Simulative Investigation on the Electronic, Vibrational and Optical Properties of the Ge2Sb2Te5 Chalcogenide

Chalcogenides are chemical compounds with at least one of the following three chemical elements: Sulfur (S), Selenium (Sn), and Tellurium (Te). As opposed to other materials, chalcogenide atomic arrangement can quickly and reversibly inter-change between crystalline, amorphous and liquid phases. Therefore they are also called phase change materials. As a results, chalcogenide thermal, optical, structural, electronic, electrical properties change pronouncedly and significantly with the phase they are in, leading to a host of different applications in different areas. The noticeable optical reflectivity difference between crystalline and amorphous phases has allowed optical storage devices to be made. Their very high thermal conductivity and heat fusion provided remarkable benefits in the frame of thermal energy storage for heating and cooling in residential and commercial buildings. The outstanding resistivity difference between crystalline and amorphous phases led to a significant improvement of solid state storage devices from the power consumption to the re-writability to say nothing of the shrinkability. This work focuses on a better understanding from a simulative stand point of the electronic, vibrational and optical properties for the crystalline phases (hexagonal and faced-centered cubic). The electronic properties are calculated implementing the density functional theory combined with pseudo-potentials, plane waves and the local density approximation. The phonon properties are computed using the density functional perturbation theory. The phonon dispersion and spectrum are calculated using the density functional perturbation theory. As it relates to the optical constants, the real part dielectric function is calculated through the Drude-Lorentz expression. The imaginary part results from the real part through the Kramers-Kronig transformation. The refractive index, the extinctive and absorption coefficients are analytically calculated from the dielectric function. The transmission and reflection coefficients are calculated using the Fresnel equations. All calculated optical constants compare well the experimental ones.

(Table 1) Compressional- and share-wave velocieties at elevated confining pressure of ODP Holes 136-842C and 136-843A

Identification of a sediment/basement contact using seismic reflection recordings has proven to be extremely difficult in wide areas of the North Pacific Ocean owing to the presence of massive, highly reflective chert layers within the sediment column. Leg 136 of the Ocean Drilling Program recovered coherent pieces of chert of sufficient size for the first comprehensive laboratory measurements of the seismic properties of this material. Compressional-wave velocities of six samples at 40-MPa confining pressure averaged 5.33 km/s, whereas shear-wave velocities at the same pressure averaged 3.48 km/s. Velocities were independent of porosity, which ranged from 5% to 13%, suggesting that pores within the samples were mostly high aspect ratio vugs as opposed to low aspect ratio cracks. Back-scattered electron images made with a scanning electron microscope confirmed this observation. Acoustic impedances were calculated for the chert samples and from shipboard measurements of the red clay sediment overlying the chert layers. An extremely large compressional-wave reflection coefficient (0.73) characterized the interface between the two lithologies. A synthetic seismogram was calculated using chert and typical pelagic carbonate properties to illustrate the influence of chert layers on a marine seismic-reflection section. Compressional-wave to shear-wave velocity ratios of the chert samples (Vp/Vs =1.53) are close to that of single-crystal quartz in spite of variable porosity. Shear-wave reflection coefficients are estimated to be approximately 0.94. A compressional-wave reflection coefficient for a basement/sediment (carbonate) interface is estimated to be approximately 0.50, significantly less than that of sediment/chert.

