für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray World is facing severe energy crisis, the most excellent way to overcome the energy crisis is using renewable energy resources. Thousands of gallon of water have been wasted through our sewage system, if we use that water to produce electricity that will be beneficial. The main purpose of this project is to present a new alternative method for electric power generation based on utilizing waste water. ····· 10361113958
für 45.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Aufgrund ihrer vielfältigen Anwendbarkeit z.B. im Explosionsschutz, zur Detektion von Gaslecks, zu Emissionsmessungen oder in der Prozessüberwachung wächst der globale Markt für Gassensor- und Gasanalysesysteme stetig. Als optischer Gassensor findet dabei gerade der Halbleiterlaser ein immer breiteres Anwendungsspektrum. Im Wellenlängenbereich von ca. 2,8 µm bis ca. 4 µm standen bis vor kurzem jedoch keine Halbleiterdiodenlaser zur Verfügung, die bei Raumtemperatur im Dauerstrichbetrieb arbeiten und dabei die benötigte Leistung erbringen. Ziel der vorliegenden Arbeit war es daher, den Wellenlängenbereich GaSb-basierter Laser zu erweitern und so die fundamentalen Absorptionsmoden weiterer Gase für die Detektion zugänglich zu machen. Parallel wurde die Untersuchung und Verbesserung fundamentaler Wachstums- und Laserparameter angestrebt. ····· 10361108000
für 48.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Im Mittelpunkt dieser Arbeit stehen die Herstellung und die Charakterisierung von Halbleiter- Heterostrukturen der Gruppe-III-Nitride, welche für einen Einsatz in Lichtemittern im grünen Spektralbereich bestimmt sind. Das Wachstum der Halbleiterschichten erfolgt dabei mittels Metallorganischer Gasphasenepitaxie sowohl auf der konventionellen c-plane Fläche der Wurtzitstruktur als auch auf nicht- oder semipolaren Oberflächen, die in den letzten Jahren zunehmend an Bedeutung gewonnen haben. Im ersten Teil der Arbeit werden Ergebnisse an c-plane GaInN/GaN QW-Strukturen mit hohen Indium-Gehalten vorgestellt. Dabei wurde untersucht, wie die Qualität von hoch-In-haltigen QW-Strukturen durch verschiedene Wachstumsparameter sowie die Wahl des Substrats beeinflusst wird. Es zeigt sich, dass eine verspannungsinduzierte Bildung von Defekten in der aktiven Zone die Hauptursache für die starke Abnahme der Effizienz im grünen Spektralbereich sein könnte. In Experimenten zur Temperaturstabilität von GaInN/GaN QW-Strukturen wurde zudem beobachtet, dass das Wachstum einer Deckschicht bei hohen Temperaturen zu einer Degradation der QWs führen kann. Auch in diesem Fall deutet sich an, dass die zusätzliche Bildung von Defekten, die während des Deckschichtwachstums erfolgt, wiederum verspannungsinduziert ist. Der zweite Teil der Arbeit ist dann der Untersuchung von nitridbasierten Halbleiter-Heterostrukturen auf nicht- und semipolaren Oberflächen der Wurtzitstruktur gewidmet. Beim Wachstum von GaInN/GaN QW-Strukturen wurde beobachtet, dass unter identischen Wachstumsbedingungen die Wachstumsraten sowie der Indium-Einbau auf den nichtpolaren Oberflächen (a-plane und m-plane) vergleichbar sind mit denen auf der konventionellen c-plane Oberfläche. Auf der semi-polaren (1122) Fläche deutet sich hingegen ein etwas höherer Indium-Einbau an. In der Analyse der optischen Eigenschaften zeigt sich anhand der Übergangsenergien sowie der Rekombinationsdynamik, dass der Einfluss des elektrischen Feldes in den nichtpolaren QW-Strukturen tatsächlich verschwindet. Darüber hinaus zeigen die optischen Experimente, dass in QW-Strukturen auf m-plane SiC, die eine hohe Stapelfehlerdichte aufweisen, an den Kreuzungspunkten zwischen Stapelfehlern und QWs quantendrahtartige Strukturen ausgebildet werden, die eine effektive strahlende Rekombination der Ladungsträger ermöglichen. Desweiteren wurden die Polarisationseigenschaften von nicht- und semipolaren Quantenfilm- Strukturen untersucht. Dabei konnte beobachtet werden, dass auf bulk GaN-Substraten die Polarisationsanisotropie von m-plane GaInN QWs mit zunehmendem Indium-Gehalt ansteigt. Dieser Anstieg des Polarisationsgrades geht auf die größere Verspannung mit zunehmendem Indium-Gehalt zurück, die zu einer stärkeren Aufspaltung der obersten Valenzbäder führt. Auf m-plane 6H-SiC-Substraten wird jedoch in allen QW-Strukturen ein sehr hoher Polarisationsgrad von 90 % oder mehr beobachtet. Dieser Effekt ist auf eine stark anisotrope Verspannung der QW-Strukturen zurückzuführen, welche zu einer starken Aufspaltung der obersten Valenzbänder und damit zu eben diesen hohen Polarisationsgraden führt. ····· 10361107863
