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  • 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.
11

Spinduliuotės sklidimas sandūrose su kairinėmis medžiagomis / Propagation of radiation at interfaces with left-handed media

Marcinkevičius, Jonas 30 June 2009 (has links)
Šiame darbe išnagrinėjome paviršines elektromagnetines bangas kairinių medžiagų sandūrose. Tyrėme, ar sandūrose tarp įprastinių aplinkų, kurių μ > 0 ir ε > 0, ir kairinių medžiagų, kurių μ < 0 ir ε < 0, gali susidaryti paviršiniai plazmonai. Įrodėme, kad, kai dviejų aplinkų magnetinės skvarbos , paviršiniai plazmonai visada susiformuoja įprastinės ir kairinės medžiagų sandūroje. Taip pat nustatėme, kad įprastinės aplinkos, kurios , ir kairinės medžiagos aplinkos, kurios , sandūroje, kai ir , gali susiformuoti paviršiniai plazmonai. Ištyrę paviršinių plazmonų susidarymo sąlygas, išanalizavome dažnines dielektrinių ir magnetinių skvarbų priklausomybes ir nustatėme, kad įprastinių aplinkų, kurių , ir kairinių medžiagų aplinkų, kurių , sandūrose paviršiniai plazmonai susidaro, kai metamedžiagų dažniai yra rezonansinių dažnių eilės. / Dielectric materials are characterized by two parameters, magnetic permeability and electric permittivity determining its responseto the electromagnetic radiation. A left-handed material is a material whose permeability and permittivity are simultaneously negative, μ < 0 and ε < 0. Such a material can be a structure composed of metal split ring resonators and rods that causes microwaves to behave in an unusual manner. A left-handed material reverses a basic feature of light. Specifically the phase of the electromagnetic wave propagates in the opposite direction to the energy flow leading to the negative refraction. A possible application of the left-handed materials was suggested in 2000 by Pendry, who considered the optical properties of a rectangular lens made of a slab of negatively refracting material. Some of the radiation waves emitted or reflected by ordinary objects decay very quickly. As a result, the subwave length structural information about the object carried by these ‘evanescent’ waves is lost. Left-handed materials would amplify evanescent wave thus retaining the information they contain and achieving unprecedented resolution that overcomes diffraction limit of conventional imaging. The aim of this work is to analyse the formation of the surface plasmons at an interface between an ordinary material and a metamaterial characterized by negative electric polarisability and negative magnetic permeability. For this purpose we have first analyzed the boundary... [to full text]
12

Implementation of a Microstrip Square Planar N-Way Metamaterial Power Divider

Zong, Junyao January 2008 (has links)
The work done in this thesis focuses on the design of a square-shaped 20-way metamaterial power divider which is fabricated in microstrip technology and operates at 1 GHz. The divider comprises 12 square-shaped left-handed unit cells and 13 square-shaped right-handed unit cells, and these unit cells have the same size and are placed in a checker-board tessellation, where the left-handed unit cells are connected only to right-handed unit cells and vice versa. The divider is based upon the infinite wavelength phenomenon in two-dimensions, and this means that the insertion phase between any two ports of the left-handed unit cell is equal, but with opposite sign, to that of the right-handed unit cell. The divider gives an equal-amplitude equal-phase power division from the central input port to the output ports which are located on a straight line on each side. Thus, it is convenient to integrate with, or interconnect to, other planar circuits in a system, such as power amplifier modules. The design concept can be extended to an N-way power divider, where N = 4n and n is an odd integer.
13

Lateral dominance and directional orientation in the writing of American and Israeli children.

Shimrat, Niusia. January 1970 (has links)
Thesis (Ed.D.)--Teachers College, Columbia University, 1970. / Typescript; issued also on microfilm. Sponsor: Paul E. Eiserer. Dissertation Committee: Anne Selley McKillop. Includes bibliographical references.
14

Composite Right/Left-Handed (CRLH) Microstrip Resonant Antennas

Zhao, Bo 27 September 2005 (has links)
No description available.
15

Hygienické a pracovní návyky u levorukých žáků na 1. stupni ZŠ / Hygienic and Working Habits of Left-handed Pupils at Primary School

KOLÁŘOVÁ, Lucie January 2018 (has links)
The diploma thesis deals with the hygienic and working habits of left-handed pupils at the first level of elementary schools. The thesis is divided into two main parts, theoretical and research. The theoretical part of the thesis deals with basic information about laterality, brain hemispheres and school maturity. The main focus is on leftist and writing, where we focus on preparation for writing and individual hygiene and working habits of pupils. Problems of written speech and famous leftists are also mentioned. The research part is focused on the survey of the level of hygienic and working habits of primary school pupils. The research was conducted in the form of observations. The obtained results are graphically processed and interpreted. In conclusion, there is a recommendation for working with left-handers in practice.
16

Theoretical Investigation Of Metamaterials: Srr Structures And Periodic Arrays Of Thin Conducting Wires

