Double-base Research Articles

A Novel Method of Improving the Mechanical Properties of Propellant Using Energetic Thermoplastic Elastomers with Bonding Groups.

The relatively poor mechanical properties of extruded modified double base (EMDB) propellants limit their range of applications. To overcome these drawbacks, a novel method was proposed to introduce glycidyl azide polymer-based energetic thermoplastic elastomers (GAP-ETPE) with bonding groups into the propellant adhesive. The influence of the molecular structure of three kinds of elastomers on the mechanical properties of the resultant propellant was analyzed. It was found that the mechanical properties of the propellant with 3% CBA-ETPE (a type of GAP-ETPE that features chain extensions using N-(2-Cyanoethyl) diethanolamine and 1,4-butanediol) were improved at both 50 °C and -40 °C compared to a control propellant without GAP-ETPE. The elongation and impact strength of the propellant at -40 °C were 7.49% and 6.58 MPa, respectively, while the impact strength and maximum tensile strength of the propellant at 50 °C reached 21.1 MPa and 1.19 MPa, respectively. In addition, all three types of GAP-ETPE improved the safety of EMDB propellants. The friction sensitivity of the propellant with 3% CBA-ETPE was found to be 0%, and its characteristic drop height H50 was found to be 39.0 cm; 126% higher than the traditional EMDB propellant. These results provide guidance for studies aiming to optimize the performance of EMDB propellants.

Seismic performance of rocking braced frames with double base plate connections

This paper presents a rocking system for concentrically braced frames (CBFs) to mitigate the seismic demands induced by seismic motions. The proposed system incorporates double base plate connections (DBPCs) at the base of the braced-bay columns, enabling them to uplift and initiate a rocking motion. The DBPC comprised two base plates: the upper one is thin, connected to the column and designed to yield under uplift loading, while the lower one primarily distributes compressive loads to the foundation. The DBPC was modeled using a combination of spring and gap elements in SAP2000 software. A comparative study was performed to investigate the seismic performance of the proposed rocking system against a conventional CBF system. Key parameters such as the thickness of the upper base plate and the arrangement of anchor rods were considered. Four prototype frames of different heights (3, 6, 9, and 12 stories) were investigated under the Sylmar-x record using the nonlinear time history analysis. The results demonstrated that utilizing rocking braced frames with double base plate connections can remarkably mitigate the base shear force by softening the structural response, decreasing the seismic damage experienced by the structure. The upper base plate acted similarly to a footing damper, absorbing a substantial amount of energy by yielding. Importantly, the residual drifts caused by the plastic deformations of the upper base plate remained within the acceptable performance limits for self-centering systems. Moreover, the self-centering mechanism was achieved solely through the structure’s self-weight, eliminating the need for additional re-centering devices.

Canine detection of explosives under adverse environmental conditions with and without acclimation training.

Canines are one of the best biological detectors of energetic materials available; however, canine detection of explosives is impacted by a number of factors, including environmental conditions. The objectives of this study were: 1) determine how canine detection limits vary when both the canine and odorant are tested in varying temperature and humidity conditions (canine and odor interactive effects); and 2) determine if an acclimatization plan can improve detection limits in an adverse environmental condition. Eight working line canines were trained to detect four energetics: prill ammonium nitrate (AN), Composition 4 (C4), trinitrotoluene (TNT) and double base smokeless powder (SP). In Experiment 1, canines completed a 3-alternative forced choice 3-down-1-up staircase threshold assessment in five environmental conditions: 40°C and 70% relative humidity (RH), 40°C and 40% RH, 0°C and 90% RH, 0°C and 50% RH and 21°C and 50% RH. Canines showed a 3.5-fold detection limit increase (poorer detection) for C4 in 40°C and 70% RH compared to their detection limit at 21°C and 50% RH. In Experiment 2, the eight canines were split into two groups (n = 4), control and acclimation groups. The control group completed the threshold assessment for C4 at 21°C and 50% RH each day for 20 days, with 5 minutes of petting prior to testing. The acclimation group completed the same assessment daily starting at 21°C and 50% RH but temperature and RH were incremented daily over the course of 6 days to the 40°C and 70% RH condition. After the initial six days, the acclimation group completed daily assessments at 40°C and 70% RH condition for the remainder of the experiment. All acclimatization group canines started their session with 5 minutes of toy or food retrieves. Detection limits for C4 for all dogs were tested in 40°C and 70% RH on day 11 and day 22. The acclimatization plan improved detection limits in the 40°C and 70% RH condition for C4 compared to the non-acclimated group. In this set of experiments, canine detection limits for four explosive odorants were found to vary based on environmental condition and were mostly driven by impacts on the canine rather than odor availability. The acclimatization plan did result in lower detection limits (i.e., increased performance). Future work should determine what factor (exercise or environmental exposure) is more effective in acclimatization for odor detection work.

