Identification of high explosives using single-particle aerosol mass spectrometry

The application of single-particle aerosol mass spectrometry (SPAMS) to the real-time detection of micrometer-sized single particles of high explosives is described. Dual-polarity time-of-flight mass spectra from 1000 single particles each of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN), as well as those of complex explosives, Composition B, Semtex 1A, and Semtex 1H, were obtained over a range of desorption/ionization laser fluences between 0.50 and 8.01 nJ/microm2. Mass spectral variability with laser fluence for each explosive is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle ( approximately 1 pg) without the need for consumables is demonstrated.     

Separation of explosives using capillary electrochromatography

The identification of explosives and their degradation products is important in forensic and environmental applications. Complete separation of these structurally similar compounds using reversed-phase liquid chromatography has proven to be a challenge. Here we present a demonstration of the use of capillary electrochromatography on the separation of a series of 14 nitroaromatic and nitramine explosive compounds. A separation with baseline resolution is achieved for all of the compounds in under 7 min, featuring efficiencies of over 500?000 theoretical plates/m. Using more aggressive running conditions, 13 of the 14 compounds are separated in under 2 min.     

Near-Earth object deflection using conventional explosives

Due to the large number and distribution of asteroids and comets in the solar system, there is the distinct possibility of one of them striking Earth just as comet Shoemaker-Levy 9 struck Jupiter. A debate is ongoing in the scientific community as to how best to divert such a threat. In 2005 NASA was directed by Congress to provide a report on the detection of near-Earth objects (NEOs) and their mitigation if determined to be a threat. The report was delivered in March 2007; as input to that report, the work reported here provided information on conventional methods to divert a potentially hazardous object (PHO) including conventional explosives and direct impact with a rocket. Other slow push conventional approaches include propulsion systems attached to the asteroid or comet and the recently proposed gravitational tractor. Advantages of conventional explosives are that they can be delivered in small packages so that the asteroid or comet is in no danger of being broken up and it is possible to accurately compute the momentum transferred to the asteroid or comet through modern validated numerical techniques. This work demonstrates that conventional explosives can be an efficient conventional method to divert an asteroid or comet and computes the amounts of explosives needed.     

Detonation temperature of high explosives from structural parameters

A new scheme is introduced for calculating detonation temperature of different classes of high explosives. The ratio of oxygen to carbon and hydrogen to oxygen as well as specific structural parameters are the fundamental factors in the new method. An empirical new correlation is used to calculate detonation temperature of energetic compounds without considering heat contents of explosives and detonation products. Calculated detonation temperatures for both pure and explosive formulations show good agreement with respect to measured detonation temperatures and complicated computer code using BKWR and BKWS equations of state. Predicted detonation temperatures have root-mean-square (rms) percent deviation of 4.6, 14.2 and 4.6 from measured values for new method, BKWR and BKWS equations of state, respectively.     

A remote welding technique for high explosives containers

Samples of high explosives for environmental testing have been successfully enclosed in all-welded assemblies. Proper container design, fixturing, welding power supply, and welding parameters ensure the safe, timely completion of the task.     

Fracture surface energies of high explosives PETN and RDX

Journal of Materials Science -     

超微晶合金高频磁特性检测中的波形调理

针对超微晶合金高频磁特性检测时出现的波形非对称畸变问题进行分析与探讨,研究测量过程中由于磁饱和与非对称磁路引起的波形畸变原因。对测试系统进行建模,提出一种基于压缩映射原理的反馈控制算法。设计基于NI高速数据采集卡的全自动测控系统,实现超微晶合金高磁通密度下波形的控制与波形补偿。通过设计第三补偿绕组,补偿磁场强度的非对称分量,得到标准的磁滞回线。最后,测量日立金属所提供的FT-3M磁芯的磁滞回线与比损耗曲线,验证方法的可行性,对超微晶合金的高频磁特性测量对发展高频电力变压器具有参考价值。     

装填RDX基含铝炸药射孔弹的性能试验

为了提高含能射孔弹综合性能,降低致密油气储层的开采难度,对装填RL-F含铝炸药射孔弹的性能进行了研究。首先以RL-F含铝炸药为研究对象,对RL-F含铝炸药进行了机械感度、静电火花感度、5 s延滞期爆发点和DSC热分解测试;其次分别将RL-F含铝炸药和JH-16炸药装填在89型射孔弹中,进行了地面模拟装枪穿钢靶和穿柱状混凝土靶试验。结果显示:RL-F含铝炸药具有合适的机械感度,耐热性良好,适用于射孔弹压装工艺;与装填JH-16炸药的89型射孔弹穿深性能相比,装填RL-F含铝炸药的89型射孔弹地面侵彻钢靶和地面侵彻柱状混凝土靶穿深分别降低了10.6%和27.5%,而装填RL-F炸药在侵彻混凝土靶时射流孔道干净清晰、无杵堵,孔道无压实带。     