Electrical resistivity, formation factors, and sound velocity at DSDP Holes 75-530A and 75-530B

From 0 to 277 m at Site 530 are found Holocene to Miocene diatom ooze, nannofossil ooze, marl, clay, and debrisflow deposits; from 277 to 467 m are Miocene to Oligocene mud; from 467 to 1103 m are Eocene to late Albian Cenomanian interbedded mudstone, marlstone, chalk, clastic limestone, sandstone, and black shale in the lower portion; from 1103 to 1121 m are basalts. In the interval from 0 to 467 m, in Holocene to Oligocene pelagic oozes, marl, clay, debris flows, and mud, velocities are 1.5 to 1.8 km/s; below 200 m velocities increase irregularly with increasing depth. From 0 to 100 m, in Holocene to Pleistocene diatom and nannofossil oozes (excluding debris flows), velocities are approximately equivalent to that of the interstitial seawater, and thus acoustic reflections in the upper 100 m are primarily caused by variations in density and porosity. Below 100 or 200 m, acoustic reflections are caused by variations in both velocity and density. From 100 to 467 m, in Miocene-Oligocene nannofossil ooze, clay, marl, debris flows, and mud, acoustic anisotropy irregularly increases to 10%, with 2 to 5% being typical. From 467 to 1103 m in Paleocene to late Albian Cenomanian interbedded mudstone, marlstone, chalk, clastic limestone, and black shale in the lower portion of the hole, velocities range from 1.6 to 5.48 km/s, and acoustic anisotropies are as great as 47% (1.0 km/s) faster horizontally. Mudstone and uncemented sandstone have anisotropies which irregularly increase with increasing depth from 5 to 10% (0.2 km/s). Calcareous mudstones have the greatest anisotropies, typically 35% (0.6 km/s). Below 1103 m, basalt velocities ranged from 4.68 to 4.98 km/s. A typical value is about 4.8 km/s. In situ velocities are calculated from velocity data obtained in the laboratory. These are corrected for in situ temperature, hydrostatic pressure, and porosity rebound (expansion when the overburden pressure is released). These corrections do not include rigidity variations caused by overburden pressures. These corrections affect semiconsolidated sedimentary rocks the most (up to 0.25 km/s faster). These laboratory velocities appear to be greater than the velocities from the sonic log. Reflection coefficients derived from the laboratory data, in general, agree with the major features on the seismic profiles. These indicate more potential reflectors than indicated from the reflection coefficients derived using the Gearhart-Owen Sonic Log from 625 to 940 m, because the Sonic Log data average thin beds. Porosity-density data versus depth for mud, mudstone, and pelagic oozes agree with data for similar sediments as summarized in Hamilton (1976). At depths of about 400 m and about 850 m are zones of relatively higher porosity mudstones, which may suggest anomalously high pore pressure; however, they are more probably caused by variations in grain-size distribution and lithology. Electrical resistivity (horizontal) from 625 to 950 m ranged from about 1.0 to 4.0 ohm-m, in Maestrichtian to Santonian- Coniacian mudstone, marlstone, chalk, clastic limestone, and sandstone. An interstitial-water resistivity curve did not indicate any unexpected lithology or unusual fluid or gas in the pores of the rock. These logs were above the black shale beds. From 0 to 100 m at Sites 530 and 532, the vane shear strength on undisturbed samples of Holocene-Pleistocene diatom and nannofossil ooze uniformly increases from about 80 g/cm**2 to about 800 g/cm**2. From 100 to 300 m, vane shear strength of Pleistocene-Miocene nannofossil ooze, clay, and marl are irregular versus depth with a range of 500 to 2300 g/cm**2; and at Site 532 the vane shear strength appears to decrease irregularly and slightly with increasing depth (gassy zone). Vane shear strength values of gassy samples may not be valid, for the samples may be disturbed as gas evolves, and the sediments may not be gassy at in situ depths.

Seismic modelling and ava analysis of hidrocarbon traps

In this study, forward seismic modelling of four geological models with Hydrocarbon (HC) traps were performed by ray tracing method to produce synthetic seismogram of each model. The idea is to identify the Hydrocarbon Indicators (HCI‟s) such as bright spot, flat spot, dim spot and Bottom Simulating Reflector (BSR) in the synthethic seismogram. The modelling was performed in DISCO/FOCUS 5.0 seismic data processing programme. Strong positive and negative reflection amplitudes and some artifact reflection horizons were observed on produced seismograms due to rapid changes in subsurface velocity and geometry respectively Additionally, Amplitude-versus-angle (AVA) curves of each HCIs was calculated by the Crewes Zoeppritz Explorer programme. AVA curves show that how the reflection coefficients change with the density and the P and S wave velocities of each layer such as oil, gas, gas hydrate or water saturated sediments. Due to AVA curves, an increase in reflection amplitude with incident angle of seismic waves corresponds to an indicator of a hydrocarbon reservoir

