Computational studies on two novel energetic nitrogen‐rich compounds based on tetrazolone

Two novel energetic nitrogen‐rich compounds 1,4‐diaminotetrazol‐5‐one ( DATO ) and 1,4‐dinitrotetrazol‐5‐one ( DNTO ) were proposed first and studied by quantum chemistry method with B3LYP/6‐31G* level of theory. The optimized geometry, IR predicted spectrum and thermochemical parameters, frontier molecular orbitals and molecular electrostatic potential were calculated for inspecting the electronic structure, molecular stability and chemical reactivity. The important macroscopic properties including density, enthalpy of formation, detonation parameters and impact sensitivity have been predicted as well. As a result, two designed compounds DATO and DNTO possess positive enthalpy of formation (395.79 and 342.77 kJ/mol), impressive detonation parameters (D = 8.80 km/s, P = 33.69 GPa; D = 8.89 km/s, P = 34.98 GPa) superior to the remarkable explosive RDX, acceptable sensitivities and might be promising candidates of energetic materials. Copyright © 2015 John Wiley & Sons, Ltd.     

认知无线电网络中利用FEC和DE的多节点频谱感知算法

针对认知无线电网络(CRN)中空闲频谱感知困难的问题,本文提出了基于前向纠错和差分进化算法的多节点频谱感知算法。首先,利用基于差分进化算法的协同检测完成信号感知;然后,研究了信道噪声对频谱感知性能的影响;最后,分析了前向纠错技术在信道存在噪声时对频谱感知性能的影响。仿真实验将纠错和无纠错控制信道的不同信噪比作为依据,采用三种不同的检测方法评估了本文算法。仿真实验结果表明,在存在噪声的认知无线电网络中,本文算法提高了系统的性能和检测概率,且协同感知算法的性能随着节点数目的增加而提高,该算法适合应用于实时性要求较高的应用程序。     

Real-World Forward Rate Dynamics With Affine Realizations

We investigate the existence of affine realizations for Lévy driven interest rate term structure models under the real-world probability measure, which so far has only been studied under an assumed risk-neutral probability measure. For models driven by Wiener processes, all results obtained under the risk-neutral approach concerning the existence of affine realizations are transferred to the general case. A similar result holds true for models driven by compound Poisson processes with finite jump size distributions. However, in the presence of jumps with infinite activity we obtain severe restrictions on the structure of the market price of risk; typically, it must even be constant.     

自支撑NH2-MIL-125/聚噁二唑复合正渗透膜的制备及性能

合成了高强度亲水性含羧基聚噁二唑材料(POD-COOH)和含氨基金属有机框架材料(NH₂-MIL-125), 以NH₂-MIL-125为填料, 与POD-COOH基体材料进行溶液共混, 并通过溶液浇铸法制备系列新型自支撑复合正渗透膜, 研究NH₂-MIL-125的引入对复合正渗透膜结构和性能的影响. 研究结果表明, 所制备的系列复合正渗透膜均呈致密结构, 且随着NH₂-MIL-125含量的增加, 复合膜的表面亲水性增加、 电负性增强, 并保持良好的机械性能. 以去离子水为进料液, 1.5 mol/L硫酸钠溶液为汲取液, 对上述自支撑复合膜进行正渗透性能测试, 发现由于消除了传统正渗透膜支撑层的内浓差极化现象, 该新型复合正渗透膜在分离过程中具有优异的正渗透性能.     

Theoretical modeling of the chemical synthesis and detonation performance of polynitrocubane derivatives

Theoretical work was performed based on experimental methods described in the literature to simulate and explore feasible routes for the synthesis of energetic octanitrocubane (ONC) and polynitrocubane derivatives. In respective gaseous and liquidous environments, using cubane as the raw material, ONC was successfully synthesized through carboxylation, amination, oxidation and nitration stages, and the related reaction energy barriers were simultaneously acquired. In particular, the polyparametric calibrated gaseous molecular formation enthalpy and the group additivity approach-estimated molecular density were incorporated using the Kamlet-Jacobs equation to evaluate the detonation performance of polynitrocubane derivatives. Some high-energy-density derivatives were found to have superior characteristics as compared with traditional hexagon (RDX) and octagon (HMX) explosives.     