für 49.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Graphene - a two-dimensional allotrope of carbon - offers many opportunities for research in fundamental science, as well as for technological applications. First, for being a single layer of carbon atoms, which are bound in a honeycomb geometry, it represents a two-dimensional electron gas that is accessible for investigation and manipulation directly, in contrast to conventional semiconductor-based, two-dimensional systems. Second, it is chemically and mechanically robust and offers a high electrical and thermal conductivity, while being widely transparent for visible light. And third, charge carriers in graphene mimic massless Dirac fermions as graphene exhibits a linear energy dispersion. In the present thesis, epitaxial graphene that is grown by the thermal decomposition of silicon carbide (SiC) on its (0001) basal plane is investigated. Here, monolayer graphene (MLG) with reproducible properties is formed when silicon atoms sublime at high temperatures in a well-controlled manner. In addition to MLG, a carbon-rich interface layer is formed between graphene and the SiC surface. It is electrically insulating but has a strong impact on the properties of MLG. The buffer layer can be converted to a quasi-free-standing monolayer graphene (QFMLG) by intercalation of hydrogen between buffer layer and SiC surface. This treatment reduces the coupling between QFMLG and SiC. The graphene-substrate interaction can be further reduced when free-standing epitaxial graphene (FEG) is patterned. With this method, the SiC substrate is selectively etched away with a photo-electrochemical reaction, while suspended graphene devices remain. The main topics of the present thesis are the fabrication and the electrical characterization of these three materials MLG, QFMLG and FEG. In particular, classical and quantum corrections to resistivity and conductivity, as well as the interaction with the substrate are investigated with transport and magnetotransport measurements. We observe Shubnikov-de Haas oscillations in strong fields for MLG and QFMLG samples. The sequence of maxima and minima is a strong indication that charge carriers in epitaxial graphene behave as quasi-relativistic, chiral particles. The observation of the half-integer quantum Hall effect in MLG confirms this finding. Consequently, the pseudo-relativistic physics, which is theoretically expected and is visible in exfoliated graphene, is also present in epitaxial graphene despite the graphene-substrate interaction. Furthermore, we study the weak localization (WL) correction, and present a routine which allows to extract the elastic scattering times for intravalley and intervalley scattering. The latter can be identified with the scattering of charge carriers on short-range potentials. Universal conductance fluctuations are observed in the mesoscopic FEG samples. In the presence of disorder (in the diffusive regime), electron-electron interaction (EEI) is enhanced and results in a resistivity correction that is logarithmic in temperature. Moreover, EEI causes a parabolic magnetoresistivity in intermediate fields. The curvature of these parabolas also exhibit a logarithmic temperature dependence. We show that the slope of this temperature dependence can unambiguously be identified with the EEI correction. In particular, it allows to separate the contribution of EEI from other quantum corrections that cause a logarithmic temperature dependence. We present a parameter-free description of the underlying physics. The Kondo effect - the interaction of the conduction electrons with local spin moments - also causes a logarithmic temperature dependence of the resistivity. Consequently, the contribution of the Kondo effect is difficult to identify from temperature-dependent resistivity measurements and EEI can easily be misinterpreted as Kondo effect. We discuss the similarity of the Kondo and EEI correction critically and present measurements of MLG samples that are decorated with ferrocenium ions, which carry an unpaired spin. In the latter, we observe a Kondo-like signal in the temperature-dependent resistivity whose amplitude increases with increasing ferrocenium concentration. ····· 10361107823
