Temporal variations of IEEE 802.11b signal strengths in an in-building environment

Recent popularity of the IEEE 802.11b Wireless Local Area Networks (WLANs) in a host of current-day applications has instigated a suite of research challenges. The 802.11b WLANs are highly reliable and wide spread. In this work, we study the temporal characteristics of RSSI in the real-working environment by conducting a controlled set of experiments. Our results indicate that a significant variability in the RSSI can occur over time. Some of this variability in the RSSI may be due to systematic causes while the other component can be expressed as stochastic noise. We present an analysis of both these aspects of RSSI. We treat the moving average of the RSSI as the systematic causes and the noise as the stochastic causes. We give a reasonable estimate for the moving average to compute the noise accurately. We attribute the changes in the environment such as the movement of people and the noise associated with the NIC circuitry and the network access point as causes for this variability. We find that the results of our analysis are of primary importance to active research areas such as location determination of users in a WLAN. The techniques used in some of the RF-based WLAN location determination systems, exploit the characteristics of the RSSI presented in this work to infer the location of a wireless client in a WLAN. Thus our results form the building blocks for other users of the exact characteristics of the RSSI.

Summer Sprite for Orchestra

Summer Sprite for Orchestra was completed in December, 2004. The piece originated from a singular encounter with little angels at Chang-Kyung Palace, which is the oldest and the most beautiful palace in Korea, and where the kings of the Chosun Dynasty (1393-1897) lived. This encounter was in the summer of 2002. I certainly could not prove that those angels I met were real. Possibly they were the reflection of drops of water after a sudden shower on that summer day. However, I definitely remember that short, unforgettable, and mysterious moment and the angels' beautiful dance-like celebration. Summer Sprite is based on these special memories and the encounter with the little angels that summer. Summer Sprite consists of 3 movements: "Greeting," "Encounter," and "Celebration." These follow the course of my encounter with the little angels. In Summer Sprite, I wished to describe the image of the angels as well as the progression of greeting, encounter, and celebration with them. The moods that follow in Summer Sprite are by turns lyrical, poetic, fantastic, mysterious, and dream-like. In each movement, I describe the meeting of angels and composer through the use of the soloists -- violin (sometimes viola) and cello. As suggested by the subtitle of the first movement, "Greeting" portrays the moment when a surprised I met the angels. It begins with tam-tam, marimba, harp, and piano and sets a mysterious and dark mood. The second movement, "Encounter," is shorter than the first movement. This movement provides a more tranquil mood as well as more unique timbres resulting from the use of mutes and special instruments (English horn, harp, crotales, suspended cymbal, and celesta). The delicate expression of the percussion is particularly important in establishing the static mood of this movement . The last movement, °?Celebration,°± is bright and energetic. It is also the longest. Here, I require the most delicate changes of dynamics and tempo, the most vigorous harmonies, and the fastest rhythmic figures, as well as the most independent, lyrical, and poetic melodies. For bright orchestral tone color, I used various kinds of percussion such as timpani, xylophone, marimba, vibraphone, cymbals, side drum, tambourine, triangle, and bass drum. This last movement is divided rondo-like into five sections: The first (mm.1-3), second (mm.4 - rehearsal number 1), third (rehearsal numbers 2-4), fourth (rehearsal numbers 5-7), and fifth, (rehearsal numbers 8 -18). To sum up, Summer Sprite describes an unforgettable and mysterious moment in a my life. My intention was to portray this through a concerto-like framework. A model for this would be Brahms°Ø °?Double Concerto°± in A minor, op.102, in which the solo cello stands for my angel and the solo violin (sometimes solo viola) for me.

