Typed Abstraction of Complex Network Compositions

The heterogeneity and open nature of network systems make analysis of compositions of components quite challenging, making the design and implementation of robust network services largely inaccessible to the average programmer. We propose the development of a novel type system and practical type spaces which reflect simplified representations of the results and conclusions which can be derived from complex compositional theories in more accessible ways, essentially allowing the system architect or programmer to be exposed only to the inputs and output of compositional analysis without having to be familiar with the ins and outs of its internals. Toward this end we present the TRAFFIC (Typed Representation and Analysis of Flows For Interoperability Checks) framework, a simple flow-composition and typing language with corresponding type system. We then discuss and demonstrate the expressive power of a type space for TRAFFIC derived from the network calculus, allowing us to reason about and infer such properties as data arrival, transit, and loss rates in large composite network applications.

A Formal Semantics for Weak References

A weak reference is a reference to an object that is not followed by the pointer tracer when garbage collection is called. That is, a weak reference cannot prevent the object it references from being garbage collected. Weak references remain a troublesome programming feature largely because there is not an accepted, precise semantics that describes their behavior (in fact, we are not aware of any formalization of their semantics). The trouble is that weak references allow reachable objects to be garbage collected, therefore allowing garbage collection to influence the result of a program. Despite this difficulty, weak references continue to be used in practice for reasons related to efficient storage management, and are included in many popular programming languages (Standard ML, Haskell, OCaml, and Java). We give a formal semantics for a calculus called λweak that includes weak references and is derived from Morrisett, Felleisen, and Harper’s λgc. λgc formalizes the notion of garbage collection by means of a rewrite rule. Such a formalization is required to precisely characterize the semantics of weak references. However, the inclusion of a garbage-collection rewrite-rule in a language with weak references introduces non-deterministic evaluation, even if the parameter-passing mechanism is deterministic (call-by-value in our case). This raises the question of confluence for our rewrite system. We discuss natural restrictions under which our rewrite system is confluent, thus guaranteeing uniqueness of program result. We define conditions that allow other garbage collection algorithms to co-exist with our semantics of weak references. We also introduce a polymorphic type system to prove the absence of erroneous program behavior (i.e., the absence of “stuck evaluation”) and a corresponding type inference algorithm. We prove the type system sound and the inference algorithm sound and complete.

Towards Formalizing Java's Weak References

Weak references provide the programmer with limited control over the process of memory management. By using them, a programmer can make decisions based on previous actions that are taken by the garbage collector. Although this is often helpful, the outcome of a program using weak references is less predictable due to the nondeterminism they introduce in program evaluation. It is therefore desirable to have a framework of formal tools to reason about weak references and programs that use them. We present several calculi that formalize various aspects of weak references, inspired by their implementation in Java. We provide a calculus to model multiple levels of non-strong references, where a different garbage collection policy is applied to each level. We consider different collection policies such as eager collection and lazy collection. Similar to the way they are implemented in Java, we give the semantics of eager collection to weak references and the semantics of lazy collection to soft references. Moreover, we condition garbage collection on the availability of time and space resources. While time constraints are used in order to restrict garbage collection, space constraints are used in order to trigger it. Finalizers are a problematic feature in Java, especially when they interact with weak references. We provide a calculus to model finalizer evaluation. Since finalizers have little meaning in a language without side-effect, we introduce a limited form of side effect into the calculus. We discuss determinism and the separate notion of uniqueness of (evaluation) outcome. We show that in our calculus, finalizer evaluation does not affect uniqueness of outcome.

