In this case the composite consists of two parts: a matrix and a reinforcement. In CFRP the reinforcement is carbon fiber, which provides its strength. The matrix is usually a polymer resin, such as epoxy, to bind the reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements Metallic glasses or amorphous metals are novel engineering alloys in which the structure is not crystalline (as it is in most metals) but rather is disordered, with the atoms occupying more-or-less random positions in the structure. In this sense, metallic glasses are similar to the more familiar oxide glasses such as the soda-lime glasses used for windows and bottles Polyrhythm is the simultaneous use of two or more rhythms that are not readily perceived as deriving from one another, or as simple manifestations of the same meter. The rhythmic layers may be the basis of an entire piece of music (cross-rhythm), or a momentary blogger.comythms can be distinguished from irrational rhythms, which can occur within the context of a single part; polyrhythms
Polyrhythm - Wikipedia
Polyrhythm is the simultaneous use of two or more rhythms that are not readily perceived as deriving from one another, or as simple manifestations of the same meter. Polyrhythms can be distinguished from irrational rhythmswhich can occur within the context of a single part ; polyrhythms require at least two rhythms to be played concurrently, one of which is typically an irrational rhythm.
Concurrently in this context means within the same rhythmic cycle. The underlying pulse, whether explicit or implicit can be considered one of the concurrent rhythms. For example, the son clave is poly-rhythmic because its 3 section suggests a different meter from the pulse of the entire pattern.
In some European art musicpolyrhythm periodically contradicts the prevailing meter. For example, in Mozart 's opera Don Giovannitwo orchestras are heard playing together in different metres 3 4 and 2 4 :. They are later joined by a third band, playing in 3 8 time. Polyrhythm is heard near the opening of Beethoven 's Symphony No.
See also syncopation. It is a particularly common feature of the music of Brahms. Writing about the Violin Sonata in G major, Op. These ideas gather at the climax at measurephd thesis composite material, with the layering of phrases making an effect that perhaps during the phd thesis composite material century only Brahms could have conceived.
In "The Snow is Dancing" from his Children's Corner suite, Debussy introduces a melody "on a static, repeated B-flat, cast in triplet-division cross rhythms which offset this stratum independently of the sixteenth notes comprising the two dancing-snowflake lines below it. Concerning the use of a two-over-three hemiola in Beethoven's String Quartet No.
The illusion of simultaneous 3 4 and 6 8suggests polymeter : triple meter combined with compound duple meter. However, the two beat schemes interact within a metric hierarchy a single meter. The phd thesis composite material beats are primary and the duple beats are secondary; the duple beats are cross-beats within a triple beat scheme, phd thesis composite material. The four-note ostinato pattern of Mykola Leontovych 's " Carol of the Bells " the first measure below is the composite of the two-against-three hemiola the second measure.
Another example of polyrhythm can be found in measures 64 and 65 of the first movement of Mozart 's Piano Sonata No. Three evenly-spaced sets of three attack-points span two measures. Cross-rhythm refers to systemic polyrhythm. The New Harvard Dictionary of Music states that cross-rhythm is: "A rhythm in which the regular pattern of accents of the prevailing meter is contradicted by a conflicting pattern and not merely a momentary displacement that leaves the prevailing meter fundamentally unchallenged" A simple example of a cross-rhythm is 3 evenly spaced notes against 2also known as a hemiola.
Two simple and common ways to express this pattern in standard western musical notation would be 3 quarter notes over 2 dotted quarter notes within one bar of 6 8 time, quarter note triplets over 2 quarter notes within one bar of 2 4 time. Other cross-rhythms are with 4 dotted eight notes over 3 quarter notes within a bar of 3 4 time as an example in standard western musical notation,phd thesis composite material,etc. In auditory processing, rhythms are perceived as pitches once they have been sufficiently sped up.
Furthermore, phd thesis composite material, intervals of rhythms are perceived as intervals of pitch once sufficiently sped up. As such, there is a parallel between cross-rhythms and musical intervals : in an audible frequency range, the ratio produces the musical interval of a perfect fifththe ratio produces a perfect fourthand the ratio produces a major third.
