418,965 research outputs found
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
No full textRepetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
Interview with Theodore Y. Wu
Full text linkAn interview in three sessions, February-March 2002, with Theodore Y. Wu, professor of engineering science, emeritus, in the Division of Engineering and Applied Science. Dr. Wu was born in China and received his BSc from Chiao-Tung University (1946), his MS from Iowa State University (1948), and his PhD from Caltech (1952).
In this interview, he recalls his boyhood and tribulations during Japan's invasion of China in World War II, his emigration and matriculation at Iowa State in 1948, and his arrival at Caltech a year later. Recollections of H. S. Tsien, R. A. Millikan, Theodore von Kármán, Julian Cole. Works with Paco Lagerstrom's aeronautics group developing asymptotic perturbation method pioneered by Ludwig Prandtl. Joins faculty as a research fellow in 1952. Interest in hydrodynamics. Origins of the department of engineering science in the mid-1950s by Tsien, Milton Plesset, and Charles De Prima.
Interest in bioengineering, beginning in 1960; studies bird flight and fish locomotion. Discusses influence of G. I. Taylor and James Lighthill, and recalls his own work on flagellar and ciliary motion of microorganisms. Caltech's 1974 pioneering symposium on Swimming and Flying in Nature; new field of biofluiddynamics. Recollections of Y. C. (Burt) Fung.
Recalls his sabbatical, 1964-65, at University of Hamburg with Georg Weinblum. Joins Advisory Committee for Reactor Safeguards. Recollections of Caltech presidents Lee DuBridge and Marvin L. Goldberger. Visit to China in 1979.
Discusses his work, since 1996 retirement, on modeling of water waves; solitons and tsunamis. Concludes with comments on good relations between Chinese and Chinese American scientists and the flood of Chinese students to US for graduate work in late 1970s, after reestablishment of diplomatic relations
Empress Wu the Great Tang Dynasty China
No full textEurope and Great Britain have had many sovereign queens in the course of history. In ancient China, there was none of that. Only one Empress ever ruled China in her own name Empress Wu. Given her startling performance in a world of deadly intrigue and shifting loyalties, Wu is still respected as an effective and clear-sighted ruler.Intro -- Preface -- Chapter 1. Origins of a Future Sovereign -- The Wu Family -- Wu's Father Rises from a Merchant to a Nobleman -- Mr. Wu Marries Up -- Mr. Wu Becomes a Governor -- Mr. Wu Leaves His Family Bereft -- The Establishment of the Tang Dynasty -- Mr. Wu's Sponsor Becomes the Second Emperor of the Tang Dynasty -- Empress Changsun and a Few of the Courtiers -- Chapter 2. Miss Wu Becomes an Imperial Concubine -- The Sons Vie for the Succession -- Selecting the Crown Prince -- Introduction to the Crown Prince -- Sent to a Nunnery -- The New Emperor Reigns -- Empress Wang Brings Wu Back to the Palace -- Empress Wang and Concubine Xiao Unite against Concubine Wu -- Concubine Wu Fights Back -- The Courtiers Take Sides -- Empress Wang and Her Supporters Take a Mis-Step -- Empress Wang and the Crown Prince are Removed -- Wu Becomes Empress -- Chapter 3. From Empress to Empress Dowager -- Advancing Supporters and Annihilating Opponents -- Taking Part in Politics -- The Pleasures of Traveling -- Relationship With Her Children -- Chapter 4. The Empress Dowager Consolidates Her Power -- Standing at the Top -- View from the Summit -- Chapter 5. Rebellions -- The Largest Rebellion -- The Rebellions of the Princes Li -- Other Rebellions -- Abuse of Power at Every Level -- Chapter 6. Picking Favorites -- Naming a Successor -- Empress Wu's Favorites -- Chapter 7. Relations with Other Nations -- Tibet -- Korea -- The Tujue Clan -- Japan and Arabia -- Chapter 8. Famous Legends About Empress Wu -- Face Reading -- Flowers Blooming in Winter -- Other LegendsEurope and Great Britain have had many sovereign queens in the course of history. In ancient China, there was none of that. Only one Empress ever ruled China in her own name Empress Wu. Given her startling performance in a world of deadly intrigue and shifting loyalties, Wu is still respected as an effective and clear-sighted ruler.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Statistical and geometric properties of tree-shifts and fractals : a dynamical perspective
Full text linkAbstract
This thesis investigates the statistical and geometric properties of various symbolic and geometric fractals. Utilizing techniques from dynamical systems, ergodic theory, and large deviation theory, it provides a comprehensive analysis of key questions concerning Markov subshifts on rooted d-trees, self-conformal and self-affine fractals, and their associated measures. The research is organized into four central themes: the thermodynamic formalism of Markov subshifts over d-trees, the recurrence properties in Bedford--McMullen carpets, the decay in the Fourier spectrum of self-similar measures, and the local statistics of conformal measures.
