贫铀合金球对Q235钢靶侵彻性能研究

目的 研究贫铀合金球对Q235钢靶的侵彻行为,为贫铀合金材料侵彻行为的深入研究以及在战斗部中广泛应用提供支撑。方法 采用Johnson-Cook强度模型和失效模型建立贫铀合金球撞击Q235钢靶的模型,利用Abaqus/explicit模块模拟研究贫铀合金球初速与尺寸对剩余速度、扩孔面积、侵彻深度的影响,并对结果进行分析。结果 通过试验与模拟得到了贫铀合金球的穿靶极限速度,两者结果基本吻合,验证了模型参数的准确性。相同尺寸下,贫铀合金球的剩余速度随初速的增大呈线性增大趋势,穿靶后速度衰减率为14.6%~33.2%。初速为900~1 300 m/s、直径为5~9 mm时,扩孔面积比为1.08~1.286。贫铀合金球的侵彻深度(H)随直径(d)和初速(v)的增大逐渐增大,三者的关系为 。结论 贫铀合金球初速和尺寸是影响侵彻深度的关键因素,但对扩孔直径没有显著影响。     

温度梯度下钛合金热防护结构的导波特性研究

目的 实现可重复使用钛合金热防护结构的导波健康监测。方法 针对钛合金热防护结构,提出热–力–电多物理场耦合导波传播建模仿真分析方法,研究温度梯度下钛合金热防护结构中导波的传播特性,以及在温度梯度和裂纹损伤耦合作用下导波的传播特性。结果 20~500 ℃的温度梯度会导致钛合金结构中导波的群速度降低、幅值衰减降低,裂纹损伤使得钛合金结构中导波的群速度、幅值降低,且损伤越大,影响越明显。裂纹扩展至20 mm时,S0模式群速度降低了1.5%,A0模式群速度降低了2%。结论 此模型可为大范围的温度梯度条件下,钛合金热防护结构上传感器优化布置以及导波监测方法的研究提供指导。     

基于有限元法对亥姆霍兹线圈磁场的分析

为进一步明确亥姆霍兹线圈所产生磁场的近场特性,文中尝试采用基于有限元方法的ANSYS软件对亥姆霍兹线圈进行了分析,首先采用ANSYS软件对亥姆霍兹线圈进行三维实体有限元模型和仿真,并将结果与用MATLAB语言绘制磁感应强度的空间分布图进行比较.仿真结果说明ANSYS有限元模型优于MATLAB语言,并且通过实验验证了所建的三维亥姆霍兹线圈有限元模型的有效性和正确性.     

异常性检测算法在引信干扰信号识别中的应用

目的 解决传统分类引信抗干扰算法因干扰信号难获取、特征信号样本少、正负样本数不平衡而导致计算精度低的问题,克服引信抗干扰算法对样本的依赖性,并提高引信信号识别准确率。方法 通过WVD时频变换的方法,将拆分后的真实含扰引信信号切片进行重组,使其由一维时序信号向二维图片信息进行扩展,基于数据倍增策略,提升算法泛化性,并降低其对真实数据样本的依赖。融合GANomaly与EfficientNet网络,在扩充的引信数据集上进行线下干扰信号特征学习,并对含扰引信图像数据进行线上异常性判断与干扰信号识别。结果 GE-FS网络能够在真实引信小样本信号的基础上进行有效数据扩充,基于扩充数据训练后,引信含扰识别准确率达到98.4%。结论 GE-FS网络能有效针对引信异常信号进行精确检测与识别,可以增强引信系统的抗干扰能力与作战自适应性。     

基于弹性模型的飞机操纵动响应分析

目的 更好地研究飞机在操纵情况下的机体载荷和机体响应,同时验证动态响应分析模型和方法。方法 以某型飞机突风载荷分析用的动气弹仿真模型为基础,考虑机体弹性修正和气动模型修正,梳理试验试飞的舵偏数据,利用MSC软件的动气弹仿真分析模块,将试飞的舵偏数据作为输入信号,开展舵面操纵情况下的机体响应仿真,并将飞机操纵情况下的机体响应分析结果与试验试飞结果进行对比。结果 经过仿真和对比分析可以发现,分析数据和试飞数据整体吻合较好,能够较好地表征飞机的气动特性和结构动力学特性,同时在分析数据和试飞数据中均有比较明显的机体弹性响应成分。对于弹性飞机而言,除操纵造成的机体刚体响应外,机体弹性会带来额外的振动响应,对于特定的部位,这种振动可能是不可忽略的,需要根据具体情况进行详细分析。结论 这种振动响应对飞机操纵、乘客舒适性是否会产生不利影响,需要进一步开展研究工作。     