für 48.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Die Motivation dieser Arbeit ist die Erforschung potentieller Seltenerd-dotierter Laserkristalle auf Basis von oxidischen Wirtsmaterialien, welche mit Hilfe von blauem Pumplicht sichtbares Laserlicht erzeugen können. Oxide weisen im Vergleich zu anderen Materialklassen meistens bessere thermomechanische Eigenschaften auf und sind zumeist einfacher herzustellen. Es wurden die schmalbandigen intrakonfiguralen 4 f -4 f -Übergänge des Pr 3+ - und des Ho 3+ - Ions sowie die zur Realisierung durchstimmbarer Laser geeigneten interkonfiguralen 5d-4 f - Übergänge des Ce 3+ -Ions untersucht, welche in unterschiedliche Oxidkristalle dotiert wurden. Neben der Herstellung der Kristalle, welche größtenteils mit dem Czochralski- und dem Nacken-Kyropoulos-Verfahren erfolgte, lag das Hauptaugenmerk auf der spektroskopischen Charakterisierung der Materialien in Bezug auf ihre Lasereigenschaften und - sofern möglich - der Charakterisierung der entsprechenden Laser. Anders als bei vielen anderen Pr 3+ -dotierten Oxiden ist bei Pr 3+:SrAl12O19 der Verlustprozess durch Multiphononenrelaxation vom oberen Laserniveau in das benachbarte 1 D2-Multiplett vernachlässigbar gering. Weiterhin tritt keine Absorption aus angeregten Zuständen (ESA) im sichtbaren Spektralbereich auf, so dass weder Pump- noch Laserwellenlängen durch diesen Verlustprozess beeinträchtigt sind. Unter Verwendung von InGaN-Laserdioden als Pumpquellen konnte mit Pr 3+:SrAl12O19 erstmals Lasertätigkeit im Dauerstrichbetrieb gezeigt werden. Mit einem differentiellen Wirkungsgrad von 47% bei einer Wellenlänge von 643,5 nm stellt dieses System den effizientesten, jemals demonstrierten Pr 3+ -Festkörperlaser im sichtbaren Spektralbereich auf der Basis von Oxiden dar. Bei einer absorbierten Pumpleistung von 281 mW wurde eine maximale Ausgangsleistung von 75 mW erzielt. Die Ausgangsleistung ist vor allem durch die zur Verfügung stehende Pumpleistung begrenzt. Im tiefroten Spektralbereich bei 724,4 nm wurde mit diesem Material zum ersten Mal Lasertätigkeit nachgewiesen. Für Pr 3+:LuAlO3 konnte erstmals Lasertätigkeit im roten und tiefroten Spektralbereich im Dauerstrichbetrieb demonstriert werden. Bei 724,1 nm wurde eine maximale Ausgangsleistung von 6,7 mW bei einem differentiellen Wirkungsgrad von 14% erzielt. Spektroskopischen Untersuchungen zeigen, dass es prinzipiell möglich sein sollte, einen Laser mit Ho 3+:Lu2O3 im grünen und mit Pr 3+:Gd3Sc2Al3O12 im orangenen Spektralbereich zu realisieren. Für Ce 3+:Ca3Sc2Si3O12, Ce 3+:Y3Al5O12 und Ce 3+:Sr3SiO5 ist gemäß den Messungen zur ESA kein Laserbetrieb zu erwarten. Bei Ce 3+:CaSc2O4 ist die Verstärkung durch stimulierte Emission in Teilen des sichtbaren Spektralbereichs größer als die Verluste durch ESA, so dass die Realisierung eines Lasers möglich sein sollte. Die energetische Lage des untersten 5d-Zustandes wurde mit spektroskopischen Messungen relativ zum Leitungsband bestimmt. Aufgrund der berechneten Breite des Leitungsbandes von maximal 1,6 eV finden ESA-Prozesse vom untersten 5d-Zustand in das Leitungsband hauptsächlich im nahen infraroten Spektralbereich statt. Insgesamt zeigen die Ergebnisse, dass auf Basis oxidischer Wirtsmaterialien effiziente Festkörperlaser im sichtbaren Spektralbereich erzielt werden können. ····· 10361107661
für 45.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Low-field NMR techniques are used to study porous system, from simple to complex structures, and objects of cultural heritage. It is shown that NMR relaxometry can be used to study the fluid dynamics inside a porous system. A simple theoretical model for multi-site relaxation exchange NMR is used to extract exchange kinetic parameters when applied on a model porous systems. It provides a first step towards the study of more complex systems, where continuous relaxation distributions are present, such as soil systems or building materials. Moisture migration is observed in the soil systems with the help of 1D and 2D NMR relaxometry methods. In case of the concrete samples, the difference in composition makes a significant difference in the ability of water uptake. The single-sided NMR sensor proves to be a useful tool for on-site measurements. This is very important also in the case of the cultural heritage objects, as most of the objects can not be moved out of their environment. Mobile NMR turns out to be a simple but reliable and powerful tool to investigate moisture distributions and pore structures in porous media as well as the conservation state and history of objects of cultural heritage. ····· 10361107595
