Avancerad sökning

Visar resultat 1 - 5 av 104 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Localization, supersymmetric gauge theories and toric geometry

    Författare :Jacob Winding; Maxim Zabzine; Sara Pasquetti; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supersymmetry; gauge theory; localization; toric geometry; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : Gauge theories is one of the most pervasive and important subject of modern theoretical physics, and there are still many things about them we do not understand. In particular dealing with strongly coupled theories where normal perturbative techniques do not apply is a fundamental open problem. LÄS MER

  3. 2. Voltage Transients in the Field Winding of Salient Pole Wound Synchronous Machines : Implications from fast switching power electronics

    Författare :Roberto Felicetti; Urban Lundin; Jon Kjellin; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency;

    Sammanfattning : Wound Field Synchronous Generators provide more than 95% of the electricity need worldwide. Their primacy in electricity production is due to ease of voltage regulation, performed by simply adjusting the direct current intensity in their rotor winding. LÄS MER

  4. 3. Run-Up Transient Analysis for Salient Pole Wound Field Synchronous Motors : Field winding and power electronics implications for a smoother and cooler asynchronous start

    Författare :Roberto Felicetti; Urban Lundin; Andreas Binder; Uppsala universitet; []
    Nyckelord :apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency; asynchronous start; run-up; torque ripple; reluctance torque; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : Salient Pole Wound Field Synchronous Machines have better efficiency at full load than asynchronous machines of the same capability. Moreover, where asynchronous machines need inherently to draw a magnetizing current from the grid, Salient Pole Wound Field Synchronous Machines can work efficiently at unity power factor. LÄS MER

  5. 4. Partial Discharges in Large Rotating Machines - Continuous On-line Monitoring and Localisation, Based on a New Developed Technique (InTech)

    Författare :Abkar Kheirmand; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; InTech; detection; on-line monitoring; insulation; stator; condition control; PD measurement; Powerformer; winding; rotating machine; partial discharge;

    Sammanfattning : Partial discharges (PD) that originate from dielectrically defective parts of the insulation system result in its degradation, which may ultimately lead to a failure of high voltage apparatus. This has resulted in development of numerous PD measuring techniques. One of the most widespread applications of PD measurement is in rotating machines. LÄS MER

  7. 5. Den raka och den krokiga vägen : om genus, ingenjörer och teknikkarriärer

    Författare :Line Holth; Ann Bergman; Lena Gonäs; Ulf Mellström; Mari Teigen; Karlstads universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Gender; technology; gender stereotypes; choice of education; gender segregation; working life; fatherhood; masculinities; technology careers; IT engineers; mechanical engineers; genus; teknik; könsstereotyper; utbildningsval; könssegregering; arbetsliv; faderskap; maskuliniteter; teknikkarriärer; IT-ingenjörer; maskiningenjörer; Working Life Science; Arbetsvetenskap;

    Sammanfattning : Abstract The purpose of this doctoral thesis is to shed light on, explain, and problematize women’s and men’s paths both to and within the profession of engineer. Computer and mechanical engineers are in focus and the overarching issues that this thesis attempts to answer are: How can women’s and men’s paths to the profession of engineer be explained and what has governed/motivated their choice of education? How do women’s and men’s career patterns look in professional life, and how can these patterns be explained? This study is based on a social-constructivistic approach, entailing a focus on how choices of education and profession have been negotiated through social and cultural practices, norms, and values. LÄS MER