Wyniki wyszukiwania - Biblioteka Nauki

1

Molecular Dynamics Study of Vibrational Nonequilibrium in Detonation of Polyatomic Liquids

100%

Smirnov A. L. , Dremin A. N.

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2008

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tom Vol. 5, nr 1

63-74

EN

Energy transfer mechanisms to internal molecular degrees of freedom in shock and detonation waves in polyatomic liquids are investigated. The proposed approach uses a new version of the method of nonequilibrium molecular dynamics based on the simplest model potential energy surfaces of reacting polyatomic molecules. The main feature is adaptation of some results and approaches of gas theory to liquids. It is shown that vibrational nonequilibrium is produced by shock compression and influences on chemical reactions. So, the structure of shock and detonation waves depends strongly on the peculiarities of vibrational spectra and the structure of normal modes of compounds. Numerical simulations have been carried out for steady state detonation waves and processes of initiation of detonation by shock waves or by local heating. The results demonstrate different shock wave chemistry for substances of almost identical behaviour at static conditions.

2

Estimation of the deflection angle of plate driven by the products of grazing detonation

80%

Trzciński W. A.

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1999

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tom Vol. 47, iss. 3

285-297

EN

The deflection angle of a metal plate launched by the products of detonation grazing along the surface of the plate has been estimated theoretically. The influence of parameters characterising the plate and an explosive charge on quantitative characteristics of the launching process has been analysed. Results of the numerical calculations presented in the form of diagrams enable simple estimation of a dynamic deflection angle of the plate for given parameters of the explosive system. Estimated values of the angle can be applied in construction of the explosive schemes destined for cladding and strengthening.

3

On the Mechanism of Molecular Condensed EMs Transformation under the Effect of Shock and Detonation Waves

80%

Dremin A. N.

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2008

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tom Vol. 5, nr 1

31-44

EN

Considerations based on available experimental data on regularities of molecular condensed EMs decomposition under the effect of shock waves of different intensities are presented. It follows from the considerations that there exist shock wave pressures p* typical for each charge (for TNT charges p* ~ 12 GPa) and the charges’ initial density ?0* (for TNT 0* ~ 1.40 g/cm3) such that at larger pressure and density EMs' decomposition proceeds according to the homogeneous mechanism (does not depend on the charge structure: initial density, size and structure of explosive particles, explosive state-liquid or solid, …) and at lower pressure and density – according to the hot spots mechanism (depends on the charge structure).

4

Detonation Performance of Aluminium - Ammonium Nitrate Explosives

80%

Paszula J. , Trzciński W. A. , Sprzątczak K.

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2008

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tom Vol. 5, nr 1

3-11

EN

The research on an effect of aluminium contents on detonation characteristics of ammonium nitrate explosives was carried out. Measurements of detonation velocity were performed. Parameters of blast waves produced by charges of the investigated explosives detonating in an open space were measured by the use of piezoelectric gauges. Quasi-static pressure measurements were conducted in a steel chamber of 0.15 m3 volume filled with air. Moreover, the heat of detonation was measured with a calorimetric set in a 5.6 dm3 bomb filled with argon. The results of measurements of QSP, detonation velocity and heat were compared with those obtained from thermochemical calculations.

5

Accounts of the new aspects of nitromethane initiation reactivity

80%

Zeman S. , Atalar T. , Friedl Z. , Ju X.-H.

