• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 95
  • 79
  • 12
  • 10
  • 6
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 219
  • 114
  • 79
  • 78
  • 78
  • 50
  • 38
  • 38
  • 38
  • 38
  • 28
  • 24
  • 24
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Strategie zur digitalen Transformation der Sächsischen Staatsverwaltung

02 April 2024 (has links)
Das vorliegende Dokument benennt die strategischen Grundsätze und Ziele für die umfassende und kontinuierliche Transformation der Sächsischen Staatsverwaltung hin zu einer digital agierenden Organisation. Die Umsetzung der im Jahr 2014 beschlossenen „Strategie für IT und E-Government des Freistaates Sachsen“ (ITEG-Strategie) hat den Weg bereitet für die Entwicklung der vorliegenden Strategie. Mit dieser richtet sich die Sächsische Staatsverwaltung an den zukünftigen Anforderungen der Gesellschaft an eine moderne Verwaltung aus. Redaktionsschluss: 27.11.2023
62

Die landwirtschaftlichen Vergleichsgebiete im Freistaat Sachsen

Albrecht, Christoph, Ullrich, Frank 25 June 2024 (has links)
Die Broschüre informiert über die Gliederung Sachsens in Gebiete, die relativ einheitliche Naturräume mit typischen Agrarstrukturen umfassen. Im Vergleich zur ersten Ausgabe 1999 wurden die Abgrenzungen der Gebiete überarbeitet. Weiterhin wird ein allgemeiner Überblick über die Agrarstruktur in Sachsen im Vergleich zur gesamtdeutschen Situation präsentiert. Die Broschüre richtet sich an Landwirte, Pädagogen, Schülerinnen und Schüler, Auszubildende im Agrarbereich und alle, die an einem kompakten Überblick über die sächsische Landwirtschaft interessiert sind. Redaktionsschluss: 18.11.2022, mit redaktionellen Bearbeitungen vom 26.01.2024
63

Beschleunigte Zusammenlegung: Rasch, preiswert, effizient

Tussing, Karin 04 July 2024 (has links)
Das Beschleunigte Zusammenlegungsverfahren nach dem Flurbereinigungsgesetz ist eine besondere, vereinfachte Form der Flurbereinigung, um Grundstücke neuzuordnen. Diese Verfahren eigenen sich vor allem dann, wenn kein neues Wegenetz benötigt wird und größere bauliche oder sonstige Maßnahmen nicht erforderlich sind. Es werden die Voraussetzungen, der Ablauf und die Kosten eines solchen Flurbereinigungsverfahrens dargestellt. Redaktionsschluss: 14.05.2024
64

Magnetostrukturelle Transformation in epitaktischen Ni-Co-Mn-In-Schichten

Niemann, Robert Ingo 20 October 2015 (has links) (PDF)
In der magnetischen Formgedächtnislegierung Ni-Co-Mn-In kann eine reversible Umwandlung von einer niedrigsymmetrischen, para- oder antiferromagnetischen Phase (Martensit) in eine hochsymmetrische ferromagnetische Phase (Austenit) sowohl durch eine Temperaturerhöhung als auch durch das Anlegen eines Magnetfelds induziert werden. Da dünne Schichten sich als interessantes Modellsystem für magnetische Formgedächtnislegierungen erwiesen haben, wird diese Umwandlung und der mit ihr verbundene inverse magnetokalorische Effekt an epitaktischen Ni-Co-Mn-In-Schichten untersucht. Die Temperatur des Substrats während der Herstellung wird als entscheidender Parameter für die Zusammensetzung und chemische Ordnung der Schicht identifiziert. Untersuchungen der Struktur mittels Röntgenbeugung zeigten, in Übereinstimmung mit dem Konzept des adaptiven Martensits, die Koexistenz von Austenit, moduliertem und nichtmoduliertem Martensit bei Raumtemperatur. Dieses Ergebnis wird durch Gefügeabbildungen untermauert. Die Transformation wird sowohl durch temperaturabhängige Röntgenbeugung als auch durch temperatur- und feldabhängige Magnetisierungsmessungen untersucht. Die berechnete Änderung der magnetischen Entropie ist etwa halb so groß wie in massivem Ni-Co-Mn-In. Schließlich wird bei tiefen Temperaturen eine unidirektionale Austauschkopplung zwischen Restaustenit und Martensit nachgewiesen, die auf einen antiferromagnetischen Martensit schließen lässt. / The magnetic shape memory alloy (MSMA) Ni-Co-Mn-In shows a reversible transformation from a para- or antiferromagnetic low symmetry phase (martensite) into a ferromagnetic phase of high symmetry (austenite). This transformation can either be induced by raising the temperature or applying a magnetic field. Since thin films have be shown to be an interesting model system for MSMAs, this transformation and the associated inverse magnetcaloric effect are investigated in epitaxial Ni-Co-Mn-In films. The temperature of the substrate during deposition is identified as the essential parameter controlling both composition and chemical order. By studying structure using x-ray diffraction (XRD) the coexistence of austenite and modulated (14M) as well as nonmodulated martensite (NM) is shown. Coexistence of NM and 14M is also visible in micrographs of the films surface. This confirms results obtained for epitaxial Ni-Mn-Ga and validates the concept of adaptive martensite in this alloy. The transformation is investigated by temperature-dependent XRD and temperature- and field-dependent magnetometry. A positive change in entropy is calculated which is about half compared to bulk. Finally, an exchange bias between residual austenite and martensite is observed, which suggests an antiferromagnetic order in the martensitic state.
65