Design of digital differentiators

A digital differentiator simply involves the derivation of an input signal. This work includes the presentation of first-degree and second-degree differentiators, which are designed as both infinite-impulse-response (IIR) filters and finite-impulse-response (FIR) filters. The proposed differentiators have low-pass magnitude response characteristics, thereby rejecting noise frequencies higher than the cut-off frequency. Both steady-state frequency-domain characteristics and Time-domain analyses are given for the proposed differentiators. It is shown that the proposed differentiators perform well when compared to previously proposed filters. When considering the time-domain characteristics of the differentiators, the processing of quantized signals proved especially enlightening, in terms of the filtering effects of the proposed differentiators. The coefficients of the proposed differentiators are obtained using an optimization algorithm, while the optimization objectives include magnitude and phase response. The low-pass characteristic of the proposed differentiators is achieved by minimizing the filter variance. The low-pass differentiators designed show the steep roll-off, as well as having highly accurate magnitude response in the pass-band. While having a history of over three hundred years, the design of fractional differentiator has become a ‘hot topic’ in recent decades. One challenging problem in this area is that there are many different definitions to describe the fractional model, such as the Riemann-Liouville and Caputo definitions. Through use of a feedback structure, based on the Riemann-Liouville definition. It is shown that the performance of the fractional differentiator can be improved in both the frequency-domain and time-domain. Two applications based on the proposed differentiators are described in the thesis. Specifically, the first of these involves the application of second degree differentiators in the estimation of the frequency components of a power system. The second example concerns for an image processing, edge detection application.

STUDIES AND PERFORMANCES OF TRANSCRIPTIONS FOR CELLO FROM THE VIOLIN REPERTOIRE

The potential of the violoncello as a solo instrument was recognized and supported by cellists such as Luigi Boccherini (1743-1805), Luis Duport (1749-1819), Auguste Franchomme (1808-1884), and Alfredo Piatti (1822-1901). These pioneers composed technically demanding etudes, exercises, and caprices for the cello that were comparable to those already present in the violin literature. Even so, in the late nineteenth century and early twentieth century, considerably fewer substantial works were brought forth for the cello as compared with the violin. Consequently, many cellists such as Luigi Silva (1903-1961), Gregor Piatigorsky (1903-1976), Pierre Fournier (1906-1986), and Janos Starker (b. 1924) selected notable pieces from the violin repertoire and transcribed these for the cello. Some composers themselves actually adapted for the cello their own works originally written for the violin. Johannes Brahms with his Violin Sonata Op. 78, Igor Stravinsky with his Suite Italienne, and Béla Bartók with his First Rhapsody all belong to this category. Adaptations such as these further raised awareness among composers and performers of the possibilities of the cello as an independent and expressive instrument. Thus, many composers from the early 1900s to the present were encouraged to write increasing numbers of more soloistic and demanding works for cello. Herein, I explore the repertoire of cello transcriptions in order to analyze the differences between the original and transcribed versions and the challenges found therein. The performer may attempt to recreate the effect originally intended for the violin or, more daringly, may strive to search for alternate presentations of the music more suitable and expressive of the cello's own character. The project includes two recitals of the following transcribed works presented at the University of Maryland College Park, School of Music: Sonata in A by César Franck, transcribed by Jules Delsart, Variations on a Theme from Rossini by Nicolo Paganini, transcribed by Fournier, Suite Italienne by Igor Stravinsky, transcribed with the help of Piatigorsky, Sonatina Op. 137, No. 1 by Franz Schubert, transcribed by Starker, First Rhapsody by Béla Bartók and Sonata, Op. 108 by Johannes Brahms, transcribed by Hsiao-mei Sun.

COMPOSITIONS FEATURING THE PIANO IN FANTASY FORM: 1820-1920

The Fantasy form offered a composer the freedom to create a work without concerns for fitting into the current stylistic and traditional structures. The flowering of the form seems to be concentrated from 1820-1920 since the composer started to use it as a way to convey a personal idea or to portray a special spirit. This dissertation is comprised of three recitals with fantasies in different genres and styles. Through performing these diverse fantasies, I have been inspired to connect with the imagery and spirit of the compositions in order to capture the unique sentiments of each piece. Also, in order to keep the audience absorbed in the music that is without structure, I have focused on expanding my technical abilities to vary color, sonority, and phrasing. Program one (April 26,2004) includes Fantasie, Op. 17 and Piano Concerto, Op. 54 (assisted by Ya-Hsin Wu) by R. Schumann. Program two (December 10, 2004) includes Three Fantastic Dances, Op. 5 by D. Shostakovitch, Fantasy "Sonataecossaise ", Op. 28 by F. Mendelssohn, Sonata No.2 "Sonata-Fantasy", Op. 19 by A. Scriabin and Fantasie for Piano and Violin, D 934 by F. Schubert with violinist, TaoChang Yu. The last program (November 1, 2005) includes Fantasia baetica by E. de Falla, Morceaux de Fantaisie, Op. 3 by S. Rachrnaninoff, Fantaisie, Op. 49, Impromptu No. 4 '%h.ntasy-hpromptu", Op. 66 and Polonaise-Fantaisie, Op. 61 by F. Chopin.