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2009

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tom Vol. 6, nr 1

119-133

EN

A well-known effect of amines, and also of water, on detonation characteristics of nitromethane (NM) is discussed from the point of view of the published knowledge about the study of initiation reactivity of this nitro paraffin. It is documented that bimolecular and higher interactions during the initiation of NM are impossible. The most widespread concepts of the primary steps of this initiation, i.e. formation of aci-NM anion [CH2=NO2]— by intermolecular hydrogen transfer in the neat NM submitted to shock and formation of this anion by action of an amine, have been scrutinized by the DFT B3LYP/cc-pVTZ+ method and evaluated as thermodynamically disadvantageous. Also the 1,3-intramolecular hydrogen shift in the NM molecule was characterized as a higher-barrier process. Two favorable primary mechanisms of fission in the NM initiation and development of its detonation were investigated by DFT B3LYP/cc-pVTZ+ calculations: homolysis of C–NO2 bond in the neat NM and homolysis of N–OH bond in its aci-form. The second mentioned pathway was found to be thermodynamically the most preferable mechanism of fission. Consequently, a detonation wave of NM with admixture of amine or water has a considerably reduced reaction zone length in comparison with the detonation of neat NM. The B3LYP/6-311++G(d,p) calculations of transition states revealed that an admixture of methylamine and/or water influences the conversion of nitromethane to its aci-form, and this effect is more feasible in the case of methylamine rather than water.

6

Self-sustained regimes of non-ideal detonation of aluminium particle aerosuspension (two-temperature model)

70%

Fedorov A. V. , Fomin V. M. , Khmel T. A.

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tom Vol. 18 nr 1-4

135-147

EN

Steady detonation regimes in an aerosuspension of aluminium particles is studied on the basis of the mathematical model of heterogenerous detonation with regard for differences in phase velocities and temperatures. The presence of unburned particles in detonation products conditions the sound speed dispersion in the final steady state. The manifolds of existance of Chapman-Jouguet and weak solutions in the plane of relaxation parameters are obtained. Steady-state solutions are tested for stability in the problem of propagation of piston-assisted detonation wave. All steady regimes are stable including the weak regime with a saddle final point. The problem of detonation wave interaction with an adjacent nonequilibrium rarefaction wave at instantaneous removal of thepiston is solved. It is obtained that Chapman-Jouguet and weak regimes including a regime with intermediate sonic final point are self-sustained. Strong regimes are transformed to either Chapman-Jouguet or weak regime depending on the relaxation parameters.

7

Forensic Investigation of Some Peroxides Explosives

70%

Kuzmin V. V. , Solov'ev M. Y. , Tuzkov Y. B. , Kozak G. D.

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2008

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tom Vol. 5, nr 3-4

77-85

EN

Some of pe roxide s : t r i a c e tone t r ipe roxide (TATP) , hexamethylenetriperoxidediamine (HMTD) have been used recently as "irregular" explosives for delinquency and international terrorism purposes. The intimate knowledge of properties and methods of analysis of these substances is necessary for experts. Forensic investigations of some peroxides explosives: triacetonetriperoxide (TATP) and hexamethylenetriperoxidediamine (HMTD) were carried out in this work. The detonation process of peroxides initiation by means of pyroxylin layer ignition was investigated, velocity of detonation at apparent density (ρ HMTD = 0.38 g/cm3, ρ TATP = 0.47 g/cm3) was measured by means of a Russian fotoregister GFR-3. These data were compared with literature detonation velocity values that had been measured at larger densities. The values of detonation velocities complement each other rather well, linear dependencies of D vs. ρ found at densities ρ = 0.35-1.2 g/cm3. The high sensitivity of the investigated analytical methods, that were applied (10-5 -10<-8 g) facilitate the determination of possible times for finding traces of TATP after an explosion. Time t = 6 hours after explosion is the critical time for finding peroxides traces of TATP on a metal surface by means of analytical methods used in this work.

8

Natryskiwanie powłok detonacyjnych - niektóre procesy im towarzyszące

60%

Babul T. , Oleszak D.

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tom Vol. 31, nr 4

846-851

PL

W pracy przedstawiono charakterystyczne zjawiska występujące w procesach udarowych, mające istotne znaczenie oraz wpływ na jakość formowania powłok detonacyjnych. Dotyczą one stanu materiału w warunkach działania wysokiego ciśnienia i jednocześnie dużych odkształceń plastycznych (płynięcia materiałów), mechanizmu odkształcania poślizgowego po granicach ziaren w materiale o silnie rozdrobnionych ziarnach, roli strumienia odwrotnego i wzajemnego przenikania się zderzających się materiałów i formowania strefy pośredniej.