Accurate characterization of multi-resonant reflectarray cells by artificial neural networks

This paper describes the accurate characterization of the reflection coefficients of a multilayered reflectarray element by means of artificial neural networks. The procedure has been tested with different RA elements related to actual specifications. Up to 9 parameters were considered and the complete reflection coefficient matrix was accurately obtained, including cross polar reflection coefficients. Results show a good agreement between simulations carried out by the Method of Moments and the ANN model outputs at RA element level, as well as with performances of the complete RA antenna designed.

Contribución al estudio de propiedades ópticas en medios heterogéneos

Como contribución del estudio de medios heterogéneos, esta tesis recoge el trabajo llevado a cabo sobre modelado teórico y simulación del estudio de las propiedades ópticas de la piel y del agua del mar, como ejemplos paradigmáticos de medios heterogéneos. Se ha tomado como punto de partida el estudio de la propagación de la radiación óptica, más concretamente de la radiación láser, en un tejido biológico. La importancia de la caracterización óptica de un tejido es fundamental para manejar la interacción radiación-tejido que permite tanto el diagnóstico como la terapéutica de enfermedades y/o de disfunciones en las Ciencias de la Salud. Sin olvidar el objetivo de ofrecer una metodología de estudio, con un «enfoque ingenieril», de las propiedades ópticas en un medio heterogéneo, que no tiene por qué ser exclusivamente el tejido biológico. Como consecuencia de lo anterior y de la importancia que tiene el agua dentro de los tejidos biológicos se decide estudiar en otro capítulo las propiedades ópticas del agua dentro de un entorno heterogéneo como es el agua del mar. La selección del agua del mar, como objeto de estudio adicional, es motivada, principalmente, porque se trata de un sistema heterogéneo fácilmente descriptible en cada uno de sus elementos y permite evaluar una amplia bibliografía. Además se considera que los avances que han tenido lugar en los últimos años en las tecnologías fotónicas van a permitir su uso en los métodos experimentales de análisis de las aguas. El conocimiento de sus propiedades ópticas permite caracterizar los diferentes tipos de aguas de acuerdo con sus compuestos, así como poder identificar su presencia. Todo ello abre un amplio abanico de aplicaciones. En esta tesis doctoral, se ha conseguido de manera general: • Realizar un estudio del estado del arte del conocimiento de las propiedades ópticas de la piel y la identificación de sus elementos dispersores de la luz. • Establecer una metodología de estudio que nos permita obtener datos sobre posibles efectos de la radiación en los tejidos biológicos. •Usar distintas herramientas informáticas para simular el transporte de la radiación laser en tejidos biológicos. • Realizar experimentos mediante simulación de láser, tejidos biológicos y detectores. • Comparar los resultados conocidos experimentalmente con los simulados. • Estudiar los instrumentos de medida de la respuesta a la propagación de radiación laser en tejidos anisotrópicos. • Obtener resultados originales para el diagnóstico y tratamiento de pieles, considerando diferente razas y como alteración posible en la piel, se ha estudiado la presencia del basalioma. • Aplicación de la metodología de estudio realizada en la piel a la simulación de agua de mar. • Obtener resultados originales de simulación y análisis de cantidad de fitoplancton en agua; con el objetivo de facilitar la caracterización de diferentes tipos de aguas. La tesis doctoral se articula en 6 capítulos y 3 anexos perfectamente diferenciados con su propia bibliografía en cada uno de ellos. El primer capítulo está centrado en la problemática del difícil estudio y caracterización de los medios heterogéneos debidos a su comportamiento no homogéneo y anisotrópico ante las radiaciones ópticas. Así pues, presentaremos una breve introducción al comportamiento tanto de los tejidos como del océano ante radiaciones ópticas y definiremos sus principales propiedades: la absorción, el scattering, la anisotropía y los coeficientes de reflexión. Como continuación, un segundo capítulo trata de acercarnos a la resolución del problema de cómo caracterizar las propiedades ópticas descritas en el primer capítulo. Para ello, primero se introducen los modelos teóricos, en segundo lugar los métodos de simulación más empleados y, por último, enumerar las principales técnicas de medida de la propagación de la luz en los tejidos vivos. El tercer capítulo, centrado en la piel y sus propiedades, intenta