VISION OF EQUINOX FOR ORCHESTRA

The artistic play of light seen on a pyramid in some Mayan ruins located in Cancun, Mexico provided the inspiration for Vision of Equinox. On both the spring and autumn equinox days, the sunlight projected on the pyramid forms a shape which looks like a serpent moving on the stairway of the pyramid. Vision of Equinox was composed with an image of light as the model for the artistic transfiguration of sound. The light image of sound changes its shape in each stage of the piece, using the orchestra in different ways - sometimes like a chamber ensemble, sometimes like one big instrument. The image of light casting on a pyramid is expressed by descending melodic lines that can be heard several times in the piece. At the final climax of the work, a complete and embodied artistic figure is formed and stated, expressing the appearance of the Mayan god Quetzalcoatl, the serpent, in my own imagination. The light and shadow which comprise this pyramid art are treated as two contrasting elements in my composition and become the two main motives in this piece. To express these two contrasting elements, I picked the numbers "5" and "2," and used them as "key numbers" in this piece. As a result, the intervals of a fifth and a second (sometimes inverted as a seventh) are the two main intervals used in the structure. The interval of a fifth was taken into account for the construction of the pyramid, which has five points of contact. The interval of a second was selected as a contrasting sonority to the fifth. Further, the numbers "5" and "2" are used as the number of notes which form the main motives in this piece; quintuplets are used throughout this piece, and the short motive made by two sixteenth notes is used as one of the main motives in this piece. Moreover, the shape of the pyramid provided a concept of symmetry, which is expressed by the setting of a central point of the music (pitch center) as well as the use of retrograde and inversion in this piece.

Doubt, for narrator and orchestra

Doubt is a single-movement composition of roughly twelve minutes for narrator and orchestra (woodwinds, horns, and trumpets in pairs, timpani, percussion, strings). The piece explores the controversial issue of capital punishment. The text was compiled from resources found on the websites of Death Penalty Information Center (http://www.deathpenaltyinfo.org) and Anti-Death Penalty Information (http://www.antideathpenalty.org), as well as excerpts from the Bible. Doubt was conceived of as a dramatic work in which a narrator recites factual information in a direct and unemotional manner and the orchestra provides a response to the mixed emotions elicited by the text. The list of dates and case summaries presented in the middle section of the piece seemed most powerful and effective when recited in a natural speaking voice, which is why I chose not to set the text as song. Also, I chose the orchestral medium rather than a chamber setting because the nature of the topic demanded a larger range of colors and combinations, as well as a louder, fuller sound. Much of the music was composed while deciding which texts to include. Thus the music influenced the choice of text as much as the text suggested the musical setting. The four formal divisions of the piece are delineated primarily by the text. The first section is an orchestral introduction representing various emotional perspectives suggested by the texts. The narrator begins the second section with a Biblical verse over sparse orchestration. The third and main section of the piece begins with a new melody in the low strings that is closely related to the harmonic organization of the piece. The narrator lists dates of convictions, executions, exonerations and facts related to doubtful cases. The third section and the narration conclude with another brief passage from the Bible. The fourth section is a dramatic orchestral coda, bringing back the opening harmonies of juxtaposed perfect fifths. The final chord is full of tension and discord, reflecting the oppositions inherent in the topic of capital punishment: life vs. death, sympathy vs. reproach, pain vs. hope, but above all, doubt about guilt vs. innocence.

The Interloping Beguiler: for Bass Clarinet and Orchestra

The Interloping Beguiler is an nineteen-minute concerto in four movements for bass clarinet solo and orchestra. The title refers to the role of the solo instrument, which continually thrusts itself into the affairs of the orchestra, deceiving and diverting the members of the orchestra away from their task of performing a "serious" orchestral composition. The bass clarinet portrays a comical, cartoon-like character whose awkward, and sometimes goofy, interjections cause chaos. Attempts are made by various members of the orchestra, especially the horns, to regain control of the work, but the bass clarinet always succeeds in its distracting antics. By the final movement of the composition, the bass clarinet has propelled the work into a cartoon-like landscape of quickly changing textures, dissonant intervals, and overlapping themes. The first movement, Introduction, sets the serious tone of the music to follow, or so it would seem. The entrance of the bass clarinet immediately changes this texture with its out-of-rhythm alternations between high and low pitches. This gesture provides a glimpse into the personality of the bass clarinet, an instrument here to mislead the members of the orchestra. Deception truly begins in the second movement, The Interloping Initiates. The bass clarinet starts the movement with a driving theme and is immediately supported by the orchestra. As the movement progresses, the bass clarinet quickly begins altering the theme, making it more playful and cartoonish. A struggle ensues between the horns and the bass clarinet, with the bass clarinet catapulting the piece into a latin-inspired section. The struggle continues through to the end of the movement. The third movement, Calm, is exactly what the title suggests. A sectional form distinguishes this movement from the second movement. Throughout Calm, the bass clarinet behaves with decorum, except for very large melodic leaps. The seed of anarchy planted by the bass clarinet in the second movement comes to fruition in the final movement, The Beguiling Builds. Here, the bass clarinet sends the work into chaos with sections recalling Looney Tunes cartoons, Hollywood western music, and children's folk songs.

