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排序方式: 共有4795条查询结果,搜索用时 15 毫秒
941.
942.
943.
介绍了极板转运装置自动控制系统的设计思想.详细阐述了系统的组成,检测开关的现场布置以及系统程序的设计. 相似文献
944.
对煤矿安全量化管理方法进行了理论上的深化和手段上的完善,提出了利用层次分析法确定安全管理目标标准分的方法,研制了实用、有效的应用软件系统。 相似文献
945.
946.
Andrew O. Finley Sudipto Banerjee Ronald E. McRoberts 《Environmental and Ecological Statistics》2008,15(2):241-258
In efforts such as land use change monitoring, carbon budgeting, and forecasting ecological conditions and timber supply,
there is increasing demand for regional and national data layers depicting forest cover. These data layers must permit small
area estimates of forest area and, most importantly, provide associated error estimates. This paper presents a model-based
approach for coupling mid-resolution satellite imagery with plot-based forest inventory data to produce estimates of probability
of forest and associated error at the pixel-level. The proposed Bayesian hierarchical model provides access to each pixel’s
posterior predictive distribution allowing for a highly flexible analysis of pixel and multi-pixel areas of interest. The
paper presents a trial using multiple dates of Landsat imagery and USDA Forest Service Forest Inventory and Analysis plot
data. The results describe the spatial dependence structure within the trial site, provide pixel and multi-pixel summaries
of probability of forest land use, and explore discretization schemes of the posterior predictive distributions to forest
and non-forest classes. Model prediction results of a holdout set analysis suggest the proposed model provides high classification
accuracy, 88%, for the trial site.
相似文献
Ronald E. McRobertsEmail: |
947.
PETER W. J. BAXTER†‡†† JOHN L. SABO§ CHRIS WILCOX‡ MICHAEL A. McCARTHY † HUGH P. POSSINGHAM‡ 《Conservation biology》2008,22(1):89-98
Abstract: Introduced predators can have pronounced effects on naïve prey species; thus, predator control is often essential for conservation of threatened native species. Complete eradication of the predator, although desirable, may be elusive in budget‐limited situations, whereas predator suppression is more feasible and may still achieve conservation goals. We used a stochastic predator–prey model based on a Lotka‐Volterra system to investigate the cost‐effectiveness of predator control to achieve prey conservation. We compared five control strategies: immediate eradication, removal of a constant number of predators (fixed‐number control), removal of a constant proportion of predators (fixed‐rate control), removal of predators that exceed a predetermined threshold (upper‐trigger harvest), and removal of predators whenever their population falls below a lower predetermined threshold (lower‐trigger harvest). We looked at the performance of these strategies when managers could always remove the full number of predators targeted by each strategy, subject to budget availability. Under this assumption immediate eradication reduced the threat to the prey population the most. We then examined the effect of reduced management success in meeting removal targets, assuming removal is more difficult at low predator densities. In this case there was a pronounced reduction in performance of the immediate eradication, fixed‐number, and lower‐trigger strategies. Although immediate eradication still yielded the highest expected minimum prey population size, upper‐trigger harvest yielded the lowest probability of prey extinction and the greatest return on investment (as measured by improvement in expected minimum population size per amount spent). Upper‐trigger harvest was relatively successful because it operated when predator density was highest, which is when predator removal targets can be more easily met and the effect of predators on the prey is most damaging. This suggests that controlling predators only when they are most abundant is the “best” strategy when financial resources are limited and eradication is unlikely. 相似文献
948.
A~2/O法应用于酒店污水处理工程的实例 总被引:2,自引:0,他引:2
某酒店污水处理工程设计规模 80 0m3 d ,进水CODCr2 50~ 30 0mg L ,BOD51 50~ 1 0 0mg L ,SS 1 4 0~ 1 2 0mg L ,氨氮2 5mg L ,动植物油 50mg L。采用处理工艺 ,2年来的运行效果显示 ,出水水质稳定达到广东省《水污染物排放限值》(DB4 4 2 6 2 0 0 1 )第二时段第一级标准。 相似文献
949.
950.
详细介绍了污水处理厂的设计规模、SDAO污水处理工艺、各个单体构筑物的主要设计参数,SDAO工艺采用圆形曝气池,在工艺和结构设计上有所创新。污泥采用消化处理,污泥加热方式比较科学。 相似文献