All these interval ratios are found in the harmonic series. These are called harmonic polyrhythms. In traditional European "Western" rhythms, the most fundamental parts typically emphasize phd thesis composite material primary beats.
By contrast, in rhythms of sub-Saharan African origin, the most fundamental parts typically emphasize the secondary beats. This often causes the uninitiated ear to misinterpret the secondary beats as the primary beats, and to hear the true primary beats as cross-beats. In other words, the musical "background" and "foreground" may phd thesis composite material be heard and felt in reverse—Peñalosa In non-Saharan African music traditionscross-rhythm is the generating principle; the meter is in a permanent state of contradiction.
Cross-rhythm was first explained as the basis of non-Saharan rhythm in lectures by C. Ladzekpo and the writings of David Locke. From the philosophical perspective of the African musician, cross-beats can symbolize the challenging moments or emotional stress we all encounter. Playing cross-beats while fully grounded in the main beats, prepares one for maintaining a life-purpose while dealing with life's challenges.
Many non-Saharan languages do not have a word for rhythmor even music. From the African viewpoint, phd thesis composite material, the rhythms represent the very fabric of life itself; they are an embodiment of the people, symbolizing interdependence in human relationships—Peñalosa At the center of a core of rhythmic traditions within which the composer conveys his ideas is the technique of cross-rhythm.
The technique of cross-rhythm is a simultaneous use of contrasting rhythmic patterns within the same scheme of accents or meter By the very nature of the desired resultant rhythm, the main beat scheme cannot be separated from the secondary beat scheme. It is the interplay of the two elements that produces the cross-rhythmic texture—Ladzekpo Eugene Novotney observes: "The relationship and [its] permutations is the foundation of most typical polyrhythmic textures found in West African musics.
Victor Kofi Agawu succinctly states, "[The] resultant [] rhythm holds the key to understanding there is no independence here, because 2 and 3 belong to a single Gestalt. The two beat schemes interact within the hierarchy of a single meter. The duple beats are primary and the triple beats are secondary. The example below shows the African cross-rhythm within its proper metric structure. The music of African xylophonessuch as the balafon and gyilis often based on cross-rhythm.
In the following example, a Ghanaian gyil sounds a based ostinato melody. The left hand lower notes sounds the two main beats, while the right hand upper notes sounds the three cross-beats. The following notated example is from the kushaura part of the traditional mbira piece "Nhema Mussasa". The mbira is a lamellophone. The left hand plays the ostinato bass line while the right hand plays the upper melody. The composite melody is an embellishment of the cross-rhythm.
Sub-Saharan instruments are constructed in a variety of ways to generate polyrhythmic melodies. Some instruments organize the pitches in a uniquely divided alternate array, not in the straight linear bass to treble structure that is so common to many western instruments such as the pianoharpor marimba. Lamellophones including mbirambila, mbira huru, mbira njari, mbira nyunga, marimba, karimba, kalimbalikembe, and okeme.
This family of instruments are found in several forms indigenous to different regions of Africa and most often have equal tonal ranges for right and left hands. The kalimba is a modern version of these instruments originated by the pioneer ethnomusicologist Hugh Tracey in the early 20th century which has over the years gained worldwide popularity.
Chordophonessuch as the West African koraand doussn'gouni, part of the harp-lute family of instruments, phd thesis composite material have this African separated double tonal array structure.
Trough zithers also have the phd thesis composite material to play polyrhythms. The Gravikord is a new American instrument closely related to both the African kora and the kalimba was created in the latter 20th century to also exploit this adaptive principle in a modern electro-acoustic instrument.
On these instruments, one hand of the musician is not primarily in the bass nor the other primarily in the treble, but both hands can play freely across the entire tonal range of the instrument. Also, the fingers of each hand can play separate independent rhythmic patterns, and these can easily cross over each other from treble to bass and back, either smoothly or with varying amounts of syncopation.
This can all be done within the same tight tonal range, without the left and right hand fingers ever physically encountering each other. This characteristically African structure allows often simple playing techniques to combine with each other to produce polyrhythmic music.
