19 research outputs found
Investigation of the Flow Characteristics in a Pintle Controlled Rocket Motor Nozzle
No full textUnlike a liquid rocket-engine, it is not possible to actively throttle the overall combustion of a solid rocket-motor. It is however possible to alter the thrust of an individual thruster by varying its throat area. The throat area can be altered by inserting a pintle of a conical or other shape into the nozzle throat. A setup which consist of multiple thrusters each with a pintle to alter its throat area, and which are connected to a single solid-propelled combustion chamber, can be used for attitude control of a rocket or spacecraft.The goal of this thesis was to investigate the flow in a single thruster of such a system. For this purpose, a simple 1D simulation was developed. Additionally, multiple CFD simulations both static and dynamic were setup. The results of the simulations were then analysed in detail and compared amongst each other and with externally obtained test-data.Aerospace Engineerin
REGULARIZED PETERSSON INNER PRODUCTS FOR MEROMORPHIC MODULAR FORMS (Automorphic Forms, Automorphic L-Functions and Related Topics)
No full textWe investigate the history of inner products within the theory of modular forms. We first give the history of the applications of Petersson 's original definition for the inner product of S_{2k} and then recall Zagier' s extension to a nondegenerate (but not necessarily positive-definite) inner product on all holomorphic modular forms. We then recall the history of the so-called "regularization" of the inner product to extend it to weakly holomorphic modular forms originally by Petersson and then later independently rediscovered by Harvey-Moore and Borcherds, as well as its applications to theta lifts by Borcherds, Bruinier-Funke, and many more recent authors. This has been recently extended to a well-defined inner product on all weakly holomorphic modular forms by Bringmann, Diamantis, and Ehlen. Finally, we consider inner products on meromorphic modular forms which have poles in the upper half-plane. Petersson also defined a regularization in this case by cutting out small neighborhoods around each pole occurring in the fundamental domain; Bringmann, von Pippich, and the author have recently constructed an extension of this regularization, which, when combined with the regularization of Bringmann, Diamantis, and Ehlen, yields an inner product that is well-defined and finite on all meromorphic modular forms
Interpretation of Frédéric Chopin’s pedal markings on modern pianos
No full textThis project offers new approaches to pedaling in Frédéric Chopin’s piano works for modern pianos, utilizing Chopin’s original pedal markings. The project begins with the review of the existing literature regarding Chopin’s pedaling, including books, articles, dissertations, score sources, and audio materials. A brief explanation of historical and syncopated pedaling follows, including a comparison between Chopin’s piano (the Pleyel piano) and modern ones. The next, and central part of this paper is an analysis of Chopin’s musical style and pedaling, with detailed examples of selected works. Finally, the author presents his own pedaling suggestions, with modifications for modern pianos. The musical examples are selected from Chopin’s Mazurkas, Op. 41, Op. 50, and Op. 68; the Nocturnes; and the second movement from the Piano Concerto no. 1, Op. 11. The majority of musical examples are taken from the Polish National Edition (WN edition) edited by Jan Ekier (1913-2014). The aim of this project is to demonstrate why Chopin’s original pedal markings, when used with the necessary adaptations,are still preferable, and effective on modern instruments.U of I OnlySchool of Music polic
Regularized Petersson inner products for meromorphic modular forms
No full textWe investigate the history of inner products within the theory of modular forms. We first give the history of the applications of Petersson's original definition for the inner product of and then recall Zagier's extension to a non-degenerate (but not necessarily positive-definite) inner product on all holomorphic modular forms. We then recall the history of the so-called ``regularization'' of the inner product to extend it to weakly holomorphic modular forms originally by Petersson and then later independently rediscovered by Harvey--Moore and Borcherds, as well as its applications to theta lifts by Borcherds, Bruinier--Funke, and many more recent authors. This has been recently extended to a well-defined inner product on all weakly holomorphic modular forms by Bringmann, Diamantis, and Ehlen. Finally, we consider inner products on meromorphic modular forms which have poles in the upper half-plane. Petersson also defined a regularization in this case by cutting out small neighborhoods around each pole occurring in the fundamental domain; Bringmann, von Pippich, and the author have recently constructed an extension of this regularization, which, when combined with the regularization of Bringmann, Diamantis, and Ehlen, yields an inner product that is well-defined and finite on all meromorphic modular forms
Interpretation of Frédéric Chopin’s pedal markings on modern pianos
No full textThis project offers new approaches to pedaling in Frédéric Chopin’s piano works for modern pianos, utilizing Chopin’s original pedal markings. The project begins with the review of the existing literature regarding Chopin’s pedaling, including books, articles, dissertations, score sources, and audio materials. A brief explanation of historical and syncopated pedaling follows, including a comparison between Chopin’s piano (the Pleyel piano) and modern ones. The next, and central part of this paper is an analysis of Chopin’s musical style and pedaling, with detailed examples of selected works. Finally, the author presents his own pedaling suggestions, with modifications for modern pianos. The musical examples are selected from Chopin’s Mazurkas, Op. 41, Op. 50, and Op. 68; the Nocturnes; and the second movement from the Piano Concerto no. 1, Op. 11. The majority of musical examples are taken from the Polish National Edition (WN edition) edited by Jan Ekier (1913-2014). The aim of this project is to demonstrate why Chopin’s original pedal markings, when used with the necessary adaptations,are still preferable, and effective on modern instruments.U of I Only Restriction set for Item 114051 on 2020-03-06T16:26:51Z with date by [email protected] by David Butler ([email protected]) on 2020-03-06T16:38:16Z
No. of bitstreams: 1
Gang Zhu_thesis.pdf: 4502464 bytes, checksum: cf7bd5914417a4b317c6195933fb5f18 (MD5)Made available in DSpace on 2020-03-06T16:38:16Z (GMT). No. of bitstreams: 1
