between the experimental and theoretical results reported in literature

Parametrized Equations for Excitons in Quantum Wires

A set of analytic equations for calculating the binding energies of excitons in T-shaped and squared quantum well wires are established within the effective mass approximation and the two-band model. The resolution is performed in the framework of the variational method. The projections of the relative movement in a lateral plane (2D exciton) and along the free movement direction (1D exciton) are examined as limiting cases. Binding energies and spatial extensions of the exciton as functions of the size of the wire for both the ground and the first excited states are calculated in the case of GaAs/GaAlAs heterostructures for T-shaped and squared geometries. The method is applied to calculate the effects on the excitons induced by the application of crossed electric and magnetic fields. Comparison between quantum wells, T-wires and squared wires is given

Properties and hydration behavior of blended clinker and portland-sediment cement pastes

In recent years, an increase of the interest in the use of secondary raw materials (sediment, sludge…) in construction has been observed.  This paper aims to contribute to the use of dredging sediments in the cement industry. Despite the literature on this subject, the available data on the aspects and phenomena related to the hydration process of such mixtures are incomplete. This paper aims to specify the calorimetric curves of hydration of mixtures made, from the sediment trapped at the site of Lyvet in the Brittany region of France. The mixtures are made ??using in one hand clinker and in the other hand Portland cement. Pastes with 8%, 16% and 33% of clinker or Portland cement substituted by sediment are used to determine the hydraulic properties of mixtures. The physico-chemical characterization of materials is made by different techniques to determine the chemical composition and physical properties. X-ray diffraction is used to determine the mineralogical compositions of samples before and after treatment. A  Tian-Calvet microcalorimeter is used to explore hydration behavior of the blended Sediment-Portland cement pastes. The addition of untreated sediment to both clinker or Portland cement increase the dormant period duration. On the contrary, this period becomes shorter when the sediment is thermally treated. The results show that 8% of treated sediment improve hydration of blended Sediment-Portland cement pastes. Mechanical properties of blended sediment-cements are also investigated. After 28 days of curing in water, the mortar containing 8% of treated sediment exhibits a compressive strength equal to 93.7% of the one of the reference mortar, maintaining it in the same cement class (52.5)

Polarizability of D+X complex in bulk semiconductors

The electric polarizability α of ionized-donor-bound exciton D+X in bulk semiconductor is calculated for all values of the effective electron-to-hole mass ratio σ included in the range of stability (σ<σχ). The calculation is performed within the variational method by using 56-term wave function. An asymptotic behavior of α in the vicinity of the critical value σc is deduced. We have also calculated the limiting value σ for which the polarizability equals that of D− system

Formación de hidroxiapatita, Ca5(PO4)3∙OH, en presencia de silicatos

Hydroxyapatite Ca5(PO4)3OH (HAp) is a crystalline phase which has several applications within the domain of special cements. This phase takes an important role in the cement reactions for the reconstruction of skeletal functions (medical domain). It is used also to improve properties of dental material. On the other hand, it is investigated to develop chemically bonded ceramics. In this paper we study the formation of HAp with β-C2S and C5PS, using some compositions in the rich lime portion of the system CaO-SiO2-P2O5-H2O (at atmospheric pressure and open system). These compositions lie in the range of: CaO: 67-71 %; SiO2: 3-18%; P2O5: 9-29% (Wt%). The preparations are made using solid state reactions, with thermal treatment at open system. The identification of phases was carried out using X-ray diffraction, Infra-Red absorption and Differential Thermal Analysis. We delimit a spectroscopy little domain lies in the range of CaO-69,5-70%; P2O5-16,2-19,5%; SiO2-11,1-13,6%. Within this domain, the crystalline phases solid state compatibility at temperature near 1000ºC are HAp, β-C2S, C5PS.La hidroxiapatita, Ca5(PO4)3OH (HAp), es una fase cristalina que tiene diversas aplicaciones en el ámbito de determinados cementos especiales. Esa fase juega un importante papel en las reacciones de cementos utilizados en medicina para la reconstrucción defunciones del esqueleto. Se utiliza también para mejorar propiedades de materiales de aplicación odontológica. Por otra parte, se está estudiando para desarrollar conglomerantes cerámicos. En el presente trabajo se estudia la compatibilidad en estado sólido de la HAp con β-C2S y C5PS utilizando, a presión atmosférica y recinto abierto, composiciones en la zona rica en cal del sistema CaO-SiO2-P2O5-H2O dentro de los límites siguientes. CaO: 67-71 %; SiO2: 3-18%; P2O5: 9-29% (en peso). El tratamiento térmico se realizó en estado sólido y en atmósfera abierta. La identificación de las fases se realizó a través de Difracción de Rayos X, Espectroscopia de Absorción Infrarroja y Análisis Térmico Diferencial. Se define una pequeña zona del diagrama de composición: CaO=69,5-70%; P2O5=16,2-19,5%; SiO2=11,1-13,6%. En este campo las fases cristalinas compatibles en estado sólido, formadas a 1.000ºC, son HAp, β-C2S y C5PS