EN

In a work description of a key physical processes which occur during percussive processes is presented. The processes are related to a state of a substrate and coating material in high pressure and high plastic strains conditions. Slip strains on grain boundaries in highly fragmented material occur in the production of coatings. Grain size is in order of nanometers. Inverse stream of material and mutual penetration of materials in formed gradient layer play a substantial role in the coatings production process.

9

Pomiar parametrów fali podmuchu jako sposób oceny zdolności do wykonania pracy przez produkty wybuchu górniczych materiałów wybuchowych

60%

Maranda A. , Sobala J. , Witkowski W. , Gołąbek B. , Zawadzka-Małota I. , Kasperski J.

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2007

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tom nr 9/1

67-69

PL

Opisano sposób pomiaru wybranych parametrów fali podmuchu generowanej detonacją górniczych materiałów wybuchowych. Na podstawie zmierzonej intensywności fali wyznaczono tzw. równoważnik trotylowy i heksoge-nowy badanych materiałów. Wskazano na zalety zastosowanej metody.

EN

The measurements of some blast wave parameters have been carried out. The blast wave was generated by detonation of emulsion mining explosives. Experimental results were used for calculating TNT and HX-equivalent. The advantages of the method have been presented.

10

Wyznaczanie zdolności miotających i energii detonacji materiałów wybuchowych z testu cylindrycznego

60%

Trzciński W. , Cudziło S. , Szymańczyk L.

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tom Vol. 49, nr 9

73-83

PL

Dla wybranych wojskowych materiałów wybuchowych wykonano test cylindryczny. Do rejestracji procesu miotania rurki miedzianej produktami detonacji zastosowano impulsową fotografię rentgenowską. Na podstawie rezultatów testu cylindrycznego określono zależność energii Gurneya od objętości produktów detonacji oraz oszacowano energię detonacji. Wyniki obliczeń porównano z rezultatami uzyskanymi za pomocą kodu do obliczeń do obliczeń termochemicznych oraz wynikami kalorymetrycznego pomiaru ciepła detonacji.

EN

In the work a cylinder test is performed for selected high explosives. Impulse X-ray photography is used for recording of the process of acceleration of a copper tube by detonation products. The dependence of the Gurney energy on the volume of detonation products as well as the detonation energy are established on the basis of the cylinder test results. Calculated parameters are compared with those obtained from a thermochemical code and from calorimetric measurements.

11

Możliwości i metody oceny parametrów wybuchu na podstawie składu chemicznego MW

60%

Papliński A.

|

2006

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tom z. spec.

99-112

PL

Rozpatrzono metody teoretycznej oceny parametrów wybuchu. Za podstawę przyjęto dane jakie można wyprowadzić na podstawie znajomości składu chemicznego wyjściowego materiału wybuchowego. Rozpatrzono metody pozwalające na określanie parametrów detonacji, wybuchu w stałej objętości oraz składu końcowego produktów wybuchu. Przeprowadzono dyskusję przydatności poszczególnych metod, zwłaszcza określania prędkości detonacji, w odniesieniu do przemysłowych materiałów wybuchowych.

12

Cellular structure of detonation wave in hydrogen-methane-air mixtures

51%

Porowski R. , Teodorczyk A.

Journal of Power Technologies

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2011

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tom Vol. 91, nr 3

130-135

EN

The paper reports on an experimental study of the cellular structure of detonation waves in hydrogen-methane-air mixtures. Experiments were performed in a 6-m circular cross section tube with inner diameter of 140 mm (full diameter of 170 mm) and a 0.8-m driver section tube with inner diameter of 90 mm. The initial conditions of stoichiometric hydrogen-methane-air mixtures were 1 atm and 293 K with varoius hydrogen content. The average detonation cell size for stoichiometric hydrogen-methane-air mixtures obtained by the smoked foil technique during the experiments was calculated with the 2D Fourier transform. Using the Cantera program, the detonation cell width was computed as a function of initial pressure and molar methane fraction in fuel for a stoichiometric methane-hydrogen-air mixture at initial temperature 295 K. The results of the computations were compared against the experimental results.

