Double-base Research Articles

Applying Mechanically Activated Al/PTFE in CMDB Propellant

AbstractA novel reactive powder (aluminum/polytetrafluoroethylene, Al/PTFE 75/25 mass %) containing two kinds of PTFE (pre‐sintering PTFE and fresh PTFE, P‐PTFE and F‐PTFE) was prepared by a two‐step mechanical activation (MA) method. By introducing it into composite modified double base (CMDB) propellant, an attempt to improve the propellant performance of this mechanically activated Al/PTFE was made. Scanning electron microscopy (SEM) characterization indicated that F‐PTFE in activated powders deformed to abundant fibers under uniform shear forces. These fibers significantly enhanced propellant tensile properties and show improved safety performance. Compared to blank CMDB propellant (without PTFE), the elongation at maximum strength for propellant with activated Al/PTFE inclusions was increased to 3.7 times at −40 °C and to 3.9 times at −70 °C, the friction sensitivity and impact sensitivity were reduced by 88.9 % and 20.4 %, respectively. P‐PTFE in activated powders promoted the Al reaction activity, thereby reducing the propellant combustion agglomeration. The average diameter (D50) of coarse products for propellant with activated Al/PTFE 75/25 mass‐% was reduced by 82 % compared to that of blank CMDB propellant with spherical aluminum. This novel activated Al/PTFE shows increased propellant mechanical performance, decreased sensitivity and improved combustion efficiency of Al, which might expand the application field of CMDB propellants.

Hearing Double: how to use the double bass in the VI Concerti Armonici by Unico Wilhelm van Wassenaer.

Name: Eva Euwe Main Subject: Violone Research Supervisor: Johannes Boer Title of Research: Hearing Double Research Question: Was the double bass used in the VI Concerti Armonici by Unico Wilhelm Van Wassenaer, and if so, how was it used? Summary of Results: As far as we know, the VI Concerti Armonici by Unico Wilhelm van Wassenaer were written for a chamber music setting with one instrument per part. We do not know which basso continuo instrumentation was intended or preferred by the composer, but it could have been possible that a double bass was to be used. At that time in the Netherlands, double basses and bassists were around and it is not unlikely that they also played in relatively small settings such as chamber music. If the double bass played the basso continuo line in this piece, there are many reasons that it was used in a different way than the more usual 'concerto grosso' style of playing the continuo line. It is also likely that instead of a double bass, a smaller bass instrument in the 8 foot register was used to double the continuo line with. This would be an instrument that is perhaps bigger than most baroque cellos and close to a basse de violon or a G-violone. To illustrate these possibilities, I have recorded several versions of the same Concerto with different basso continuo instrumentations. Biography: Eva Euwe (Amsterdam, 1988) studies historical double bass and violone with Margaret Urquhart at the Royal Conservatoire of The Hague. She received her Bachelor’s diploma from the Utrecht Conservatory where she studied modern double bass with Quirijn van Regteren Altena. She received masterclasses from world-class bassists such as Joel Quarrington and Edicson Ruiz. Alongside her studies, Eva works as a freelance bassist with several ensembles such as De Nieuwe Philharmonie Utrecht, BarokOpera Amsterdam and Música Temprana. She also performs with the Orchestra of the Age of Enlightenment as a participant of the OAE Experience 2018.

From divisions to divisi: improvisation, orchestration and the practice of double bass reduction

From divisions to <i>divisi</i>: improvisation, orchestration and the practice of double bass reduction

Influence of Polytetrafluorethylene on the Mechanical and Safety Properties of a Composite Modified Double Base Propellant

Influence of Polytetrafluorethylene on the Mechanical and Safety Properties of a Composite Modified Double Base Propellant

BuNENA-DNDA57 Combined Energetic Plasticizer for Modified Cast Double Base Propellants

K ziskani kvalitnich nasakovaných TPH je nutne najit vhodný kompromis mezi energii TPH (danou obsahem energetických komponent) a dalsimi vlastnosti TPH. Tato prace je zaměřena na charakterizaci TPH, v nichž je nitroglycerin nahrazen energetickými aditivy hexogenem a plastifikatory BuNENA a DNDA57. Sledovan byl pak vliv těchto aditiv na nasledujici vlastnosti: na rychlost hořeni TPH v zavislosti na okolnim tlaku (měřeno v uzavřene bombě SV-2), na termicke a stabilitni parametry (měřeno metodami DTA a DSC) a na citlivost TPH k narazu. Nejvyssi rychlost hořeni, nevyssi aktivacni energii a zaroveň nejnižsi citlivost maji směsi jen s obsahem energetických plastifikatorů.