10.36871/hon.202402137

This article is devoted to the musical style of Yuri Kasparov (b. 1955), Russian composer and music teacher, Professor at the Moscow State Tchaikovsky Conservatory, who writes primarily chamber music. Many of his compositions are scored for a chamber orchestra comprising flute, oboe, clarinet, bassoon, horn, trumpet, trombone, harp, piano, percussion, two violins, viola, cello and double bass (an instrumentation derived from A. Schoenberg’s Chamber Symphony No. 1). His works include over 80 chamber compositions of different genres written for one to 17 instruments. He tends to use non-standard instrumentation rather than ensembles typical for classical music such as string quartet, string trio, piano quintet, etc. Most of the techniques common to the avant-garde music are found in Kasparov’s works: the twelve-tone technique, sonorism, aleatoric music, electroacoustic music, musique concrète, performance, instrumental theatre, sound collage. Still, he remains quite a traditional composer that does not break down the boundaries of what is considered “musical” and “non-musical” sound. Kasparov’s music is beautiful, emotional, easy to understand, full of melodies and continuous instrumental solos. A simple word “beauty” becomes a stylistic innovation in his music. Kasparov believes that contemporary music can be divided into two categories: sonorism and “musical graphics”. Sonorism is focused on timbre, while “musical graphics” is distinguished by a greater use of pitch. Most of Kasparov’s works can be considered sonoristic, but today he prefers “musical graphics” — “colorless black and white composition” in which “line is important”.

КОРАНИЧЕСКИЕ ТЕКСТЫ В ХОРОВЫХ СОЧИНЕНИЯХ СОВРЕМЕННЫХ ТАТАРСКИХ КОМПОЗИТОРОВ

The purpose of this work is to concentrate the reader’s gaze on the choral works of Tatar composers, to show that the creation of these works was inspired directly by a religious idea, and this idea manifested itself at the level of the use of Koranic texts. The research material was partly the work of S. Gabyasha, as well as works by Sh. Sharifullin, R. Kalimullin, M. Shamsutdinova, S. Zoryukova for choir, alto flute, double bass, prepared piano and percussion. The author of the article comes to the conclusion that the appeal to the Koranic texts of modern Tatar composers is not only due to the desire to join Muslim spiritual ethics, but also to comprehend their past from the present, thereby outlining the appropriate vector of musical development into the future.

IDENTITY THROUGH DIFFERENCE IN BEAT FURRER'S LOTÓFAGOS

AbstractIn Homer's The Odyssey, Odysseus and his men are on their way home to Ithaca when they land on a remote island inhabited by lotus-eaters. The locals share their indolent-making lotus plants with the Greeks, such that the troops’ homeward journey is disrupted and they find themselves in a state of limbo. Identities, both individual and communal, become entangled and blurred. Beat Furrer takes these sorts of uncertainties of self as inspiration in his Lotófagos (2007) – that is, Lotus-eaters – scored for soprano and double bass, which sets José Ángel Valente's poem of the same name. Drawing on Gilles Deleuze's conception of bodies, this article argues that the identity of an elusive but persistent collective subject in Valente's text can be found within the difference between the two performers’ bodies in Furrer's setting. The pair's movements weave in and out of each other, moving through spectres of each other's material, fleetingly suggesting cohesion through tension before jettisoning this for what contextually appears as relief. As such, the series of surreptitious vignettes presents a ‘conatus’ of the piece defined by tension, emulation and transience; Furrer's Lotófagos creates space for Valente's mysterious subject to be presented as the immanence of forces between two performing bodies.