SELECTED VARIATIONS BY COMPOSERS IN GERMANY AND FRANCE

The Haward of Dictionary of Music (1983), defines variation as "a technique modifying a given musical idea." From the Baroque period on, the form and the techniques of variation were developed and enriched in Germany and France. Therefore, I presented the works of composers from these two nations. Even though there was a vast number of possibilities, I wanted to be scholastically fair and interesting in making my selections by choosing well-known pieces along with lesser-known ones. Haydn's well-known Variations in F minor consist of two sets of double variations which break into an improvisation fantasy. The first movement of Beethoven Sonata in A flat major, Op. 26, is a set of five variations on the composer's original theme. The variations are positioned in the first movement instead of Sonata-Allegro form. In 1861 Brahrns composed the Variations and Fugue, Op. 24, on the theme of Handel. Brahms displays a wealth of rhythmic, harmonic and textural contrasts in the variations. Chopin's E Major Variations without opus number are written on a Swiss influenced German folksong. Faure's Theme and Variations in C sharp minor, Op. 73, includes eleven variations. The work displays the composer's subtlety, grace and reticence. 12 Variationen iiber ein eigenes Thema were written by Alban Berg as a composition study with Schonberg. The Finale of Dutilleux's Piano Sonata, titled "Chorale with Variations", is written in an impressionistic style. A rich expressiveness is well blended in a classical form. In 1742, the remarkable Aria and thirty variations known as the Goldberg Variations were composed by J. S. Bach. The thirty Variations are unified by the bass line, which forms the foundation of the Aria. The pieces discussed above were presented in three recitals. Compact disc recordings of these recitals are available in the Michelle Smith Performing Arts Library of the Clarice Smith Performing Arts Center at the University of Maryland.

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.

ELGAR AND MART&: THE CELLO WORKS AND MUSICAL CHARACTERISTICS OF TWO REMARKABLE, SELF-TAUGHT, NATIONALISTIC COMPOSERS

The British Edward Elgar and Czech Bohuslav MartinB were two of the most prominent Nationalistic composers of their respective countries during the late nineteenth and early twentieth centuries. Their musical patriotism incorporates the unique paths of their lives as socially isolated and self-taught composers as expressed their outstanding Nationalistic compositions produced through the period of history encompassing the two World Wars.In the first chapter of this dissertation, a brief biography of Elgar is presented and the essential aspects of his formative years influencing him to become a self-taught musician are discussed. The second chapter demonstrates Elgar's musical characteristics through the study of a selection of his masterpieces. In the third chapter, a brief biography of Martinti is presented along with a history of his musical development, characterized by his social isolation during four different periods of his life-his residences in PoliCka, Prague, Paris, and then in the United States. The fourth chapter considers MartinB's musical characteristics as revealed through the study of a selection of his greatest works. In support of this doctoral project, I performed two recitals of cello works by Elgar and Martini3 at the University of Maryland, College Park. The first recital, accompanied by Susan Slingland and Hiroko Yamazaki, included three of Martini3's works, Sonata No. 2 for Cello and Piano (1941); Variations on a Theme of Rossini for Cello and Piano (1 942); and Sonata No. 3 for Cello and Piano (1952). The second recital, accompanied by Wonyoung Chang and Naoko Takao, presented Martini3's Sonata No. 1 for Cello and Piano (1939) and Elgar's Concerto for Cello and Orchestra Op. 85 in E minor (1 919).

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.

