HTPB药柱老化对SRM内弹道性能的影响及偏差分析

为了定性和定量的描述药柱燃面、密度、燃速等因素对固体火箭发动机（SRM）内弹道性能的影响,在HTPB复合固体推进剂老化研究和SRM内弹道性能预估研究的基础上,分析了HTPB推进剂因贮存老化引起的SRM内弹道性能偏差,建立了性能偏差计算模型。结果表明,老化引起的药柱燃面、密度、燃速变化以及侵蚀燃烧引起的喷喉烧蚀是SRM贮存过程中影响内弹道性能偏差的直接因素,老化引起它们微小的波动都会引起发动机内弹道性能较大的偏离。在发动机寿命预估和进行可靠性分析时必须考虑老化对内弹道性能的影响。     

HAZOP技术在溴化丁基橡胶装置的应用

介绍了危险与可操作性分析(HA-ZOP)的程序以及在溴化丁基橡胶装置的应用,根据分析结果提出相应的安全措施。     

HAZOP分析技术在聚丙烯装置的应用

介绍HAZOP分析方法在聚丙烯装置的应用,根据分析结果,有效地识别聚丙烯装置运行过程中存在的风险,并提出了降低风险的措施和建议。     

用EDTA代替CDTA测定SO2的探索

通过实验验证了盐酸副玫瑰苯胺分光光度法测定大气中SO2的标准方法中,用EDTA代替CDTA去掩蔽金属离子的干扰是可行的,即方便,又经济。     

可持续发展评价指标(体系)及其确定方法的探讨

通过对目前已有的可持续发展指标体系的研究,指出现有指标体系忽略了可持续性内涵、环境的限制作用、社会公平性及经济增长的影响作用等主要内容．提出采用离差法来计算可持续发展评价指标．建议采用限制型指标、发展型指标、协调型指标来评价系统的可持续性;标准值或参考值采用反映系统不可持续性状态的底线值以及反映整个人类状况的全球、区域或国家现时平均值．同时还提出了不可持续性标准值、不可持续状态、远离不可持续状态、迈进可持续发展过程等概念．强调单项指标的重要性,指出单项指标离差度对系统可持续性的指示作用．     

Natural variability and correlations in the metabolic profile of healthy Eisenia fetida earthworms observed using ¹H NMR metabolomics

¹H NMR metabolomics can be used to assess the sub-lethal toxicity of contaminants to earthworms by identifying alterations in the metabolic profiles of contaminant- exposed earthworms in contrast to those of healthy (control) individuals. In support of this method this study sought to better characterize the baseline metabolic profile of healthy, mature earthworms of the species, Eisenia fetida, which is recommended for both acute and sub-lethal toxicity testing for soil contaminants. Profiles of D₂O-buffer extracted metabolites were determined using ¹H NMR spectroscopy and both inter-individual metabolic variability and pair-wise metabolic correlations were assessed. The control earthworm extracts exhibited low overall inter-individual metabolic variability, with a spectrum-wide median relative standard deviation (%RSD = standard deviation/mean × 100) of 14%, which suggests that the metabolic profile of E. fetida earthworms is well controlled in laboratory conditions and supports further use of this organism in environmental metabolomics research. In addition, strong positive correlations were detected between the levels of maltose, betaine, glycine, and glutamate as well as between the levels of lactate, valine, leucine, alanine, lysine, tyrosine, and phenylalanine which had not previously been reported. Since comparison of pair-wise metabolic correlations between control and treated organisms can reveal changes in the underlying pattern of biochemical relationships between the metabolites, identification of these significant metabolic correlations in control earthworms provides an additional characteristic that may be applied to delineate between control and treated earthworms in future NMR-based metabolomic studies.     

