Dissertations / Theses on the topic 'State mode'
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Ånstrand, Melina. "State of mind." Thesis, Konstfack, Textil, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-3563.
Full textTextil formgivning / Master 2009 Textile in the Expanded Field
Ritsataki, Aliki. "A numerical model of Kerr-Lens mode-locking in solid-state lasers." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325064.
Full textKrist, Peter. "Diamagnetic mode of open gradient magnetic separation." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244846.
Full textChesworth, Andrew Alexander. "Mode control in thin slab, diode pumped solid state lasers." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/649.
Full textScharnhorst, Nils [Verfasser]. "Multi-mode ground state cooling of trapped ions / Nils Scharnhorst." Hannover : Technische Informationsbibliothek (TIB), 2018. http://d-nb.info/1166269965/34.
Full textMajor, Arkady. "Diode-pumped passively mode-locked ultrashort pulse solid-state lasers." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273384.
Full textMu, Jianqiu. "State feedback sliding mode control of complex systems with applications." Thesis, University of Kent, 2018. https://kar.kent.ac.uk/65793/.
Full textMcConnell, Gail. "Nonlinear optical frequency conversion of mode-locked all-solid-state lasers." Thesis, University of Strathclyde, 2001. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=20367.
Full textHechenblaikner, Gerald. "Mode coupling and superfluidity of a Bose-Einstein condensed gas." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249397.
Full textGuerreiro, Paulo Tiago Ferraz de Meira 1967. "Solid-state laser mode-locking and ultrafast studies in quantum semiconductor structures." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282515.
Full textGu, Min. "Raman Mode-Selective Spectroscopic Imaging of Redox State in FMN and Flavoprotein." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1398866391.
Full textRanjit, Narendran. "Multiagent Referral Systems: Maintaining and Applying Trust and Expertise Mode." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-05112007-143631/.
Full textKay, Benjamin P. "Resting-State Functional Connectivity in Treatment-Resistant Idiopathic Generalized Epilepsy." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1380612937.
Full textHo, Bo-shan, and 何寶山. "State policy and urban politics in Hong Kong: a mode of production analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31976256.
Full textHo, Bo-shan. "State policy and urban politics in Hong Kong : a mode of production analysis /." [Hong Kong : University of Hong Kong], 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13008912.
Full textPrasankumar, Rohit Prativadi 1975. "Development and application of saturable absorbers to femtosecond solid-state laser mode-locking." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29620.
Full textIncludes bibliographical references (p. 209-228).
Semiconductor saturable absorbers have had a major impact on the field of ultrashort pulse generation by increasing the stability and reliability of ultrashort pulse lasers, making them more useful in many applications. These versatile devices can be grown both epitaxially with molecular beam epitaxy and non-epitaxially using RF sputtering. In this thesis, the development and application of both types of saturable absorbers to self-starting mode-locking in solid-state lasers was examined. The first part of this thesis describes the use of an epitaxially grown saturable Bragg reflector to mode-lock an extended cavity femtosecond Cr:LiSAF laser. Inexpensive single mode diodes were used as a pump source and a multi-pass cavity was used to lower the laser repetition rate. Pulses with durations of 39 fs and energies of 0.75 nJ were generated at an 8.6 MHz repetition rate. These pulse energies and durations are comparable to those produced from commercially available Ti:sapphire lasers that have a significantly higher cost. The second part of this thesis explored the further development and application of non-epitaxially grown semiconductor-doped silica films. A novel pump-probe system with independent pump and probe wavelength tunability from 700 to 1000 nm and a time resolution of 17 fs was developed for device characterization. The linear and nonlinear optical properties of InAs-doped silica films deposited by RF sputtering were characterized as a function of fabrication parameters, including nanocrystallite size, pump and probe wavelength relative to the absorption edge, and rapid thermal annealing temperature. Guidelines for the optimization of semiconductor-doped silica films for saturable absorber applications were extracted from the experimental data.
(cont.) Large nanocrystallites, high annealing temperatures, and an operating wavelength close to the absorption edge were found to optimize saturable absorber performance, with a low saturation fluence of 640 pJ/cm2 obtained at 1.54 grm. These saturable absorber devices were then designed to self-start mode-locking in a Cr:forsterite laser, obtaining self-starting 25 fs pulses with 91 nm bandwidth at 1.3 gm. These versatile devices can be designed for any solid-state laser system using the guidelines developed in this work and have the potential to replace epitaxially grown saturable absorbers in many applications.
by Rohit Prativadi Prasankumar.
