基于背景插值的空空导弹攻击区在线模拟方法

针对空战态势迅速变化对空空导弹攻击区模拟实时性的需求,提出基于背景插值的攻击区在线模拟方法。首先预测下一采样时刻态势,并针对预测态势模拟解算攻击区信息;当下一采样时刻到来时,利用攻击区预测值和先前两次攻击区模拟信息及相应的态势记录插值估计攻击区真实值。背景插值方法将攻击区模拟解算放到先前计算周期中,实时性高。理论分析证明了背景插值误差随着采样时间的减小收敛于零。仿真结果表明,背景插值模拟方法的误差与传统攻击区模拟方法相当,而前者平均可在7.16×10^-6s内给出结果,后者平均计算耗时为0.290 s。     

FeCo-based hybrid MOF derived active species for effective oxygen evolution

Metal-organic frameworks(MOFs) have been regarded as promising catalyst materials due to the richness of coordinately unsaturated metal sites on the surface,which can act as catalytic active centres.In this study,a hybrid MOF material composed of Fe-based MOF and Co-based MOF was prepared with the involvement of graphene oxide nanosheets as additive.It was demonstrated that the hybrid MOF materials showed much higher electro-catalytic activity towards oxygen evolution than the single-phase counterparts.To drive current density of 10 mA cm~(-2),the hybrid CoFe-based MOF only needed an over potential of 290 mV in 1 M KOH.The catalytic activity could sustain for a longer time with only slight current density decrease.During oxygen evolution operation,the MOF catalyst evolved into catalytic active species but kept well the microscale sheet-like structure.It is thus believed that this study will provide an avenue for the development of advanced electrocatalysts.     

Acyl-chloride functionalized graphene oxide chemically grafted with hindered phenol and its application in anti-degradation of polypropylene

In this study,graphene oxide (GO) nanosheets were first functionalized by the acyl-chloride reaction and then reacted with hindered phenol (HP) to obtain HP grafted GO (GO-g-HP).The GO-g-HP prepared under the optimized condition exhibited a high efficiency against both thermal and photo oxidation of isotactic polypropylene (iPP).GO-g-HP exhibited a much better anti-aging efficiency than that of HP and GO used individually or that of their physical mixture.The outstanding anti-aging effect of GO-g-HP was attributed to the excellent synergistic effect produced between the chemically bonded GO and HP,which resulted in an improved oxygen barrier property of GO and excellent utilization of the free radical scavenging capability of GO and HP.Also,thanks to the grafting of HP on GO,the physical loss of HP,which was one of the main shortcomings for traditional small molecular antioxidants,was largely suppressed.It is expected that the GO-g-HP prepared can well meet the requirement of long-term applications of polymers in some harsh service conditions.     

丙酸盐对厌氧氨氧化除氮性能及群落结构的影响

为了探究有机碳对厌氧氨氧化的长期影响, 向厌氧氨氧化膜生物反应器中添加不同浓度的丙酸钠, 研究对反应器的除氮效能以及微生物的种群结构和功能变化。结果表明: 反应器主要的脱氮过程由CandidatusBrocadia完成, 当丙酸钠浓度为100 mg/L时, 反应器中由于异养细菌的生长, 可实现碳氮的同步去除, 平均总氮去除率可达91.9%。当丙酸钠浓度为200 mg/L 时, 对Candidatus Brocadia的抑制作用导致反应器除氮性能下降, Candidatus Brocadia的丰度降至41.2%, 总氮去除率降至 78.8%。在有机碳抑制作用解除后, 反应器的除氮性能恢复为86.8%, Candidatus Brocadia丰度增加到54.0%, 但群落多样性下降, 属水平的微生物组成有较大的改变。     

Neural network structure identification in inflation forecasting

Neural networks (NNs) are appropriate to use in time series analysis under conditions of unfulfilled assumptions, i.e., non‐normality and nonlinearity. The aim of this paper is to propose means of addressing identified shortcomings with the objective of identifying the NN structure for inflation forecasting. The research is based on a theoretical model that includes the characteristics of demand‐pull and cost‐push inflation; i.e., it uses the labor market, financial and external factors, and lagged inflation variables. It is conducted at the aggregate level of euro area countries from January 1999 to January 2017. Based on the estimated 90 feedforward NNs (FNNs) and 450 Jordan NNs (JNNs), which differ in variable parameters (number of iterations, learning rate, initial weight value intervals, number of hidden neurons, and weight value of the context unit), the mean square error (MSE), and the Akaike Information Criterion (AIC) are calculated for two periods: in‐the‐sample and out‐of‐sample. Ranking NNs simultaneously on both periods according to either MSE or AIC does not lead to the selection of the ‘best’ NN because the optimal NN in‐the‐sample, based on MSE and/or AIC criteria, often has high out‐of‐sample values of both indicators. To achieve the best compromise solution, i.e., to select an optimal NN, the preference ranking organization method for enrichment of evaluations (PROMETHEE) is used. Comparing the optimal FNN and JNN, i.e., FNN(4,5,1) and JNN(4,3,1), it is concluded that under approximately equal conditions, fewer hidden layer neurons are required in JNN than in FNN, confirming that JNN is parsimonious compared to FNN. Moreover, JNN has a better forecasting performance than FNN.     

