排序方式: 共有15条查询结果,搜索用时 46 毫秒
1.
The synthesis of 3,3′‐bis(dinitromethyl)‐5,5′‐azo‐1H‐1,2,4‐triazole ( 5 ) using the readily available starting material 2‐(5‐amino‐1H‐1,2,4‐triazol‐3‐yl)acetic acid ( 1 ) is described. All compounds were characterized by means of NMR, IR, and Raman spectroscopy. The energetic compound 5 was additionally characterized by single‐crystal X‐ray diffraction and DSC measurements. The sensitivities towards impact, friction and electrical discharge were determined. In addition, detonation parameters (e.g. heat of explosion, detonation velocity) of the target compound were computed using the EXPLO5 code based on the calculated (CBS‐4M) heat of formation and X‐ray density. 相似文献
2.
A. C. Marta C. A. Mader J. R. R. A. Martins E. Van der Weide J. J. Alonso 《International Journal of Computational Fluid Dynamics》2013,27(9-10):307-327
A methodology for the rapid development of adjoint solvers for computational fluid dynamics (CFD) models is presented. The approach relies on the use of automatic differentiation (AD) tools to almost completely automate the process of development of discrete adjoint solvers. This methodology is used to produce the adjoint code for two distinct 3D CFD solvers: a cell-centred Euler solver running in single-block, single-processor mode and a multi-block, multi-processor, vertex-centred, magneto-hydrodynamics (MHD) solver. Instead of differentiating the entire source code of the CFD solvers using AD, we have applied it selectively to produce code that computes the transpose of the flux Jacobian matrix and the other partial derivatives that are necessary to compute sensitivities using an adjoint method. The discrete adjoint equations are then solved using the Portable, Extensible Toolkit for Scientific Computation (PETSc) library. The selective application of AD is the principal idea of this new methodology, which we call the AD adjoint (ADjoint). The ADjoint approach has the advantages that it is applicable to any set of governing equations and objective functions and that it is completely consistent with the gradients that would be computed by exact numerical differentiation of the original discrete solver. Furthermore, the approach does not require hand differentiation, thus avoiding the long development times typically required to develop discrete adjoint solvers for partial differential equations, as well as the errors that result from the necessary approximations used during the differentiation of complex systems of conservation laws. These advantages come at the cost of increased memory requirements for the discrete adjoint solver. However, given the amount of memory that is typically available in parallel computers and the trends toward larger numbers of multi-core processors, this disadvantage is rather small when compared with the very significant advantages that are demonstrated. The sensitivities of drag and lift coefficients with respect to different parameters obtained using the discrete adjoint solvers show excellent agreement with the benchmark results produced by the complex-step and finite-difference methods. Furthermore, the overall performance of the method is shown to be better than most conventional adjoint approaches for both CFD solvers used. 相似文献
3.
The reactions of 5‐nitriminotetrazole ( 4 ) with 1‐methyl‐5‐aminotetrazole ( 2 ) as well as 2‐methyl‐5‐aminotetrazole ( 3 ) were investigated. In the first reaction 2 was protonated yielding 1‐methyl‐5‐aminotetrazolium 5‐nitrimino‐1H‐tetrazolate monohydrate ( 7 ). In the latter case no protonation could be observed and a co‐crystallization of 5‐nitraminotetrazole and 2‐methyl‐5‐aminotetrazole was obtained. In this compound a new tautomer of 4 could be found. Both products were determined by low temperature single crystal X‐ray diffraction, IR, Raman and multinuclear (1H, 13C, 15N) NMR spectroscopy, elemental analysis as well as differential scanning calorimetry. In addition the heats of formation were calculated using experimentally obtained heats of combustion. With these and the X‐ray densities several detonation parameter were computed using the EXPLO5 software. In addition the sensitivities towards impact, friction and electrostatic discharge were determined. Further, two crystal structures of the important starting materials in energetic research 5‐nitriminotetrazole monohydrate ( 4 ·H2O) and 1‐methyl‐5‐nitriminotetrazolemonohydrate ( 5 ·H2O) are presented and compared with the water‐free compounds. The heats of formation of 4 , 4 ·H2O, 5 , 5 ·H2O have been calculated by the atomization method using the CBS basis set. Inclusion of crystal water decrease heats of formation about 265 kJ mol?1. Also the influence of crystal water on sensitivities (impact, friction, electrostatic discharge) but also performance is discussed. 相似文献
4.