The exploration of thermodynamic formalism for Markov subshifts over d-trees aligns with current research on statistical mechanical systems on trees, providing a large deviation description for d-tree-indexed Markov chains, characterizing pressure, entropy, and dimension in this non-Euclidean setting. Regarding recurrence in fractal systems, this work extends knowledge on recurrence in self-affine fractals by examining Bedford--McMullen carpets with coinciding Hausdorff and box-counting dimensions, providing new insights into quantitative recurrence under non-conformal dynamics. The investigation of Fourier decay in self-similar measures establishes a van der Corput lemma for one-dimensional non-atomic self-similar measures, with applications to metric theorems and absolutely pointwise normality. Finally, the study of local statistics of conformal measures expands the known class of fractal scaling measures by demonstrating that projections of ergodic measures through self-conformal iterated function systems are scaling measures, unveiling deep connections between scaling measures and ergodic theory.
These results collectively contribute to a deeper understanding of the interplay between fractal geometry, probability theory, and dynamical systems, providing novel approaches to addressing problems and offering potential directions for future research. Original papers Wu, Y.-L., & Yuan, N. (2025). Quantitative recurrence problem on some Bedford-McMullen carpets. Journal of Mathematical Analysis and Applications, 543(2), 128938. https://doi.org/10.1016/j.jmaa.2024.128938 https://doi.org/10.1016/j.jmaa.2024.128938 Self-archived version Ban, J.-C., & Wu, Y.-L. (2025). On the topological pressure of axial product on trees. Stochastics and Dynamics, 25(01), 2550007. https://doi.org/10.1142/S0219493725500078 https://doi.org/10.1142/S0219493725500078 Algom, A., Chang, Y., Wu, M., & Wu, Y.-L. (2025). Van der Corput and metric theorems for geometric progressions for self-similar measures. Mathematische Annalen. https://doi.org/10.1007/s00208-025-03233-3 https://doi.org/10.1007/s00208-025-03233-3 Self-archived version Wu, M., & Wu, Y.-L. (2025). Scaling properties of invariant measures for conformal iterated function systems. Manuscript in preparation. Tiivistelmä
Tämä väitöskirja tutkii erilaisten symbolisten ja geometristen fraktaalien tilastollisia ja geometrisia ominaisuuksia. Hyödyntäen tekniikoita, jotka liittyvät dynaamisiin systeemeihin, ergodiateoriaan ja suurpoikkeamateoriaan, se tarjoaa kattavan analyysin keskeisistä kysymyksistä, jotka koskevat Markovin siirtoja juurellisilla d-puilla, itse-konformeja ja itse-affiinisia fraktaaleja sekä niihin liittyviä mittoja. Tutkimus on jaettu neljään keskeiseen teemaan: Markovin siirtojen termodynaaminen formalismi d-puilla, toistuvuuden ominaisuudet Bedford--McMullen -matoissa, Fourier-spektrin heikkeneminen itse-similaareille mitoille ja konformien mittojen paikallinen tilastollinen käyttäytyminen.