Ph.D.
Reed, Mark W. (Mark Wilbert). "A steady-state L-mode tokamak fusion reactor : large scale and minimum scale." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58088.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 69-70).
We perform extensive analysis on the physics of L-mode tokamak fusion reactors to identify (1) a favorable parameter space for a large scale steady-state reactor and (2) an operating point for a minimum scale steady-state reactor. The identification of the large scale parameter space is part of the 2008 MIT Nuclear Systems Design Project, which also includes sustainability and economic optimizations to identify a plausible operating point for a large scale (a 14 m major radius) hydrogen production reactor dubbed HYPERION. Due to the potentially prohibitive capital cost (a $50 billion) and exorbitant thermal power (a 35 GWth) of HYPERION, we identify a conservative estimate for the minimum scale of a similar steady-state L-mode reactor of approximately 7.5 meters, half the size of HYPERION and only 20% larger than ITER. This minimum scale reactor would require an on-coil magnetic field of a 16 T and a blanket power density of ~ 5 MW/m 2 . It would produce 7 GWth of power with a power gain of 30, and it would operate far from all stability and confinement limits. To confirm the viability of this operating point, we perform various 1-D calculations. The crucial advantage of a steady-state (or fully non-inductive) reactor is that it is not limited by flux swing and can operate continuously, recharging its solenoid during operation. The crucial advantages of L-mode are that it avoids instabilities associated with edge localized modes (ELMs) and that it allows volumetric heating in the mantle due to the absence of a pedestal. Steady-state L-mode tokamak reactors could be the future of controlled fusion research and even play an important role in meeting the world's clean energy needs.
by Mark Reed.
S.B.
Robinson, Karen E. (Karen Elizabeth) 1980. "Stabilization of passively mode locked solid-state lasers by use of electronic feedback." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87894.
Full textIncludes bibliographical references (p. 51-52).
by Karen E. Robinson.
M.Eng.
Majdabadi, Abbas. "Investigation and development of mode-locking techniques of diode pumped solid-state lasers." Thesis, University of Southampton, 1994. https://eprints.soton.ac.uk/399138/.
Full textSeger, Kai. "Compact solid-state lasers in the near-infrard and visible spectral range." Doctoral thesis, KTH, Laserfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121976.
Full textQC 20130507
Aitken, Victor C. (Victor Charles) Carleton University Dissertation Engineering Systems and Computer. "Sliding mode state estimation for nonlinear discrete-time systems; applications in image sequence analysis." Ottawa, 1995.
Find full textNguyen, Van Liem. "Modeling and control coordination of power systems with FACTS devices in steady-state operating mode." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0036.
Full textBirge, Jonathan R. (Jonathan Richards). "A preconditioned Newton-Krylov method for computing steady-state pulse solutions of mode-locked lasers." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/42454.
Full textIncludes bibliographical references (p. 47-48).
We solve the periodic boundary value problem for a mode-locked laser cavity using a specially preconditioned matrix-implicit Newton-Krylov solver. Solutions are obtained at least an order of magnitude faster than with dynamic simulation, the standard method. Our method is demonstrated experimentally on a one-dimensional temporal model of an eight femtosecond mode-locked laser operating in the dispersion-managed soliton regime. Our solver is applicable to finding the steady-state solution of any nonlinear optical cavity with moderate self phase modulation, such as those of solid state lasers, and requires only a model for the round-trip action of the cavity. We conclude by proposing avenues of future work to improve the method's convergence and expand its applicability to lasers with higher degrees of cavity nonlinearity. Our approach can be extended to spatio-temporal cavity models, potentially allowing for the first feasible simulation of the full dynamics of Kerr-lens mode locking.
by Jonathan R. Birge.
S.M.
Reed, Mark Wilbert. "A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76535.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 215-218).
