Towards a formal definition of methods

The absence of a formal specification of methods permits application engineers to interpret method concepts in any way they want. Further, different CASE tool designers can implement the same method concepts in different ways. The approach to formal method specification described here is in three levels: the generic level, the method independent level, and the method level. The generic level provides a model of a method which can be instantiated to yield a method-independent view of methods. This view can, in turn, be instantiated to yield the formal method of interest. The attempt is to represent methods independently of any underlying way-of-working or paradigm, remove the process/product dichtomy by tight coupling of the process and product aspects of methods, and permit extensibility of methods. The formal specification can be used as a basis for building CASE tools, as an output to be produced by a CAME tool, and for defining development processes.     

Diversity of 16S ribosomal DNA-defined bacterial population in acid rock drainage from Japanese pyrite mine

Four acidophilic bacteria (YARDs1-4) were isolated from an acid rock drainage (ARD) from Yanahara mine, Okayama prefecture, Japan. The physiological and 16S rDNA sequence analyses revealed that YARD1 was closely affiliated with Acidithiobacillus ferrooxidans, YARD2 was an Acidiphilium-like bacterium, and YARD3 and YARD4 were sulfur-oxidizing bacteria with a relatively close relationship to A. ferrooxidans in the phylogenetic analysis. A molecular approach based on the construction of a 16S rDNA clone library was used to investigate the microbial population of the ARD. Small-subunit rRNA genes were PCR amplified, subsequently cloned and screened for variation by a restriction fragment length polymorphism (RFLP) analysis. A total of 284 clones were grouped into 133 operational taxonomic units (OTUs) by the RFLP analysis. Among them, an OTU showing the same RFLP pattern as those of the isolates from the ARD was not detected. The phylogenetic analysis based on the 16S rDNA sequences from 10 major OTUs and their close relatives revealed that 4 OTUs containing 32.1% of the total clones were loosely affiliated with Verrucomicrobia, 2 OTUs containing 6.6% of the total clones were loosely affiliated with Chloribi, and other OTUs were affiliated with Actinobacteria, Nitrospirae, and beta-Proteobacteria.     

RTS与帧分段机制在地空数据链中的应用与改进

将IEEE802．11的RTS／CTS握手机制与MSDU帧分段机制引入地空数据链,建立了基于改进Markov链的地空数据链MAC层协议模型。以最大饱和吞吐量为性能参数推导出合理的RTS阈值和分段阈值算法。分析表明该方法能够提高无线通信效率,降低了误帧率,解决了隐藏终端等问题。     

HCV核心抗原N-端片段生物素化表达质粒的构建及表达

目的构建HCV核心(C)抗原N-端1～130aa片段的生物素化表达质粒,并在大肠杆菌中进行表达。方法PCR扩增HCV C抗原N-端1～130aa片段的编码基因,拼接上生物素-蛋白连接酶底物肽序列(BSP),构建重组原核表达质粒pGEX4T-1-CN130BSP,转化大肠杆菌Rosetta,IPTG诱导表达。表达产物经SDS-PAGE后,电转至硝酸纤维素膜上,以抗HCVC抗原的单克隆抗体和辣根过氧化物酶标记的亲和素对表达产物进行分析。结果PCR扩增出约466bp的目的基因片段;质粒pGEX4T-1-CN130BSP经PCR及双酶切鉴定,与预期结果一致,测序鉴定基因无突变;SDS-PAGE显示表达产物相对分子质量约为42000,22℃诱导16h可溶性表达产物含量较高;表达的重组蛋白可被抗HCV C抗原的单克隆抗体所识别,并能特异性结合辣根过氧化物酶标记的亲和素。结论已成功构建了HCV C抗原N-端1～130aa片段生物素化表达质粒,并表达出带生物素标签的GST融合蛋白,为进一步研制HCV双抗原夹心检测试剂奠定了基础。     

弹丸破片速度衰减规律研究

采用理论分析和试验测试相结合的方法,对弹丸破片的速度衰减规律进行了研究.通过理论分析得到计算弹丸破片迎风面积的数学模型,由试验得到某型远程杀伤弹破片的质量分布情况和初速分布情况,通过数值分析,用Matlab绘出了该弹破片速度衰减曲线.结果表明,初速和飞散距离相同的破片,破片质量越大,存速越大.该方法对于计算弹丸杀伤半径和杀伤面积有实际意义.     

