Recursive residuals and model diagnostics for normal and non-normal state space models

Model diagnostics for normal and non-normal state space models are based on recursive residuals which are defined from the one-step ahead predictive distribution. Routine calculation of these residuals is discussed in detail. Various diagnostic tools are suggested to check, for example, for wrong observation distributions and for autocorrelation. The paper also discusses such topics as model diagnostics for discrete time series and model discrimination via Bayes factors. The case studies cover environmental applications such as analysing a time series of the number of daily rainfall occurrences and a time series of daily sulfur dioxide emissions.     

An assessment of tree health and trace element accumulation near a coal-fired generating station, Manitoba, Canada

A forest health assessment was performed in stands dominated by bur oak and trembling aspen to study the potential effects of airborne emissions from a 132 MW coal-fired station. Forty-two stands were sampled within a 16-km radius of the station for both foliar stress symptoms and trace element toxicology. The concentrations of tracer elements (As, Ba, Sr, and V) in the leaf litter were not spatially congruent with airborne emission deposition models (except Ba, which showed elevated levels immediately SE of the station), nor were they at phytotoxic levels. Elemental concentrations were significantly related to soil parameters including organic matter and texture. No patterns were found in forest health along directional or distance gradients from the generating station. Trembling aspen stands demonstrated little decline in general, but three of the 19 bur oak plots, all located on thin sandy soils developed on calcareous till, demonstrated branch dieback. In addition to poor soil conditions, two of these sites also had high water tables, and exhibited tree mortality. The bur oak decline did not appear to be related to emissions from the station, but is suspected to be a result of poor site quality, with urban development as a confounding factor.     

Assessment of Present-Day Reproduction Efficiency in Stellate Sturgeon Acipenser stellatus in Different Spawning Zones of the Lower Volga

Studies performed from 1979 to 1998 provided data on the efficiency of natural reproduction of the stellate sturgeon Acipenser stellatus in the upper, middle, and lower spawning zones of the Volga. A correlation between the size of the progeny and environmental factors was revealed. Today, the main factors limiting the efficiency of reproduction in the stellate sturgeon are the numbers of fish admitted to the spawning grounds (especially in 1997 and 1998) and water level in the Volga during the summer low-water season. Measures to support natural reproduction of the stellate sturgeon are proposed.     

Can Nutrient Spiralling be Used to Detect Seasonal Nutrient Uptake in a Forested Stream?

Nutrient spiralling measurements were conducted in Lyrebird Creek, a forested stream in the Dandenong Ranges, Victoria, Australia. Spiralling indices from several nutrient (, ) enrichment experiments were correlated with seasonal variation in factors thought to control nutrient uptake, i.e., temperature, light and algal biomass. It was hypothesized that nutrient uptake would be higher in summer as increased temperatures would promote both biotic and abiotic processes and higher light levels in summer would stimulate photosynthesis. However, results did not support this hypothesis. Uptake length for and and uptake velocity were not correlated with chlorophyll-a, light or temperature (r ² < 0.30, P > 0.1) despite the seasonality of these biophysical factors (r ² > 0.42, P < 0.02). Lyrebird Creek might had no seasonal trend in nutrient uptake and/or nutrient spiraling measurements only appears suitable for contrasting streams with large differences in biophysical factors that supports biotic and abiotic nutrient processing. In addition, small errors in measuring a nutrient concentration can result in a large range in the estimated S _w and increased difficulty in determining significant differences in nutrient spiralling indices.     

某催化裂化装置生产过程中职业病危害因素调查

通过对催化裂化装置生产过程中职业病危害因素调查,找出职业病危害的关键控制点,并提出防护要求。     

危险品道路运输企业风险管理与对策探讨

阐述了危险品运输企业存在和面临的风险,以及产生风险基本要素之间的相互关系。通过风险分析、评价,提出缩减风险的管理对策,从而减小危险品运输安全风险、降低事故概率和频率.     

电-Fenton法处理甲醛废水

研究了IrO2／Ta2O5电极做阳极、自制石墨电极做阴极电-Fenton法对低浓度甲醛废水处理方法。并对影响因素进行讨论。结果显示在pH为3,Na2SO4浓度8mg/L,FeSO4浓度0．4mmo／L,通以20ml／min／L空气,电流密度10mA/cm^2甲醛去除率可达到87％。     

生物柴油制备工艺影响因素的探讨

介绍了生物柴油制备的基本工艺,着重阐述了催化剂、反应温度、反应时间、醇油比、水分以及游离脂肪酸含量对生物柴油制备的影响,并提出了生物柴油制备工艺今后的研究方向和开发前景。     

Reduction of nitrobenzene by the catalyzed Fe/Cu process

The polarization behavior of the couple Fe/Cu in 100 mg/L nitrobenzene aqueous solution was studied using Evans coupling diagrams.The results indicated that the iron corrosion was limited by both anodic and cathodic half-cell reactions under the neutral conditions,and cathodically controlled under the alkaline conditions.Batch experiments were performed to study the effect of solution pH,reaction duration,concentration,type of electrolyte,and dissolved oxygen(DO)on the reduction of nitrobenzene by the ca...     

空气质量与气象因子间关联规则的挖掘方法研究

传统数据相关性分析仅能揭示空气质量与气象因子之间的相关系数,关联规则挖掘方法使用支持度、置信度、作用度、兴趣度等指标能够发掘隐藏在大量监测数据内部的关联规则。文章使用SQL语言实现了Apriori算法,挖掘出研究区内空气主要污染物浓度与气象因子之间的关联规则,定量表示气象因子变化对主要污染物浓度的影响。