Exploration of rigid double schiff base with a symmetrical plane as highly effective corrosion inhibitor for mild steel in hydrochloric acid environment: Experimental and theoretical approaches

A rigid double Schiff base with a symmetrical plane, (1E,1′E)-N,N’-(1,4-phenylene)bis(pyrazin-2-yl)ethanimine) (PBPE), has been synthesized and characterized by 1H NMR and FTIR spectroscopies. The corrosion inhibition performance of PBPE for mild steel in 1.0 mol L−1 HCl solution was systematically measured by weight loss method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization technique, field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), atomic force microscope (AFM), and water contact angle measurement. The inhibition efficiency depends upon the PBPE concentration and the maximum inhibition efficiency by weight loss analysis is 93.10 % at 800 mg L−1 PBPE. The potentiodynamic polarization measurement revealed that PBPE behaves as a mixed-type inhibitor with a predominant anodic reaction. The thermodynamics adsorption analysis showed the adsorption of the PBPE molecules on the surface of mild steel obeys Langmuir adsorption isotherm, with both physisorption and chemisorption. In the corrosion reaction, the activation energy, activation enthalpy, and activation entropy all increased with increasing PBPE concentration. The surface morphology analysis such as SEM-EDS, AFM, and water contact angle further confirmed adsorption on the mild steel surface and resulted in the formation of protective film on the mild steel surface in PBPE solution. The quantum chemical parameters obtained such as global softness, electron transfer fraction, and energy gap together with Fukui indices can explain the good inhibition efficiency. Molecular dynamics simulations discovered that the PBPE molecules in a flat manner are adsorbed on the surface of mild steel, thus giving rise to a more effective adsorption and corrosion inhibition.

Assessment of the effect of lignin biopolymer on the thermal stability of energetic nitrocellulose/diethylene glycol dinitrate composite

AbstractThis study explored the stability and thermo‐kinetic features of double base nitrocellulose (NC)/diethylene glycol dinitrate (DEGDN) propellant supplemented with Kraft lignin. For this purpose, the impact of 2‐nitrodiphenylamine (2‐NDPA), 1,3‐dimethyl‐1,3‐diphenylurea (C‐II) and lignin stabilizers on the molecular structure, morphology, and thermokinetic behavior of NC/DEGDN composite were thoroughly analyzed. Experimental results showed that lignin exhibits promising stabilizing efficiency comparable to that of the conventional 2‐NDPA and C‐II. In addition, thermal findings highlighted that the incorporation of 2‐NDPA, C‐II, and lignin has improved the thermal decomposition temperature of NC/DEGDN propellant. The investigation of the thermolysis kinetics of stabilized NC/DEGDN composites demonstrated an increase in the Arrhenius parameters with respect to the NC/DEGDN baseline. Above all, this investigation contributes to the ongoing efforts to develop new environmentally friendly stabilizers for nitrate esters‐based composites.

A double inference engine belief rule base for oil pipeline leakage

Accurate prediction of oil pipeline leakage is important for energy security and environmental protection. The belief rule base (BRB) is a rule-based modeling approach that can make use of information with uncertainty to describe causal relationships in predicting oil pipeline leaks. Due to the complexity and uncertainty of oil pipeline systems, traditional BRB models produce a large rule base, which reduces the modeling capability and interpretability of BRB. Therefore, this paper proposes a double inference engine BRB (BRB-DI) model. Compared with the traditional BRB models, the new model diminishes the number of the rules from 56 to 25, while maintaining the accuracy. In the BRB-DI model, firstly, rule reduction is used to reduce the complexity of the model by comprehensively analyzing the importance of rules. Secondly, to ensure the completeness of the model rule base, a double inference engine consisting of the evidence reasoning (ER) algorithm and ER rule is proposed, and a new reasoning computation process is designed. Finally, an optimization algorithm based on projection covariance matrix adaptation evolution strategy (P-CMA-ES) is proposed to prevent the diminishing interpretability of the optimized model. In order to verify the effectiveness of the proposed method, an oil pipeline leakage prediction problem is studied as a numerical example.