Markovin siirtojen termodynaamisen formalismin tutkiminen d-puilla on linjassa nykyisen tutkimuksen kanssa tilastollisista mekaanisista systeemeistä puilla, tarjoten suurpoikkeamateoreettisen kuvauksen d-puuindeksoiduille Markovin ketjuille, ja paineen, entropian ja ulottuvuuden karakterisoinnin tässä ei-Euklidisessa ympäristössä. Mitä tulee toistuvuuteen fraktaalisissa järjestelmissä, tämä työ laajentaa tietämystä itse-affiinisten fraktaalien toistuvuudesta tarkastelemalla Bedford--McMullen -mattoja, joiden Hausdorffin dimensio ja laatikkodimensio ovat samat, tuoden uusia näkökulmia kvantitatiiviseen toistuvuuteen ei-konformaalisissa dynamiikoissa. Fourierin heikkenemisen tutkiminen itse-similaareille mitoille luo van der Corput'n lemman yksiulotteisille ei-atomisille itse-similaareille mitoille, jolla on sovelluksia metrisiin teoreemiin ja absoluuttisesti pisteittäiseen normaalisuuteen. Viimeisenä, konformaalisten mittojen paikallisten tilastojen tutkiminen laajentaa tunnettua fraktaalisten skaalautuvien mittojen luokkaa osoittaen, että ergodisten mittojen projisoinnit itse-konformaalisten iteratiivisten funktiosysteemien kautta ovat skaalautuvia mittoja, paljastaen syviä yhteyksiä skaalautuvien mittojen ja ergodiateorian välillä.
Nämä tulokset yhdessä tarjoavat syvemmän ymmärryksen fraktaaligeometrian, todennäköisyysteorian ja dynaamisten systeemien välisestä vuorovaikutuksesta, tarjoten uusia lähestymistapoja avoimiin ongelmiin ja mahdollisia suuntaviivoja tulevalle tutkimukselle. Osajulkaisut Wu, Y.-L., & Yuan, N. (2025). Quantitative recurrence problem on some Bedford-McMullen carpets. Journal of Mathematical Analysis and Applications, 543(2), 128938. https://doi.org/10.1016/j.jmaa.2024.128938 https://doi.org/10.1016/j.jmaa.2024.128938 Rinnakkaistallennettu versio Ban, J.-C., & Wu, Y.-L. (2025). On the topological pressure of axial product on trees. Stochastics and Dynamics, 25(01), 2550007. https://doi.org/10.1142/S0219493725500078 https://doi.org/10.1142/S0219493725500078 Algom, A., Chang, Y., Wu, M., & Wu, Y.-L. (2025). Van der Corput and metric theorems for geometric progressions for self-similar measures. Mathematische Annalen. https://doi.org/10.1007/s00208-025-03233-3 https://doi.org/10.1007/s00208-025-03233-3 Rinnakkaistallennettu versio Wu, M., & Wu, Y.-L. (2025). Scaling properties of invariant measures for conformal iterated function systems. Manuscript in preparation. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in the OP auditorium (L10), Linnanmaa, on 25 October 2025, at 12 noonAbstract
This thesis investigates the statistical and geometric properties of various symbolic and geometric fractals. Utilizing techniques from dynamical systems, ergodic theory, and large deviation theory, it provides a comprehensive analysis of key questions concerning Markov subshifts on rooted d-trees, self-conformal and self-affine fractals, and their associated measures. The research is organized into four central themes: the thermodynamic formalism of Markov subshifts over d-trees, the recurrence properties in Bedford--McMullen carpets, the decay in the Fourier spectrum of self-similar measures, and the local statistics of conformal measures.
The exploration of thermodynamic formalism for Markov subshifts over d-trees aligns with current research on statistical mechanical systems on trees, providing a large deviation description for d-tree-indexed Markov chains, characterizing pressure, entropy, and dimension in this non-Euclidean setting. Regarding recurrence in fractal systems, this work extends knowledge on recurrence in self-affine fractals by examining Bedford--McMullen carpets with coinciding Hausdorff and box-counting dimensions, providing new insights into quantitative recurrence under non-conformal dynamics. The investigation of Fourier decay in self-similar measures establishes a van der Corput lemma for one-dimensional non-atomic self-similar measures, with applications to metric theorems and absolutely pointwise normality. Finally, the study of local statistics of conformal measures expands the known class of fractal scaling measures by demonstrating that projections of ergodic measures through self-conformal iterated function systems are scaling measures, unveiling deep connections between scaling measures and ergodic theory.