In this article, we provide a review and development of sequential Monte Carlo (SMC) methods for option pricing. SMC are a class of Monte Carlo-based algorithms, that are designed to approximate expectations w.r.t a sequence of related probability measures. These approaches have been used successfully for a wide class of applications in engineering, statistics, physics, and operations research. SMC methods are highly suited to many option pricing problems and sensitivity/Greek calculations due to the nature of the sequential simulation. However, it is seldom the case that such ideas are explicitly used in the option pricing literature. This article provides an up-to-date review of SMC methods, which are appropriate for option pricing. In addition, it is illustrated how a number of existing approaches for option pricing can be enhanced via SMC. Specifically, when pricing the arithmetic Asian option w.r.t a complex stochastic volatility model, it is shown that SMC methods provide additional strategies to improve estimation. 相似文献
5.
Bi‐Dong Wu Yan‐Gang Bi Fu‐Gang Li Li Yang Zun‐Ning Zhou Jian‐Guo Zhang Tong‐Lai Zhang 《无机化学与普通化学杂志》2014,640(1):224-228
The multi‐ligand coordination compound copper(II) 1,2‐diaminopropane (pn) azide, [Cu(pn)(N3)2]n ( 1 ), was synthesized using pn and azido groups. It was characterized by X‐ray single crystal diffraction, elemental analysis, and FT‐IR spectroscopy. The crystal structure of 1 belongs to the monoclinic system, space group C2/c. The copper(II) cation is six‐coordinated by one pn molecule and four azido ligands with μ‐1 and μ‐1,1,3 coordination modes. Thermogravimetric investigations with a heating rate of 10 K · min–1 under nitrogen showed one main exothermic stage with a peak temperature of 215.7 °C in the DSC curve. The non‐isothermal kinetics parameters were calculated by Kissinger and Ozawa methods, respectively. The heat of combustion was measured by oxygen bomb calorimetry, and the enthalpy of formation, the critical temperature of thermal explosion, the entropy of activation (ΔS≠), the enthalpy of activation (ΔH≠), and the free energy of activation (ΔG≠) were calculated. The measurements showed that 1 has very high impact, friction, and flame sensitivities. 相似文献
6.
Quirin J. Axthammer Thomas M. Klapötke Burkhard Krumm Richard Moll Sebastian F. Rest 《无机化学与普通化学杂志》2014,640(1):76-83
A new simple synthesis route for 2,2,2‐trinitroethyl chloroformate ( 1 ), from easily available starting materials 2,2,2‐trinitroethanol and phosgene is presented. 2,2,2‐Trinitroethyl carbamate ( 2 ) was obtained by the reaction of 1 with aqueous ammonia. The nitration of 2 with anhydrous nitric acid and sulfuric acid yields 2,2,2‐trinitroethyl nitrocarbamate ( 3 ), which has potential as a perchlorate free high energetic dense oxidizer with a high oxygen balance of Ω(CO2) = +14.9 %. The thermal stability was studied using differential scanning calorimetry and the energies of formation were calculated on the CBS‐4M level of theory, as well as several detonation parameters and propulsion properties were determined. In addition to full spectroscopic characterization, X‐ray diffraction studies were performed for 2 and 3 . 相似文献
7.
8.
