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71.
易燃液体燃烧痕迹识别对助燃剂放火火灾调查至关重要。选用丙纶地毯和PVC地板革作为纤维和塑料地板的代表,以工业酒精作为易挥发助燃剂的代表,研究酒精用量、灭火方式等对燃烧痕迹形成及痕迹稳定性的影响。通过与未加载酒精的痕迹对比,发现丙纶地毯因热稳定性较差,燃烧后往往能形成烧坑或烧洞,其燃烧轮廓以典型的灰化形式存在,加载酒精的部位熔融严重,与地面紧紧粘连在一起;PVC地板革因为表面光滑,酒精在其表面不断流淌,燃烧后会留下清晰的轮廓,类似于细线状的印痕,而地板革本身基本不会燃烧。燃烧熄灭的方式也会对其炭化程度、燃烧图痕、残余形状产生影响。  相似文献   
72.
Eucalyptus forest; and in the composition of understorey herbs, sedges, and grasslands. Pollen concentration and charcoal and organic content also exhibit post-European changes. Thus, pollen analysis provides a technique for determining changes in sediment budgets and identifying major vegetation changes in floodplains.  相似文献   
73.
Several international initiatives, including the European Biodiversity Strategy to 2020, promote the identification and mapping of ecosystems as basic tools for the conservation of biodiversity and related services. On coarse scales, the spatial representation of ecosystems is usually based on broad land cover categories that largely overlook important ecological and biogeographic features of the biotic communities they are meant to exemplify. This paper presents a nationwide ecosystem mapping approach that promotes a degree of thematic detail, which is more suited than that found in the continental maps to meeting biodiversity conservation targets in Italy. The approach is based on the rationale that current and potential vegetation cover are valuable proxies for outlining ecosystems. The resulting Ecosystem Map of Italy includes 43 types of forest ecosystems instead of the 5 woodland, forest and other wooded land types recognized at the European level. We outline the expected advantages of this enhanced thematic detail for a number of conservation purposes and highlight how the resulting maps may help to meet biodiversity conservation targets at the national level. In particular, we refer to the assessment of conservation status, the definition of restoration priorities, the planning of green infrastructure and the identification of collapse risks for the ecosystems identified. Comprehensively, the definition, characterization and assessment of ecosystem types represent the carrying structure of the recently launched national system of natural capital accounting.  相似文献   
74.
Remotely sensed vegetation indices correspond to canopy vigor and cover and have been successfully used to estimate groundwater evapotranspiration (ETg) over large spatial and temporal scales. However, these data do not provide information on depth to groundwater (dtgw) necessary for groundwater models (GWM) to calculate ETg. An iterative approach is provided that calibrates GWM to ETg derived from Landsat estimates of the Enhanced Vegetation Index (EVI). The approach is applied to different vegetation groups in Mason Valley, Nevada over an 11‐year time span. An uncertainty analysis is done to estimate the resulting mean and 90% confidence intervals in ETg to dtgw relationships to quantify errors associated with plant physiologic complexity, species variability, and parameter smoothing to the 100 m GWM‐grid, temporal variability in soil moisture and nonuniqueness in the solution. Additionally, a first‐order second moment analysis shows ETg to dtgw relationships are almost exclusively sensitive to estimated land surface, or maximum, ETg despite relatively large uncertainty in extinction depths and hydraulic conductivity. The EVI method of estimating ETg appears to bias ETg during years with exceptionally wet spring/summer conditions. Excluding these years improves model performance significantly but highlights the need to develop a methodology that accounts not only on quantity but timing of annual precipitation on phreatophyte greenness.  相似文献   
75.
采用固相微萃-气相色谱/质谱法(SPME-GC/MS)对GSM和2-MIB进行富集检测。实验对萃取富集和仪器条件进行了优化,得出最佳实验条件:NaCl投加量30%,萃取温度65℃,萃取时间40 min,解吸3 min,不分流进样,SIM模式采集数据。实验还对萃取头的使用次数和维护进行了探讨。利用已经建立的SPME-GC/MS法对佛山市28家水厂的出厂水和原水、佛山典型景观千灯湖和亚艺公园湖水进行普查。该法具有操作简单快速、能实现自动化连续检测、准确、灵敏度高等特点,适用于饮用水中嗅味物质定性和定量。  相似文献   
76.
