基于指标模糊权和协调性下的地下水水质评价模型构建及应用

在地下水质量标准中,各指标权重的选择与权重的内涵存在着不确定性;同一指标的分级界点值差异显著,近似地呈现几何级数变化。基于以上这两种情况,构建基于指标模糊权和协调性下的地下水水质评价模型。应用层次分析法和专家调查9标度法确定指标的相对权重,结合贝塔系数计算出指标的模糊权重。对评价标准及待评价地下水水质监测值进行对数变换,采用距离测度法来构造隶属函数,并对其进行求余,按最大隶属原则来评判地下水质量等级。应用此模型对徐州市的重要水源地——张集地下水水质进行评价。结果表明:研究区的20个采样点水质为Ⅱ、Ⅲ级的占90%,符合饮用水的要求。与投影寻踪法的评价结果基本一致。     

An assessment of how distance and diesel oxidation catalyst will impact thermal decomposition behaviors of particles

Decomposition mass loss and pyrolysis products analyses of particles sampled at various locations along the tailpipe of a Euro-IV diesel engine were performed using a thermogravimetry in conjunction with Fourier transformation infrared spectrometry-mass spectrum. Diesel particles were collected at the same location with and without diesel oxidation catalyst (DOC) mounted on the test engine separately. The three poles in thermal gravity-differential thermal gravity images suggested that the decomposition process of diesel particles could be divided into three stages which correspond to the decompositions of lower boiling substances, higher boiling substances and soot respectively. It is noticed that no matter whether DOC was mounted or not, the further the particles were sampled away from the engine block, the lower the peak temperatures and the heavier the mass losses within the first two stages, which indicated that the soluble organic fraction in the particle samples increased and therefore lowering the activation energy of thermal decomposition. Hydroxyl, ammonia, C_xH_y fragments, benzene, toluene, and phenol were found to be the primary products of particle decomposition, which didn't change with the location of particle sample point. The employment of DOC increased the activation energy for particle oxidation and resulted in a higher peak temperature and lower mass loss within the first-stage. Moreover, the CO stretching bands of aldehyde and ketone at 1771 cm^?1 was only detected without a DOC, while the NO₂ peak at 1634 cm^?1 was solely noticed with the presence of DOC. Compared to the first-stage pyrolysis products, more polycyclic aromatic hydrocarbons and less C_xH_y fragments were seen in the second-stage.     

北京市空气质量及其与能源消费结构的动态关联

运用模糊集理论中的Euclidean权距离评价2002—2011年北京市空气质量。根据最大隶属度原则确定空气质量等级值,结合灰色系统理论中的关联动态矩阵分析法,研究北京市主要大气污染物与9种能源消费因子的动态关系。结果表明,2002、2004—2007年北京市空气质量处于Ⅲ级,2003、2008—2011年处于Ⅱ级,空气质量由劣到优的年份排序为2002、2011、2010、2006、2007、2009、2008、2005、2004、2003年,2003、2008年空气质量得到改善,2009年以来有所恶化;燃料油、焦炭和煤炭是造成北京市大气污染的前3位能源,天然气是最清洁的能源;同种能源与不同污染物的关联程度相似;同种能源与污染物在不同时间段的关联序基本不变,不同能源因子分别表现出"缓慢上升"、"逐渐升高"、"水平S"型和"倒U"型4种态势;燃料油与大气污染物"同增同减",大气污染物与燃料油正相关;天然气与大气污染物"此涨彼消",天然气与大气污染物负相关。     

输油管线反打孔盗油抢修施工中的HSE管理初探

笔者就长输原油管道反打孔盗油抢修施工中如何进行HSE管理提出自己的看法，建议从5个方面重点考虑，并对此5个方面中应当注意的事项一一说明。     

A closer look at detectability

Environmental and Ecological Statistics - The theory underlying line transect and variable circular plot surveys—distance sampling—begins with an assumed detectability function, giving...     

Quantifying the efficiency of soil sampling designs: A multivariate approach

The objective of this paper is to quantify and compare the loss functions of the standard two-stage design and its composite sample alternative in the context of multivariate soil sampling. The loss function is defined (conceptually) as the ratio of cost over information and measures design inefficiency. The efficiency of the design is the reciprocal of the loss function. The focus of this paper is twofold: (a) we define a measure of multivariate information using the Kullback–Leibler distance, and (b) we derive the variance-covariance structure for two soil sampling designs: a standard two-stage design and its composite sample counterpart. Randomness in the mass of soil samples is taken into account in both designs. A pilot study in Slovenia is used to demonstrate the calculations of the loss function and to compare the efficiency of the two designs. The results show that the composite sample design is more efficient than the two-stage design. The efficiency ratio is 1.3 for pH, 2.0 for C, 2.1 for N, and 2.5 for CEC. The multivariate efficiency ratio is 2.3. These ratios primarily reflect cost ratios; influence of the information is small.     

外来有害生物风险评估技术

概述了有害生物风险分析的概念、必要性、生物学基础和一般程序 ;论述了生态气候图、农业气候相似距库、生态气候评价的分析模型、地理信息系统、专家系统、基于定性分析与定量估算相结合的数学模型等有害生物风险分析技术的原理和特点 ;认为应用网络技术 ,建立基于分布式计算的全球入侵物种风险评价数据体系 ,可有效提高风险评价的速度和准确性。     

自由飞行下基于航空器定位误差修正的碰撞风险研究

自由飞行能够提高空域容量从而缓解空域拥挤问题,在保障自由飞行安全性的基础上尽可能减小飞机的安全间距,需要研究自由飞行条件下飞机的安全评估问题。分析了所需CNS性能、防撞系统、风的因素等自由飞行下航空器定位误差的影响因素,考虑到航空器定位误差在短时间内具有累积性,提出采用INS、GPS数据融合算法对定位误差进行周期性修正。给出修正后的航空器定位误差分布在时间上的变化规律,并将其运用到自由飞行下碰撞风险评估中。结果表明,碰撞风险随安全间距增加呈下降趋势,以1.5×10-8次/飞行小时的目标安全水平为例,对航空器定位误差修正的最小安全间距为8 600 m,不对航空器定位误差进行修正的最小安全间距为9 100 m。     

纳米乳化油缓解多孔介质渗透性损失的实验研究

为有效缓解乳化油在原位修复地下水污染过程中所产生的堵塞及修复效率降低的问题,采用升温相转变技术手段,制备纳米乳化油.并采用一维柱实验,开展微米及纳米乳化油在多孔介质中的迁移研究,对比分析微米及纳米乳化油造成多孔介质的渗透性损失、在多孔介质中的截留比率及迁移距离等问题,探究纳米乳化油缓解多孔介质渗透性损失的效果.实验结果显示,微米及纳米乳化油所导致的中砂介质渗透性损失分别为20.40%和3.20%,乳化油截留比率分别为28.51%和20.15%.由此可见,乳化油截留是多孔介质渗透性损失的重要原因,减小乳化油粒径可有效缓解多孔介质的渗透性损失.与微米乳化油相比,纳米乳化油有效降低中、细砂介质渗透性损失84.3%和47.5%.此外,乳化油截留对多孔介质渗透性损失的影响在一定程度上也影响到其在多孔介质中的迁移距离,微米及纳米乳化油在中砂介质中的迁移距离分别为6.53 m和8.19 m.相比之下,纳米乳化油所导致的细砂介质渗透性损失为10.70%,截留比率为25.71%,迁移距离为7.36 m,说明纳米乳化油迁移效果更佳,可适用介质范围更广.