Redefinition of Nipponbathynella based on the four new species from East Asia (Crustacea: Bathynellacea: Parabathynellidae)

Four new species of the parabathynellid genus Nipponbathynella Schminke, 1973 are described from South Korea (Nipponbathynella leesookyungae sp. nov., Nipponbathynella donggangensis sp. nov. and Nipponbathynella wanjuensis sp. nov.) and Japan (Nipponbathynella shigaensis sp. nov.), raising the number of known species to seven. Nipponbathynella leesookyungae is characterized by the convex ventral surface of the labrum and the rich ornamentation (with three spinules and two teeth) of the exopod of male thoracopod VIII; N. donggangensis by the distal spine on the distal maxillular segment with many dentils; N. wanjuensis by the endopod of the male thoracopod VIII with one seta (instead of two) and the serrated endopodal spur of the uropod; and N. shigaensis by the basipod of thoracopods II–VII carrying strong hairs on their outer margin. The three new and one known (Nipponbathynella pectina) South Korean species share a bur-like inner lobe of the male thoracopod VIII, suggesting their close relationship. Based on the one-segmented exopod on thoracopod I and two-segmented exopod on the thoracopods II–VII, the bell-shaped male thoracopod VIII and the uropod with sympod carrying a large distal spine in addition to several proximal spines of smaller size, with endopod drawn into a spur and with exopod carrying a seta, a close phylogenetic relationship between Nipponbathynella and Arisubathynella Park and Eun, 2012 is proposed.

http://zoobank.org/urn:lsid:zoobank.org:pub:9650379F-C249-473C-AAA4-B3D638B96322     

基于有符号移位序列的零相关区互补序列集交织构造方法

提出有符号的移位序列,将移位序列分为移位和符号两部分,并基于此提出一种零相关区互补序列集的交织构造方法.该方法利用完备互补序列对作为初始序列,根据初始序列与移位序列长度的关系分2种情况构造移位序列.第1种情况,二者长度互素,分析并证明移位序列中未引入与引入1个、2个负号后新序列对相关函数的分布情况,提出当移位序列长度为3时,获得完备互补序列集的方法;第2种情况,移位序列长度被初始序列长度整除,当移位序列长度为偶数时,提出获得完备互补序列集的方法.实例仿真证明了以上构造的有效性.     

热输入对Q420FRE钢焊接热影响区组织和力学性能的影响

采用全自动埋弧焊法研究不同热输入对智能型耐火钢Q420FRE焊接热影响区微观组织和力学性能的影响。结果表明,随着焊接热输入的增大,熔合线及粗晶区组织没有明显粗化,组织类型及组成也没产生明显变化,均由粒状贝氏体和少量针状铁素体组成;细晶区组织为铁素体和珠光体;未相变区组织为粒状贝氏体和针状铁素体。随着热输入的增加,在热影响区Q420FRE钢表现出一定程度的软化,软化区域向母材方向推移并稍有扩大。热影响区Q420FRE钢的高温屈服强度和拉伸强度以及低温冲击韧性随焊接热输入的增加而降低,而其低温冲击韧性在-40℃低温下仍保持在240~330J的高水平。     

低合金超高强度钢跨尺度疲劳失效行为分析

为了研究40CrNi2Si2MoVA低合金超高强度钢的跨尺度疲劳失效行为,以约束应力区描述材料的损伤过程,以跨尺度应变能密度因子作为疲劳裂纹扩展的控制参量,建立宏微观跨尺度疲劳裂纹扩展统一模型。采用上述模型,利用光滑试样(应力集中系数Kt=1)的试验S-N曲线,拟合出疲劳模型中的材料参数。当考虑材料微结构对疲劳寿命的影响时,该模型可精确再现出疲劳试验数据的发散特性。利用该模型对不同应力集中系数下(Kt=2,3)含缺口试样的疲劳寿命进行了预测,理论计算结果与试验结果吻合良好。研究结果表明,合金钢材料的初始缺陷及微结构的演化特性,对疲劳寿命有显著影响,是疲劳试验数据发散的主要原因。     

卷筒小行星齿轮断裂失效分析

卷筒小行星齿轮在运转中发生异常断齿。为了查明断裂原因,运用宏观及微观分析方法,对断裂齿轮进行了分析。结果表明:齿轮断裂为多源疲劳断裂,且多数未断齿根部位亦发现裂纹;齿轮基材存在贝氏体及铁素体组织,说明淬火时冷却速度不足;表面淬火也不均匀。这些工艺问题导致齿轮综合机械性能下降。在循环工作应力及应力集中作用下,齿根部位产生多处疲劳裂纹源,并不断扩展,最终导致齿轮断裂失效。