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81.
本文介绍了一种用于溶解氧测定的自制快速移液器.大量实践证明,这种移液器的应用,可明显提高溶解氧测定结果的准确度和精密度,并可缩短样品分析时间. 相似文献
82.
一种化纤废水处理的运行及分析 总被引:5,自引:0,他引:5
化纤废水含有各种难降解有机物,国内外一直未能提出一套较好的处理方法,本文介绍了一种化纤废水的研究,处理工艺及其主要设计参数以及运行管理,事实证明了这种方法是可行的,其具有处理效果稳产,产泥量少,具有一定的消泡作用等优点。 相似文献
83.
84.
A Sensitivity Analysis of Nitrogen Losses from Dairy Farms 总被引:2,自引:0,他引:2
International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms. 相似文献
85.
亭子口库区水质汞的污染特征及建库后水体中汞的预测 总被引:1,自引:1,他引:1
亭子口水利枢纽位于喜陵江平流苍溪县城以上,15km处。本文根据嘉陵江广元段水质监测资料,分析库区地面水体中汞的现状污染特征,并运用沉积物的负指数方程预测库区建坝后水体中汞的浓度。 相似文献
86.
从管理学、心理学的角度研究安全的价值,探讨其时代性、广义性、差异性、观念性,进一步认识到安全的重要性,并用安全价值观来为安全生产服务 相似文献
87.
Characteristics of large cooking oil pool fires and their extinguishment by water mist 总被引:1,自引:0,他引:1
Z. Liu D. Carpenter A.K. Kim 《Journal of Loss Prevention in the Process Industries》2006,19(6):516-526
Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker. 相似文献
88.
E. Conrad Lamon Song S. Qian Daniel D. Richter 《Journal of the American Water Resources Association》2004,40(5):1219-1229
ABSTRACT: Dynamic linear models (DLM) and seasonal trend decomposition (STL) using local regression, or LOESS, were used to analyze the 50‐year time series of suspended sediment concentrations for the Yadkin River, measured at the U.S. Geological Survey station at Yadkin College, North Carolina. A DLM with constant trend, seasonality, and a log10 streamflow regressor provided the best model to predict monthly mean log10 suspended sediment concentrations, based on the forecast log likelihood. Using DLM, there was evidence (odds approximately 69:1) that the log10 streamflow versus log10 suspended sediment concentration relationship has changed, with an approximate 20 percent increase in the log10 streamflow coefficient over the period 1981 to 1996. However, sediment concentrations in the Yadkin River have decreased during the decade of the 1990s, which has been accompanied by a concomitant increase in streamflow variability. Although STL has been shown to be a versatile trend analysis technique, DLM is shown to be more suitable for discovery and inference of structural changes (trends) in the model coefficient describing the relationship between flow and sediment concentration. 相似文献
89.
90.
我国东南沿海是世界上台风最集中的地区之一,也是我国经济最发达和财富最集中的地区,台风引起的灾害损失巨大.数值模拟方法是目前进行台风危险性分析和估算极值风速普遍采用的方法,已有较多风场模型应用于台风区的极值风速估算,Shapiro风场模型是其中之一.首先介绍了Shapiro台风风场模型,然后采用有限差分法求解描述该风场模型的非线性偏微分方程组,利用两个实测台风的风速记录对该模型进行了验证,对该风场模型在我国东南沿海地区的应用做了初步尝试. 相似文献