für 45.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Anwendungen eines hochauflösenden Röntgendetektors sind die Kleinwinkelstreuung an Muskelfasern, um deren Kontraktion zu bestimmen oder die Verwendung in üblichen Kristalluntersuchungen bei hohen Energien. In der medizinischen Forschung mit Röntgenstrahlung, speziell bei Untersuchungen der Herzdynamik, werden hochauflösende Röntgendetektoren benötigt, die sowohl eine Auslesegeschwindigkeit im Submillisekundenbereich, als auch eine Kontrastauflösung von besser als 1 % leisten können. Eine medizinische Untersuchung der Flussdynamik wird nur durch die Verwendung eines Kontrastmittels möglich, so dass man Gefäße durch die K-Kanten Subtraktionsmethode deutlich vom restlichen Gewebe unterscheiden und den Absolutbetrag der Konzentration des Kontrastmittels bestimmen kann. Übliche Kontrastmittel sind Iod und Gadolinium, so dass Energien bis 51 keV benötigt werden. Verschiedene Detektoren bzw. Detektormaterialien sind im Gebrauch bzw. im Test um diese Bedingungen zu erfüllen. Si-, Ge-, CdZnTe-, CdMnTe- und CdTe-Halbleiterdetektoren werden hauptsächlich benutzt oder getestet, wobei jeder Typ physikalische und/oder technische Schwierigkeiten besitzt, die eine Erfüllung der Forderungen verhindern. Diese Schwierigkeiten sind die geringe Absorptionseffizienz (Si) und verschlechterte Ortsauflösung unter Verwendung von Szintillatoren, Kühlung und schlechte Auflösung (Ge) und Elektronenüberlaufen der Pixel sowie technische Probleme beim Bau eines Detektorchips (CdZnTe-, CdMnTe- und CdTe). Der Ansatz dieser Arbeit ist nun eine gasgefüllte Ionisationskammer, als integrierender Zeilendetektor aufgebaut. Allgemein besteht bei einer Ionisationskammer immer der Nachteil der geringeren Absorptionseffizienz. Betreibt man die Ionisationskammer allerdings bei einem hohen Druck in der Größenordnung von 50 bar, kann man unter Verwendung der Edelgase Ar, Kr oder Xe für eine entsprechende Länge des sensitiven Bereichs (im Bereich von cm) dieses Problem lösen. Bei diesen Längen der Auslesestreifen machen sich allerdings Parallaxefehler bemerkbar, deshalb muss man eine Strahlungsquelle verlangen, deren Strahl eine minimale Divergenz aufweist. In Kombination mit der eingangs geforderten Zeitauflösung und dem gewünschten Kontrast, sind nur Synchrotronstrahlungsquellen der 3. Generation wie das ESRF in Grenoble oder der DORIS Ring in Hamburg in der Lage, eine entsprechend kleine Strahldivergenz bei sehr hohem Photonenfluss zu liefern. Die Aufgabe dieser Arbeit ist es nun, herauszufinden wo die Grenzen der Ortsauflösung einer oben beschriebenen gasgefüllten Ionisationskammer liegen. Dazu wurde eine Simulationssoftware entwickelt und ein Testdetektor gebaut. Die Simulation berücksichtigt sowohl die physikalischen Effekte im Gasvolumen nach einer Belichtung mit monoenergetischen Photonen als auch die Geometrie des Detektordesigns zur Berechnung der Ausdehnung der Ladungswolke. Der Bau des Detektors erfüllt nun zum Einen den Zweck, die technische Realisierung eines solchen Designs zu demonstrieren, als auch über eine einfache Messung die physikalischen Grenzen der Simulation aufzuzeigen. Desweiteren soll über diese Software eine Voraussage über mögliche Ortsauflösungen eines solchen Detektors gemacht werden. ····· 10361107392
für 48.80€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Gallium arsenide (GaAs) is a group III/V semiconductor and is a very important material for modern technology. It has a broad range of applications and it is extensively used in light emitting diodes, laser diodes [81, 37, 46, 40], sensors and detectors [81, 55] among others. In electronics it complements silicon devices, where its applications reach from robust logic circuitry and transistors to microwave waveguides [36, 81, 13]. Gallium arsenide also serves as a photovoltaic power source [37, 46, 40]. Especially due to the ever advancing technological applications, there is a keen scientific interest in new and improved methods for the analysis of the material properties, the development of new techniques and experimental schemes. Motivated by the timescale of the dynamics of a nuclear spin system in a solid state device, a very active field of research is the realisation of semiconductor-based devices for spintronics [56], quantum computation [45, 17, 88] and quantum memories [65]. GaAs is often used, not as a bulk semiconductor, but in nanoscale assemblies of different semiconductors, i.e. heterostructures. Due to their unique properties, heterostructures are of particular interest to ongoing academical and industrial research efforts. It is possible to construct devices