TWENTIETH CENTURY VARIATIONS ON BORROWED THEMES

Mergers and acquisitions are words that are usually associated with the modern business world. Such joint efforts toward improvement, however, existed long before our time, in the form of musical partnerships. It was not unusual for composers to share in each other's works, borrowing themes and recreating them to generate new meanings; in the process, new masterpieces were often created. My performance project, Twentieth Century Variations on Borrowed Themes, explores the fruits of such labor. The main objective of this project is to demonstrate how certain composers of the twentieth century have taken famous themes and used them to create variations, imbuing their own creative ideas, musical styles and pianistic challenges. This objective was accomplished by performing three recorded public recitals. These programs consisted of early to late twentieth century pieces that are based on borrowed themes, either in theme and variations form, fantasia form, paraphrase form, or transformal variation form. I have selected the pieces based on their artistic merits and technical challenges, thus allowing me to grow as a pianist and artist. In addition, I wanted to choose some pieces that are rarely performed, as I believe the public delights in hearing unfamiliar gems. The first recital consisted of the music of two legendary pianists: Variations on a Theme of Chopin by Rachmaninoff and Goldberg Variations by BachIBusoni. The second program featured Grand Fantasy on Gershwin's Porgy and Bess by Earl Wild, Sonatina No. 6 (Fantasy on Bizet 's "Carmen") by Busoni, and Rhapsody on a Theme by Paganini, op.43 by Rachmaninoff. Some unusual and seldom-performed pieces, as well as a familiar favorite, were spotlighted in the third recital. The pieces performed on this program were John Rea's Twenty-one Transformal Variations on the "Kindersznen " by Robert Schumann (Las Meninas), Muczynski's Desperate Measures (Paganini Variations), Busoni's Elegie No. 3 (Turandot 's room), and Rhapsodie Espagnole by LisztIBuson. These composers artfully breathed new life into the material borrowed from others, and in the process, the "borrowed" themes became undoubtedly and uniquely their own music.

All This the World Well Knows: a symphonic cantata in Sonnets and Proverbs for mixed chorus, four solo voices, and orchestra

All This the World Well Knows is a 30-minute symphonic cantata for mixed chorus, four solo voices (soprano, mezzo-soprano, tenor, and baritone), and orchestra. The libretto, adapted by the composer, weaves together texts from Shakespeare's Dark Lady sonnets and from the King James Bible's book of Proverbs in a loose narrative of love, betrayal, and reconciliation. The composition's pitch material includes microtonality that arises from the just intonation of sonorities derived from the harmonic series. In passages in which the solo voices express this microtonality, they are amplified in order to allow precise, non vibrato intonation. The modest size of the orchestra, which includes pairs of winds and only two percussionists, makes the composition practical for a wide range of performing groups.

THE PIANO MUSIC OF ROBERT SCHUMANN (1810-1856) AND JOHANNES BRAHMS (1833- 1897): A SURVEY OF CONCERTI, VARIATIONS, AND CHARACTER PIECES

Robert Schumann (1810-1856) and Johannes Brahms (1833-1897), in some ways Robert Schumann's artistic descendant, are the most important and representative German piano composers during the Romantic period. Schumann was already a mature and established musician in 1853 when he first met the young Brahms and recognized his talents, an encounter that had a long-lasting affect on the lives and careers of both men. After Schumann’s mental breakdown and death, Brahms maintained his admiration of Schumann’s music and preserved an intimate relationship with Clara Schumann. In spite of the personal and musical closeness of the two men, Schumann’s music is stylistically distinct from that of Brahms. Brahms followed traditions from Baroque and Classical music, and avoided using images and expressive titles in his music. Brahms extraordinarily intermingled earlier musical forms with multicolored tones of German Romanticism. In contrast, Schumann saw himself as a radical composer devoted to personal emotionalism and spontaneity. He favored programmatic titles for his character pieces and extra-musical references in his music. While developing their own musical styles as German Romantic composers, Schumann and Brahms both utilized the piano as a resourceful tool for self-realization and compositional development. To investigate and compare the main characteristics of Schumann and Brahms’s piano music, I looked at three genres. First, in the category of the piano concerto, I chose two major Romantic works, Schumann’s A minor concerto and Brahms’s B-flat major concerto. Second, for the category of piano variations I included two sets by Brahms because the variation framework was such an important vehicle for him to express his musical thoughts. Schumann’s unique motivic approach to variation is displayed vividly in his character-piece cycle Carnaval. Third, the category of the character piece, perhaps the favorite medium of Romantic expression at the piano, is shown by Schumann’s Papillons and Brahms’s sets of pieces Op.118 and Op.119. This performance dissertation consists of three recitals performed in the Gildenhorn Recital Hall at the University of Maryland, College Park. These recitals are documented on compact disc recordings that are housed within the University of Maryland Library System.