Effect of silica filler on peroxide cured ethylene propylene diene terpolymer insulation for large rocket motors

AbstractNon‐compatibility with double base propellant and nitrate ester plasticized polyether based propellant and poor aging resistance limit the overall life of sulfur cured EPDM insulation and warranted the development of peroxide cured EPDM insulation in order to reap the full benefits of EPDM insulation. This article describes the effect of silica filler on the physical, mechanical, thermal, and ablative properties of peroxide cured EPDM insulation, free from chlorosulphonated polyethylene and filled with conventional precipitated silica, which has been validated for the requirements of large composite rocket motor casing. Significant findings, which have been corroborated by instrumental techniques viz. DSC, TGA, FTIR, and SEM are presented in this article.

Research on Intelligent Space Construction Path of University Innovation and Entrepreneurship Base

In order to promote the improvement of innovation and entrepreneurship ability of college students, with continuing education, colleges and universities give full play to the advantages of integration of production and education to build college students' double creation base. By analyzing the function positioning and construction ideas of college students' innovation and entrepreneurship base, the intelligent construction path of college students' double innovation base is pointed out. The construction of college students' innovation and entrepreneurship base explores its intelligent construction path from the four aspects of network information flow, media information flow, space flow and emotional flow, so as to build up the growth space of talent education in line with the current and future.

Synthesis of Zn/Al-ZnO Composite Using Zn/Al-Layered Double Hydroxide for Oxidative Desulfurization of 4-Methyldibenzothiophene

Zn/Al-ZnO composites made from Zn/Al-Layered Double Hydroxide base material and ZnO as a precursor were successfully made in this study. Characterization analysis using SEM-EDS, XRD, and FTIR. The SEM analysis results show the Zn/Al-LDH has a smooth surface, overlapping, and is prone to aggregation, resulting in non-uniform particle size. However, it forms a uniform grain shape. Zn/Al-ZnO have rough surfaces with uniform particle shape and size, and the presence of pores on the particle surface. EDS analysis shows the Zn element which is more abundant in Zn/Al-ZnO. XRD analysis of Zn/Al-LDH showed the hydrotalcite. XRD analysis on ZnO showed the hexagonal wurtzite crystal structure. Zn/Al-ZnO composites at an angle of 2θ show the same peak of the base material and the precursor. FTIR analysis of the composite revealed the presence of O-H groups at wave numbers 3445 cm−1, 1633 cm−1, and 1504 cm−1, indicating the presence of nitrate. Additionally, vibrations at wave numbers 1382 cm−1 corresponded to antisymmetric (v3) stretching of nitrate, while wave numbers 418 cm−1 and 606 cm−1 indicated metal-oxygen stretching vibrations. Of all the factors used in the desulfurization of 4-methyldibenzothiophene, Zn/Al-ZnO composites had the highest %conversion rate of both the base material and the precursor. The %conversion values of Zn/Al-ZnO at the time of contact were 99.40%, catalyst dosage 99.38%, solvent 99.10%, and temperature 99.56%, respectively. The catalyst is heterogeneous and reusable for the desulfurization of 4-methyldibenzothiophene.

An Investigation Into the Bowing Techniques in Performing Bach Cello Suite NO.2 For Double Bass

An Investigation Into the Bowing Techniques in Performing Bach Cello Suite NO.2 For Double Bass

Influence of humidity on the decomposition process of double base rocket propellant

The decomposition mechanisms of the polymer cellulose nitrate (NC) which is used in double base (DB) rocket propellants, have been extensively studied, and the influence of storage temperature on the lifetime of these energetic formulations is well known. However, the impact of humidity and water on the polymer decomposition process is poorly understood. This paper studies the influence of humidity on the decomposition chemistry of NC and its impact on shelf life. Stabiliser consumption was first analysed by ageing the propellant in sealed vials at different humidity levels for 7 days at an isothermal temperature of 90 °C. Samples were also analysed using heat flow calorimetry (HFC) at isothermal temperatures of 80 °C, 90 °C, and 100 °C. The results indicates that stabiliser depletion increases with increasing water content. Life assessment calculations (AOP 48 ed2) show that increasing the absolute humidity from 6 to 22 g m-3 will decrease the propellant life from 11 to 6 years (25 °C equivalents). The HFC results follow the same trend as the stabiliser depletion where greater absolute humidity increases the heat flow by up to 400 %. Unlike the pass/fail criteria for stabiliser depletion, the HFC samples passed the 10-year (25 °C equivalent) life criteria (STANAG 4582). A multi-temperature (80, 90, 100 °C) kinetic analysis of the initial heat flow showed that the heat flow rate increased with increasing humidity, but the activation energy for all humidity levels remained at 131 (± 3) kJ mol−1.

