基于多元随机效应Wiener过程的某弹用弹簧可靠性评估

目的 解决某弹用弹簧可靠性评估中存在的不确定性问题。方法 对某弹用弹簧进行加速退化试验,试验过程中发现其具有多个性能退化参数,并且其退化过程具有非线性、随机性及样本差异性的特征。为了对其退化过程进行数学表征,提出一种基于多元随机效应Wiener过程的退化模型。采用基于时间尺度变换的非线性Wiener过程,描述弹簧退化过程中的非线性与随机性。基于随机效应模型,对样本的差异性进行表征,利用Copula函数描述多元性能参数之间的相互作用关系。最后推导弹簧失效寿命的概率密度函数、可靠度函数。结果 在贮存条件为25 ℃、可靠度为0.9时,基于构建的多元随机效应Wiener过程模型,当考虑性能间的相关性时,得到某弹用弹簧的贮存寿命为12 a;不考虑性能间的相关性时,得到其贮存寿命为11.5 a。结论 构建的多元随机退化模型为该弹药健康状态管理提供了相应的理论依据。     

机器学习在材料服役性能预测中的应用

针对材料服役性能预测存在误差大、计算复杂、适用性差等问题,提出了基于数据挖掘的机器学习预测方法。首先阐述了机器学习的应用流程,并总结了常用模型原理及其在材料性能预测中的应用。然后采用多种机器学习模型对RPV钢的辐照性能进行预测,并通过Stacking集成方法提高了模型的预测精度。结果表明,机器学习可用于材料服役性能预测,具有较高的预测精度和可靠性。根据材料服役数据的不同特征选择合适的学习模型,同时进行模型融合和参数优化,可有效提高模型的预测精度及运算速度。     

基于突变级数法的武汉市农地利用绩效评价及影响因素分析

根据突变级数法基本原理,对武汉市2002-2011年农地利用绩效动态变化情况进行分析,并利用障碍度模型找出影响其绩效水平的主要障碍因子.研究结果表明,研究时段内武汉市农地利用绩效整体呈上升趋势,且带有明显的阶段性特征;经济绩效是影响农地利用绩效的最主要障碍因素;从单项指标来看,随着生态理念的不断深化,未来农地利用程度及资源安全将对农地利用绩效产生较大影响.     

Molecularly imprinted polymer for analysis of trace atrazine herbicide in water

A molecularly imprinted polymer (MIP) for atrazine was synthesized by non-covalent method. The binding capacity of MIP was 1.00 mg g^{? 1} polymer. The selectivity and recovery were investigated with various pesticides which are mostly, found in the environment, for both similar and different chemical structure of atrazine. The competitive recognition between atrazine and structurally similar compounds was evaluated and it was found that the system provided highest recovery and selectivity for atrazine while low recovery and selectivity were obtained for the other compounds. The highest recovery was obtained from MIP compared with non-imprinted polymer (NIP), a commercial C₁₈ and a granular activated carbon (GAC) sorbent. The method provided high recoveries ranged from 94 to 99% at two spiked levels with relative standard deviations less than 2%. The lower detection limit of the method was 80 ng L^{? 1}. This method was successfully applied for analysis of environmental water samples.     

Evaluation and validation of two different chromatographic methods (HPLC and LC-MS/MS) for the determination and confirmation of ochratoxin A in pig tissues

This study was undertaken to compare two different analytical methods for the determination and confirmation of ochratoxin A (OTA) in blood serum, kidney and liver of pigs. Sample clean-up was based on liquid-liquid phase extraction. The detection of OTA was accomplished with high-performance liquid chromatography (HPLC) combined either with fluorescence detection (FL) or electro spray ionization (ESI+) tandem mass spectrometry (MS–MS). Comparative method evaluation was based on the investigation of 90 samples of blood serum, kidney and liver per animal originating from different regions of Serbia. The analytical results are discussed in view of the respective method validation data and the corresponding experimental protocols. In general, analytical data obtained with (LC–MS–MS) liquid chromatography electro spray tandem mass spectro metry detection offered comparable good results at the sub-ppb concentration level. The results indicate that the liquid chromatography electro spray tandem mass spectrometric (LC-MS/MS) method was more specific and sensitive for the analysis and confirmation of ochratoxin A in pig tissues then high pressure liquid chromatography (HPLC) method after methylation of OTA.     