在役GIS内置特高频传感器校验方法研究

运行中的GIS内置传感器因其不易拆装,很难对其可靠性及有效性进行校验。根据GIS的结构特点以及特高频信号在GIS内的传输特点,提出一种对内置式特高频传感器的有效性进行校验的方法。通过在相邻传感器注入特高频信号并对信号幅值进行检测,通过检测及计算结果来判断特高频传感器的有效性,经现场验证,该方法简单有效。     

基于发射环境炮–弹–引耦合仿真的中大口径加榴炮机械触发引信失效分析

目的 研究高动态发射环境中大口径加榴炮机械触发引信及其内部典型机构的响应特性和底层失效原因。方法 建立炮–弹–引耦合数值模型,开展0号装药、1号装药、0.4''装填角和身管中等程度磨损等4种工况下的动力学仿真,对比不同工况下引信典型部位的响应特性。结果 装药量和火炮身管磨损量是引信典型部位载荷响应的主要影响因素,身管磨损量是弹丸出炮口姿态角的主要影响因素。身管中期磨损条件下,引信夹板部位膛内径向过载响应峰值达2 498.4g,为初始状态的6.1倍;回转体轴响应峰值达4 296.1g,为初始状态的1.5倍;弹丸出炮口俯仰角达0.4°,为初始状态的4.4倍。试验验证结果表明,典型特征参量的仿真模拟误差不大于5%。结论 弹丸发射过程中,远离弹轴的引信安全系统轴类零件会承受更大的轴向载荷冲击和径向多维度载荷冲击,更容易导致与夹板配合的轴孔结合处发生失效。火炮身管磨损会导致榴弹配用引信在内弹道和出炮口承受更高的径向过载,以更大的姿态角进入外弹道飞行,是中大口径加榴炮机械触发引信外弹道飞行章动角增大的主要因素之一。     

跟踪微分器频率特性分析

目的 解决跟踪微分器(TD)的参数设计问题。方法 对TD的工作原理、参数进行解释,提出其参数R与工作频率上限的关系,建立扫频仿真模型,通过扫频仿真获得TD的频率特性。通过不同输入幅值仿真研究其频率特性的非线性,通过添加白噪声,研究TD的抗噪声能力。结果 仿真表明,对于输入幅值为1的情况,由R计算的频率上限确实反映了TD的工作频率范围。在该范围内,TD跟踪信号的幅值、相位良好;频率超出范围后,幅值、相位很快变差。输出幅值变小时,频率上限扩展。时域仿真的波形展示了与频率特性一致的结果。与平滑滤波器对比仿真显示,一般情况下,TD的跟踪信号、微分信号优于平滑滤波器,但是信噪比很差时,平滑滤波器反而优于TD。结论 解决了TD参数R的定量设计问题,仿真展示了TD的时域、频域特性,为TD的应用提供了参考。     

某车载油箱在随机振动环境下的疲劳寿命研究

目的 针对某车载油箱高周疲劳寿命难以预测问题,研究该设备在随机载荷环境下的疲劳寿命。方法 首先通过模态试验得到油箱固有频率及振型,然后利用Solidworks建立该车载油箱的仿真模型,在ANSYS Workbench软件中进行模态分析、随机振动分析、谐响应分析。最后利用ANSYS Workbench软件中的nCode SN Vibration (DesignLife)模块,在随机振动疲劳寿命频域分析法基础上,通过nCode模块中的Narrowband法进行油箱在多个加速度功率谱密度下的疲劳寿命研究。结果 该油箱在约束模态试验和仿真分析下所表现的动力学特性基本相同,油箱纵向为振动严酷方向。在已知加速度功率谱密度下,油箱疲劳寿命随低阶固有频率处功率谱密度幅值的增加而降低,但油箱薄弱部位始终保持不变。结论 建立的仿真模型准确,可为油箱优化设计及后续油箱疲劳试验提供参考。     

一种基于离心机试验辨识惯导平台误差系数的方法

针对离心机试验中惯导平台误差系数辨识问题,提出了一种基于谐波分析辨识误差系数的方法。首先,根据惯性器件误差模型推导了离心机试验下陀螺和加速度计的输出方程,其输出由各阶谐波分量构成。然后通过傅里叶分析得到各项谐波的幅值。最后根据谐波幅值与各项误差系数之间的关系反解得到各项误差系数。仿真结果验证了方法的有效性。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.