Coherent clusters in source code

This paper presents the results of a large scale empirical study of coherent dependence clusters. All statements in a coherent dependence cluster depend upon the same set of statements and affect the same set of statements; a coherent cluster's statements have ‘coherent’ shared backward and forward dependence. We introduce an approximation to efficiently locate coherent clusters and show that it has a minimum precision of 97.76%. Our empirical study also finds that, despite their tight coherence constraints, coherent dependence clusters are in abundance: 23 of the 30 programs studied have coherent clusters that contain at least 10% of the whole program. Studying patterns of clustering in these programs reveals that most programs contain multiple substantial coherent clusters. A series of subsequent case studies uncover that all clusters of significant size map to a logical functionality and correspond to a program structure. For example, we show that for the program acct, the top five coherent clusters all map to specific, yet otherwise non-obvious, functionality. Cluster visualization also brings out subtle deficiencies in program structure and identifies potential refactoring candidates. A study of inter-cluster dependence is used to highlight how coherent clusters are connected to each other, revealing higher-level structures, which can be used in reverse engineering. Finally, studies are presented to illustrate how clusters are not correlated with program faults as they remain stable during most system evolution

Design and Implementation of Wireless Zigbee Sensor Based On Embedded 32-Bits FPGA Processor

Wireless Sensor Networks (WSN) has become an emerging area of research in recent years. Today this wireless sensors are used in many industrial and consumer applications, such as industrial process monitoring and control, machine health monitoring, automotive, home appliance, smart grid applications and so on. In this work, an intelligent wireless sensor system for real time functionality has been suggested. The proposed solution is based on the embedded FPGA design using a new Xilinx MicroBlaze Soft Processor to Increases the performance of the system. The effectiveness of the proposed method is verified by the experimental results. The hardware components include Xilinx FPGA board, XBee Series 2 wireless communication module and end device sensors to capture the physical or environmental quantity, such as temperature, sound or pressure..

Esquistos bituminosos como materia prima alternative en la fabricación de clínker de cemento Portland. Reacciones de clinkerización y caracterización del clínker

For some time the cement industry has been seeking procedures to effectively lower the higher energy costs involved in cement manufacture. Timahdit oil shale and Jerada coal waste could potentially be used as alternative raw materials to produce clinker. This study explored the possibility of applying those materials to a greener use, based on the reactivity and burnability of raw mixes containing Moroccan oil shale and coal waste. The findings showed that, irrespective of particle size, oil shale mixes delivered higher reactivity than coal waste materials, although reactivity was highest in the oil shale clinker with a particle size 70 %).La industria cementerabusca desde hace algún tiempo procedimientos que reduzcan el alto consumo de energía de la producción de cemento. La pizarra bituminosa de Timahdit (BOS) y los desechos de carbón de Jerada (CW) se pueden utilizar potencialmente como materiales alternativos en la fabricación de clinker. Este estudio se enfoca en evaluar esta posibilidad, valorizar dichos materiales y considerar un uso más ecológico para ellos. Exploramos la reactividad y la aptitud a la cocción de mezclas crudas de clínker que contienen BOS o CW. La reactividad de los crudos que contienen BOS es mejor que la de los que contienen CW, independientemente de su tamaño de partícula, siendo el que contiene BOS con un tamaño de partícula 70%

«Consultas sagradas» en atención primaria: ¿qué suponen para el personal médico? “Sacred encounters” in primary care: What do they mean for family physicians?

Objetivo Conocer las percepciones y actitudes de profesionales médicos de familia (MF) ante consultas con gran componente emocional, denominadas inicialmente «consultas sagradas», e identificar ámbitos de mejora en su atención. Diseño Metodología cualitativa con enfoque sociosubjetivo orientado a los servicios de salud. Estudio descriptivo-interpretativo. Emplazamiento Centros de salud de Araba y Bizkaia. Participantes y/o contextos Selección de 23 MF de 23 centros de salud urbanos y rurales. Método Muestreo intencional buscando la diversidad discursiva. Datos generados en 2016 mediante 3 grupos de discusión y 3 entrevistas individuales grabadas y transcritas tras consentimiento informado. Presentación al Comité de Ética de Euskadi. Análisis temático con ayuda de mapas conceptuales y programa MaxQDA. Triangulación de los resultados entre investigadores y verificación por los participantes. Resultados y discusión Los hallazgos se agruparon en áreas temáticas solapadas entre sí y relacionadas con el significado de dichas consultas, actitudes profesionales, contexto sanitario y pacientes. Se subraya la importancia de lo emocional en las consultas de atención primaria y su invisibilización, pero se cuestiona la idoneidad del término «sagradas». Su expresión se construye en la interrelación MF-paciente si el personal médico lo favorece y el paciente lo permite, discutiéndose las principales circunstancias que intervienen en una dimensión considerada clave de la integralidad de la atención. Conclusiones La atención a la dimensión emocional en la consulta presenta deficiencias que es necesario subsanar. Además de su reconocimiento y evaluación, sería preciso modificar los factores organizativos, formativos y profesionales que condicionan la implicación del personal MF en su buena asistencia