Gang Zhu_thesis.pdf: 4502464 bytes, checksum: cf7bd5914417a4b317c6195933fb5f18 (MD5)
Previous issue date: 2020Embargo set by: David Butler for item 114051
Lift date: 10000-01-01
Reason: School of Music policySchool of Music policyU of I Onl
Regularized inner products and errors of modularity
No full textWe develop a regularization for Petersson inner products of arbitrary weakly holomorphic modular forms, generalizing several known regularizations. As one application, we extend work of Duke, Imamoglu, and Toth on regularized inner products of weakly holomorphic modular forms of weights 0 and 3=2. These regularized inner products can be evaluated in terms of the coefficients of holomorphic parts of harmonic Maass forms of dual weights. Moreover, we study the errors of modularity of the holomorphic parts of such a harmonic Maass forms and show that they induce cocyles in the first parabolic cohomology group introduced by Bruggeman, Choie, and the second author. This provides explicit representatives of the cohomology classes constructed abstractly and in a very general setting in their work
Sleep Deprivation alters the influence of biological sex on active phase sleep behavior
No full textPoor sleep is a hazard of daily life that oftentimes cannot be avoided. Gender differences in daily sleep and wake patterns are widely reported; however, it remains unclear how biological sex, which is comprised of genetic and endocrine components, directly influences sleep regulatory processes. In the majority of model systems studied thus far, sex differences in daily sleep amount are predominant during the active (wake) phase of the sleep-wake cycle. The pervasiveness of sex differences in sleep amount throughout phylogeny suggests a strong underlying genetic component. The goal of the current study is to determine if sex differences in active-phase sleep amount are dependent on sex chromosomes in mice. Sleep was examined in the four-core genotype (FCG) mouse model, whose sex chromosome complement (XY, XX) is independent of sex phenotype (male or female). In this line, sex phenotype is determined by the presence or absence of the Sry gene, which is dissociated from the Y chromosome. Polysomnographic sleep recordings were obtained from gonadectomized (GDX) FCG mice to examine spontaneous sleep states and the ability to recover from sleep loss. We report that during the active-phase, the presence of the Sry gene accounts for most sex differences during spontaneous sleep; however, during recovery from sleep loss, sex differences in sleep amount are partially driven by sex chromosome complement. These results suggest that genetic factors on the sex chromosomes encode the homeostatic response to sleep loss
Development and Performance of the 10 kN Hybrid Rocket Motor for the Stratos II Sounding Rocket
No full textThis paper presents the development work of the 10 kN hybrid rocket motor DHX-200 Aurora. The DHX-200 Aurora was developed by Delft Aerospace Rocket Engineering (DARE) to power the Stratos II and Stratos II+ sounding rocket, with the later one being launched in October 2015. Stratos II and Stratos II+ are the flagship projects of DARE, a student group working on rocketry at Delft University of Technology. Successors of Stratos II have the eventual goal of reaching space. During the development process two major revisions of the motor have been designed with smaller changes between tests. The second major design revision was made after a first test series showed low combustion efficiency, through the usage of a CFD model to improve mixing. Both revisions have been tested statically in total for 14 times both at facilities of ’Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek’ (TNO) and ’Deutsches Zentrum f ¨ ur Luft- und Raumfahrt’ (DLR). All tests were conducted in a full-scale, flight-ready configuration with the primary goal of demonstrating the required performance for the Stratos II and Stratos II+ sounding rocket. It was found out that the motor suffered from combustion instabilities at around 450 Hz, when operated at its design oxidizer mass flux level of 600 kg=m2=s, that caused low combustion efficiency and elevated heat flux levels in the pre-combustion chamber. Through design changes the instabilities could be lowered and both problems removed. The design goal of total impulse could not be met, but the specific impulse measured was higher than expected. Still, the overall performance proofed to be sufficient enough for the system to be used as the propulsion system for Stratos II+
Author response: Bmal1 function in skeletal muscle regulates sleep
No full textSleep loss can severely impair the ability to perform, yet the ability to recover from sleep loss is not well understood. Sleep regulatory processes are assumed to lie exclusively within the brain mainly due to the strong behavioral manifestations of sleep. Whole-body knockout of the circadian clock gene Bmal1 in mice affects several aspects of sleep, however, the cells/tissues responsible are unknown. We found that restoring Bmal1 expression in the brains of Bmal1-knockout mice did not rescue Bmal1-dependent sleep phenotypes. Surprisingly, most sleep-amount, but not sleep-timing, phenotypes could be reproduced or rescued by knocking out or restoring BMAL1 exclusively in skeletal muscle, respectively. We also found that overexpression of skeletal-muscle Bmal1 reduced the recovery response to sleep loss. Together, these findings demonstrate that Bmal1 expression in skeletal muscle is both necessary and sufficient to regulate total sleep amount and reveal that critical components of normal sleep regulation occur in muscle
Modulation of ionic conduction using polarizable surfaces
No full textHybrid ionic-electronic conductors have the potential to generate memory
effects and neuronal behavior. The functionality of these mixed materials
depends on ion motion through thin polarizable channels. Here, we explore
different polarization models to show that the current and conductivity of
electrolytes is higher when confined by conductors than by dielectrics. We find
non-linear currents in both dielectrics and conductors, and we recover the
known linear (Ohmic) result only in the two-dimensional limit between
conductors. We show that the polarization charge location impacts electrolyte
structure and transport properties. This work suggests a mechanism to induce
memristor hysteresis loops using conductor-dielectric switchable materials.Comment: 7 pages, 5 figures, A. P. dos Santos and F. Jim\'enez-\'Angeles
contributed equally to this work and both are equal first author