These results collectively contribute to a deeper understanding of the interplay between fractal geometry, probability theory, and dynamical systems, providing novel approaches to addressing problems and offering potential directions for future research.Tiivistelmä
Tämä väitöskirja tutkii erilaisten symbolisten ja geometristen fraktaalien tilastollisia ja geometrisia ominaisuuksia. Hyödyntäen tekniikoita, jotka liittyvät dynaamisiin systeemeihin, ergodiateoriaan ja suurpoikkeamateoriaan, se tarjoaa kattavan analyysin keskeisistä kysymyksistä, jotka koskevat Markovin siirtoja juurellisilla d-puilla, itse-konformeja ja itse-affiinisia fraktaaleja sekä niihin liittyviä mittoja. Tutkimus on jaettu neljään keskeiseen teemaan: Markovin siirtojen termodynaaminen formalismi d-puilla, toistuvuuden ominaisuudet Bedford--McMullen -matoissa, Fourier-spektrin heikkeneminen itse-similaareille mitoille ja konformien mittojen paikallinen tilastollinen käyttäytyminen.
Markovin siirtojen termodynaamisen formalismin tutkiminen d-puilla on linjassa nykyisen tutkimuksen kanssa tilastollisista mekaanisista systeemeistä puilla, tarjoten suurpoikkeamateoreettisen kuvauksen d-puuindeksoiduille Markovin ketjuille, ja paineen, entropian ja ulottuvuuden karakterisoinnin tässä ei-Euklidisessa ympäristössä. Mitä tulee toistuvuuteen fraktaalisissa järjestelmissä, tämä työ laajentaa tietämystä itse-affiinisten fraktaalien toistuvuudesta tarkastelemalla Bedford--McMullen -mattoja, joiden Hausdorffin dimensio ja laatikkodimensio ovat samat, tuoden uusia näkökulmia kvantitatiiviseen toistuvuuteen ei-konformaalisissa dynamiikoissa. Fourierin heikkenemisen tutkiminen itse-similaareille mitoille luo van der Corput'n lemman yksiulotteisille ei-atomisille itse-similaareille mitoille, jolla on sovelluksia metrisiin teoreemiin ja absoluuttisesti pisteittäiseen normaalisuuteen. Viimeisenä, konformaalisten mittojen paikallisten tilastojen tutkiminen laajentaa tunnettua fraktaalisten skaalautuvien mittojen luokkaa osoittaen, että ergodisten mittojen projisoinnit itse-konformaalisten iteratiivisten funktiosysteemien kautta ovat skaalautuvia mittoja, paljastaen syviä yhteyksiä skaalautuvien mittojen ja ergodiateorian välillä.