Accidents in university laboratories not only create a great threat to students’ safety but bring significant negative social impact. This paper investigates the university laboratory safety in China using questionnaire and Bayesian network (BN) analysis. Sixteen influencing factors for building the Bayesian net were firstly identified. A questionnaire was distributed to graduate students at 60 universities in China to acquire the probability of safe/unsafe conditions for sixteen influencing factors, based on which the conditional probability of four key factors (human, equipment and material, environment, and management) was calculated using the fuzzy triangular theory and expert judgment. The determined conditional probability was used to develop a Bayesian network model for the risk analysis of university laboratory safety and identification of the main reasons behind the accidents. Questionnaire results showed that management problems are prominent due to insufficient safety education training and weak management level of management personnel. The calculated unsafe state probability was found to be 65.2%. In the BN analysis, the human factor was found to play the most important role, followed by equipment and material factor. Sensitive and inferential analysis showed that the most sensitive factors are personnel incorrect operation, illegal operation, and experiment equipment failure. Based on the analysis, countermeasures were proposed to improve the safe management and operation of university laboratories.  相似文献   
77.
In the Heihe River Basin in the arid inland area of northwest China, the distribution of water resources in vegetation landscape zones controls the ecosystems. The carbon sequestration capacity of vegetation is analyzed in relation to water resources and vegetation growing conditions. During the last 20 years, the vegetation ecosystems have degenerated in the Heihe River Basin. Simulation using the C-FIX model indicates that, at present, the total amount of NPP of vegetation accounts for about 18.16 TgC, and the average value is 106 gC/m(2)/yr over the whole basin. NPP has generally the highest value in the upperstream mountain area, middlestream artificial oases area, downstream river bank area, alluvial fan and the terminal lake depression where vegetation grows relatively well. The lowest value is found in the vast downstream desert and Gobi area. Protection of vegetation ecosystems and enhancement of carbon sequestration require such inland river basins as the Heihe River Basin to be brought under management in a comprehensive way, taking water as a key, to carry out a rational and efficient allocation and utilization of water resources.  相似文献   
78.
Spatial scaling between leaf area index maps of different resolutions   总被引:1,自引:0,他引:1  
We developed algorithms for spatial scaling of leaf area index (LAI) using sub-pixel information. The study area is located near Liping County, Guizhou Province, in China. Methods for LAI spatial scaling were investigated on LAI images with 960 m resolution derived in two ways. LAI from distributed calculation (LAID) was derived using Landsat ETM+ data (30 m), and LAI from lumped calculation (LAIL) was obtained from the coarse (960 m) resolution data derived through resampling the ETM+ data. We found that lumped calculations can be considerably biased compared to the distributed (ETM+) case, suggesting that global and regional LAI maps can be biased if surface heterogeneity within the mapping resolution is ignored. Based on these results, we developed algorithms for removing the biases in lumped LAI maps using sub-pixel land cover-type information, and applied these to correct one coarse resolution LAI product which greatly improved its accuracy.  相似文献   
79.
选取典型小区,对秦皇岛市室内甲醛污染现状进行了调查,调查结果表明秦皇岛市住宅内甲醛污染严重,并将全过程控制理论应用于住宅装修过程中,有效降低了室内甲醛污染,提出了通过通风、选材、加温加湿、负离子功能产品、室内净化设施等多种措施来有效控制室内甲醛污染。  相似文献   
80.
An accident occurred during a production process of hydroxyurea. Several thermoanalytical techniques were used in order to understand the reason for the accident, even utilising a simulation program. Thermogravimetric analysis and Fourier transform infra-red spectroscopy were performed to identify the decomposition products according to European Directive 96/82/EC, the so-called Seveso II.  相似文献   
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