工业园区循环经济绩效评价方法研究

针对当前循环经济绩效内涵不明确,评价指标体系多局限于对循环经济发展水平等循环经济绩效评价中存在的问题,在系统归纳总结该领域研究现状基础上,明确了循环经济绩效的概念;进一步构建了基于生态效率-物质流分析的循环经济绩效评估指标体系,利用模糊数学和灰色聚类方法分别建立了循环经济绩效评估模型;最后,以上海化工园区和南通农药化学工业园为案例,对2个园区循环经济绩效进行评估。结果表明:从理论和方法上,构建的工业园区循环经济绩效评价指标体系是适用的;模糊综合评价和灰色聚类评价的结果存在一定的差异,模糊评价结果更为合理,而且该模型可以直观地表示出园区循环经济绩效的优劣势所在。进而,以上海化工园区作为标杆,针对南通农药化学工业园存在的资源效率偏低等问题,提出若干循环经济绩效改进措施。     

鱼类游泳能力研究进展

对鱼类游泳能力及其游泳状态下的生态行为研究,可以为水利水电工程过鱼、拦鱼和诱鱼等设施的设计提供依据,保证其水电工程储能设施能够发挥较大的功能。对鱼类的游泳类型及游泳能力的评价指标进行了总结,介绍了目前国内外鱼类游泳能力及行为的研究方法,并和自行设计的鱼类游泳能力装置进行了比较;从洄游鱼道设计的角度,综述了国外已有的鱼类游泳能力评价模型,主要包括最优游泳速度模型,最大游泳速度模型,跳跃高度模型及游泳耐力模型,可为鱼道设计提供关键参数。最后简述了鱼类游泳能力在鱼道设计的应用及主要的研究趋势,旨在为鱼类游泳能力相关研究及水利水电过鱼设施的设计与建设提供一定基础资料,从而促进我国生态系统的平衡和物种多样化的保护。     

石油类污染地下水中挥发性有机物低温生物降解性能的研究

针对地下水石油类污染的问题,从某污染场地土壤中筛选驯化出了适用于处理挥发性有机物的3株低温高效降解菌,并以苯和萘作为特征组分考察了pH、DO、温度、氮磷等因素对降解效果的影响;实验结果表明,在8℃左右的地下环境中,DO和氮磷的含量对污染物的降解影响较大;在pH 7.5、DO＞4 mg/L和投加氮磷的条件下,18 d内降...     

城市污水条件下ASBR厌氧氨氧化的启动与脱氮性能

采用ASBR在城市污水条件下进行厌氧氨氧化的启动与脱氮性能研究。实验接种好氧硝化污泥,在温度为(35±1)℃、HRT为24 h、pH为7.3～8.5的条件下经过130 d的培养,成功启动了厌氧氨氧化反应。实验结果表明,厌氧氨氧化反应稳定运行时,TN容积负荷平均为0.179 kg/(m3.d),NH4+-N、NO2--N和TN去除率分别达到了95.30%、91.30%和76.28%。启动期和稳定运行期NH4+-N、NO2--N去除量和NO3--N生成量的比值分别达到1∶1.54∶0.25和1∶1.27∶0.27;稳定运行期进出水pH差值由启动时的0.85下降到0.24。启动期反硝化和厌氧氨氧化反应同时存在而在稳定运行期厌氧氨氧化发展成为主导反应。MLSS和MLVSS/MLSS先减少后增加,反映了启动过程中硝化细菌、反硝化细菌的衰亡和厌氧氨氧化菌逐渐富集的过程,这与反应器的宏观运行效果相一致。     

Development and application of LC–APCI–MS method for biomonitoring of animal and human exposure to imidacloprid

Imidacloprid (IMI) is a relatively new neuro-active neonicotinoid insecticide and nowadays one of the largest selling insecticides worldwide. In the present study a LC–APCI–MS based method was developed and validated for the quantification of imidacloprid and its main metabolite 6-chloronicotinic acid (6-CINA) in urine and hair specimens. The method was tested in biomonitoring of intentionally exposed animals and subsequently applied for biomonitoring of Cretan urban and rural population.