TRANSCENDING FACH: A SEARCH FOR IDENTITY INSIDE AND OUT OF MEZZO-SOPRANO REPERTOIRE

The German Fach system is a tool to classify voices in classical singing. This dissertation comprises three different programs that reflect my search for identity as a mezzo-soprano and my desire to transcend the limitations of Fach. The three programs, all presented at The Clarice Performing Arts Center, contain repertoire written for male and female voices thus allowing me to explore areas outside of the mezzo-soprano Fach, gain a better understanding of the Fach system and guide me as I strive to become a more mature performer. In my first program, I sang the role of Sesto, a role that was composed originally for a castrate, in the opera La Clemenza di Tito by W.A. Mozart. The Maryland Opera Studio production took place April 30, May 2,4&6,2003. Performing this gender-bending role provided an experience of physical behavior from the male view point along with the demands of coloratura singing. Program two (November 30,2004) contained the song cycle Dichterliebe by Robert Schumann and songs by Ludwig van Beethoven, Franz Schubert and Felix Mendelssohn, which are usually sung by male voices. This program experimented with extended range, tessitura and a gender-bending performance in the art song arena. 8 In program three (April 21 &23,2005), I sang the contralto role of Cornelia from Giulio Cesare in Egitto by George Frederic Handel. The role of Cornelia is psychologically complex, expressing emotions such as love, melancholy, rage, malice, joy and fear. To convey these emotions a voice needs warmth and darkness of quality. Although the range is close to that of the mezzo-soprano, Handel wrote Cornelia for contralto voice because he wanted a dark timbre and this role allowed me to develop my lower register and manage suitable ornamentations. The programs are documented in a digital format available on compact disc and are accompanied by the oral presentation at the defense of this dissertation.

The Development of Piano Variations in the Romantic Era

The purpose of this study is to illustrate the development of piano variations as a genre during the Romantic era. In order to facilitate this examination of piano variations techniques, a brief look at the types of variation procedures used by composers of previous eras will assist in understanding developments that later occurred in the Romantic period. Throughout the Baroque era, composers preferred the fured-bass, fixed-melody, and harmonic forms of variation. The crowning achievement of Baroque keyboard music, Bach's Goldberg Variations (1725), contains examples of the "constantharmonic" method in its collection of 30 variations, each of which maintains both the bass and harmonic structure of the themes. While most composers of the classical period favored the "melodic-outline" form of variation, Haydn developed hybrid variation procedure that exhibits recurrence of material rather than repetition, alternating variation (ABABA), rondo variation (ABACA), and ternary variation (ABA). Haydn, Mozart and early Beethoven variations also exhibit simpler textures than do their Baroque predecessors. The nineteenth century produced numerous compositions that display variation techniques, some based on such older, classical models as melodic-outline variation and hybrid variation, others in the style of the character variation or fiee variation. At the beginning of the nineteenth century, Beethoven and Schubert used such classical variation techmques as melodic-outline variations and hybrid variations. Beethoven's late sonatas displayed such new means of expression as variation, fugue, and dramatic recitatives. The third movement of the Sonata in E major, Op. 109 (1820) has a theme and six variations of the melodic-outline type. Johannes Brahms was particularly fond of composing variations for piano. Among the best known examples of formal-outline variations are those found in the Variations and Fugue on a Theme of Handel, Op. 24 (1861). Character variations, in which styles are characterized by the retention and variability of particular elements, also flourished during the Romantic period. Cesar Franck's Variations Symphoniques (1885) are, perhaps, among the most important examples of free variations. This composition is a one-movement work consisting of three sections, Introduction, Variations, and Finale (all movements played "attaca"). This work combines two independent classical formal structures, the concerto and the variation.