with significantly different characteristics compared to those of the bulk material. Especially at nanometer-scale miniaturisation, quantum effects have a significant impact on the electronic and optical properties [81, 29]. In material analysis nuclear magnetic resonance (NMR) techniques are commonly applied to semiconductor systems and NMR is the natural choice to implement a spintronic device and operate on a quantum device. Nevertheless, applying classical NMR techniques can be challenging, especially when it comes to the detection of small nuclear spin sub-ensembles in nanometer-sized heterostructures or the probing of such sub-ensemble when a much larger group, such as a substrate, contributes as significant background. In these cases the sensitivity can be greatly enhanced by optical methods [1]. Laser assisted nuclear magnetic resonance methods can be divided into two major flavours, optically polarised and optically detected nuclear magnetic resonance. Both methods require the use of coherent light in order to polarise the electron spin system in the semiconductor. The electron spin system can exchange angular momentum with the nuclei, causing a polarisation of the nuclear spin system as well. ····· 10361107389
für 71.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Superconducting radio-frequency (SRF) cavities are used to increase the energy of a charged particle beam in particle accelerators throughout the world. Bulk niobium is the material of choice to fabricate SRF cavities and their performance at cryogenic temperatures is characterized by a non-linearity of the surface resistance as a function of the RF field, in absence of field emission, which limits the operational accelerating gradient. This book presents the results on the investigation of such non-linearity in cavities which received different surface and bulk treatments as well as cavities made of single-crystal niobium. The experimental methods include measurements of the surface impedance as a function of temperature, of the quality factor as a function of the RF field below 4.2 K, and the excitation of different resonant modes. A thermometry system was used to better characterize the loss mechanisms. This book consists of the author s PhD dissertation at Old Dominion University (ODU) under the supervision of Prof. Colm T. Whelan of ODU and Dr. Peter Kneisel of Jefferson Lab. This book should be useful to students or young researchers in the field of SRF for accelerators. ····· 10361102401
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray There has been an unfortunate tendency among most of the empirical econometricians to ignore model adequacy diagnostic checking, indispensably required to verify the empirical validity of the residual whiteness assumptions underlying the model. Most of these studies have also failed to account for possible non-stationarity in the data series and to benefit from an analytical framework for a meaningful long-run equilibrium and short-run causality` in a cointegrating space of error correction. Again, these studies, by adopting a methodology suitable to a developed power system in advanced economies, have sought to correlate the less correlatables in the context of an underdeveloped power system in a less developed economy. The present study, while casting scepticism on the validity and value of the results of these studies, also finds that cointegration approach is superfluous given the model adequacy criteria if the regression model is adequate, then it is as valid as supported by a residual-based cointegration! ····· 10361101343
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Renewable power can`t compete with fossil fuels without financial support because they are expensive and their technologies are not yet mature enough. As a result, support schemes are in place. However, the multitude of support schemes raises concerns from the angle of a single EU electricity market. Solutions at the national level may alter competition in the EU internal market. Then, is there a need to integrate the support schemes and have a single support scheme applicable throughout the EU Since there are benefits and drawbacks to integration, is integration required This analysis sheds more light on this issue and should be relevant to policy makers in EU member states. It should also be relevant to academics around the world that conduct research in this field. ····· 10361101009