realizar una síntesis de lo que se conoce sobre el comportamiento de la piel frente a la propagación de las radiaciones ópticas. Se estudian sus elementos constituyentes y los distintos tipos de pieles. Por último se describe un ejemplo de aplicación más inmediata que se beneficia de este conocimiento. Sabemos que el porcentaje de agua en el cuerpo humano es muy elevado, en concreto en la piel se considera de aproximadamente un 70%. Es obvio, por tanto, que conocer cómo afecta el agua en la propagación de una radiación óptica facilitaría el disponer de patrones de referencia; para ello, se realiza el estudio del agua del mar. En el cuarto capítulo se estudian las propiedades del agua del mar como medio heterogéneo de partículas. En este capítulo presentamos una síntesis de los elementos más significativos de dispersores en el océano, un estudio de su comportamiento individual frente a radiaciones ópticas y su contribución al océano en su conjunto. Finalmente, en el quinto capítulo se describen los resultados obtenidos en los distintos tipos de simulaciones realizadas. Las herramientas de simulación empleadas han sido las mismas tanto para el caso del estudio de la piel como para el agua del mar, por ello ambos resultados son expuestos en el mismo capítulo. En el primer caso se analizan diferentes tipos de agua oceánica, mediante la variación de las concentraciones de fitoplancton. El método empleado permite comprobar las diferencias que pueden encontrarse en la caracterización y diagnóstico de aguas. El segundo caso analizado es el de la piel; donde se estudia el comportamiento de distintos tipos de piel, se analizan para validar el método y se comprueba cómo el resultado es compatible con aplicaciones, actualmente comerciales, como la de la depilación con láser. Como resultado significativo se muestra la posible metodología a aplicar para el diagnóstico del cáncer de piel conocido como basalioma. Finalmente presentamos un capítulo dedicado a los trabajos futuros basados en experimentación real y el coste asociado que implicaría el llevarlo a cabo. Los anexos que concluyen la tesis doctoral versan por un lado sobre el funcionamiento del vector común de toda la tesis: el láser, sus aplicaciones y su control en la seguridad y por otro presentamos los coeficientes de absorción y scattering que hemos utilizado en nuestras simulaciones. El primero condensa las principales características de una radiación láser desde el punto de vista de su generación, el segundo presenta la seguridad en su uso y el tercero son tablas propias, cuyos parámetros son los utilizados en el apartado de experimentación. Aunque por el tipo de tesis que defiendo no se ajusta a los modelos canónicos de tesis doctoral, el lector podrá encontrar en esta tesis de forma imbricada, el modelo común a todas las tesis o proyectos de investigación con una sección dedicada al estado del arte con ejemplos pedagógicos para facilitar la compresión y se plantean unos objetivos (capítulos 1-4), y un capítulo que se subdivide en materiales y métodos y resultados y discusiones (capítulo 5 con sus subsecciones), para finalizar con una vista al futuro y los trabajos futuros que se desprenden de la tesis (capítulo 6). ABSTRACT As contribution to the study of heterogeneous media, this thesis covers the work carried out on theoretical modelling and simulation study of the optical properties of the skin and seawater, as paradigmatic examples of heterogeneous media. It is taken as a starting point the study of the propagation of optical radiation, in particular laser radiation in a biological tissue. The importance of optical characterization of a tissue is critical for managing the interaction between radiation and tissues that allows both diagnosis and therapy of diseases and / or dysfunctions in Health Sciences. Without forgetting the aim of providing a methodology of study, with "engineering approach" of the optical properties in a heterogeneous environment, which does not have to be exclusively biological tissue. As a result of this and the importance of water in biological tissues, we have decided to study the optical properties of water in a heterogeneous environment such as seawater in another chapter. The selection of sea water as an object of further study is motivated mainly because it is considered that the advances that have taken place in recent years in photonic technologies will allow its use in experimental methods of water analysis. Knowledge of the optical properties to characterize the different types of waters according to their compounds, as well as to identify its presence. All of this opens a wide range of applications. In this thesis, it has been