Nitro-, Cyano-, and Methylfuroxans,and Their Bis-Derivatives: From Green Primary to Melt-Cast Explosives

In the present work, we studied in detail the thermochemistry, thermal stability, mechanical sensitivity, and detonation performance for 20 nitro-, cyano-, and methyl derivatives of 1,2,5-oxadiazole-2-oxide (furoxan), along with their bis-derivatives. For all species studied, we also determined the reliable values of the gas-phase formation enthalpies using highly accurate multilevel procedures W2-F12 and/or W1-F12 in conjunction with the atomization energy approach and isodesmic reactions with the domain-based local pair natural orbital (DLPNO) modifications of the coupled-cluster techniques. Apart from this, we proposed reliable benchmark values of the formation enthalpies of furoxan and a number of its (azo)bis-derivatives. Additionally, we reported the previously unknown crystal structure of 3-cyano-4-nitrofuroxan. Among the monocyclic compounds, 3-nitro-4-cyclopropyl and dicyano derivatives of furoxan outperformed trinitrotoluene, a benchmark melt-cast explosive, exhibited decent thermal stability (decomposition temperature >200 °C) and insensitivity to mechanical stimuli while having notable volatility and low melting points. In turn, 4,4′-azobis-dicarbamoyl furoxan is proposed as a substitute of pentaerythritol tetranitrate, a benchmark brisant high explosive. Finally, the application prospects of 3,3′-azobis-dinitro furoxan, one of the most powerful energetic materials synthesized up to date, are limited due to the tremendously high mechanical sensitivity of this compound. Overall, the investigated derivatives of furoxan comprise multipurpose green energetic materials, including primary, secondary, melt-cast, low-sensitive explosives, and an energetic liquid.     

The spreading behaviour of perfluoropolyether droplets on solid surfaces

The spread of perfluoropolyether （PFPE） droplets on solid surfaces has been measured from the top-down view through a microscope system. Effects of substrates, molecular weight and end-group functionality on spreading of the PFPE droplets have been studied experimentally and the results were compared with those by molecular dynamics （MD） simulations. Silicon wafer and diamond-like carbon （DLC） substrates were used to study the effect of substrates on spreading. Two types of PFPE, Z-dol and Z-tetraol, with the same chain structure and various molecular weights （2000 and 4000 g/mol） were employed in experiments. Effect of molecular weight has been investigated through comparing the spreading of Z-dol 2000 and Z-dol 4000, and it is found that the increase of molecular weight will decrease the mobility of PFPE. Comparison between spreading of Z-dol and Z-tetraol of the same molecular weight proved that functional end group plays a significant role on the spreading of PFPE, which confirmed the MD simulation results.     

快脉冲直线变压器驱动源模块的原理及实验

 介绍了直线型变压器驱动源（LTD）产生快脉冲的基本原理及技术优势，阐述了快脉冲LTD模块设计的要点，设计了输出脉冲上升时间小于100 ns的快脉冲LTD模块，并进行了初步的实验研究。实验得到该LTD模块充电±16 kV时，短路放电的电流峰值为23.7 kA，电流振荡1/4周期为69.6 ns；充电±50 kV驱动0.85 Ω负载时，电流峰值为41.4 kA，上升时间为36.8 ns（10%~90%）和60.8 ns（0~100%）。     

脉冲爆震发动机性能分析

本文发展了一种新的脉冲爆震发动机性能分析模型,考虑了流体阻力和油珠直径对爆震波速度、压力及脉冲爆震发动机比冲的影响。性能分析模型计算结果与试验结果比较表明,当进行了两相流和流体阻力影响修正后,两者较好。     

The Osher scheme for non-equilibrium reacting flows

An extension of the Osher upwind scheme to non-equilibrium reacting flows is presented, Owing to the presence of source terms, the Riemann problem is no longer self-similar and therefore its approximate solution becomes tedious. With simplicity in mind, a linearized approach which avoids an iterative solution is used to define the intermediate states and sonic points. The source terms are treated explicitly. Numerical computations are presented to demonstrate the feasibility, efficiency and accuracy of the proposed method. The test problems include a ZND (Zeldovich-Neumann-Doring) detonation problem for which spurious numerical solutions which propagate at mesh speed have been observed on coarse grids. With the present method, a change of limiter causes the solution to change from the physically correct CJ detonation solution to the spurious weak detonation solution.