für 71.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray The rapid expansion of photovoltaic (PV) systems has revealed the presence of losses due to module coupling, better known as mismatch losses, that deprive producers from additional and available electric energy. This book aims to better understand the causes and mechanisms of mismatch losses in grid-connected installations. Two solutions to reduce these losses are proposed, studied, and compared. Also, the modelling techniques for PV systems submitted to shade, along with experimental results, will be presented. The first solution proposed consists in modifying the connection scheme of the array. The second solution uses power electronic devices within the solar array to reduce mismatch losses. This study will conclude with a global comparison of the proposed solutions in both residential and commercial-sized installations. ····· 10361100993
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Present work concerned with preparation of bio-waste reinforced polymer composites which enhances optimal utilization of natural resources and particularly of renewable resources. Coir dust composites prepared by hand lay up method. In this work we have investigated the dielectrical and wear behaviour of bio waste reinforced polymer composites.Experimental results shows that the strong dependence of dielectrical properties on frequency of applied electric field and testing temperature. In order to improve the strength and to reduce the sensitivity to environmental influences the interfacial adhesion between the natural fiber and matrix was improved by chemical treatment of the coir dust.Dielectric constant of treated coir dust composite was lower than of that of untreated coir dust composite, i.e. the dielectric strength of the composite increases and the increased dielectric strength make these composites quite suitable for use as insulators.This book is dedicated to my father late Aireddy Krishna Reddy. ····· 10361100356
für 61.20€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Key Features: (1)An introductory look on multiferroics and their types.(2)Fabrication of nanomultiferroics and their characterizations.(3)Size dependent tuneability and intercoupling of magnetic and dielectric properties of some rare earth ferrites and chromites.(4)Probing the magnetoelectric coupling of nanomultiferroics.Introduction to Nanomultiferroics is designed to serve as a reference book for varied group of postgraduate & research students of Physics and many material chemistry discipline,research scientist.During the past five decades,revolutionary breakthrough has occurred in the understanding of multiferroics and magnetoelectric phenomena,both from perspective of theory and experiments.The book is divided into five parts.The first covers the brief overview of multiferroics,their types and applications.The second is devoted to the effect of reduced particle size by developing new routes from wet-chemical synthesis method,on the dielectric,magnetic,magnetoelectric properties and Raman spectra.Third and fourth parts deal the rich interplay of competing magnetic interactions between rare earth ions.The part fifth concludes summary and future prospects of nanomultiferroics. ····· 1036199837
····· lezzter Preis 61.20€ ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray This book presents transmission properties in one- and two-dimensional plasmonic metamaterials with periodically and randomly structured arrays of various shaped perforated-apertures on metallic surfaces in the terahertz region. At a specific frequency at which the plasmonic metamaterials are perfectly transparent, the metal materials become essentially invisible. In the case of one-dimensional arrays of slits, Fabry-Perot like shape resonance enhances transmission of nearby horizontal surface resonance by the periodicity. Whereas in the case of two-dimensional arrays of various shaped holes, the shape resonance supported by guided-mode resonance, generally cutoff frequency, enhances transmission to be essentially unity near specific resonance frequencies. These understanding for the perfect transmission in the plasmonic metamaterials can contribute to the development of sensitive imaging systems, waveguides, and terahertz and infrared transmission filters. ····· 1036199662