generally achieved: • Conduct a study of the state of the art knowledge of the optical properties of the skin and identifying its light scattering elements. • Establish a study methodology that allows us to obtain data on possible effects of radiation on biological tissues. • Use different computer tools to simulate the transport of laser radiation in biological tissues. • Conduct experiments by simulating: laser, detectors, and biological tissues. • Compare the known results with our experimentally simulation. • Study the measuring instruments and its response to the propagation of laser radiation in anisotropic tissues. • Get innovative results for diagnosis and treatment of skin, considering different races and a possible alteration in the skin that we studied: the presence of basal cell carcinoma. • Application of the methodology of the study conducted in the skin to simulate seawater. • Get innovative results of simulation and analysis of amount of phytoplankton in water; in order to facilitate the characterization of different types of water. The dissertation is divided into six chapters and three annexes clearly distinguished by their own literature in each of them. The first chapter is focused on the problem of difficult study and characterization of heterogeneous media due to their inhomogeneous and anisotropic behaviour of optical radiation. So we present a brief introduction to the behaviour of both tissues at the cellular level as the ocean, to optical radiation and define the main optical properties: absorption, scattering, anisotropy and reflection coefficients. Following from this, a second chapter is an approach to solving the problem of how to characterize the optical properties described in the first chapter. For this, first the theoretical models are introduced, secondly simulation methods more used and, finally, the main techniques for measuring the propagation of light in living tissue. The third chapter is focused on the skin and its properties, tries to make a synthesis of what is known about the behaviour of the skin and its constituents tackle the spread of optical radiation. Different skin types are studied and an example of immediate application of this knowledge benefits described. We know that the percentage of water in the human body is very high, particularly in the skin is considered about 70%. It is obvious, therefore, that knowing how the water is affected by the propagation of an optical radiation facilitate to get reference patterns; For this, the study of seawater is performed. In the fourth chapter the properties of seawater as a heterogeneous component particles are studied. This chapter presents a summary of the scattering elements in the ocean, its individual response to optical radiation and its contribution to the ocean as a whole. In the fifth chapter the results of the different types of simulations are described. Simulation tools used were the same for the study of skin and seawater, so both results are presented in the chapter. In the first case different types of ocean water is analysed by varying the concentrations of phytoplankton. The method allows to check the differences that can be found in the characterization and diagnosis of water. The second case analysed is the skin; where the behaviour of different skin types are studied and checked how the result is compatible with applications currently trade, such as laser hair removal. As a significant result of the possible methodology to be applied for the diagnosis of skin cancer known as basal cell carcinoma is shown. Finally we present a chapter on future work based on actual experimentation and the associated cost which it would involve carrying out. The annexes conclude the thesis deal with one hand on the functioning of the common vector of the whole thesis: laser, control applications and safety and secondly we present the absorption and scattering coefficients we used in our simulations. The first condenses the main characteristics of laser radiation from the point of view of their generation, the second presents the safety in use and the third are own tables, whose parameters are used in the experimental section. Although the kind of view which I advocate does not meet the standard models doctoral thesis, the reader will find in this thesis so interwoven, the common model to all theses or research projects with a section on the state of the art pedagogical examples to facilitate the understanding and objectives (Chapters 1-4), and a chapter is divided into materials and methods and results and discussions (Chapter 5 subsections) arise, finishing with a view to the future and work future arising from the thesis (Chapter 6).