Ates, Kazim Ozan 01 May 2008 (has links) (PDF)
In recent years, there has been an increasing interest on left handed metamaterials because of their possible innovative applications. The pioneer study introducing such materials was brought out by V. G. Veselago in 1968 [1]. In his work, Veselago proposed a medium having simultaneously negative electric permittivity and magnetic permeability and investigated its electromagnetic characteristics. He found out that the electric field, magnetic field and the propagation vector form a left handed triplet, thus named such materials as &ldquo / Left Handed Materials&rdquo / . Despite the significance of Veselago&rsquo / s inferences, the metamaterial theory stayed dormant for nearly 30 years. Towards the end of 1990s, the physically realizable left handed materials were built as the combination of two periodical structures / Split Ring Resonators (SRRs) and metallic thin wire arrays [4-5]. In this thesis, electrical and magnetic characteristics of the left handed metamaterials are theoretically investigated by using the analytical models for their permittivity and permeability functions with respect to frequency. For this purpose, first, two basic metamaterial structures / the Split Ring Resonators and Thin Metallic Wire Arrays are studied individually and their electrical and magnetic characteristics are examined. Finally, the composite left handed structure containing both SRRs and thin wires is studied to investigate the resulting simultaneous resonance properties and to estimate their overall effective permeability and permittivity functions.
17

A handwriting analysis of the achievement of sinistrals in grades three through six

Jones, Marian P. January 1956 (has links)
Thesis (Ed.M.)--Boston University / The intention of this study is to examine the quality and quantitative achievements of two hundred seventy-nine left handed children located in the elementary schools of New England.
18

Development of Bioactive Peptidomimetics

She, Fengyu 01 October 2018 (has links)
Peptidomimetics are synthetic foldamers that expected more resistant to proteolytic degradation and enormous chemodiversity when compared with peptides. To date, the functional peptidomimetics such as β-peptides, peptoids, oligoureas, etc have been developed in many science fields. In order to explore the unnatural foldameric architectures, it’s necessary to discover the novel frameworks and molecular scaffolds. γ-AApeptides were reported to be a new class of peptidomimetics that showed its potential applications in drug discovery and chemical biology. However, a wide function and property of γ-AApeptides need to be further explored. To expand the potential application of γ-AApeptides in biochemistry, I have been focusing on the development of bioactive peptidomimetics, such as exploring the antibacterial activity of helical 1:1 α-sulfono-γ-AA heterogeneous peptides, developing the helical peptidomimetic as the inhibitor of the protein Ras_Raf interaction, identifying the protein/peptide ligands by the novel one-bead-two compound macrocyclic γ-AApeptide screening library, and elucidating the de novo dragon-boat-shaped synthetic foldamers.
19

Optical Studies ofNano-Structures in the Beetle<em>Cetonia Aurata</em><em></em>

Shamim, Rizwana January 2009 (has links)
<p> </p><p> </p><p> </p><p><p>The main</p><p>objective of this thesis is to study the polarization effects of the beetle <em>Cetonia aurata </em>using Mueller-matrix ellipsometry. The outer shell of the beetle consists of complex microstructures which control the polarization of the reflected light. It has metallic appearance which originates from helicoidal structures. When these microstructures are exposed to polarized or unpolarized light, only left-handed circularly polarized light is reflected. Moreover, the exo-skeleton of the beetle absorbs right-handed polarized light. Multichannel Mueller-matrix ellipsometer or dual rotating compensator ellipsometer, called RC2, from J.A.Woollam is used to measure the polarization caused by different parts of beetle’s body. The 16 Mueller matrix elements are measured in the spectral range 400-800 nm at multiple angles of incidencein the range 40<sup>0</sup>-70<sup>0</sup>. An Optical model is developed to help us understand the nature and type of microstructure which only reflects the green colour circularly polarized light. With the help of multiparametric modeling, we were able to find optical properties and structural parameters. The parameters are: the number of layers, the numbers of sub-layers, their thicknesses, and the orientation with respect to optical axes. This optical model describes the nanostructures which provide the reflection properties similar to the nanostructure found in the beetle <em>Cetonia aurata. </em>The model is also useful for analysis of the optical response data of different materials with multilayer structures.</p></p><p> </p>
20

Optical Studies ofNano-Structures in the BeetleCetonia Aurata

Shamim, Rizwana January 2009 (has links)
The main objective of this thesis is to study the polarization effects of the beetle Cetonia aurata using Mueller-matrix ellipsometry. The outer shell of the beetle consists of complex microstructures which control the polarization of the reflected light. It has metallic appearance which originates from helicoidal structures. When these microstructures are exposed to polarized or unpolarized light, only left-handed circularly polarized light is reflected. Moreover, the exo-skeleton of the beetle absorbs right-handed polarized light. Multichannel Mueller-matrix ellipsometer or dual rotating compensator ellipsometer, called RC2, from J.A.Woollam is used to measure the polarization caused by different parts of beetle’s body. The 16 Mueller matrix elements are measured in the spectral range 400-800 nm at multiple angles of incidencein the range 400-700. An Optical model is developed to help us understand the nature and type of microstructure which only reflects the green colour circularly polarized light. With the help of multiparametric modeling, we were able to find optical properties and structural parameters. The parameters are: the number of layers, the numbers of sub-layers, their thicknesses, and the orientation with respect to optical axes. This optical model describes the nanostructures which provide the reflection properties similar to the nanostructure found in the beetle Cetonia aurata. The model is also useful for analysis of the optical response data of different materials with multilayer structures.

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