13

Propagation of hydrogen-air detonation in tube with obstacles

51%

Rudy W. , Porowski R. , Teodorczyk A.

Journal of Power Technologies

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2011

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tom Vol. 91, nr 3

122-129

EN

An experimental and computational study of flame propagation, acceleration and transition to detonation in stoichiometric hydrogen-air mixtures in 6 m long tube filled with obstacles located at different configurations was performed. The initial conditions of the hydrogen-air mixtures were 0.1 MPa and 293 K. Four different cases of obstacle blockage ratio (BR) 0.7, 0.6, 0.5 and 0.4 and three cases of obstacle spacing were used. The wave propagation was monitored by piezoelectric pressure transducers PCB. Pressure transducers were located at different positions along the channel to collect data concerning detonation propagation. Tested mixtures were ignited by a weak electric spark at one end of the tube. In order to support the experimental results we performed series of CFD simulations for the same conditions of hydrogen-air mixtures and the geometry of the tube. The simulation tool used in this study was a two-dimensional DETO2D code, dedicated to simulate the propagation of gaseous detonations in complex geometries.

14

Chemiczna modyfikacja nanoproszków diamentowych wytwarzanych metodą detonacyjną

51%

Adach K. , Skolimowski J. , Mitura K.

|

2011

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tom Vol. 52, nr 11

84-86

PL

Jednym z najciekawszych proszków węglowych jest nanoproszek diamentowy uzyskiwany w procesie detonacji, albowiem posiada rozwiniętą powierzchnię warstwy diamentu, którą można udoskonalać poprzez modyfikacje chemiczne. Idealna cząsteczka nanodiamentu oprócz wysokiej kompatybilności z układami biologicznymi powinna charakteryzować się również niską toksycznością oraz zdolnością powierzchni do łączenia się z wieloma grupami organicznymi - biomolekułami w celu uzyskania nowych właściwości, co cieszy się ostatnio dużym zainteresowaniem. W związku z tym podjęto próby chemicznej modyfikacji powierzchni. Zmierzano do otrzymania dostatecznie funkcjonalnych nanodiamentów, wyniki zostały przedstawione w niniejszym artykule.

EN

One of the most interesting carbon powders is diamond nanopowder obtained in the detonation process, because the diamond surface layer has developed, which could be improved via chemical modifications. The ideal nanodiamond molecule except the high biocompatibility with biological systems should also have low toxicity and surface ability to bind with many organic groups - biomolecules in order to obtain new properties, which have enjoy a lot of interest lately. Therefore, attempts were made to chemically modify the surface. Seeks to obtain a sufficiently functional nanodiamonds, the results are presented in this article.

15

Badania doświadczalne i analiza modelowa parametrów detonacji i składu produktów wybuchu górniczych materiałów wybuchowych

51%

Maranda A. , Papliński A. , Zawadzka-Małota I. , Sobala J.

|

2007

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tom nr 9/1

63-66

PL

Przeprowadzono analizę parametrów detonacyjnych oraz składu produktów wybuchu górniczych materiałów wybuchowych. Zastosowano dwie metody badawcze. Rozpatrzono badania doświadczalne oraz analizę obliczeniową w zakresie składu chemicznego produktów wybuchu i detonacji. Przeprowadzono pomiary prędkości detonacji oraz analizę parametrów wybuchu takich, jak objętość produktów wybuchu, kruszność, zdolność do wykonania pracy dla wybranych materiałów wybuchowych. Przedstawiono dyskusję znaczenia wartości prędkości detonacji jako charakterystyki własności użytkowych gómiczych materiałów wybuchowych, które detonują w nieidealnym reżimie detonacji. Przeprowadzono rozszerzoną analizę termodynamiczną badanych materiałów wybuchowych. Do przeprowadzenia obliczeń wykorzystano program MWEx rozwijany w Instytucie Przemysłu Organicznego. Program określa skład chemiczny i parametry termodynamiczne produktów przemiany wybuchowej, detonacji lub wybuchu. Parametry detonacji i wybuchu określano dla jednakowej gęstości badanych materiałów, wynoszącej 1,0g/cm^ oraz dla gęstości nominalnych, z jakimi sporządzane są poszczególne materiały wybuchowe. Określano parametry w płaszczyźnie Chapmana-Jougueta: prędkość detonacji, ciśnienie detonacji, energię detonacji oraz parametry wybuchu w stałej objętości: ciśnienie wybuchu, temperaturę wybuchu i ciepło wybuchu. Przedstawiono przykładowe wyniki dla reprezentantów dwóch grup materiałów wybuchowych, dynamitów i emulsyjnych materiałów wybuchowych.