Reflexión y refracción de la luz en medios anisótropos

En este proyecto se pretende estudiar el comportamiento de la luz al atravesar medios de diversos materiales, tanto isótropos como anisótropos uniáxicos. Para ello se requiere realizar un estudio previo de las condiciones de contorno aplicables a las ecuaciones de Maxwell en la interfase de dos medios que pueden ser isótropos o anisótropos. En el caso de dos materiales isótropos, la solución del problema son los conocidos coeficientes de Fresnel de reflexión y transmisión. En este trabajo se pretende generalizar el estudio al caso del paso de la luz desde un medio isótropo a otro anisótropo uniáxico (con su eje óptico en orientación arbitraria) y viceversa y al caso de dos materiales anisótropos uniáxicos con ejes ópticos en orientaciones arbitrarias. Es de especial interés el caso de un mismo material uniáxico en el que las dos partes tienen el eje óptico con distinta orientación. Una vez planteadas las condiciones de contorno específicas en cada caso, se obtendrá un conjunto de ecuaciones algebraicas cuya resolución permitirá obtener los coeficientes de reflexión y transmisión buscados. Para plantear el sistema de ecuaciones adecuado, será necesario tener una descripción de las características ópticas de los materiales empleados, la orientación de los ejes ópticos en cada caso, y los posibles ángulos de incidencia. Se realizará un tratamiento matricial de modo que el paquete MatLab permite su inversión de manera inmediata. Se desarrollará una interfaz sencilla, realizada con MatLab, que permita al usuario introducir sin dificultad los datos correspondientes a los materiales de los medios incidente y transmitido, la orientación en espacial del o de los ejes ópticos, de la longitud de onda de trabajo y del ángulo de incidencia del haz de luz, con los que la aplicación realizará los cálculos. Los coeficientes de reflexión y refracción obtenidos serán representados gráficamente en función del ángulo de incidencia. Así mismo se representarán los ángulos transmitidos y reflejados en función del de incidencia. Todo ello de esta forma, que resulte sencilla la interpretación de los datos por parte del usuario. ABSTRACT. The reason for this project is to study the behavior of light when light crosses different media of different materials, isotropic materials and uniaxial anisotropic materials. For this, a previous study is necessary where the boundary conditions apply to Maxwell equations at the interface between two media which can be isotropic and anisotropic. If both materials are isotropic, the Fresnel ccoefficients of reflection and refraction are used to solve the problem. The aim of this work is to generalize a study when light crosses from an isotropic media to a uniaxial anisotropic media, where its axis have arbitrary directions, and vicecersa. The system consisting of two materials with axis in arbitrary directions are also being studied. Once the specific boundary conditions are known in each case, a set of algebraic equations are obtained whose solution allows obtaining the reflection coefficients and refraction coefficients. It is necessary to have a description of the optical characteristics of the materials used; of the directions axis in each case and the possible angle of incidence. A matrix is proposed for later treatment in Matlab that allows the immediate inversion. A simple interface will de developed, manufactured with Matlab, that allows the user to enter data easily corresponding to the incident media and transmission media of the different materials, the special axis directions, the wavelength and the angle of incidence of the light beam. This data is used by the application to perform the necessary calculations to solve the problem. When reflection coefficients and refraction coefficients are obtained, the application draws the graphics in function of the angle of incidence. Also transmitted and reflected angles depending on the incidence are represented. This is to perform a data representation which is a simple interpretation of the user data.