The most prevalent criticism of fission-fusion hybrids is simply that they are too exotic - that they would exacerbate the challenges of both fission and fusion. This is not really true. Intriguingly, hybrids could actually be more viable than stand-alone fusion reactors while mitigating many challenges of fission. This work develops a conceptual design for a fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with a subcritical natural or depleted uranium pebble bed blanket. A liquid lithiumlead alloy breeds enough tritium to replenish that consumed by the D-T fusion reaction. Subcritical operation could obviate the most challenging fuel cycle aspects of fission. The fission blanket augments the fusion power such that the fusion core itself need not have a high power gain, thus allowing for fully non-inductive (steady-state) low confinement mode (L-mode) operation at relatively small physical dimensions. A neutron transport Monte Carlo code models the natural uranium fission blanket. Maximizing the fission power while breeding sufficient tritium allows for the selection of an optimal set of blanket parameters, which yields a maximum prudent fission power gain of 7.7. A 0-D tokamak model suffices to analyze approximate tokamak operating conditions. If the definition of a "reactor" is a device with a total power gain of 40, then this fission blanket would allow the fusion component of a hybrid reactor with the same dimensions as ITER to operate in steady-state L-mode very comfortably with a fusion power gain of 6.7 and a thermal fusion power of 2.1 GW. Taking this further can determine the approximate minimum scale for a steady-state L-mode tokamak hybrid reactor, which is a major radius of 5.2 in and an aspect ratio of 2.8. This minimum scale device operates barely within the steady-state L-mode realm with a thermal fusion power of 1.7 GW. This hybrid, with its very fast neutron spectrum, could be superior to pure fission reactors in terms of breeding fissile fuel and transmuting deleterious fission products. It could operate either as a breeder, producing fuel for pure fission reactors from natural or depleted uranium, or as a deep burner, fissioning heavy metal and transmuting waste with a cycle time of decades. Despite a plethora of potential functions, its primary mission is deemed to be that of a deep burner producing baseload commercial power with a once-through fuel cycle. Although hybrids are often purported a priori to pose an elevated proliferation risk, this reactor breeds plutonium that could actually be more proliferation-resistant than that bred by fast reactors. Furthermore, a novel method (the "variable fixed source method") can maintain constant total hybrid power output as burnup proceeds by varying the neutron source strength. As for engineering feasibility, basic thermal hydraulic analysis demonstrates that pressurized helium could cool the pebble bed fission blanket with a flow rate below 10 m/s. The Brayton cycle thermal efficiency is 41%. This device is dubbed the Steady-State L-Mode Non-Enriched Uranium Tokamak Hybrid (SLEUTH). The purpose of this work is not any sort of elaborate design, but rather the exploration of an idea coupled with corroborating numerical analysis. At this point in the hybrid debate, viable conceptual designs are persuasive while intricate build-ready designs are superfluous. This work conceives such a conceptual design, demonstrates its viability, and will perhaps, incidentally, spur a profusion of pro-fusion sentiment!
by Mark Wilbert Reed.
S.M.
Eibna, Halim Md Zubaer. "Passively mode-locked picosecond Nd:KGW laser with low quantum defect diode pumping." Astro Ltd, 2016. http://hdl.handle.net/1993/31913.
Full textFebruary 2017
Sholtis, Tadd. "One helluva roar : US Air Force public communication since 1942 /." Maxwell AFB, Ala. : School of Advanced Air and Space Studies, 2008. https://www.afresearch.org/skins/rims/display.aspx?moduleid=be0e99f3-fc56-4ccb-8dfe-670c0822a153&mode=user&action=downloadpaper&objectid=f6ea7bb1-2b97-4d90-8b90-1cf4474c5a7c&rs=PublishedSearch.
Full textAblay, Gunyaz. "Sliding Mode Approaches for Robust Control, State Estimation, Secure Communication, and Fault Diagnosis in Nuclear Systems." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354551858.
Full textBrunzell, Martin. "Free-Space Dark Pulse Mode-Locked Laser." Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296524.
Full textFramtagningen av ljusa pulser i kristall baserade lasrar finns i en stor utsträckning av tillämpningar inom forskning och industri. Utvecklandet av mörkpulskällor i kristall baserade kaviteter har till vår kunskap inte tagits fram. I detta arbete presenteras en metod att utveckla en modlåst mörkpuls laser i en rak kavitet som utnyttjar intrakavitär förlust som periodiskt induceras av en ickelinjär interaktion som styrs av en ljus modlåst källa. Vi kan visa att en mörk puls propagerar inuti kaviteten. En utförlig analys och experiment med hjälp av en hemagjord korskorrelator belyser hur den mörka pulsen kan formas. En symmetrisk mörk puls formas med en 10 ps bredd och över 90 % modulations djup. Detta arbete kommer användas i ett framtida projekt inom passiv tvåfärgs puls synkronisation.