TECHNICAL SUGGESTIONS WITH SELECTIONS FROM DRAGONETTI DOUBLE BASS CONCERTO IN LA MAJOR

The first movement “Allegro Moderato” and the second movement “Andante” of this concerto, composed by Edouard Nanny and thought to be attributed to Domenico Dragonetti, which, although it was a soloist’s preference until 20-25 years ago, today remains at the level of learning and will undoubtedly benefit the student in terms of self-development, are the subject of my thesis (Sabuncu, 2021). During the years I taught at the University of North Texas in the United States of America, these two movements of the concerto, rather than the third movement, were the subject of this study because they were pedagogically preferred. It is worth mentioning briefly that the concerto in A major was notated in G major due to the solo tuning of the double bass for the performance of the work. The aim of this article, which is based on my doctoral thesis, is to provide a pedagogical path and recommendations for this original work through technical exercises and etudes that will provide maximum benefit for the preparation of this work and for possible parts that may pose problems in its performance. In this way, the study is intended to guide the student in the preparation of basic double bass technique and the two parts of the concerto under two main headings: “Intonation” and “Right Hand and Dynamics”.

Storage-life prediction and relationship between maximum elongation and stabilizer depletion for a composite modified double base propellant (CMDB) propellant

Storage-life prediction and relationship between maximum elongation and stabilizer depletion for a composite modified double base propellant (CMDB) propellant

Correlation between microstructural evolution and mechanical properties of CMDB propellant during uniaxial tension

AbstractNumerical simulation of the deformation and damage evolution process of composite modified double base (CMDB) propellant based on the microstructure is of great significance for improving its macro‐mechanical properties. The macro‐mechanical properties and damage evolution of CMDB propellant were studied experimentally and numerically in current work. To establish the correlation between microstructural evolution and the macro‐mechanical response of the propellant, a three‐dimensional microstructure model of the CMDB propellant was constructed utilizing the molecular dynamics particle filling approach. At the interface between RDX particles and the nitrocellulose‐nitroglycerine (NC‐NG) matrix, the conventional cohesive element was replaced by cohesive contact, and the parameters of the cohesive zone model (CZM) at the interface between the particles and the matrix were obtained by parameter inversion based on the Hooke‐Jeeves parameter optimization algorithm. The processes of damage initiation, propagation, convergence, and failure at the cohesive interface were simulated using the bilinear cohesive zone model (BCZM). The results revealed that the fracture strength of NC‐NG propellant with added RDX particles was significantly increased and the fracture elongation was reduced. The three‐dimensional microstructure model can accurately describe the microstructure of CMDB, and dewetting at the interface is the primary cause of propellant degradation when subjected to an external load, which compromises the mechanical properties of the propellant.

Kyle Motl, Bells Plucked from Air: A Guide to (Mostly) Pizzicato Harmonic Techniques for the Double Bass, Bandcamp, $26.

Kyle Motl, Bells Plucked from Air: A Guide to (Mostly) Pizzicato Harmonic Techniques for the Double Bass, Bandcamp, $26.

Determining kinetic parameters for the thermal decomposition of double base propellant catalyzed by a graphene oxide–barium oxide nanocomposite

Determining kinetic parameters for the thermal decomposition of double base propellant catalyzed by a graphene oxide–barium oxide nanocomposite

Elucidating the effect of nitrocellulose-encapsulated MgAl–CuO on the thermal behavior of double base propellant based on nitrocellulose and diethylene glycol dinitrate

Elucidating the effect of nitrocellulose-encapsulated MgAl–CuO on the thermal behavior of double base propellant based on nitrocellulose and diethylene glycol dinitrate