煤矿风险预控连续统一体理论研究

为了使煤矿被动式的安全管理模式真正转变为主动式预控管理模式,从而打造本质安全型矿井,借鉴领导方式连续统一体理论,提出煤矿风险预控连续统一体理论,建立煤矿风险梯度控制框架。将煤矿风险预控对象划分为4种类型,即稳定的安全系统、失稳的安全系统、事故紧急状态和事故,针对不同预控对象所实施的安全管理模式就构成风险预控的"连续统一体"。对煤矿风险应实施梯度控制,控制方案从高梯度到低梯度依次为预防控制、校正控制、应急控制和事故控制。研究表明:只有做好每一个风险阶段的安全管理工作,才能实现煤矿本质安全的目的。     

高梯度磁分离技术在水处理中的应用及发展

高梯度磁分离技术是一种新型的水处理技术,目前已经得到了大量应用,具有广阔的应用前景。本文介绍了它的基本原理,综述了该技术在水处理中的应用现状,并做出了展望。     

基于轻量级梯度提升机的南京大气臭氧浓度预测

采用南京地区2015年1月至2016年12月期间的空气质量数据和常规气象资料数据,分析了南京地区O₃浓度变化特征,建立基于轻量级梯度提升机(LightGBM)的O₃浓度预测模型,并将该模型与支持向量机、循环神经网络和随机森林等3种在空气质量预测方向上常用的机器学习方法进行了对比,验证模型的有效性和可行性.结果表明,南京地区O₃浓度变化具有显著的季节性差异,浓度变化受前期浓度、气象因子和其他空气污染物浓度的共同影响.LightGBM模型较为准确地预测了南京地区地面O₃浓度(R²=0.92),且该模型的预测精度和计算效率等性能优于其他模型.尤其是在容易出现臭氧污染的高温天气,该模型预测准确性明显高于其他模型,模型稳定性较好.LightGBM具有预测准确度高、稳定性好、有良好的泛化能力和运算时间短等特点,在O₃浓度预测方面具有显著的优势.     

Plankton community composition in the Three Gorges Reservoir Region revealed by PCR-DGGE and its relationships with environmental factors

To explore the relationships between community composition and the environment in a reservoir ecosystem, plankton communities from the Three Gorges Reservoir Region were studied by PCR-denaturing gradient gel electrophoresis fingerprinting. Bacterial and eukaryotic operational taxonomic units （OTUs）, generated by DGGE analysis of the PCR-amplified 16S and 18S rRNA genes, were used as surrogates for the dominant ＂biodiversity units＂. OTU composition among the sites was heterogeneous; 46.7% of the total bacterial OTUs （45） and 64.1% of the eukaryotic OTUs （39） were identified in less than half of the sampling sites. Unweighted pair group method with arithmetic averages （UPGMA） clustering of the OTUs suggested that the plankton communities in the Xiangxi Rive sites were not always significantly different from those from the Yangtze River sites, despite clear differences in their environmental characterizations. Canonical correspondence analysis （CCA） was applied to further investigate the relationships between OTU composition and the environmental factors. The first two CCA ordination axes suggested that the bacterial community composition was primarily correlated with the variables of NO3^--N, dissolved oxygen （DO）, and SiO3^2--Si, whereas, the eukaryotic community was mainly correlated with the concentrations of DO, PO4^3--P, and SiO3^2--Si.     

Effect of methamidophos on soil fungi community in microcosms by plate count, DGGE and clone library analysis

Methamidophos was widely used a pesticide in northern China. The potential influences of methamidophos on soil fungal community in black soil were assessed by plate count, 28S rDNA-PCR-DGGE, and clone library analysis. Three methamidophos levels (50, 150, and 250 mg/kg) were tested in soil microcosms. Results from plate count during a 60-d microcosm experiment showed that high concentrations of methamidophos (250 mg/kg) could significantly stimulate fungal populations. DCGE (denaturing gradient gel electrophoresis) fingerprinting patterns showed a significant difference between the responses of culturable and total fungi communities under the stress of methamidophos. Shannon diversity indices calculated from DGGE profiles indicated that culturable fungi in all microcosms with methamidophos treatment increased after 1 week of incubation. However, the diversity indices of total fungi decreased in the first week, as compared to the stimulation of culturable fungi. At the 8th week, however, all the microcosms treated by methamidophos were similar to the control microcosms in community structure as suggested by the Shannon diversity indices for both culturable and total fungi. In contrast, after 1 week the fungal structure of culturable and unculturable both were disturbed to different extent under the stresses of methamidophos by clustering analysis. Clone sequencing analysis indicated the stimulation of pathogenic and unculturable fungal populations by methamidophos treatment, suggetsing potential risks of plant disease outbreak.     