(Table 1) Age and depth of reflectors of the 3.5-kHz and airgun seismic record and their corresponding depth of ash layers, carbonate peaks, and transition zones from DSDP Hole 83-504B

DSDP cores from areas of low (Site 505) and high heat flow (Site 504 B) near the Costa Rica Rift, together with seismic profiles from the Panama Basin, have been studied to determine the relationship between: (1) carbonate content and physical and acoustic properties; and (2) carbonate content, carbonate diagenesis and acoustic stratigraphy. Except for ash and chert layers, bulk density correlates strongly and linearly with carbonate content. Velocity is uniform downcore and only small variations at a small scale are measured. Thus an abrupt change in carbonate content will cause abrupt changes in acoustic impedance and should cause reflectors that can be detected acoustically. A comparison of seismic profiler reflection records with physical properties, carbonate content and reflection coefficients indicates that the main reflectors can be identified with ash layers, diagenetic boundaries, and carbonate content variations. Diagenesis of carbonate sediments is present at Site 504B in a 260 m-thick ooze-chalk-limestone/chert sequence. These diagenetic sequences occur in areas of higher heat flow (200 mW/m**2). Seismic profiler records can be used to map the extent and depth of these diagenetic boundaries.

Osmotic flow in porous membranes:effects of electric charge

The electrostatic model for osmotic flow across a porous membrane in our previous study (Akinaga et al. 2008)" was extended to include the streaming potential, for solutes and pores of like charge and fixed surface charge densities. The magnitude of the streaming potential was determined to satisfy zero current condition along the pore axis. It was found that the streaming potential affects the velocity profiles of the pressure driven flow as well as the osmotic flow through the pore, and decreases their flow rates, particularly in the case of large Debye length relative to the pore radius, whereas it has little effect on the reflection coefficients of spherical solutes through cylindrical pores.

Effects of electric charge on osmotic flow across periodically arranged circular cylinders

An electrostatic model is developed for osmotic flow across a layer consisting of identical circular cylinders with a fixed surface charge, aligned parallel to each other so as to form an ordered hexagonal arrangement. The expression of the osmotic reflection coefficient is derived for spherical solutes with a fixed surface charge suspended in an electrolyte, based on low-Reynolds-number hydrodynamics and a continuum, point-charge description of the electric double layers. The repulsive electrostatic interaction between the surface charges with the same sign on the solute and the cylinders is shown to increase the exclusion region of solute from the cylinder surface, which enhances the osmotic flow. Applying the present model to the study of osmotic flow across the endothelial surface glycocalyx of capillary walls has revealed that this electrostatic model could account well for the reflection coefficients measured for charged macromolecules, such as albumin, in the physiological range of charge density and ion concentration.

Through wafer 3D Vertical Micro-Coaxial Probe for high frequency material characterization and millimeter wave packaging systems

This work presents the development of an in-plane vertical micro-coaxial probe using bulk micromachining technique for high frequency material characterization. The coaxial probe was fabricated in a silicon substrate by standard photolithography and a deep reactive ion etching (DRIE) technique. The through-hole structure in the form of a coaxial probe was etched and metalized with a diluted silver paste. A co-planar waveguide configuration was integrated with the design to characterize the probe. The electrical and RF characteristics of the coaxial probe were determined by simulating the probe design in Ansoft's High Frequency Structure Simulator (HFSS). The reflection coefficient and transducer gain performance of the probe was measured up to 65 GHz using a vector network analyzer (VNA). The probe demonstrated excellent results over a wide frequency band, indicating its ability to integrate with millimeter wave packaging systems as well as characterize unknown materials at high frequencies. The probe was then placed in contact with 3 materials where their unknown permittivities were determined. To accomplish this, the coaxial probe was placed in contact with the material under test and electromagnetic waves were directed to the surface using the VNA, where its reflection coefficient was then determined over a wide frequency band from dc-to -65GHz. Next, the permittivity of each material was deduced from its measured reflection coefficients using a cross ratio invariance coding technique. The permittivity results obtained when measuring the reflection coefficient data were compared to simulated permittivity results and agreed well. These results validate the use of the micro-coaxial probe to characterize the permittivity of unknown materials at high frequencies up to 65GHz.