FPGA Implementation of MAC Unit for Double Base Ternary Number System (DBTNS) and its Performance Analysis

FPGA Implementation of MAC Unit for Double Base Ternary Number System (DBTNS) and its Performance Analysis

”The image” of the violin in the creative work of A. Corelli (on the example of the concerto grosso genre)

Statement of the problem. The violin style of A. Corelli, a composer-violinist who laid the foundation for the development of the violin art in Europe, represents a special “image of the instrument” that entered the professional-academic arena during the Baroque era. The research of A. Corelli’s violin style belongs to the field of organology, which is dedicated to the integrated study of instruments as the “organs” of musicians’ thinking. The close relationship, connection of the individual who is playing music with his/her instrument is not only one of the little developed theoretical problems, but also the basis of the practice for performing music, as well as learning this art. Analysis of recent publications on the topic. The available sources on the creative work of A. Corelli (written by K. Kuznetsov, I. Yampolsky, L. Ginzburg, N. Harnoncourt) contain either general information or individual observations on the image of the violin in the Baroque era. It is necessary to point out the significance of the general theory of the violin style (E. Nazaikinsky, V. Medushevsky, V. Kholopova, Y. Bentya) for the development of scientific ideas about the "image of the violin". The purpose of the article is to identify the special features of the “image” of the violin in the style of A. Corelli on the material of Concerti grossi op.6. The presentation of the main material. At the time of the creation of Concerts op.6 by A. Corelli, in Italy there was a violin school, which was distinguished by an exceptional variety of playing techniques. It was here that the historical process of replacing the viol with the violin was finally completed. The violin becomes the leading instrument in the instrumental genres of the 17th century music – suite, trio-sonata, solo sonata, and by the end of the century – concerto grosso. The path of movement to A. Corelli’s universal, generalized-reduced violin style ran along the line “ensemble feature – concert feature – solo feature”. The creation of the academic style of the violin playing logic is the merit of the Bologna school. The main thrust of the violin style of Bologna masters (Torelli, Antonia, Bassani, Vitali, and later Corelli and Vivaldi) is the combination of “church” and “chamber” models of the violin playing. For instrumental sound in an ensemble or orchestra, a “canon” and certain limitations in the technique of the playing are necessary, allowing establishing the balance of the parts of instruments and instrumental groups. The “invention” (inventio) in the violin playing, characteristic of the Italian school of the first half of the 17th century, was aimed at identifying the whole complex of the possible techniques of playing this instrument. The violin plating logic in Concertі grossi by A. Corelli is subordinated to the combination of two artistic and aesthetic tasks arising from two styles of concert making – the “church” one and the “chamber” one. Hence the choice of the appropriate techniques for playing. The “church” style, despite its democratization inherent in the Italian violin school, acquired the functions of a public concert for a mass audience and was distinguished by greater severity and regulation of the complex of the violin playing techniques. This stemmed from the genre style (“concert in the church”), where polyphonic presentation prevailed in the fast parts, the “tempo” names of the parts were used, and the organ in the numbered bass part was used. The “chamber” style opened up wider possibilities for the violin and the creation of an expressive technical complex associated with the genre (“dance” parts), replacing the organ in basso continuo with the harpsichord (cembalo), other stringed and plucked instruments (lute, theorbo), low string-and-bow instruments (gamba, cello, double bass), which gave a mono-articulate character to the general sounding. Playing shades of "lively speech" on the violin is a characteristic feature of A. Corelli’s violin style, reflected in the instrumental-playing complex through phrasing, attention to details and to micro-intonation. Conclusions. In describing the historical and artistic situation, in the context of which the style of the “great citizen of Bologna” was formed, its innovations have been outlined. The signs of the turning epoch have been indicated – they are the transition from the Renaissance polyphony and the “church” style to the secular homophony, with the instruments of the violin family singled out as the main ones. The particular attention has been paid to the principles of the violin intonation in the form of a speech playing (sprechendes Spiel) and dance motor skills, which together formed the semantics of A. Corelli’s violin style in the genres of concerto grosso, trio sonatas, solo sonata with bass. The main features of A. Corelli’s violin style, which became determinant for compositional decisions in the field of thematic, texture, and harmony, have been revealed.