Lorentz Group In Polarization Optics

Oktay, Onur 01 September 2012 (has links) (PDF)
The group theory allows one to study different branches of physics using the same set of commutation relations. It is shown that a formulation of the polarization optics that depends on the representations of the Lorentz group is possible. The set of four Stokes parameters, which is a standard tool of polarization optics, can be used to form a four-vector that is physically unrelated but mathematically equivalent to the space-time four-vector of the special relativity. By using the Stokes parameters, it is also possible to generate four-by-four matrix representations of the ordinary optical filters that are traditionally represented with the two-by-two Jones matrices. These four-by-four matrices are treated as the entities of the Lorentz group. They are like the Lorentz transformations applicable to the four-dimensional polarization space. Besides, optical decoherence process can be formulated within the framework of the SO(3,2) de Sitter group. The connection between the classical and quantum mechanical descriptions of the polarization of light allows the extension of the Stokes parameters to the quantum domain. In this respect, the properties of the polarization of the two-photon system can also be studied within the framework of the Lorentz group.
66

Modeling On Rayleigh Scattering In Optical Waveguides

Camak, Burak 01 September 2003 (has links) (PDF)
In the last few years, interest in polymer optical fibers (POF) has increased because of their low cost, easy handling and good flexibility even at large diameters. Moreover, optical cables do not have the problem of electromagnetic interference, which gives, for instance, the problem of cross-talk in copper telephone cables. In the usage of current communication and computer systems the yield has gained a big importance and it has seen from studies that light scattering loss is the only loss, which cannot be eliminated entirely. Besides, this loss causes its attenuation loss intrinsically and determines the lower limit of loss in the POF. In this work, the importance and the dependencies of light scattering were studied, and calculations were done in order to find more appropriate polymer for using as core material of POFs. For this aim, a computer program that calculates the light scattering loss of several amorphous polymers and plots the graph of isotropic scattering loss versus isothermal compressibility and total attenuation loss versus wavelength was written.
67

Design And Realization Of A New Concentrating Photovoltaic Solar Energy Module Based On Lossless Horizontally Staggered Light Guide

Selimoglu, Ozgur 01 January 2013 (has links) (PDF)
Concentrating Photovoltaic systems are good candidates for low cost and clean electricity generation from solar energy. CPV means replacing much of the expensive semiconductor photovoltaic cells with the cheaper optics. Although the idea is simple, CPV systems have several problems inherent to their system design, such as module thickness, expensive PV cells and overheating. Light guide systems are good alternatives to classical CPV systems that can clear off most of the problems of those systems. In this thesis we explore a new light-guide based solar concentrator by optical design and simulations. It is shown that this solar concentrator can reach 1000x geometric concentration, 96.5% optical efficiency with a &plusmn / 1 degree acceptance angle. As a result of simulations, effectiveness of the horizontally staggered light guide solar concentrators is proved. A practical module study is carried on to improve the knowledge related to light guide CPV systems. The concentrator geometry is fabricated as a medium concentrator system with a geometric concentration of 45x and +-2 degrees acceptance angle. With the prototype level injection molding 74% optical efficiency is achieved and can be improved with a better mold manufacturing. A cost analyses is also performed with real manufacturing parameters and it is shown that grid parity can be achieved with this kind of light guide solar concentrators.
68