The Scherzo in Selected Works for Piano

This performance project will cover performing issues in terms of technique in the scherzo. The Dictionary of Musical Terms defines technique as "the system of creating music, the musical slull to show personality by controlling tones that is not an abstract theory but a practical ability in composition or performance." My project focuses on techniques in fast tempos, specifically those found in the scherzo form and in concertos containing a scherzo character. The term scherzo has varied in its meaning and form throughout history. In the Baroque period, a scherzo was a work of light vocal or instrumental character. In the Classical period, scherzo still meant light in style, but it also indicated a quick tempo, often in 2/4 time. The scherzo was usually a single movement in a suite or multi-movement work. Like the minuet form, the scherzo contained a contrasting trio section. The scherzo was also standard in Romantic and post-Romantic symphonies and related genres. Because of the high degree of subjectivity in Romantic music, genres that stressed emotional content over abstract form developed rapidly. Some composers even wrote one-movement pieces entitled scherzo. These pieces became very important because they usually expressed a particular character or mood. The objective of my dissertation project is to research scherzo-like concertos, scherzo as single movements in larger forms, and scherzo as independent works. My first recital will consist of two concertos with a scherzo-like character. These are Mozart's Piano Concerto No. 9 i ?nl Major; K. 271 and Ravel's Piano Concerto in G Major. I will perform these works in December 2002 with a second piano. In addition, I will perform the Ravel with an orchestra in 2003. My second recital will consist of two parts. The fxst half presents multi-movement works with scherzo movements. The pieces are Haydn's Piano Sonata No. 3 in F Majol; Hob. WI/9, Beethoven's Piano Sonata No. 10 in G Major; Op. 14, No. 2. The second half presents independent four scherzi by Chopin. The final program will also include multi-movement works containing scherzo and independent scherzo. These are Prokofiev's Piano Sonata No. 2 in D minor, Op. 14, Grieg Lyric Pieces Op. 54, Schubert Zwei Scherzi D. 593 and Copland Scherzo humoristique; Le Chat et la Souris (The Cat and the Mouse).

Selected Works from Character Pieces in the 19th - Early 20th Centuries

During the Romantic Era, the character piece flourished and became one of the most important genres. Even though character pieces existed as early as the eighteenth century, it was not until the nineteenth century that Romantic Era literary figures discovered that music was as powerful as any other artistic medium in expressing unspeakable emotions. The character piece allowed composers to express a definite mood, a programmatic idea, or a pictorial association. Character pieces often have titles that suggest briehess or casualness, such as a Beethoven Bagatelle, a Schubert Impromptu or Moment musicaux. Others have expressive programmatic titles, such as Schumann's Kreisleriana and Liszt's Apres une lecture de Dante. Ths dissertation was based on selected works from the nineteenth century and early-twentieth century in order to demonstrate the great variety of musical thought and stylistic development. I have examined composers from different countries and of different nationalities to establish what and how they contributed to the remarkable diversity in this genre. The selected works allowed for very personal programs. These concerts, in addition to being good combinations of pieces, are representative of the genre. The first program consisted of Chopin's Preludes, Op. 28; three pieces from Debussy7s Images Books I and 11; and Liszt7s Apres une lecture de Dante. The second program included seven of Beethoven's Bagatelles, Op. 33; Schumann's Kinderscenen, Op. 15; Poulenc's Mouvements perpetuels and Intermezzo in A-jlat Major; Faure7s Nocturne in B Major, Op. 33, No. 2 and Impromptu No. 2 in F Minor; three of Mompou's Canciones y Danzas; four of Villa-Lobos Prole do bebe Suite No. 1; and Albkniz's Navarra. The third and final program comprised four selections from Rachrnaninoff s Moment musicaux, Op. 16; five pieces from Grieg's Lyric Pieces; and Arensky7s Suite No. 1 for Two Pianos and Suite No. 2 for Two Pianos. I wanted to bring out nuances specific to the individual composers and show how their character pieces helped in shaping the Romantic Era. Even in the twenty-first century, an era of highly specialized musical tastes, the popularity and accessibility of character pieces stand out.