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Sustainable Electricity Production in a Developing Economy, the case study of Ghana is geared toward policy makers in developing economies and to students taking engineering courses. The book s material is also applicable to researchers working to make electricity production in developing countries sustainable. The energy system and electricity inaccessibility is a global concern which calls for immediate action. This book focuses on thermal electricity production as a complimentary option. In addition to providing updated material in the rapidly developing electricity production system in Africa,it emphasizes on the major causes of electricity supply shortages and the main barrier to electricity sustainability in a typical developing economy such as Ghana and Nigeria. The concept of alternative thermal production options are based on fuel sources. In keeping with contemporary concerns of climate change, marginal efficiencies were used to determine the fuel required in oil- equivalent and emissions in the form of carbon dioxide, sulphur dioxide and nitrogen oxides into the atmosphere. ····· 1036199489
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray This book presents theoretical and application topics in power quality in distribution systems.With this book we wished to create a resource that is relevant to the needs of the working Power System engineers by helping bridge the theory and simulation work. A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a mal-operation of end use equipments. Utility distribution networks, sensitive industrial loads and critical commercial operations suffer from various types of outages and service interruptions which can cost significant financial 1oss. With the restructuring of Power Systems and with shifting trend towards distributed and dispersed generation, the issue of Power Quality is going to take newer dimensions. In developing countries like India, where the variation of power frequency and many such other determinants of power quality are themselves a serious question, it is very vital to take positive steps in this direction. The present work is to identify the prominent concerns in this area and hence the measures that can enhance the quality of the power are recommended. ····· 1036199456
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray A quasi-Landstorfer antenna exhibits both the characteristics of a high-gain antenna as well as a small-sized antenna. This antenna extracts the advantages of both the quasi-Yagi antenna and the Landstorfer antenna. The quasi-Landstorfer antenna will be suitable for wireless applications. Moreover, there will be more developments on this antenna in the future but this book will be the pioneer for all of them. All the necessary theories and working principle of the antenna have been described explicitly in this book. A detailed description of all the measurement setup has also been provided. The book is aimed to provide the reader a complete knowledge about designing the antenna as well as understanding the theories behind this antenna. The theory has been described from both the designer perspective as well as from field perspective for the academics. ····· 1036199427
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Synthesis and characterization of nano-sized particles has currently been a topic of intense investigation. In recent years, much effort has been devoted to the research of doped nanostructured materials. This kind of nanomaterials exhibits unusual physical and chemical properties in comparison with their bulk counterpart. As an important II-VI material, ZnS is chemically more stable and technologically better than other chalcogenides. In this thesis, we report an effective doping process by chemical route method to obtain nanosized ZnS:Cu particles. I have prepare five different samples with different concentration of copper. I have taken pure Zinc sulphide nanoparticle and after that I have put the copper in percentage of 0.005%, 0.01%, 0.015% and 0.02%. The influence of Cu doping concentration on electroluminescence has been studied. ····· 1036199416
für 44.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray The Green functions are especially useful for summing over the restricted classes of perturbation theory of diagrams, and are very powerful when combined with spectral representations. They play the most important part in the field-theoretical treatment of the many-body problem, and they are flexible enough to describe the effects of retarded interactions and all quantities of physical interest like thermodynamic properties can be derived from them. There are different types of Green functions,or propagators: One particle, two-particle,..., n particle, advanced, retarded, zero-temperature, finite-temperature, real-time, imaginary time, and so on. The Green s functions enjoy popularity because they yield, in a direct way, the most important physical properties in a systematic way. Among the types, we prefer the retarded double-time Green s function (GF) for our theoretical work because this implies the principle of causality. ····· 1036199135