Oh, Yunje. "Prediction of steady state response in dynamic mode atomic force microscopy and its applications in nano-metrology." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1135222817.
Full textSenkel, Luise [Verfasser]. "Sliding Mode Techniques for Robust Control, State Estimation and Parameter Identification of Uncertain Dynamic Systems / Luise Senkel." Aachen : Shaker, 2018. http://d-nb.info/1159833230/34.
Full textOh, Yunje. "Prediction of steady state response in dynamic mode atomic force microscopy and its applications in nano-metrology." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1135222817.
Full textAyachit, Agasthya. "Steady-State and Small-Signal Modeling of A-Source Converter." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1534187954423628.
Full textZhao, Haitao. "Powerful diode-pumped ultrafast solid-state laser oscillators based on bulk Yb:KGd(WO4)2 crystals." IOP Publishing, 2010. http://hdl.handle.net/1993/30413.
Full textWang, Yicheng [Verfasser]. "Passive mode-locking of 2-μm solid-state lasers : Towards sub-10 optical cycle pulse generation / Yicheng Wang." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1147758271/34.
Full textFirdaus, Ahmad Riyad. "Design of sliding mode-based nonlinear control systems with nonlinear full-order state observers for underactuated coupled systems." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/20897/.
Full textPiloyan, Torgom. "How does the ethnic kinship affect the mode of provided external support in an intra-state armed conflict?" Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-361641.
Full textPaleocrassas, Alexander Grant. "Feasibility Investigation of Laser Welding Aluminum Alloy 7075-T6 through the use of a 300 W, Single-Mode, Ytterbium Fiber Optic Laser." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-08062005-173047/.
Full textDurmaz, Burak. "Sliding Mode Control Of Linearly Actuated Nonlinear Systems." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610666/index.pdf.
Full textGold, Carrie Elizabeth. "Exploring the Resting State Neural Activity of Monolinguals and Late and Early Bilinguals." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6671.
Full textRytty, R. (Riikka). "Resting-state functional MRI in behavioral variant of frontotemporal dementia." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211336.
Full textTiivistelmä Otsa-ohimolohkorappeuma (Frontotemporal lobar degeneration, FTLD) on toiseksi yleisin etenevä dementiaan johtava sairaus, joka ilmaantuu usein jo työikäisenä. Otsalohkodementia on otsa-ohimolohkorappeuman yleisin alamuoto, jonka oireisto painottuu persoonan ja käyttäytymisen muutoksiin sekä toiminnan ohjauksen ongelmiin. Suomessa C9ORF72-toistojaksomutaatio selittää lähes 50 % perinnöllisistä otsa-ohimolohkorappeumista. Aivojen rakenteellisella magneettikuvauksella (MK) voidaan havaita rakenteellisia muutoksia, jotka ilmaantuvat kuitenkin vasta taudin edettyä vaikeampaan vaiheeseen. Aivojen lepotilan toiminnallinen magneettikuvaus (TMK) mahdollistaa aivojen hermoverkkojen toiminnan eli konnektiviteetin kartoituksen. Aiemmin TMK:a on tutkittu esim. Alzheimerin taudissa. Otsalohkodementiassa TMK:sta on julkaistu ainoastaan yksittäisiä tutkimuksia ja tulokset ovat olleet osin ristiriitaisia. Väitöskirjatutkimuksen tarkoituksena on ollut selvittää valve-lepotilan hermoverkossa ja olennaisen tunnistavassa hermoverkossa tapahtuvia muutoksia otsalohkodementiaa sairastavilla potilailla. Toisena tavoitteena on ollut tutkia muissa kognitiivisissa hermoverkoissa tapahtuvia muutoksia. Otsalohkodementiaa sairastaville potilaille (n= 26) sekä ikä- ja sukupuolivakioiduille kontrolleille on tehty kliininen tutkimus ja rakenteellinen sekä toiminnallinen aivojen magneettikuvaus. Kahdeksalla potilaalla todettiin C9ORF72-toistojaksomutaatio. Useiden kognitiivisten hermoverkkojen toiminnassa havaittiin muutoksia, jotka korreloivat potilaiden kliinisiin oireisiin. Alentunutta konnektiviteettia todettiin olennaisen tunnistavassa hermoverkossa, joka osallistuu käyttäytymisen säätelyyn. Lisääntynyttä konnektiviteettia esiintyi valve-lepotilan hermoverkossa ja tarkkaavaisuus hermoverkossa. Potilailla, joilla on C9ORF72-mutaatio, havaittiin epänormaali yhteys valve-lepotilan hermoverkon ja talamuksen välillä. TMK:ta käytetään tällä hetkellä lähinnä tutkimustyökaluna. Analyysityökaluissa on ollut vaihtelevuutta eri julkaisuissa ja osin myös tämän väitöskirjan osatöissä. Julkaistut TMK-löydökset otsalohkodementiassa ovat osin ristiriitaisia ja se saattaa selittyä erilaisilla analyysimenetelmillä. Metodologiaa tulisi standardisoida ja lisäksi tarvitaan suurempia potilasryhmiä ja menetelmien kehittämistä, jotta TMK:n käyttö yksilötason kliinisessä diagnostiikassa olisi jatkossa mahdollista
Thorette, Aurélien. "Synchronization dynamics of dual-mode solid-state and semiconductor DFB lasers under frequency-shifted feedback : applications to microwave photonics." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S059/document.
