Insensitive energetic microspheres DAAF/RDX fabricated by facile molecular self-assembly

Insensitive energetic materials are promising in the defense weapons field. However, energetic materials still suffer from great challenges and the concern about their safety limits their utilization. In this work, insensitive energetic explosive 3,3′-diamino-4,4′-azoxyfurazan/hexahydro-1,3,5-trinitro-1,3,5-triazine (DAAF/RDX) microspheres were fabricated by self-assembly method. Rod-like DAAF/RDX was prepared by mechanical ball milling for comparison. DAAF/RDX composites with different mass ratios (90:10, 80:20, and 70:30) were obtained. The morphologies and structures of as-obtained DAAF/RDX composites were characterized by scanning electron microscopy (SEM), powder x-ray diffraction (PXRD) and fourier transform infrared spectroscopy (FT-IR). The results showed that DAAF/RDX microspheres exhibited regular shaped microspheres with sizes from 0.5 to 1.2 μm. There was no crystal transition during the modification process. The thermal properties of as-obtained materials were then evaluated by differential scanning calorimetry (DSC) and materials studio software. DAAF/RDX microspheres showed an advanced decomposition peak temperature compared with rod-like DAAF/RDX. The binding energy and peak temperature values at zero β_i (T_P0) of DAAF/RDX (90:10) increased by 36.77 kJ/mol, 1.6 °C, and 58.11 kJ/mol, 12.3 °C compared to DAAF/RDX (80:20) and DAAF/RDX (70:30), indicating the better thermal stability of DAAF/RDX (90:10). The characteristic drop height (H₅₀) of DAAF/RDX (higher than 100 cm) composites was higher than that of raw RDX (25 cm), suggesting significant improvements in mechanical safety. The preparation of DAAF/RDX microspheres is promising for the desensitization of RDX and useful for the formation of other materials and future wide applications.     

Bidirectional parallel multi-branch convolution feature pyramid network for target detection in aerial images of swarm UAVs

In this paper, based on a bidirectional parallel multi-branch feature pyramid network (BPMFPN), a novel one-stage object detector called BPMFPN Det is proposed for real-time detection of ground multi-scale targets by swarm unmanned aerial vehicles (UAVs). First, the bidirectional parallel multi-branch convolution modules are used to construct the feature pyramid to enhance the feature expression abilities of different scale feature layers. Next, the feature pyramid is integrated into the single-stage object detection framework to ensure real-time performance. In order to validate the effectiveness of the proposed algorithm, experiments are conducted on four datasets. For the PASCAL VOC dataset, the proposed algorithm achieves the mean average precision (mAP) of 85.4 on the VOC 2007 test set. With regard to the detection in optical remote sensing (DIOR) dataset, the proposed algorithm achieves 73.9 mAP. For vehicle detection in aerial imagery (VEDAI) dataset, the detection accuracy of small land vehicle (slv) targets reaches 97.4 mAP. For unmanned aerial vehicle detection and tracking (UAVDT) dataset, the proposed BPMFPN Det achieves the mAP of 48.75. Compared with the previous state-of-the-art methods, the results obtained by the proposed algorithm are more competitive. The experimental results demonstrate that the proposed algorithm can effectively solve the problem of real-time detection of ground multi-scale targets in aerial images of swarm UAVs.     

Preparation and characterization of HMX/EVA/hBNNSs micro-composites with improved thermal stability and reduced sensitivity

Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For com-parison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.     

火灾场钢筋混凝土简支梁抗弯性能分析

通过对火灾中钢筋混凝土简支梁截面温度场和材料热力学性能分析,将混凝土分为弹性区和塑性区来分别计算其强度,建立了火灾场简支梁截面内混凝土应力和梁极限抗弯承载力的计算公式,通过具体算例分析了钢筋混凝土简支梁截面温度场和极限承载力的变化规律和原因。     

编制实施三大规范推进企业技术进步——浅谈编制实施"某承制产品三大规范"的体会

“三大规范”是设计规范、工艺规范、试验规范的统称,是企业技术标准的核心组成部分。在某承制产品的设计、制造和试验等方面通过继承成熟的经验和技术诀窍,降低产品研制风险和提高质量,有利于新技术装备研制的一次成功,对加强企业技术标准体系建设,加快型号产品研制工作,做好武器装备研制具有非常重要和深远的意义。     

海蛇神经毒素Erabutoxin（Eb）的基因在大肠杆菌中的表达研究

为满足科研和医学应用上的需要,用基因工程的方法制备海蛇神经毒素。首先人工合成海蛇神经毒素Erabutoxin（Eb）的基因,重组到T载体。通过PCR扩增Eb基因,用限制性内切酶把基因片段酶切成黏性末端,然后将目标基因插入表达载体pPET22b（＋）,电转重组质粒到宿主菌BL21（DE3）,在25℃0．5mmol／L IPTG诱导培养8h收获培养物,SDS-PAGE电泳检测目标蛋白大部分存在于包涵体中,用8mol／L尿素溶解后,利用C末端的His-6与Ni^2＋离子亲和层析纯化,得到单一的电泳蛋白带。     

基于构件的软件复用技术在防化软件中的应用

软件复用是在软件开发过程中避免重复劳动的解决方案。通过构件的形式来实现软件复用,可以提高开发的效率和质量。以核侦察处理模块的实现和集成为例,介绍了基于构件的复用技术在目前信息化建设中的使用手段和方法。     

等离子体销毁日本遗弃化学武器排放气体采集方法选择探讨

等离子体销毁日本化学武器是目前正在探索的新课题,销毁过程排放尾气采集方法是该课题中需研究的内容之一。在认真分析、综合比较的基础上,提出了适应等离子体销毁日本遗弃化学武器的排放尾气采集方法的看法及其须关注的问题。     

Machine scheduling with an availability constraint and job delivery coordination

In this paper we study the scheduling problem that considers both production and job delivery at the same time with machine availability considerations. Only one vehicle is available to deliver jobs in a fixed transportation time to a distribution center. The vehicle can load at most K jobs as a delivery batch in one shipment due to the vehicle capacity constraint. The objective is to minimize the arrival time of the last delivery batch to the distribution center. Since machines may not always be available over the production period in real life due to preventive maintenance, we incorporate machine availability into the models. Three scenarios of the problem are studied. For the problem in which the jobs are processed on a single machine and the jobs interrupted by the unavailable machine interval are resumable, we provide a polynomial algorithm to solve the problem optimally. For the problem in which the jobs are processed on a single machine and the interrupted jobs are nonresumable, we first show that the problem is NP‐hard. We then propose a heuristic with a worst‐case error bound of 1/2 and show that the bound is tight. For the problem in which the jobs are processed on either one of two parallel machines, where only one machine has an unavailable interval and the interrupted jobs are resumable, we propose a heuristic with a worst‐case error bound of 2/3. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

后方司令部并非实体组织

1937年春成立的中革军委后方司令部(简称后方司令部),是一个实体组织还仅是一种名义?长期以来存在着不同见解.一种意见是:其成立及机构设置有一些原始记载,因此是实体;另一种意见是:后方司令部仅是一种名义,不是实体,实体仍是军委总司令部.