für 71.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray This book presents a new transmission line protection scheme using voltage transient waveforms and fundamental voltage and current signals. The scheme integrates the high frequency transient protection algorithms with the synchronized sampling fault location algorithms to produce high speed fault detection and accurate location to the fault. The algorithms were enhanced by a new fault classification technique based on wavelet singular entropy and neural networks to classify different fault types and detect arcing activity within the faultIn order to reach better reliability and stability to the transmission network, transient adaptive single pole auto reclosing scheme (SPAR) was introduced. In the case of transient faults, the arcing extinction time can be accurately determined and in the case of a permanent fault, breaker re-closure can be avoided. ····· 1036199056
für 53.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Phased arrays have been traditionally used in military applications for several decades. Recent growth in civilian radar-based sensors and communication systems has drawn increasing interest in utilizing phased array technology for commercial applications. Despite the broad range of potential phased array applications, phased array technology has not been widely deployed in the commercial arena. The high cost and complexity of phased arrays is the primary impediment to their deployment in any large-scale commercial application. In order to deploy phased arrays in a wide range of applications, ongoing efforts are underway to develop new architectures that allow complexity of phased array to be reduced. In this book, conventional designs of phased arrays are reviewed and various new approaches are presented to realize phased arrays with reduced complexity. ····· 1036198750
für 71.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Fundamentals of electric circuit provides a very practical approach to a somewhat difficult subject. It provides basic coverage of electric components, circuits and its analysis. Chapters are organized in a step-by-step progression of concepts and theory. Each unit of instruction covers a short, concise topic. The key concepts presented in this book are discussed using a simplified approach that enhances learning. The use of mathematics is kept to the very minimum and is discussed through applications and illustrations. Each chapter begins with an introduction and discussion of important concepts and theories follows. Features of this book are detailed and accurate illustrations are provided in each chapter, network theorems are explained using typical examples and metering and measuring equipments are introduced. ····· 1036198432
für 53.10€ kaufen ···· Rheinberg-Buch.de - Bücher, eBooks, DVD & Blu-ray Layered structures of the high Tc superconductors have reinstigated the study of two dimensional (2D) antiferromagnetic spin systems and their charge dynamics for more than a couple of decades now. As a hole moves through such a system it interacts with spin waves and phonons at finite temperature. This book contains systematic derivation of the hole spectral functions in a 2D t-J model and its extensions numerically by first finding the spin waves using linear spin wave approximation and then solving the hole Dyson`s equation within the Non-crossing approximation. The role of different parameters and scenario on the hole dynamics in such a system is investigated in detail. Particularly the three main chapters in this book deals with hole dynamics (i) when optical phonons are present in the system at finite temperature, (ii) when small but finite hole density is present in the system and (iii) when periodic antiferromagnetic domain walls are present. This book shows computational results extrapolated to thermodynamic limit and its comparison with the angle-resolved-photo-emission spectra of the high Tc Cuprates in order to understand some aspects of charge flow in such compounds. ····· 1036192432· 1 ·· 2 ·· 3 ·· 4 ·· 5 ·· 6 ·· 7 ·· 8 ·· 9 ·
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