Full textThe control of the frequency difference between two lasers is a cross-cutting challenge in many fields of photonics, either for the generation of high-purity heterodyne microwave beatnotes, or in metrology and telecommunication experiments. The advances of the comprehension of laser dynamics under various couplings has allowed to develop stabilization methods based on optical injection. We study here theoretically and experimentally a mechanism called frequency-shifted feedback (FSF), which allows to precisely control the frequency difference between two lasers in several situations.First, the FSF method is applied to a dual-frequency dual-polarization solid-state Nd:YAG laser, in order to lock the phases of its two orthogonal polarization modes. A model of rate equations is used to precisely describe the experiment, and allows to highlight partial "bounded phase" synchronization regimes. Furthermore, we show that in some cases this synchronization can subsist even with chaotic oscillations of the intensity and phase. The behavior of the laser under FSF is studied for varying values of the frequency detuning, injection rate, possible injection delay, and mode coupling in the active medium. Finally, we find that the inclusion of a phase-amplitude coupling (non-zero linewidth enhancement factor) is needed in the model to account for experimental observation. This leads to the development of an ad-hoc technique to measure the low value of this usually neglected factor in solid-laser lasers.The FSF stabilization mechanism is then applied to a custom semiconductor component embedding two DFB lasers overs InP. In spite of a more complex coupling scheme and the large effective delays into play, phase locking of the two lasers is possible. Due to the delay, locking bands appear when the detuning changes, and this behavior can be replicated using a numerical model. This model also permit to determine working conditions minimizing the influence of uncontrolled experimental optical feedback phases. Finally, as this system allows to control a microwave phase over an optical carrier, it can be integrated in a resonant loop not unlike an opto-electronic oscillator (OEO). We realized an oscillator generating a self-referenced, single sideband microwave signal over an optical carrier, with encouraging phase noise performances. In this case, it seems that most of the techniques that exist for standard OEO can be reused
Chwan-Horng, Goan, and 管傳鴻. "Complete State Integral Sliding Mode Control." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/87257380501949220404.
Full text中原大學
電機工程學系
87
A complete state integral sliding mode control is proposed in this paper. The complete state means the whole process or response of the controlled state. The sliding mode that can occur from the very beginning is done through the combination of three steps, the proper choice of initial values in sliding functions, the linear state feedback, and the integral feedback of system dynamics. The proposed sliding mode can solve the robust problem of classical sliding mode control during the reaching mode in which the high gain feedback control is applied. Lyapunov’s method is used to ensure the existence of sliding surface and result in the design of relative control inputs. The stability analysis is perfectly improved through the redesign of control gains and the transform of the sliding functions. The proposed method is not only a simple control method, but also gives a generalized form in order to apply upon the systems that encounter uncertainties and need the reduction of perturbations and the assurance of stability from the very beginning. It can be applied either on linear or nonlinear systems. The simulations are performed for tracking control of a permanent magnetic synchronous motor drive system and a two-link manipulator. The results of simulations give illustrative examples that demonstrate expected satisfactory performances. The proposed method is not only of the lowest constraint of generalization, but also suitable to a wide scope of application areas including control in linear, nonlinear, single-input and multi-input systems. It can be utilized together with basic or conventional methodologies and gives choices of design methods for different control constraints or requirements. Integration of various control methods is just a good feature of that proposed.