EN

The analysis of detonation parameters and estimation of chemical composition of explosion products of mining explosives is performed. Two methods of investigation are employed. Experimental results are inspected as well as numerical analyses are carried out. Measurements of detonation velocity values are performed. Values of such explosion parameters as explosion products volume, brisance, work capacity for several explosives are also referred. The relation and significance of the detonation velocity magnitude as the parameter characterizing the yield efficiency of mining explosives that are to detonate in nonideal regime is discussed. An extending thermodynamical analysis of the investigated explosives is performed. The parameters of detonation and explosion are evaluated by the MWEx program being developed in the Institute of Industrial Organic Chemistry. The program estimates the detonation and explosion parameters upon solving the problem of evaluation of equilibrium composition and thermodynamical parameters of reacting medium. Detonation and explosion parameters were estimated for similar mass densities of 1 g/cm3 as well as for nominal densities, at which the production lots are completed. The parameters in Chapman-Jouguet point like detonation velocity, detonation pressure and detonation energy as well as parameters of constant volume explosion: explosion pressure, temperature and heat of explosion were evaluated. Exemplary results for explosives belonging to group of dynamites and emulsion explosives are presented.

16

Wizualizacja przebiegu wybuchowego spalania aerodyspersji pyłowych metodą tomografii pojemnościowej

51%

Piotrowski T. , Pląskowski A.

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tom Vol. 49, nr 4

125-132

PL

W pracy przedstawiono badania mające na celu uzyskiwanie w czasie rzeczywistym obrazów przebiegu spalania mieszanin pyłowo-powietrznych z zastosowaniem metody tomografii pojemnościowej. Opisano stanowisko pomiarowe z inflamatorem poziomym, użytą aparaturę (tomograf PTL 300 TP-G) i pokazano rekonstrukcje przykładowych obrazów przebiegu spalania. Zarysowano kierunek dalszych badań i zdefiniowano możliwość przemysłowego zastosowania metody do śledzenia stanu bezpieczeństwa procesowego w przemyśle.

EN

The paper resents the investigations of aim to reconstruct the combustion-run images of dust-air mixtures applying the capacitance method. The test stand with the horizontal glass inflamator has been described as well as the apparatus used (PTL 300 TP-G tomograph). The examples of the reconstructed images have been shown. The direction of further investigations has been outlined and the possibility of industrial application of the described method for trasing the process safety level in chemical plants has been defined.

17

Przegląd sposobów wyznaczania parametrów fali uderzeniowej wybuchu

51%

Saska P. , Czmochowski J. , Iluk A.

|

2010

|

tom R. 51, nr 4

187-192

PL

Oddziaływanie fali uderzeniowej wybuchu na realne konstrukcje, zwłaszcza pojazdy jest przedmiotem badań w wielu ośrodkach naukowych. Obecnie istnieje szereg metod określania parametrów fali uderzeniowej wybuchu. W artykule przedstawiono teoretyczne, doświadczalne oraz numeryczne sposoby wyznaczania charakterystyk fali uderzeniowej wybuchu. Ponadto sformułowano wnioski do przeprowadzenia własnych badań eksperymentalno-numerycznych.

EN

An influence of blast wave on real constructions especially vehicles is a very specific process. Mentioned process is subject of investigation in many science institutions. Nowadays we have many methods of blast wave parameters estimation. The article presents theoretical, experimental and numerical methods of blast wave characteristics determination. Moreover authors formulate concerning of own conclusions to execution own experimental and numerical investigations.