含铝炸药爆热性能与破片加载特性关系探讨及验证

以浇注HMX 基含铝炸药为研究对象,构建炸药爆轰加载假设模型。探讨爆热与破片速度的关系,并使用 不同粒径设计了不同铝含量的炸药配方,测试了炸药爆速和爆热及其对全预制破片速度和穿甲率的影响。试验结果 表明：随着铝氧比和爆热的增加,破片速度和穿甲率呈现先升后降的趋势,当铝氧比和爆热分别为0.35 和6 200 kJ/kg 时,其破片速度和穿甲率分别为1 890 m/s 和89%,破片加载能力达到最大,验证了含铝炸药爆热与破片加载特性存 在数学极值关系,工程上存在最佳匹配点。     

遭毁伤聚能战斗部射流成型行为

针对遭毁伤聚能装药射流成型行为及其终点效应问题,采用AUTODYN-3D软件研究了侵孔位置、侵孔深度和侵孔直径对射流径向速度及其侵彻能力的影响特性。结果表明:侵孔导致射流径向速度明显增大且射流偏离轴线甚至提前断裂形成碎片,严重降低了其对靶板的侵彻能力,同等条件下,侵孔直径d=0.278倍装药直径的聚能装药比完好聚能装药对靶板侵深降低了24%;射流径向偏移速度主要受侵孔位置和侵孔直径的影响,随着侵孔到药型罩顶距离的减小,射流径向速度显著增大,同时对靶板侵彻深度也越小,x=0倍装药直径时,射流径向速度达19.0 m·s~(-1);射流径向速度随侵孔直径的增大而显著增大,d=0.278倍装药直径时,射流径向速度达41.1 m·s~(-1)。     

一种油气井用双向传爆管极限传爆距离

为评估油气井用双向传爆管在空气中的极限传爆距离(即在置信水平0.95下,可靠度为0.999的最大传爆距离),采用火工品常用的感度试验用数理统计方法——升降法,对双向传爆管进行传爆实验。用LS-DYNA软件进行了双向传爆管的传爆机理和爆炸过程的数值模拟。结果表明,在空气中,在0.95置信水平下,可靠度为0.999的双向传爆管的最大传爆距离为82.8 mm。数值模拟结果在一定程度上支持82.8 mm左右的实验结果。     

不同形状的预制钨破片正穿甲钢靶的破孔能力分析

为了探究不同形状和初始动能条件下预制钨破片对中厚钢靶的穿甲问题,采用LS-DYNA动力显示分析软件分别对不同初速条件下,3种形状破片撞击钢靶的过程进行仿真模拟.通过对比分析弹靶毁伤形貌和破片速度时程曲线等,得到了形状和初始动能对穿甲威力影响的变化规律.仿真结果表明:相同初始条件下,不同破片形状对钢靶的侵蚀程度不尽相同,但侵彻机理相似;侵彻动能的增加对穿甲威力的提升影响显著,穿甲威力随侵彻动能的增加而增大;初始动能相同时,立方体形破片破孔能力最强,圆柱形破片次之,球形破片最弱;与此同时,立方体形破片在穿甲过程中速度及动能衰减最为严重.     

装甲抗侵彻技术研究进展及对化工储罐保护层风险防控的借鉴

爆炸碎片对化工储罐的侵彻作用破坏性极强,储罐保护层技术作为侵彻事故风险防控的重要手段却仍处于起步阶段。典型的保护层技术,如军事装甲技术研究已经较为成熟,可为储罐保护层技术发展提供重要的借鉴意义。本文系统分析了国内外有关化工储罐保护层及军事装甲防护侵彻损伤的相关文献,指出化工储罐保护层技术研究亟待解决的问题,并参考装甲技术研究进展提出其进一步研究方向：在材料选取方面应考虑防弹金属、陶瓷以及一些新兴材料的应用及耦合设计;在结构设计方面可以采用实验及数值模拟两种方法,研究储罐保护层层数、各层厚度比、各层排列顺序、层间间隙等诸多关键参数对储罐保护层抗侵彻性能的影响。通过对侵彻事故发生概率及事故后果严重程度两方面的表征,为储罐保护层技术在爆炸碎片多米诺效应事故风险防控中的应用提供参考。