爆炸冲击环境下内凹蜂窝型梯度结构响应特性研究*

为提升应急救援人员防护服抗爆能力,减少爆炸事故中人员伤亡数量,以内凹蜂窝型梯度结构为研究对象,采用爆炸冲击实验与数值有限元法相结合的研究手段,通过改变胞元尺寸与胞元凹角对梯度蜂窝结构进行优化,分析梯度结构在爆炸冲击环境下冲击波衰减效率和力学响应规律。结果表明:同等质量条件下,内凹蜂窝结构尺寸梯度为2.58 mm-3.40 mm-2.58 mm、角度梯度30°-22.5°-30°时对冲击波的衰减效应最佳,衰减效率分别为85.44%,82.29%。研究结果可为同时满足轻质、高强抗爆要求的防护服结构设计提供技术支撑。     

实验室太阳辐射试验中温度测量的分析

按GJB 150.7-1986中稳态长期光化学效应的试验要求,对线缆样件进行了实验室太阳辐射试验。温度测量结果显示,样件的附加温升显著,且内部存在热梯度。     

高频间歇梯度曝气启动短程硝化反硝化除磷颗粒污泥

反硝化除磷与厌氧氨氧化耦合可进一步降低脱氮除磷所需的碳源,而稳定获取NO₂^--N是两工艺独立、联合运行的关键.因此,以低C/N生活污水为研究对象,接种絮状污泥及少量长期贮存的好氧颗粒污泥,采用两段梯度曝气,并控制停曝时间（3min：3min）,即以高频间歇梯度曝气模式,经60d的富集培养,将其诱导成具有短程硝化反硝化除磷功能的颗粒污泥,并分析了此过程中系统脱氮除磷性能变化.结果表明,稳定时期内,颗粒污泥平均粒径达841μm,SVI为31.23ml/g,颗粒结构致密,沉降性能良好.出水NO₃^--N小于0.1mg/L,TP<0.7mg/L,NO₂^--N>15mg/L,实现了P的高效去除和NO₃^--N的积累,并可为后续耦合Anammox提供稳定NO₂^--N基质.批次实验结果表明,颗粒中可利用NO₂^--N为电子受体的DPAOs占达57.63%,其富集提高了系统除磷能力.高频梯度间歇曝气可实现AOB与DPAOs的高度耦合,但仅以间歇曝气难以实现NOB的抑制,后通过在"氨谷点"前段,加入梯度曝气优化实际限氧曝气点,可强化对NOB的抑制,从而实现良好的亚硝酸盐积累.     

高效稳定纤维素分解菌复合系WSC-6的稳定性

对筛选到的一组纤维素分解菌复合系WSC-6,通过变性梯度胶电泳(DGGE)方法研究了菌种的组成稳定性.结果表明,在连续继代培养的第74～83代复合系的菌种组成没有变化,非常稳定.多代继代培养过程中各代的pH值变化趋势一致,pH值从发酵开始的8.7下降到纤维素旺盛分解时的6.5以下;随着分解结束,pH值逐渐恢复到发酵开始时的水平并保持稳定,具有较强的自我调节能力.多代继代培养后复合系各代的滤纸纤维素分解率和CMC糖化差异很小;在发酵液起始pH4～10的范围内,复合系对pH值具有缓冲能力,并正常分解纤维素;经过70～100℃高温处理10min后再转接的复合系对纤维素仍然具有分解能力,功能稳定.     

Effect of organic carbon on nitrification efficiency and community composition of nitrifying biofilms

The effects of organic carbon/inorganic nitrogen (C/N) ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (DGGE) analysis. The results showed that the nitrification rate decreased with an increasing organic concentration. However, the effect became weak when the carbon concentration reached sufficiently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8 and 16 compare to control (C/N = 0). The loss of nitrogen at C/N = 0.5, 1, 2, 4, (8 and 16 was 31%, 18%, 24%, 65%, 59% and 62% respectively, after 24 h. Sequence analysis of 16S rRNA gene fragments revealed that the dominant populations changed from nitrifying bacteria (Nitrosomonas europaea and Nitrobacter sp.) to denitrifying bacteria (Pseudomonas sp., Acidovorax sp. and Comamonas sp.) with C/N ratio increase. Although at high C/N ratio the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Conrrespondingly, nitrification process coexisted with denitrification.