Liu, Tzu-Ming. "High Repetition-rate Mode-locked Solid-state Lasers." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2007200415234900.
Full textTian, Jining. "Forwarding state reduction for sparse mode multicast communication." Thesis, 1997. http://hdl.handle.net/2429/6595.
Full textLiu, Tzu-Ming, and 劉子銘. "High Repetition-rate Mode-locked Solid-state Lasers." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/57715888223062854001.
Full text國立臺灣大學
光電工程學研究所
92
High repetition rate (HRR) mode-locked solid-state lasers have increasing importance in many applications. In optical communications, it’s a potential source for the hybrid wavelength-division multiplexed (WDM) and optical time-division multiplexed (OTDM) systems. In frequency metrology, HRR lasers can increase the resolution and signal to noise ratio (SNR) of frequency measurement. In the domain of measuring applications, HRR lasers reduce the optical pulse energy while maintaining a high average power, which is important for achieving high SNR. Although HRR mode-locked lasers are advantageous to these applications, there are still some hindrances for better development. In WDM/OTDM hybrid communication system, it still lacks a high power HRR multi-channel source to exploit the spectral domain resources. In frequency metrology, there are still some spectral black holes corresponding to specific transition level of atoms or molecules. Besides, once a HRR mode-locked solid-state laser is built, the repetition rate can’t be easily multiplied without changing the cavity geometry. In this thesis, we circumvented these hindrances and made HRR mode-locked lasers more promising and more flexible in many HRR applications. Complete information of HRR pulses can be characterized with developed auxiliary technique. For the problem of spectral black holes, we employed frequency conversion such as second harmonic generation (SHG) to achieve HRR femtosecond lasers at red and blue wavelengths. Based on an 110-MHz Cr:forsterite laser, we first used intracavity frequency doubling to obtain HRR femtosecond pulses around 620-nm. Red pulses with 170-fs pulse width were obtained with 24-mW average power. For the frequency conversion of short cavity length, it’s better to employ external resonant cavity to enhance the conversion efficiency. As a consequence, based on a 2-GHz Ti:sapphire laser, we demonstrated a 2-GHz-repetition-rate high-power femtosecond blue sources for the first time. Pumped by the 2-GHz Ti:sapphire laser with 740-mW output power, 150-mW femtosecond pulses at 409nm can be efficiently generated from the resonant cavity. For the development of high power WDM/OTDM sources, we exploit the broadband nature of HRR femtosecond lasers and demonstrated first high power HRR multi-channel sources. By inserting an intracavity etalon into a HRR femtosecond Cr:forsterite laser, 12 phase-locked channels with 9–19-ps pulse width near 1230 nm could be generated. Average output power of 280-mW can be obtained from a single laser oscillator. By tuning the etalon bandwidth, we can shorten the pulse width in a specific channel to 1.8 ps. For the improvement of repetition rate flexibility, we invented an intracavity flat surface technique to multiply the repetition rate. We first built a compact self-started HRR Cr:forsterite laser at 100-MHz for the application of portable clinical use operating around 1230 nm. Instead of prism pairs, double-chirped mirrors were employed to compensate the group delay dispersion of the laser cavity. The laser mode-locking was self-started with the help of a semiconductor saturabe absorber mirror. By adopting an intracaity flat surface with low reflectivity and controlling the ratio of subcavity lengths, the repetition rate of this compact femtosecond Cr:forsterite laser can be multiplied from 100 MHz to 500 MHz in femtosecond regime. Repetition rate higher than 1GHz can also be achieved. Compared with the conventional coupled cavity method, this newly developed technique provides a flexible and phase insensitive way to increase the repetition rate of femtosecond solid-state lasers. For the diagnosis of ultrashort HRR pulses, we developed a new technique. By adding spectral information into triple-optical-autocorrelation measurements, we made the triple-autocorrelation method capable of providing complete knowledge of HRR laser pulses. With the measured temporal intensity of an optical pulse and its corresponding spectral intensity obtained with a spectrometer, exact intensity and phase variations in time can all be recovered with the Gerchberg-Saxton algorithm through an iterative calculation with an O(n) complexity.
Hsieh, Hung Dau, and 謝弘道. "Diode-Pumped Passive Mode-Locked Solid-State Laser:Semiconductor Saturable Absorber(SESAM) versus Nonlinear Mode-Locked." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/81286425317422796073.