”The image” of the violin in the creative work of A. Corelli (on the example of the concerto grosso genre)

Statement of the problem. The violin style of A. Corelli, a composer-violinist who laid the foundation for the development of the violin art in Europe, represents a special “image of the instrument” that entered the professional-academic arena during the Baroque era. The research of A. Corelli’s violin style belongs to the field of organology, which is dedicated to the integrated study of instruments as the “organs” of musicians’ thinking. The close relationship, connection of the individual who is playing music with his/her instrument is not only one of the little developed theoretical problems, but also the basis of the practice for performing music, as well as learning this art. Analysis of recent publications on the topic. The available sources on the creative work of A. Corelli (written by K. Kuznetsov, I. Yampolsky, L. Ginzburg, N. Harnoncourt) contain either general information or individual observations on the image of the violin in the Baroque era. It is necessary to point out the significance of the general theory of the violin style (E. Nazaikinsky, V. Medushevsky, V. Kholopova, Y. Bentya) for the development of scientific ideas about the "image of the violin". The purpose of the article is to identify the special features of the “image” of the violin in the style of A. Corelli on the material of Concerti grossi op.6. The presentation of the main material. At the time of the creation of Concerts op.6 by A. Corelli, in Italy there was a violin school, which was distinguished by an exceptional variety of playing techniques. It was here that the historical process of replacing the viol with the violin was finally completed. The violin becomes the leading instrument in the instrumental genres of the 17th century music – suite, trio-sonata, solo sonata, and by the end of the century – concerto grosso. The path of movement to A. Corelli’s universal, generalized-reduced violin style ran along the line “ensemble feature – concert feature – solo feature”. The creation of the academic style of the violin playing logic is the merit of the Bologna school. The main thrust of the violin style of Bologna masters (Torelli, Antonia, Bassani, Vitali, and later Corelli and Vivaldi) is the combination of “church” and “chamber” models of the violin playing. For instrumental sound in an ensemble or orchestra, a “canon” and certain limitations in the technique of the playing are necessary, allowing establishing the balance of the parts of instruments and instrumental groups. The “invention” (inventio) in the violin playing, characteristic of the Italian school of the first half of the 17th century, was aimed at identifying the whole complex of the possible techniques of playing this instrument. The violin plating logic in Concertі grossi by A. Corelli is subordinated to the combination of two artistic and aesthetic tasks arising from two styles of concert making – the “church” one and the “chamber” one. Hence the choice of the appropriate techniques for playing. The “church” style, despite its democratization inherent in the Italian violin school, acquired the functions of a public concert for a mass audience and was distinguished by greater severity and regulation of the complex of the violin playing techniques. This stemmed from the genre style (“concert in the church”), where polyphonic presentation prevailed in the fast parts, the “tempo” names of the parts were used, and the organ in the numbered bass part was used. The “chamber” style opened up wider possibilities for the violin and the creation of an expressive technical complex associated with the genre (“dance” parts), replacing the organ in basso continuo with the harpsichord (cembalo), other stringed and plucked instruments (lute, theorbo), low string-and-bow instruments (gamba, cello, double bass), which gave a mono-articulate character to the general sounding. Playing shades of "lively speech" on the violin is a characteristic feature of A. Corelli’s violin style, reflected in the instrumental-playing complex through phrasing, attention to details and to micro-intonation. Conclusions. In describing the historical and artistic situation, in the context of which the style of the “great citizen of Bologna” was formed, its innovations have been outlined. The signs of the turning epoch have been indicated – they are the transition from the Renaissance polyphony and the “church” style to the secular homophony, with the instruments of the violin family singled out as the main ones. The particular attention has been paid to the principles of the violin intonation in the form of a speech playing (sprechendes Spiel) and dance motor skills, which together formed the semantics of A. Corelli’s violin style in the genres of concerto grosso, trio sonatas, solo sonata with bass. The main features of A. Corelli’s violin style, which became determinant for compositional decisions in the field of thematic, texture, and harmony, have been revealed.

