Sökning: "near field"

Visar resultat 1 - 5 av 516 avhandlingar innehållade orden near field.

  1. 1. Optimal Near-field Antenna Apertures in Lossy Media

    Författare :Aidin Razavi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; optimal near-field aperture; near-field focusing; near-field antennas; near-field power transfer; array signal processing.; maximum penetration;

    Sammanfattning : Antennas are traditionally designed for far-field applications such as wireless communications, radar, etc., where the antenna systems interact with other systems and objects which are located in the far-field zone of the antennas. LÄS MER

  3. 2. Characterization and Design Requirements for Antennas in the Near-field and the Random-LOS Propagation Environment

    Författare :Aidin Razavi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; polarization-MIMO; Random-LOS; OTA; Antenna measurements; near-field antennas; antenna characterization; MIMO; near-field focusing;

    Sammanfattning : The choice of antenna for a particular application depends on the requirements imposed by that application. These can be, the application's field region (i.e., near-field or far-field), polarization, radiation pattern, radiation efficiency, system throughput, etc. LÄS MER

  4. 3. Single layer near-field acoustic imaging in space-invariant reflective environments

    Författare :Elias Zea; Ines Lopez Arteaga; Efren Fernandez-Grande; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; near-field acoustic holography; field separation techniques; single layer; space-invariance; reflective envirionments; närfält akustisk holografi; fältseparationstekniker; enkelt lager; utrymmes invarians; reflekterande miljöer; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : The visualization of optical fields, or widely known as photography, is a common practice that can also be applied to acoustic fields. No less than three decades of research in acoustic imaging demonstrate its potential and relevance in plenty applications such as sound source identification and localization, as well as characterization of noise generation mechanisms. LÄS MER

  5. 4. Near field immobilization of selenium oxyanions

    Författare :Anders Puranen; Mats Jonsson; Christophe Jegou; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Se-79; Selenium; Immobilization; Redox; Iron; Corrosion; Palladium; Catalyst; Spent Nuclear Fuel; Repository; Nuclear chemistry; Kärnkemi;

    Sammanfattning : The topic of this doctoral thesis is the potential near field immobilization of the radionuclide 79Se after intrusion of groundwater into a spent nuclear fuel canister in a repository. 79Se is a non naturally occurring long lived selenium isotope formed as a result of fission in nuclear fuel. LÄS MER

  7. 5. Sound field separation with microphone arrays

    Författare :Elias Zea; Ines Lopez Arteaga; Mats Åbom; Leif Kari; Jean-Hugh Thomas; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound field separation; Microphone arrays; Near-field acoustic holography; Reflecting surfaces; Railway rolling noise; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : Sound field analysis is a fundamental tool in the design, manufacturing, testing and diagnosis of machines and transportation means, as well as the legislations that regulate noise levels in order to minimize environmental pollution. Customary solutions to the problem of sound field analysis are microphone array technologies such as near-field acoustic holography (NAH) and beamforming. LÄS MER