In vivo and in vitro metabolism of tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by the freshwater planarian, Dugesia japonica

Cigarette smoke is a risk factor for human health, and many studies were conducted to investigate its adverse effects on humans and other mammals. However, since large amounts of cigarette products are produced and consumed, it is possible that tobacco chemicals can end up in aquatic environments through several routes, thus influencing aquatic organisms. In this study, the presence of tobacco-specific nitrosamine (TSNA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in aquatic environment was demonstrated. Since toxic effects on and distribution patterns of tobacco chemicals in aquatic organisms were rarely studied, after results of an acute toxicity pretest were obtained, experiment was conducted to investigate the bioaccumulation pattern of NNK and distribution patterns of its metabolites, mainly 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), in NNK-treated freshwater planarians, Dugesia japonica. Results from in vivo and in vitro studies showed that NNK was readily converted to NNAL through the carbonyl reduction in bodies of NNK-treated planarians. Tissue concentrations of both chemicals increased in time- and dose-dependent manners. Furthermore, we examined the end products of NNK/NNAL α-hydroxylation in NNK-treated planarians, but only 1-(3-pyridyl)-1,4-butanediol was detected, suggesting that NNK metabolism in planarians partially differs from that in mammalian systems. This is the first report on NNK metabolism in an aquatic organism and can be used as a foundation for developing freshwater planarians as a new in vivo model for the study of NNK toxicology in the future.     

Nature of the field-to-field distribution of pesticide residues

The supervised trial datasets (1950), consisting of a minimum of five residue values and selected by the experts of FAO/WHO Joint Meeting on Pesticide Residues for recommending maximum residue levels between 1997 and 2011, were evaluated to obtain information on the typical spread of residue values in individual datasets. The typical relative standard deviation, CV, of field-to-field variation of pesticide residues was about 80%. The spread of residues in datasets is independent from the chemical structure of pesticides, residue level, pre-harvest interval and number of values in the datasets. The CV ranges within the Codex commodity groups and between groups overlapped and their difference were not statistically significant. The number of residues below the limit of quantification (LOQ) affects the CV at various extents depending on the ratio of LOQ/R _mean. The combined uncertainty of the highest residue in a dataset significantly affects the CV of the dataset. The lowest and intermediate ones have less influence. The residues in different fields receiving the same treatment vary within large range: 55%, 72%, 78%, 86% and 89% of the 25,766 residues values were, respectively, within 3, 4, 5, 6 and 7 times the median value of the corresponding dataset.     

气压阀门控制器设计

详细介绍了气压阀门控制器的设计过程及仿真结果。该控制器采用倍压芯片进行±15 V供电设计,采用运放+数字电位器进行反馈和给定的调理电路设计,采用运放+电阻电容进行控制电路及驱动电路的设计。该控制器采用前馈控制器B(s)+偏差控制器A(s)对压力进行控制。文中给出了控制器的设计过程和仿真实验波形。从仿真波形的控制结果看,该控制器能够快速响应大偏差,根据偏差大小提前输出负压信号,并能进行稳态精度调节,实现快速准确调节气压的目的。     

Estimating irrigation water demand in the Moroccan Drâa Valley using contingent valuation

Irrigation water management is crucial for agricultural production and livelihood security in Morocco as in many other parts of the world. For the implementation of an effective water management, knowledge about farmers' demand for irrigation water is crucial to assess reactions to water pricing policy, to establish a cost-benefit analysis of water supply investments or to determine the optimal water allocation between different users. Previously used econometric methods providing this information often have prohibitive data requirements. In this paper, the Contingent Valuation Method (CVM) is adjusted to derive a demand function for irrigation water along farmers' willingness to pay for one additional unit of surface water or groundwater. An application in the Middle Draa Valley in Morocco shows that the method provides reasonable results in an environment with limited data availability. For analysing the censored survey data, the Least Absolute Deviation estimator was found to be a more suitable alternative to the Tobit model as errors are heteroscedastic and non-normally distributed. The adjusted CVM to derive demand functions is especially attractive for water scarce countries under limited data availability.