18

Nowe kierunki rozwoju inżynierii materiałowej z wykorzystaniem metod wybuchowych

51%

Babul W. , Maranda A. , Nowaczewski J. , Paszula J.

|

2000

|

tom Z. 46 (225)

7-14

PL

W pracy mającej charakter przeglądowy przedstawiono krótkie charakterystyki metod wybuchowych stosowanych w inżynierii materiałowej: prasowania i obciążania materiałów intermetalicznych oraz magnetycznych, stopowania i umacniania połączonego z azotowaniem. Do referatu załączono obszerny spis publikacji dotyczących głównie prac wykonanych w WAT.

EN

The present review presents brief characteristics of material engineering explosion methods, including pressing and high-pressure loading of intermetallic and magnetic materials, alloying and hardening combined with nitriding. The paper includes also an extensive list of references which cover the investigations conducted by the Warsaw Military Technical Academy.

19

CПЕЦИФІКА ФОРМУВАННЯ ВОКАЛЬНОЇ ТЕХНІКИ: ОЗНАКИ НЕДОСКОНАЛОСТІ ТА ОСОБЛИВОСТІ ЇХ УСУНЕННЯ

41%

Тетяна Л.

Педагогічні науки: теорія, історія, інноваційні технології

|

2017

|

nr 4(68)

189-199

EN

The article reveals the researches on the characteristics, manifestations and defects of vocal technique with high impedance, which is the main criterion for evaluating the professionalism of each singer-performer of academic manner. The necessity and timeliness of research of the aforementioned problem is proved. The essence of the concepts of “vocal technique”, “defects of vocal sound”, “impedance”, “throat sound”, “nasal prism”, “forcing”, “detonation” is specified; the peculiarities of a number of methods and techniques for combating defects in vocal technique in general and vocal sound formation and sound behavior, in particular among students of artistic higher education institutions at vocational classes, are highlighted. As a result of working out the literature it has become clear that the problem of detection and struggle with imperfect vocal technique among pupils of artistic higher education is of paramount importance, since it is an actual task of musical-pedagogical education and one of the conditions for the development of the spiritual culture of mankind. The primary sources on the research problem interpret the singing activity as the main one, which allows, with the help of vocal hearing and muscular-vibration sensations, to form professional vocal techniques for future musicians, educators and performers, which is part of the improvement of their professional training. At the same time, the process of detecting and getting rid of the disadvantages of vocal technique is a painstaking systematic work in the classroom where the guiding vocabulary is a vocal professional technique with strong impedance and the world-renowned European academic opera-concert blended-cover style of singing, which is characterized by the covered sound, softness, roundness, callousness, homogeneity, naturalness of sound, coherence of registers, etc. The prospect of further research in the context of our study is to develop methodological support for the development of reflexive actions close to professional vocal technique with strong impedance, as well as in the formation of skills of independent work in the process of mastering vocal repertoire.

20

Umacnianie warstw wierzchnich stopowaniem udarowym.

36%

Babul T. , Babul W.

|

2002

|

tom R. XXIII, nr 5

604-607

PL

W pracy przedstawiono nowy kierunek wiedzy, obecnie intensywnie rozwijany, jakim jest umacnianie warstw wierzchnich przez wprowadzenie na duże głębokości cząstek innego materiału z prędkościami znacznie przewyższającymi prędkość dźwięku. Opisano niektóre typy akceleratorów, struktury i mechanizmy wnikania cząstek opartych na założeniu, iż wnikanie ich w podłoże na duże głębokości może dokonywać się tylko pod warunkiem wywoływania w podłożu specyficznego stanu energetycznie wysoko wzbudzonego, charakteryzującego się naruszeniem krystalicznej budowy materiału.

EN

The intended aim of the paper is to present a new line of knowledge and research under an intense development nowadays, i.e. the hardening of surface layers by means of introducing another material deep into the basis metal with a high-speed impact. What has been given consideration is accelerators, structures and mechanisms of penetration as based on the assumption that the penetration of particles deep into the basis metal can proceed provided that some specific, high excited energy state has been induced, namely the one featured with some disarrangement of crystal structure of the material.