Double Bass Techniques of the Early Jazz Era

ABSTRACTWhile it is no secret that many early jazz recordings featured the tuba as the low-end instrument of choice, something seems to be missing from the standard pedagogy in regards to jazz double bass. The double bass had been treated, it seems, with a great deal of speculation as to its true role in early jazz performance practice. In light of this, there is a pressing need for hard research into the performance practices of the early jazz bassists. This article will outline the various ways in which the most notable jazz bassists of the era employed those techniques, with particular attention to the works of Wellman Braud, Steve Brown, and Bill Johnson, as well as to highlight several examples from after the early jazz period which directly reflect the influence of traditional New Orleans style performance practices.

Composing the Jazz Bass Revolution: Duke Ellington’s Writing for the String Bass, 1925–1941

ABSTRACTThroughout his career, Duke Ellington (1899–1974) has been partial to the deep sounds of the bass, as evidenced by records ranging from “East St. Louis Toodle-Oo” (1926) to “Portrait of Wellman Braud” (1970). He always made sure he had the finest bassists at his disposal and used them to good advantage, not merely as accompanists or soloists, but also by having them provide counterpoint, double melodic lines, add percussive effects, and so forth. It can even be argued that although he did not play the string bass, Ellington was instrumental to its development. This article discusses the compositional devices and strategies Duke used to explore new approaches to the bass function between 1925 and 1941, and reveals how he in the process helped define its role in jazz.

Performing Hanne Darboven's Opus 17a and long duration minimalist music

Hanne Darboven’s (1941-2009) Opus 17a is a composition for solo double bass that is rarely performed due to the physical and mental challenges involved in its performance. It is one of four opuses from the composers monumental 1008 page Wünschkonzert (1984), and was composed during her period of making “mathematical music” based on mathematical systems where numbers were assigned to certain notes and translated to musical scores. It can be described as large-scale minimalism and it is highly repetitive, but even though the same notes and intervals keep repeating, the patterns slightly change throughout the piece. This is an attempt to unfold the many challenges of both interpreting, preparing and performing this 70 minute long solo piece for double bass consisting of a continuous stream of eight notes. It is largely based on my own experiences of preparing, rehearsing and performing Opus 17a, but also on interviews I have conducted with fellow bass players Robert Black and Tom Peters, who have both made recordings of this piece as well as having performed it live. One is met with few instrumental technical challenges such as fingering, string crossing and bowing when performing Opus 17a, but because of its long duration what one normally would take for granted could possibly prove to be challenging.

Symphonies Reframed

Symphonies Reframed recreates symphonies as chamber music. The project aims to capture the features that are unique for chamber music, at the juncture between the “soloistic small” and the “orchestral large”. A new ensemble model, the “triharmonic ensemble” with 7-9 musicians, has been created to serve this purpose. By choosing this size range, we are looking to facilitate group interplay without the need of a conductor. We also want to facilitate a richness of sound colours by involving piano, strings and winds. The exact combination of instruments is chosen in accordance with the features of the original score. The ensemble setup may take two forms: nonet with piano, wind quartet and string quartet (with double bass) or septet with piano, wind trio and string trio. As a group, these instruments have a rich tonal range with continuous and partly overlapping registers. This paper will illuminate three core questions: What artistic features emerge when changing from large orchestral structures to mid-sized chamber groups? How do the performers reflect on their musical roles in the chamber ensemble? What educational value might the reframing unfold? Since its inception in 2014, the project has evolved to include works with vocal, choral and soloistic parts, as well as sonata literature. Ensembles of students and professors have rehearsed, interpreted and performed our transcriptions of works by Brahms, Schumann and Mozart. We have also carried out interviews and critical discussions with the students, on their experiences of the concrete projects and on their reflections on own learning processes in general. Chamber ensembles and orchestras are exponents of different original repertoire. The difference in artistic output thus hinges upon both ensemble structure and the composition at hand. Symphonies Reframed seeks to enable an assessment of the qualities that are specific to the performing corpus and not beholden to any particular piece of music. Our transcriptions have enabled comparisons and reflections, using original compositions as a reference point. Some of our ensemble musicians have had first-hand experience with performing the original works as well. Others have encountered the works for the first time through our productions. This has enabled a multi-angled approach to the three central themes of our research. This text is produced in 2018.