Full text國立交通大學
電子物理系
90
The study of Nd:YVO4 and Nd:GdVO4 lasers pumped by a continuous-wave diode laser has increased in recent years. Even though Nd:GdVO4 has superior crystal properties than Nd:YVO4,its efficiency on the diode-end-pumped cw mode-locked laser has never been investigated. In this paper we study and compare the two different gain mediums, Nd:YVO4 and Nd:GdVO4, on the cw mode-locked laser with both the nonlinear mirror (NLM) and semiconductor saturable absorber mirror (SESAM) mechanisms. These two mode-locked mechanisms as well as the ultra-short pulse generation theory will be investigated and presented with the theoretical simulations and experimental results. Physical criteria for the characteristics of both NLM and SESAM will also be developed in this paper. Taking into account the nonlinear effects of nonlinear crystal and SESAM, we intend to modify Dr. Stankov’s theory in NLM cw mode-locked lasers and present new parameters for generating short pulse in SESAM.
Yeh, Cheng-Hsuan, and 葉丞軒. "DESIGN OF ADAPTIVE FUZZY SLIDING MODE CONTROLLER WITH STATE OBSERVER." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/46594759813953754610.
Full text大同大學
電機工程研究所
91
In this thesis, an observer-based adaptive fuzzy sliding mode controller for a certain class of unknown nonlinear dynamical system is presented. The total states of the nonlinear system are not to be available for measurement; hence a state observer will be designed to estimate the nonlinear system states. By using an observer-based output feedback control law and adaptive law, the parameters of the adaptive fuzzy sliding mode controller can be tuned based on the Lyapunov stability analyzes. Moreover, we provide a weighting factor, it will be adjusted by the plant knowledge or by the control information, namely, if the plant knowledge is more important and reliable than control information, we should choose a larger factor; otherwise, a smaller factor should be chosen. According to the weighting factor, we can find the control input for the nonlinear system. We apply the adaptive fuzzy sliding controller to control an inverted pendulum system and a Duffing forced oscillation system, the simulation results demonstrate the applicability of the proposed method.
Sheu, Chich-Chang, and 許智章. "Mode Degenerate Effects in an End-Pumped Solid State Laser." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/62205390018941650782.
Full text國立交通大學
光電工程研究所
86
In this thesis, we study the mode degenerate effects on the output of a Nd: YVO4 laser end-pumped by a diode laser. When the cavity length is adjusted near the position of mode degeneracy we find an increase in total power, a decrease in the fundamental mode power and the instability in output power along with the emergence of multiple transverse modes. Besides, we also find lower threshold pump power taking place a around these positions. this study shows that the mode degenerate effect should be taken into account in the design of end-pumped solid state lasers.
Yu-Pin, Lan, and 藍宇彬. "Research on fundamental mode and high-order transverse modes in diode-pumped solid-state laser." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/74959309637602146423.
Full text國立交通大學
光電工程所
91
One issue of this dissertation is to study the influence of pump-to-mode overlap in the slope efficiency and output beam quality in diode end-pumped solid-state lasers. The space-dependent rate equations were employed to analyze the thermal effects in CW and Q-switched end-pumped solid-state lasers. Including the thermal effects into the cavity design, a 30W of TEM00 CW mode output power with good beam quality and near 1 mJ pulse energy in Q switched operation were developed. The other issue of this dissertation is to study the formation of high-order transverse modes in a microchip laser. Experimentally, a technology based on a doughnut pump profile was developed to generate pure Laguerre-Gaussian (LG) TEM*0,l modes. In addition, the dynamics of a solid-state laser sustaining the oscillation of the Laguerre-Gaussian TEM*0,l mode is investigated theoretically and experimentally. On the other hand, a new type of laser transverse modes was demonstrated in an isotropic microchip laser with a doughnut pump profile. The observed transverse modes include elliptic and hyperbolic wave patterns that are analogous to the quantum states of classical trajectories of a 2D harmonic oscillator. Finally, it was found that the transverse pattern of optical vortex lattices could be generated by controlling the transverse mode spacing, the mode size and pump profile.
Ibrahim, Khaled Z. "Slipstream execution mode for CMP-based shared memory systems." 2003. http://www.lib.ncsu.edu/theses/available/etd-04252003-123737/unrestricted/etd.pdf.
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