SELECTED NINETEENTH CENTURY VARIATIONS FOR PIANO

The beauty and artistry of the variation form were fully developed and represented in the nineteenth century. The treasures of nineteenth century piano variations are a significant part of the total piano repertoire. The main goal of this dissertation is to show how various composers of the nineteenth century used the variation form to project their imagination and coloring of a simple melody. They used many different techniques to vary melodies and create their own music. Beethoven's Piano Sonata No. 12 in A-flat Major Op. 26 breaks with the conventional sonata design by using variation form instead of sonata-allegro form for the first movement, and having no movement in sonata-allegro form. Chopin's Variations Brillantes on "Je Vends des scapulaires" Op. 12 and Henri Herz's Variations on 'Non piu mesta" from "La Cenerentola" shows how they applied their art to composing variations on opera themes. Mendelssohn's Variations Serieuses Op. 54 was a reaction against the salon music in the 19" century. Schubert applies the variation form to his Impromptus in B-flat D. 935 No. 3. Schurnann's Symphonic Etudes represents a perfect example of the arts of variation, using counterpoint, and special coloring; and Faure's Theme and Variations Op. 73 represents one of the most outstanding nineteenth-century works in variation form. As a traditionalist in the nineteenth century, Brahms favored the variations over other classic forms. I have performed three of his most important sets of variations: including Variations on a theme by Schumann Op. 9, Variations on a Theme by Handel Op. 24, and Variations for two pianos on a Theme by Haydn Op. 56b. The variations listed above were divided into three recitals. These variations represent a very important part of the piano music of the nineteenth century. By discovering, preparing, and performing these wonderful works, I have grown, both as a pianist and as a musician.

AN EXAMINATION OF 19TH CENTURY AUSTROGERMAN VIOLIN SONATAS

For my dissertation recital project, I traced the course of the violin-piano sonata in Austro- German in the 19th century, after Beethoven. My project presented works in three general categories. First, I presented works that are frequently-played standards of the violin sonata repertoire, works by Johannes Brahms, Franz Schubert, and Robert Schumann. The Second category is works by composers better known for their other compositions: Felix Mendelssohn and Richard Strauss. Finally, I choose the works seldom played these days, but worth of consideration, by Carl Maria von Weber and Max Reger. For my first recital, I performed Schubert's Violin Sonata, No. 1, Op. 137 in D major, Schumann's Violin Sonata, No. 1, Op. 105 in a minor, and Brahms' Violin Sonata, No.3, Op. 108 in d minor, with Naoko Takao as pianist. My second recital included works of Weber's Sonata, No. 1, Op. lob, in F major, Mendelssohn's Sonata, in F major (1838), and Schumann's Sonata, No.Z,Op.121 in d minor with Grace Cho. I concluded my final recital with the works of Reger's Violin Sonata, No. 1, Op. 1 in d minor and Strauss' Violin Sonata, Op. 18 in E flat major, Soo-Young Jung at the piano. All three programs are documented in a digital audio format available on compact disc, with accompanying programs also available in digital format.

AUSTRO-GERMAN VIOLIN REPERTORIE FROM BAROQUE THROUGH ROMANTIC PERIOD

At the end of the sixteenth century, Germany had become one of the most active centers of early Baroque music, and therefore Austro-German music came to dominate Western music. An investigation of violin works written during this period reveals the ways in which Austro-German compositions are extraordinary contributions to the violin repertoire. This research warranted further study and performance of these works in order to determine what influence these composers had on the violin repertoire as a whole. For my dissertation recital project, I trace the history of works for violin focusing the violin concerto repertoire in particular. A genre which remained popular throughout the century, the nineteenth-century concerto served primarily as a vehicle for virtuosic display of the violin and piano as never before. For my research I studied and performed works selected from the Baroque through the Romantic period in three recorded recitals with collaborative pianists Ilya Sinaisky, Sun-ha Yun, and Seyon Lee at the Gildenhorn Recital Hall, Clarice Smith Performing Arts Center. I selected particularly prominent pieces which represent the work of significant composers from each period. The composers discussed include Johann Sebastian Bach (1685-1750), owing to the fact that his works are the culmination of the Baroque era during the first half of the eighteenth century; from the Classical period, Wolfgang Amadeus Mozart (1756-1791) all of whom emerged mixing German and Italian traditions into his own style, and Ludwig van Beethoven (1770-1827), the bridge composer between the Classical and the Romantic periods; Romantic composers, Franz Schubert (1979-1828), Johannes Brahms (1833-1897), Robert Schumann (1810-1856), Felix Mendelssohn (1809-1847), and Max Bruch (1838-1920), all who tended to mix Classic and Romantic elements. As a violinist, I learned that their own original sound, rich harmonies and unique expression made these works worthy of becoming masterpieces. I have relished the opportunity for musical and professional growth in exploring these substantial compositions.