The geometrization of N-manifolds of degree 2

This paper describes an equivalence of the canonical category of $\mathbb N$-manifolds of degree $2$ with a category of involutive double vector bundles. More precisely, we show how involutive double vector bundles are in duality with double vector bundles endowed with a linear metric. We describe then how special sections of the metric double vector bundle that is dual to a given involutive double vector bundle are the generators of a graded manifold of degree $2$ over the double base. We discuss how split Poisson $\mathbb N$-manifolds of degree $2$ are equivalent to \emph{self-dual representations up to homotopy} and so, following Gracia-Saz and Mehta, to linear splittings of a certain class of VB-algebroids. In other words, the equivalence of categories above induces an equivalence between so called \emph{Poisson involutive double vector bundles}, which are the dual objects to metric VB-algebroids, and Poisson $\mathbb N$-manifolds of degree $2$.

Expressions for Chordophone Instruments in Slovak and Slovenian Phrasemes

This article describes various construction types of Slovak and Slovenian phrasemes whose component structures include names of chordophones (i.e., instruments making sound with vibrating strings; namely, the violin, piano, double bass, harp, zither, and banjo), their derivations, and some lexemes that are closely related in meaning. It then analyses the phraseological and lexical units in terms of motivation, origin, equivalence, and so on, and links them to relevant Slovak and Slovenian cultural realia.

Novel approach to quantify the chemical stability and shelf life of modified double-base propellants

Abstract Double-base (DB) propellant is vulnerable to auto-catalytic decomposition reactions during storing with the evolution of nitrogen oxides. Modified DB propellant based on energetic nitramines (RDX) can offer enhanced thrust and action time. This study is devoted to evaluate the impact of RDX on chemical stability and shelf life of DB propellant. Extruded modified DB propellant based on RDX was manufactured by solventless extrusion process. Shelf life assessment was performed using an artificial aging at 70 °C up to 120 days and employing Van't Hoff's formula. Quantification of evolved NOx gases and stabilizer depletion with aging time was conducted using Bergmann-Junk test and HPLC respectively. Modified DB formulation based on RDX 20 wt % demonstrated enhanced chemical stability and extended service life up to 46 years compared with reference formulation. This finding was ascribed to the high chemical and thermal stability of RDX as well as its compatibility with DB constituents; no side chemical reactions could take place during storing. This manuscript shaded the light on RDX as effective energetic constituent that offered DB propellants with enhanced performance, good chemical stability, and extended service life.

Highly energetic nitramines: A novel platonizing agent for double-base propellants with superior combustion characteristics

The burning rate-pressure relation of solid propellant is an exponential relation; this is means catastrophic combustion process in case of sudden increase in operating pressure. This study reports on novel approach to minimize the dependence of burning rate on combustion pressure using highly energetic nitramines (RDX). Nitramine-based double base propellants with RDX content up to 20 wt% were manufactured by solventless extrusion technology. The impact of RDX content on burning rate, specific impulse, exhaust velocity, and thrust were evaluated using small-scale ballistic evaluation rocket motor. Specific impulse (Is) was enhanced by 20%. The action burning time (tb) was increased by 14%. The total thrust impulse (IFT) was significantly improved by 22%. One of the main outcomes of this study is that burning rate pressure exponent (n) was decreased significantly from 0.35 to 0.05. This novel ballistic performance finding means minimal change in burning rate with pressure variation. These findings confirmed that RDX has a dual function as energetic filler and platonizing agent. RDX blowing effect could alter the combustion mechanism by pushing the luminous flame from the burning surface. Furthermore, RDX decomposition can strengthen the platonization action. This is the first time ever to report on burning rate platonization using RDX. It can be concluded that many advantages have been achieved with one shot.