Erklärungsansätze für die Mitarbeiterzufriedenheit mit Arbeitszeitregelungen

Benkhoff, Birgit, Huhle, Angela, Kühn, Klaus 07 January 2002 (has links) (PDF)
Die Autoren dieses Beitrags beschäftigen sich mit den Bedingungen der Akzeptanz flexibler betrieblicher Arbeitszeitmodelle in der Belegschaft. Dazu wird in einem ersten Schritt ein theoretisches Modell entwickelt, dass die Entstehung von Zufriedenheit bzw. Akzeptanz als eine auf ein Arbeitszeitmodell gerichtete Einstellung erklärt. Ziel eines zweiten Schrittes ist dessen empirische Überprüfung anhand einer Fallstudie in einem Unternehmen der Immobilienbranche, das sein Arbeitszeitmodell ca. 6 Monate vor der Durchführung der Studie flexibilisiert hatte. Basierend auf deren Ergebnissen ist ein dritter Schritt der Entwicklung von Massnahmen für Unternehmen gewidmet, die zur Verbesserung der Akzeptanz flexibler Arbeitszeitmodelle in der Belegschaft beitragen.
69

Simulation Of Thermal, Mechanical And Optical Behavior Of Yag Ceramics With Increasing Nd3+ Concentration Under Lasing Conditions

Kenar, Necmettin 01 May 2007 (has links) (PDF)
Two-dimensional thermal, mechanical and optical simulations are carried out to investigate the effect of Nd3+ concentration on thermal, mechanical and optical behavior of Nd:YAG ceramic laser materials under continuous wave laser operation. In the analyses, rods are pumped longitudinally with laser diodes, in three, six, nine and twelve fold structures. Rods having diameters of 3 and 6 mm are pumped with 808 nm and 885 nm sources separately having Nd+3 concentrations of 0.6, 1, 2, 3, 4 and 6 at. %. Total absorbed pump power are kept constant for all rods. Absorbed pump power distribution are obtained for each rod using ray tracing method and Beer&amp / #8217 / s Law. In the analysis, temperature dependent material properties are incorporated. Nonlinear numerical solutions of thermal and stress equations have been performed. Temperature and stress results are obtained to investigate the effect of Nd concentration on the optical properties of ceramic YAG laser material. Analysis results reveal that, increase in Nd3+ concentration of YAG ceramic laser material, decreases the temperature and stress developed during optical pumping. Rods pumped with 808 nm source have large temperature and stress values compared to 885 nm pumped ones. Optical path difference (OPD) of each ray passed trough the material is calculated using thermal and elastic strain results together with photo-elastic constants of Nd:YAG material. Focal length and depolarization of each rod is calculated numerically from OPD results. Focal length of each rod is found to increase, in contrary depolarization is found to decrease with increase in the dopant concentration.
70

Numerical Simulations On Stimulated Raman Scattering For Fiber Raman Amplifiers And Lasers Using Spectral Methods

Berberoglu, Halil 01 November 2007 (has links) (PDF)
Optical amplifiers and lasers continue to play its crucial role and they have become an indispensable part of the every fiber optic communication systems being installed from optical network to ultra-long haul systems. It seems that they will keep on to be a promising future technology for high speed, long-distance fiber optic transmission systems. The numerical simulations of the model equations have been already commercialized by the photonic system designers to meet the future challenges. One of the challenging problems for designing Raman amplifiers or lasers is to develop a numerical method that meets all the requirements such as accuracy, robustness and speed. In the last few years, there have been much effort towards solving the coupled differential equations of Raman model with high accuracy and stability. The techniques applied in literature for solving propagation equations are mainly based on the finite differences, shooting or in some cases relaxation methods. We have described a new method to solve the nonlinear equations such as Newton-Krylov iteration and performed numerical simulations using spectral methods. A novel algorithm implementing spectral method (pseuodspectral) for solving the two-point boundary value problem of propagation equations is proposed, for the first time to the authors&#039 / knowledge in this thesis. Numerical results demonstrate that in a few iterations great accuracy is obtained using fewer grid points.

Page generated in 0.0255 seconds