Nämä tulokset yhdessä tarjoavat syvemmän ymmärryksen fraktaaligeometrian, todennäköisyysteorian ja dynaamisten systeemien välisestä vuorovaikutuksesta, tarjoten uusia lähestymistapoja avoimiin ongelmiin ja mahdollisia suuntaviivoja tulevalle tutkimukselle
Wu Fei, guzheng y voz (China)
No full textEl guzheng es un instrumento virtuoso con una historia de más de 2500 años. La larga historia de su reinado comenzó durante la Dinastía Qin (221 – 206 a.C.); y en la Dinastía Tang (618 – 907) ya era el instrumento más tocado en la China, y hoy en día continúa siendo el instrumento tradicional más popular en la música china. Hoy en día el continúa siendo el instrumento tradicional más popular en la música china. Tiene veintiun cuerdas que antiguamente solían ser de seda, pero ahora son de nylon y metal, lo que incrementa su volumen frente a su confección antigua. Existen muchas formas en las que se puede tocar el instrumento que, además de servir como herramientas técnicas, se utilizan para evocar paisajes o imágenes como la caída de una cascada, los truenos, el galope de los caballos o algunas escenas bucólicas, que eran elementos predilectos para las metáforas que los antiguos poetas chinos crearon para transmitir la sabiduría que milenios después, sigue transitando de voz a voz. Parece ser que cada país del Este y Sureste asiático ha tenido algún tipo de interacción con instrumentos tipo cítara como el guzheng. Desde el tatga en Mongolaia, el dan trahn en Vietnam, el gayageum en Corea y el koto en Japón, hasta el chadagan en Tuva, el kacapi en Indonesia y el jetigen de Kazakh. Diferentes pobladores y culturas alrededor de toda Asia, han creado variopintas técnicas de las que se han apropiado para formar una relación íntima con la música. En su papel de compositora, Wu Fei une la música clásica occidental y la tradición musical china, con sonidos contemporáneos. Compone para coro, cuartetos de cuerda, ensambles de cámara, gamelán balinés y para orquesta. Su programa Moon Hunter es una suite para voz y guzheng solo que se inspira en la forma en que se cantaba la antigua poesía china. La música original de Wu Fei se verá fusionada con el repertorio tradicional del guzheng, con canciones folclóricas y con la ópera china, evidenciando así su inspiración en lo antiguo, para crear algo nuevo
Reticularisus Wu, Wu & Han, a new subgenus of the genus Rhamnosa Fixsen, 1887 from China, with description of a new species (Lepidoptera: Limacodidae)
No full textA new subgenus, ReticularisusWu, Wu & Han, subgen. n., with type species Rhamnosa henanensis Wu, 2008,of the genus Rhamnosa Fixsen, 1887 is described and illustrated. For the sake of contrast, the type species of theother two subgenera in this genus have been given, including adults and male genitalia. Rhamnosa (Reticularisus) shierbeihoua Wu, Wu & Han, sp. n., a Limacodidae collected from the southwest of China is described as new to science. Also, the new species is illustrated with images of the adult and male genitalia and compared with the similar species Rh. henanensis.Se describe e ilustra un nuevo subgénero, Reticularisus Wu, Wu & Han, subgen. n., con la especie tipo Rhamnosa henanensis Wu, 2008, del género Rhamnosa Fixsen, 1887. Para contrastar, se da la especie tipo de los otros dos subgéneros en este género, incluyendo los adultos y la genitalia del macho. Se describe como nueva para la ciencia a Rhamnosa (Reticularisus) shierbeihoua Wu, Wu & Han, sp. n., un Limacodidae capturado del suroeste de China. También la nueva especie es ilustrada con imágenes del adulto y genitalia del macho y comparada con la especie similar Rh. henanensis
Electronic phase separation and the CMR effect in Pr1-xCaxMnO3 films on (001) vicinal SrTiO3 substrates
No full textOur previous work showed that Pr1-xCaxMnO3 (x=0.2-0.5) thin films reveal an electronic phase separation, in which the low-temperature phase is orbital- and charge-ordered of the Zener-polaron type [Ch. Jooss, T. Beetz, L. Wu, M. Beleggia, R. Klie, M. Schofield, Y. Zhu, S. Schramm, J. Hoffmann, submitted for publication]. Applying a magnetic field leads to a ferromagnetic and conducting phase, which gives rise to the colossal magneto resistance effect (CMR). In this article we show that the orbital- and charge-ordered state could be significantly modified by different kind of lattice defects. Quenched disorder, present after the film deposition, can suppress long-range ordering. In addition, extended defects like twin boundaries act as a nucleation center for ordered domains, i.e. the hysteretic properties depend on the density of these defects. Well-ordered artificial anti-phase boundaries (APB) can be introduced by an epitaxial growth on vicinal substrates, leading to anisotropic transport properties with respect to the orientation of the APB. (C) 2007 Elsevier B.V. All rights reserved
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