Sistemas de cálculo, análise e operação virtual: interferências de campos elétricos e magnéticos produzidas por estações radio base de acesso múltiplo por divisão de código em banda larga - WCDMA

In this work it was developed mathematical resolutions taking as parameter maximum intensity values for the interference analysis of electric and magnetic fields and was given two virtual computer system that supports families of CDMA and WCDMA technologies. The first family were developed computational resources to solve electric and magnetic field calculations and power densities in Radio Base stations , with the use of CDMA technology in the 800 MHz band , taking into account the permissible values referenced by the Commission International Protection on non-Ionizing Radiation . The first family is divided into two segments of calculation carried out in virtual operation. In the first segment to compute the interference field radiated by the base station with input information such as radio channel power; Gain antenna; Radio channel number; Operating frequency; Losses in the cable; Attenuation of direction; Minimum Distance; Reflections. Said computing system allows to quickly and without the need of implementing instruments for measurements, meet the following calculated values: Effective Radiated Power; Sector Power Density; Electric field in the sector; Magnetic field in the sector; Magnetic flux density; point of maximum permissible exposure of electric field and power density. The results are shown in charts for clarity of view of power density in the industry, as well as the coverage area definition. The computer module also includes folders specifications antennas, cables and towers used in cellular telephony, the following manufacturers: RFS World, Andrew, Karthein and BRASILSAT. Many are presented "links" network access "Internet" to supplement the cable specifications, antennas, etc. . In the second segment of the first family work with more variables , seeking to perform calculations quickly and safely assisting in obtaining results of radio signal loss produced by ERB . This module displays screens representing propagation systems denominated "A" and "B". By propagating "A" are obtained radio signal attenuation calculations in areas of urban models , dense urban , suburban , and rural open . In reflection calculations are present the reflection coefficients , the standing wave ratio , return loss , the reflected power ratio , as well as the loss of the signal by mismatch impedance. With the spread " B" seek radio signal losses in the survey line and not targeted , the effective area , the power density , the received power , the coverage radius , the conversion levels and the gain conversion systems radiant . The second family of virtual computing system consists of 7 modules of which 5 are geared towards the design of WCDMA and 2 technology for calculation of telephone traffic serving CDMA and WCDMA . It includes a portfolio of radiant systems used on the site. In the virtual operation of the module 1 is compute-: distance frequency reuse, channel capacity with noise and without noise, Doppler frequency, modulation rate and channel efficiency; Module 2 includes computes the cell area, thermal noise, noise power (dB), noise figure, signal to noise ratio, bit of power (dBm); with the module 3 reaches the calculation: breakpoint, processing gain (dB) loss in the space of BTS, noise power (w), chip period and frequency reuse factor. Module 4 scales effective radiated power, sectorization gain, voice activity and load effect. The module 5 performs the calculation processing gain (Hz / bps) bit time, bit energy (Ws). Module 6 deals with the telephone traffic and scales 1: traffic volume, occupancy intensity, average time of occupancy, traffic intensity, calls completed, congestion. Module 7 deals with two telephone traffic and allows calculating call completion and not completed in HMM. Tests were performed on the mobile network performance field for the calculation of data relating to: CINP , CPI , RSRP , RSRQ , EARFCN , Drop Call , Block Call , Pilot , Data Bler , RSCP , Short Call, Long Call and Data Call ; ECIO - Short Call and Long Call , Data Call Troughput . As survey were conducted surveys of electric and magnetic field in an ERB , trying to observe the degree of exposure to non-ionizing radiation they are exposed to the general public and occupational element. The results were compared to permissible values for health endorsed by the ICNIRP and the CENELEC .