IMPROMPTU: FROM PUBLISHER'S IMPULSE TO AN ESTABLISHED SMALL­ SCALE GENRE IN PIANO LITERATURE

The word 'impromptu' began to appear in music literature in the early 19th century, specifically as title for a relatively short composition written for solo piano. The first impromptus appear to have been named so by the publishers. However, the composers themselves soon embraced the title to indicate, for the most part, fairly short character pieces. Impromptus do not follow any specific structural pattern, although many are cast in ternary form. The formal design ranges from strict compound ternary in the early impromptus to through-composed and variation forms. The peak of impromptu's popularity undoubtedly came during the middle and late19th century. However, they are still being composed today, albeit much less frequently. Although there have been many variants of impromptus in relation to formal design and harmonic language over the years, the essence of impromptu remains the same: it is still a short character piece with a general feeling of spontaneity. Overall, impromptus may be categorized into several different groups: some appear as part of a larger cycle, such as Dvorak's G minor Impromptu from his Piano Pieces, B. 110; many others use an element of an additional genre that enhances the character ofthe impromptu, such as Liszt's Valse-Impromptu and Antonio Bibalo's Tango Impromptu; yet another group consists of works based on opera themes, such as Liszt's Impromptu Brillant sur des themes de Rossini et Spontini and Czerny's Impromptus et variations sur Oberon, Op. 134. My recording project includes well-known impromptus, such as Schubert's Op. 142 and the four by Chopin, as well as lesser known works that have not been performed or recorded often. There are four impromptus that have been recorded here for the first time, including those written by Leopold Godowsky, Antonio Bibalo, Altin Volaj, and Nikolay Mazhara. I personally requested the two last named composers to contribute impromptus to this project. My selection represents works by twenty composers and reflects the different types of impromptus that have been encountered through almost three hundred years of the genre's existence, from approximately 1817 (VoriSek) to 2008 (Volaj and Mazhara).

USE OF VARIATION AND FUGUE IN PIANO MUSIC FOLLOWING THE CLASSICAL PERIOD

The variation and fugue originated from the 15th and 16th centuries and blossomed during the Baroque and Classical Periods. In a variation, a theme with a particular structure precedes a series of pieces that usually have the same or very similar structure. A fugue is a work written in imitative counterpoint in which the theme is stated successively in all voices of polyphonic texture. Beethoven’s use of variation and fugue in large scale works greatly influenced his contemporaries. After the Classical Period, variations continued to be popular, and numerous composers employed the technique in various musical genres. Fugues had pedagogical associations, and by the middle of 19th century became a requirement in conservatory instruction, modeled after Bach’s Well-Tempered Clavier. In the 20th century, the fugue was revived in the spirit of neoclassicism; it was incorporated in sonatas, and sets of preludes and fugues were composed. Schubert's Wanderer Fantasy presents his song Der Wanderer through thematic transformations, including a fugue and a set of variations. Liszt was highly influenced by this, as shown in his thematic transformations and the fugue as one of the transformations in his Sonata in b. In Schumann’s Symphonic Études, Rachmaninoff's Rhapsody on a Theme of Paganini and Copland’s Piano Variations, the variation serves as the basis for the entire work. Prokofiev and Schubert take a different approach in Piano Concerto No. 3 and Wanderer Fantasy, employing the variation in a single movement. Unlike Schubert and Liszt's use of the fugue as a part of the piece or movement, Franck’s Prelude Chorale et Fugue and Shchedrin’s Polyphonic Notebook use it in its independent form. Since the Classical Period, the variation and fugue have evolved from stylistic and technical influences of earlier composers. It is interesting and remarkable to observe the unique effects each had on a particular work. As true and dependable classic forms, they remain popular by offering the composer an organizational framework for musical imagination.