Polyrhythm is a staple of modern jazz. Although not as common, use of systemic cross-rhythm is also found in jazz. InMongo Santamaria recorded " Afro Blue ", the first jazz standard built upon a typical African cross-rhythm two cycles of The following phd thesis composite material shows the original ostinato "Afro Blue" bass line. The cross noteheads indicate the main beats.
The famous jazz drummer Elvin Jones took the opposite approach, superimposing two cross-beats over every measure of a 3 4 jazz waltz This swung 3 4 is perhaps the most common example of overt cross-rhythm in jazz. Nigerian percussion master Babatunde Olatunji arrived on the American music scene in with his album Drums of Passionwhich was a collection of traditional Nigerian music for percussion and chanting. The album stayed on the charts for two years and had a profound impact on jazz and American popular music.
Olatunji reached his greatest popularity during the height of the Black Arts Movement of the s and s. Afro-Cuban music makes extensive use of polyrhythms.
Cuban Rumba uses 3-based and 2-based rhythms at the same time, for example, the lead drummer playing the quinto might play in 6 8phd thesis composite material, while the rest of the ensemble keeps playing 2 2. Afro-Cuban congueroor conga player, Mongo Santamaría was another percussionist whose polyrhythmic virtuosity helped transform both jazz and popular music. Another form of polyrhythmic music is south Indian classical Carnatic music. A kind of rhythmic solfege called konnakol is used as a tool to construct highly phd thesis composite material polyrhythms and to divide each beat of a pulse into various subdivisions, with the emphasised beat shifting from beat cycle to beat cycle.
Common polyrhythms found in jazz arewhich manifests as the quarter-note triplet;usually in the form of dotted-quarter notes against quarter notes;phd thesis composite material as dotted-eighth notes against quarter notes this one demands some technical proficiency to perform accurately, and was not at all common in jazz before Tony Williams used it when playing with Miles Davis ; and finally 3 4 time against 4 4which along with was used famously by Elvin Jones and McCoy Tyner playing with John Coltrane.
Frank Zappaphd thesis composite material, especially towards the end of his career, experimented with complex polyrhythms, such asand even nested polyrhythms see " The Black Page " for an example.
The metal bands MudvayneNothingfaceThreat SignalLamb of Godalso use polyrhythms in their music. Henry Cowell and Conlon Nancarrow created music with yet more complex polytempo and using irrational numbers like π : e. Peter Magadini 's album Polyrhythmwith musicians Peter MagadiniGeorge DukeDavid Young, and Don Menzafeatures different polyrhythmic themes on each of the six songs. King Crimson used polyrhythms extensively in their phd thesis composite material Discipline.
The band Queen used polyrhythm in their song " The March of the Black Queen " with 8 8 and 12 8 time signatures. Nine Inch Nails front man Trent Reznor uses polyrhythm frequently. One notable appearance is in the song "La Mer" from the album The Fragile, phd thesis composite material.
The piano holds phd thesis composite material 3 4 riff while the drums and bass back it with a standard 4 4 signature, phd thesis composite material. Talking Heads ' Remain in Light used dense polyrhythms throughout the album, most notably on the song "The Great Curve". Megadeth frequently tends to use polyrhythm in its drumming, notably from songs such as "Sleepwalker" or the ending of "My Last Words", which are both played in Carbon Based Lifeforms have a song named " Polyrytmi ", Finnish for "polyrhythm", on their album Interloper.
Jérémy Chevalier, Belgian NCTAM 2018 Best PhD Thesis award winner
, time: 8:15Cork (material) - Wikipedia
Johnson Space Center. NASA’s Johnson Space Center has served as a hub of human spaceflight activity for more than half a century. It is home to the nation’s astronaut corps, the International Space Station mission operations, the Orion Program, and a host of future space developments In this case the composite consists of two parts: a matrix and a reinforcement. In CFRP the reinforcement is carbon fiber, which provides its strength. The matrix is usually a polymer resin, such as epoxy, to bind the reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements Cork is an impermeable buoyant material, the phellem layer of bark tissue that is harvested for commercial use primarily from Quercus suber (the cork oak), which is native to southwest Europe and northwest blogger.com is composed of suberin, a hydrophobic substance. Because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products, the most common
No comments:
Post a Comment