应用多种高精度测量机制的电参量分析仪研制

针对计量测试过程中高精度电参量分析的需求,该文提出多种改善分析测量精度的测量机制,包括高精度交流电压采样分压器、高精度改进型双级交流电流互感器、利用DDS实现准同步采样原理进行信号频率跟踪实现同步采样以及非整周期傅里叶补偿谐波算法。并将这些测量方法应用到分析仪的研制设计中,实现电参数测试准确度优于0.01%、谐波分析准确度优于0.02%的高精度电参量分析仪。     

Mechanical testing of cordierite porous ceramics using high temperature diametral compression

In this study, the high temperature mechanical behavior of cordierite porous disks prepared by the starch consolidation forming method was evaluated. In this method, due to the swelling and gelatinization properties of starch in aqueous suspension at a temperature between 55 and 85 °C, the starch granules perform as both consolidator/binder of the green body and pore former at high temperature. Aqueous suspensions (29.6 vol.%) of a cordierite precursor mixture (talc, kaolin, and alumina) with the addition of potato or cassava starches (11.5 vol.%) were prepared by intensive mechanical mixing, homogenization, and vacuum degasification. Green disks were formed by thermogelling of the aqueous suspensions at 85 °C for 4 h followed by additional drying at 50 °C for 24 h. They were characterized by bulk density and apparent porosity measurements, and microstructural analysis by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Porous cordierite materials were obtained by calcination at 650 °C for 2 h and reaction-sintering at 1330 °C for 4 h, employing specific, controlled heating schedules in both treatments. Cordierite disks were characterized by bulk density and apparent porosity measurements, and microstructural analysis by SEM. Mechanical behavior was evaluated in diametral compression using a servohydraulic testing machine at room temperature (RT), 800, 1000, and 1100 °C. Apparent stress–strain relationships were obtained from load–displacement curves, and mechanical parameters, such as fracture strength (σ_F), apparent Young modulus (E _a), and yield stress (σ_Y), were determined. Moreover, crack patterns were also evaluated. The obtained results were analyzed in function of the developed microstructures, considering the presence of a silicate glassy phase and a complex porosity, and the testing temperature.     

Noninvasive detection of concealed liquid explosives using Raman spectroscopy

We present a Raman spectroscopic method for the noninvasive detection of liquid explosives within bottles, and other packaging, of substantially higher sensitivity and wider applicability than that currently available via conventional Raman spectroscopy. The approach uses a modification of the spatially offset Raman spectroscopy (SORS) concept, which permits the interrogation of a wide range of containers, including transparent, colored, and diffusely scattering plastic and glass beverage, medicine, and cosmetic bottles, with no change in experimental geometry. The enhanced sensitivity is achieved by the technique's inherent ability to effectively suppress fluorescence and Raman contributions originating from the wall of the container. The application is demonstrated on the noninvasive detection of hydrogen peroxide solution, a critical component of a number of liquid explosives. In contrast to conventional Raman spectroscopy, the modified SORS concept enables the detection of concealed hydrogen peroxide solution in all the studied cases.     

PVDF shock sensors: applications to polar materials and high explosives

Ferroelectric polymers (PVDF) with well-defined and precisely known electrical properties are now routinely available from commercial sources. Electrical processing with the Bauer cyclic poling method can produce individual films with well-defined remanent polarization up to 9 /spl mu/C/cm/sup 2/. These polymers provide an unusual opportunity to study the structure and physical properties of materials subjected to shock loading. The behavior of PVDF has been studied over a wide range of pressures using high-pressure shock loading and has yielded well-behaved, reproducible data up to 25 GPa in inert materials. The application of PVDF gauges for recording shock waves induced in polar materials such as Kel-F, PMMA, or in reactive materials is hampered by observations of anomalous responses due to shock-induced polarization or an electrical charge released inside a shock-compressed explosive. A solution using an appropriate electrical shielding has been identified and applied to PVDF for shock measurement studies of Kel-F, and for Hugoniot measurements of high explosives (PH). Furthermore, shock pressure profiles obtained with in situ PVDF gauges in porous HE (Formex) in a detonation regime have been achieved. Typical results of shock pressure profile versus time show a fast superpressure of a few nanoseconds followed by a pressure release down to a plateau level and then by a pressure decay. More accurate measurements are reported with electrically improved PVDF gauges as well as with 0.25 mm/sup 2/ active area PVDF gauges.     

