November 2022
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ItemPreparation-and-characterization-of-HMX-NH2-GO-composite-wit_2022_Defence-Te(ScienceDirect, 2022-11-05)To improve the safety of HMX, HMX/NH 2 -GO composite was prepared with aqueous ammonia func- tionalized graphene oxide (NH 2 -GO). The composite was characterized by SEM, Zeta potential, XPS, Raman spectrum, XRD, HPLC, DSC and BAM sensitivity test. The results indicated that the functionali- zation with aqueous ammonia can enhance the interaction between GO and HMX, and more efficiently desensitize the explosive. The optimal impact sensitivity of the HMX/NH 2 -GO composite can be not less than 40 J, which is also the most insensitivity compared to the previous reports prepared by coating desensitization with non-energetic desensitized material. Moreover, the potential reason for the different impact and friction sensitivity was also discussed, which may bring a novel perspective to achieve the desensitization of energetic material.
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ItemPreparation-of-ammonium-nitrate-based-solid-composite-propellant_2022_Defenc(ScienceDirect, 2022-11-05)To improve the performance of solid composite propellants (SCPs) supplemented with ammonium ni- trate (AN) as an oxidizer, the incorporation of energetic ingredients such as explosives, energetic binders or catalysts is a common effective approach. For this purpose, polyurethane (PU), a typical inert binder, was mixed with nitrocellulose (NC) as an energetic polymer. Numerous composite solid propellant compositions based on AN and NC-modified polyurethane binder with different NC ratios were prepared. The prepared formulations were characterized using Fourier transform infrared spectroscopy (FTIR), RAMAN spectroscopy, X-ray diffraction (XRD), electron densimetry, thermogravimetric (TG) analysis, and differential scanning calorimetry (DSC). A kinetic study was then performed using the iterative Kissinger- Akahira-Sunose (It-KAS), Flynn-Wall-Ozawa (It-FWO), and non-linear Vyazovkin integral with compensation effect (VYA/CE) methods. The theoretical performances, such as theoretical specific im- pulse, adiabatic flame temperature, and ideal exhaust gaseous species, were also determined using the NASA Lewis Code, Chemical Equilibrium with Application (CEA). Spectroscopic examinations revealed the existence of NC and full polymerization of PU in the prepared propellants. According to density tests, the density of the propellant increases as the nitrocellulose component increases. According to the thermal analysis and kinetics study, the increase in NC content catalyzed the thermal decomposition of the AN-based composite solid propellants. Based on the theoretical study, increasing the amount of NC in the propellant increased the specific impulse and, as a result, the overall performance.
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ItemRecent-advances-in-the-synthesis-and-energetic-properties-of-_2022_Defence-T(ScienceDirect, 2022-11-05)Primary explosives are utilized as a reliable initiator for secondary explosives in an extensive range of military and civilian operations. Heavyemetalebased primary explosives are moderate performing, more sensitive, and environmentally hazardous, posing a direct and indirect threat to health and safety. Therefore, heavyemetalebased primaries have been replaced by environment-friendly metal-based primary explosives, such as potassium complexes. This review presents not only a summary of the current progress of new-generation potassium-based primary explosives and their methods of prepa- ration, energetic properties, and applications, but also a further comparison with traditional primary explosives. In addition, this work discusses the necessity of heavy metalefree primary explosives and the major challenges faced in replacing traditional primary explosives.
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ItemResearch-on-a-MEMS-pyrotechnic-with-a-double-layer-barrier_2022_Defence-Tech( 2022-11-05)As an essential component of ammunition, pyrotechnics can control ignition with high reliability. However, due to limits of fabrication technology, traditional pyrotechnics are bulky. To achieve both functionality and miniaturization, MEMS pyrotechnics integrate initiator, safety-and-arming (S&A) de- vice and lead charge and keep all components within a small size. MEMS S&A devices, as the core component to ensure system safety, are difficult to achieve active and rapid response to control signals with high safety and reliability. In order to overcome the difficulty, we propose the design and charac- terization of a MEMS pyrotechnic with a double-layer barrier S&A device. The MEMS pyrotechnic is a high-integrated device with an overall size of 13.4 8.5 5.2 mm 3 . The initiator is a NiCr bridge foil covered with an Al/CuO energetic film, which can generate flame when ignited by an excitation voltage. To match the flame energy, lead styphnate is chosen in this study as the lead charge. The S&A device contains four semi-circular barriers, which are directly driven by V-shape electro-thermal actuators to gain active control of the pyrotechnics' ignition condition with rapid response. To improve the system's reliability, the four barriers are axisymmetrically placed in two layers, two barriers for each layer, to constitute a double-layer structure with a thickness of 100 m m. The ignition test results show that the S&A device can prevent the initiator from detonating the lead charge in safety condition. In arming condition, the lead charge will be detonated.
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ItemThe-SSA-BP-based-potential-threat-prediction-for-aerial-tar_2022_Defence-Tec( 2022-11-05)The target's threat prediction is an essential procedure for the situation analysis in an aerial defense system. However, the traditional threat prediction methods mostly ignore the effect of commander's emotion. They only predict a target's present threat from the target's features itself, which leads to their poor ability in a complex situation. To aerial targets, this paper proposes a method for its potential threat prediction considering commander emotion (PTP-CE) that uses the Bi-directional LSTM (BiLSTM) network and the backpropagation neural network (BP) optimized by the sparrow search algorithm (SSA). Furthermore, we use the BiLSTM to predict the target's future state from real-time series data, and then adopt the SSA-BP to combine the target's state with the commander's emotion to establish a threat prediction model. Therefore, the target's potential threat level can be obtained by this threat prediction model from the predicted future state and the recognized emotion. The experimental results show that the PTP-CE is efficient for aerial target's state prediction and threat prediction, regardless of commander's emotional effect.