The synthesis of 5,5′‐diamino‐3,3′‐azo‐1H‐1,2,4‐triazole ( 3 ) by reaction of 5‐acetylamino‐3‐amino‐1H‐1,2,4‐triazole ( 2 ) with potassium permanganate is described. The application of the very straightforward and efficient acetyl protection of 3,5‐diamino‐1H‐1,2,4‐triazole allows selective reactions of the remaining free amino group to form the azo‐functionality. Compound 3 is used as starting material for the synthesis of 5,5′‐dinitrimino‐3,3′‐azo‐1H‐1,2,4‐triazole ( 4 ), which subsequently reacted with organic bases (ammonia, hydrazine, guanidine, aminoguanidine, triaminoguanidine) to form the corresponding nitrogen‐rich triazolate salts ( 5 – 9 ). All substances were fully characterized by IR and Raman as well as multinuclear NMR spectroscopy, mass spectrometry, and differential scanning calorimetry. Selected compounds were additionally characterized by low temperature single‐crystal X‐ray diffraction measurements. The heats of formation of 4 – 9 were calculated by the CBS‐4M method to be 647.7 ( 4 ), 401.2 ( 5 ), 700.4 ( 6 ), 398.4 ( 7 ), 676.5 ( 8 ), and 1089.2 ( 9 ) kJ · mol–1. With these values as well as the experimentally determined densities several detonation parameters were calculated using both computer codes EXPLO5.03 and EXPLO5.04. In addition, the sensitivities of 5 – 9 were determined by the BAM drophammer and friction tester as well as a small scale electrical discharge device. 相似文献
9.
The energetic complex, [Cd(HTRTR)2(H2O)4](HTNR)2 {HTRTR = 4‐[3‐(1,2,4‐triazol‐yl)‐1,2,4‐triaozle; HTNR– = styphnic acid anion) was synthesized and characterized by FT‐IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. It crystallizes triclinic in space group P$\bar{1}$ [a = 8.156(2) Å, b = 8.374(2) Å, c = 13.267(4) Å, α = 84.925(11)°, β = 87.016(11)°, γ = 63.683(5)°, V = 808.9(4) Å3, ρ = 1.940 g · cm–3]. The CdII ion is six‐coordinate with two HTRTRs and four water molecules. The thermal stabilities were investigated by differential scanning calorimetry (DSC). Non‐isothermal reaction kinetic parameters were calculated by Kissinger's and Ozawa‐Doyle's methods to obtain EK = 144.0 kJ · mol–1, lgAK = 14.22, and EO = 144.3 kJ · mol–1. The values of thermodynamic parameters, the peak temperature while β→0 (Tp0), free energy of activation (ΔG≠), entropy of activation (ΔS≠), and enthalpy of activation (ΔH≠) were obtained. Additionally, the enthalpy of formation was calculated by Hess's law on the basis of the experimental constant‐volume heat of combustion measured by bomb calorimetry, obtaining ΔfH°298 = 4985.5 kJ · mol–1. Finally, the sensitivities toward impact and friction were assessed according to relevant methods. The result indicates it as an insensitive energetic material. 相似文献
10.
Niko Fischer Prof. Dr. Thomas M. Klapötke Davin G. Piercey Jörg Stierstorfer 《无机化学与普通化学杂志》2012,638(2):302-310
The hydroxylammonium salts of monodeprotonated 5‐nitriminotetrazole ( 4 ), double deprotonated 5‐nitriminotetrazole ( 5 ), 1‐methyl‐5‐nitriminotetrazole ( 6 ), and 2‐methyl‐5‐nitraminotetrazole ( 7 ) have been prepared in high yield from the corresponding 5‐nitriminotetrazoles as free acids and an aqueous solution of hydroxylamine or the metathesis reactions of hydroxylammonium hydrochloride with the silver salt of the corresponding nitriminotetrazole, respectively. The energetic salts 4 – 7 were fully characterized by single‐crystal X‐ray diffraction ( 4 – 6 ), NMR spectroscopy, IR‐ and Raman spectroscopy as well as DSC measurements. The sensitivities towards impact, friction and electrical discharge were determined. In addition, several detonation parameters (e.g. heat of explosion, detonation velocity) were computed by the EXPLO5.04 computer code based on calculated (CBS‐4M) heats of formation and X‐ray densities. 相似文献