ANALYSIS OF THE EFFECT OF PROPELLANT TEMPERATURE ON INTERIOR BALLISTICS PROBLEM

This study investigates the effect of conditioning temperature of double base propellants on the interior ballistic parameters such as burning gas temperature, barrel wall temperature, pressure and stresses generated in the barrel. Interior ballistic problem was solved employing experimental, numerical and analytical methods with a thermo-mechanical approach. Double base propellants were conditioned at different temperatures (52, 35, 21, 0, -20, -35, -54ºC). The maximum pressure in the barrel and projectile muzzle velocity were measured for all the propellants by conducting shooting tests with a special test barrel using 7.62x51 mm NATO ammunition. Vallier-Heydenreich method was employed to determine the transient pressure distribution along the barrel. The temperature of burnt gases was calculated by using Noble-Abel equation. The heat transfer analysis was done using the commercial software ANSYS to get the transient temperature and stress distributions. Temperature distribution through the barrel wall thickness was validated using a FLIR thermal imager. Radial, circumferential and axial stresses and corresponding equivalent Von Misses stresses were determined numerically and analytically.&amp;nbsp; The results of the analytical solution for stress analysis validated the finite element solution of interior ballistic problem. Increasing the initial temperature of the propellant resulted in higher temperature and pressure inside the barrel which in turn increased the stresses in the barrel.

Combustion characteristics of extruded nitramine double-base propellants

AbstractThe burning rate-pressure relation of solid propellant is an exponential relation; this is means catastrophic combustion process in case of sudden increase in operating pressure. This study reports on novel approach to minimize the dependence of burning rate on the operating pressure using highly energetic nitramines (RDX). Nitramine-based double base propellants with RDX content up to 20 wt % were manufactured by solventless extrusion technology. The impact of RDX content on burning rate, specific impulse, exhaust velocity, and thrust were evaluated using small-scale ballistic evaluation rocket motor. Specific impulse (Is) was enhanced by 20 %. The action burning time (tb) was increased by 14 %. The total thrust impulse (IFT) was significantly improved by 22%. One of the main outcomes of this study is that burning rate pressure exponent (n) which was decreased significantly from 0.35 to 0.05. This novel ballistic performance means minimal change in burning rate with pressure variation. These novel findings confirmed that RDX has a dual function as energetic filler and as a platonizing agent. This is the first time ever RDX has been reported to act as a platonizing agent. It can be concluded that many advantages have been achieved with one shot.

MgAl-Layered Double Hydroxide Solid Base Catalysts for Henry Reaction: A Green Protocol

A series of MgAl-layered double hydroxide (MgAl-HT), the calcined form at 500 °C (MgAlOx), and the rehydrated one at 25 °C (MgAl-HT-RH) were synthesized. Physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Surface area of the as-synthesized, calcined, and rehydrated catalysts was determined by N2 physisorption at −196 °C. CO2 temperature-programmed desorption (CO2-TPD) was applied to determine the basic sites of catalysts. The catalytic test reaction was carried out using benzaldehyde and their derivatives with nitromethane and their derivatives. The Henry products (1–15) were obtained in a very good yield using MgAl-HT-RH catalyst either by conventional method at 90 °C in liquid phase or under microwave irradiation method. The mesoporous structure and basic nature of the rehydrated solid catalyst were responsible for its superior catalytic efficiency. The robust nature was determined by using the same catalyst five times, where the product % yield was almost unchanged significantly.

Synthesis of Novel Plasticizers Based on Poly(ε-caprolactone) and A Consideration of Their Influence on Nitroglycerine Migration in Double Base Solid Propellants

Synthesis of Novel Plasticizers Based on Poly(ε-caprolactone) and A Consideration of Their Influence on Nitroglycerine Migration in Double Base Solid Propellants