基于AUTODYN的乳化炸药水下爆炸能量分布的数值研究

基于AUTODYN软件建立了水下爆炸一维楔形模型,对空气不耦合装药结构下爆炸能量的输出进行研究。首先获得炸药冲击波压力以及气泡脉动随时间的变化曲线,进一步获知径向不耦合状态下水下爆炸的冲击波峰值压力、气泡最大半径以及脉动周期等数据,并最终得到了不耦合系数下冲击波能以及气泡能的变化情况。将计算结果与已有的水下爆炸实验结果进行了比较分析。结果表明,该计算结果与实验数据吻合较好,证明了利用数值计算手段可以实现定量化表征炸药输出能量随不耦合装药结构的变化规律。     

Modular ion mobility spectrometer for explosives detection using corona ionization

Ion mobility spectrometry (IMS) has become the most widely used technology for trace explosives detection. A key task in designing IMS systems is to balance the explosives detection performance with size, weight, cost, and safety of the instrument. Commercial instruments are, by and large, equipped with radioactive (63)Ni ionization sources which pose inherent problems for transportation, safety, and waste disposal regulation. An alternative to a radioactive source is a corona discharge ionization source, which offers the benefits of simplicity, stability, and sensitivity without the regulatory problems. An IMS system was designed and built based on modeling and simulation with the goal to achieve a lightweight modular design that offered high performance for the detection of trace explosives using a corona ionization source. Modeling and simulations were used to investigate design alternatives and optimize parameters. Simulated spectra were obtained for 2,4,6-trinitrotoluene (TNT) and cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) and showed good agreement with experimentally measured spectra using a corona ionization source. The reduced mobilities for TNT and RDX obtained with corona ionization were 1.53 and 1.46 cm(2)/(V s), respectively, and this agreed well with literature values.     

Material properties of a

A study was carried out to investigate changes in mechanical properties and degradation of self-reinforced fibrillated poly-96L/4D-lactide (SR-PLA96) rods in vitro and in vivo. The viscosity-average molecular weight, Mv, of the intact sterile (gamma irradiated) rods was around 50 000 g mol-1. The SR-PLA96 rods of diameter 1.1 mm by 30 mm and diameter 4.5 mm by 50 mm were immersed in phosphate-buffered saline or implanted in the dorsal subcutis of rabbits. Bending, shear and torsion strength and bending modulus, together with the changes of viscosity and crystallinity, were measured up to 24 wk. The strength values showed only a slight decrease during the follow-up period with the exception of torsion strength, that decreased to 52% of the initial value during 24 wk. There were no statistically significant differences in the strength retention between in vitro and in vivo groups. Crystallinity increased over time, being 46–49% at 24 wk. The Mv of the rods decreased over 50% by 24 wk. These promising results motivated us to continue the studies with the fixation of experimental cortical bone osteotomies with SR-PLA96 intramedullary rods. © 1999 Kluwer Academic Publishers     

基于AUTODYN的乳化炸药水下爆炸能量分布的数值研究

基于AUTODYN软件建立了水下爆炸一维楔形模型,对空气不耦合装药结构下爆炸能量的输出进行研究。首先获得炸药冲击波压力以及气泡脉动随时间的变化曲线,进一步获知径向不耦合状态下水下爆炸的冲击波峰值压力、气泡最大半径以及脉动周期等数据,并最终得到了不耦合系数下冲击波能以及气泡能的变化情况。将计算结果与已有的水下爆炸实验结果进行了比较分析。结果表明,该计算结果与实验数据吻合较好,证明了利用数值计算手段可以实现定量化表征炸药输出能量随不耦合装药结构的变化规律。     

几种高分子乳化剂在乳化炸药中的性能研究

选取几种不同性能指标的聚异丁烯丁二酰亚胺类高分子乳化剂,通过低剪切乳化、低浓度乳化(乳化剂质量占基质比:0.1%)测试了乳化剂的乳化能力;按照现场散装乳化炸药配方制备了乳化基质,通过动力黏度、自然储存、高低温循环、超声波法等评价了基质的基本性能,测定了乳化炸药的敏化速率和初始爆速。结果表明:EMU-3高分子乳化剂制备的乳化基质储存稳定性和抗颠簸性能好,基质黏度适中,敏化速率适宜,炸药爆速达4 436 m/s,适宜于现场散装乳化炸药的生产。     

几种高分子乳化剂在乳化炸药中的性能研究

选取几种不同性能指标的聚异丁烯丁二酰亚胺类高分子乳化剂,通过低剪切乳化、低浓度乳化(乳化剂质量占基质比:0.1%)测试了乳化剂的乳化能力;按照现场散装乳化炸药配方制备了乳化基质,通过动力黏度、自然储存、高低温循环、超声波法等评价了基质的基本性能,测定了乳化炸药的敏化速率和初始爆速。结果表明:EMU-3高分子乳化剂制备的乳化基质储存稳定性和抗颠簸性能好,基质黏度适中,敏化速率适宜,炸药爆速达4 436 m/s,适宜于现场散装乳化炸药的生产。