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111.
112.
Huu Duy Nguyen Dinh-Kha Dang Quang-Thanh Bui Alexandru-Ionut Petrisor 《Transactions in GIS》2023,27(5):1614-1640
Natural hazards constitute a diverse category and are unevenly distributed in time and space. This hinders predictive efforts, leading to significant impacts on human life and economies. Multi-hazard prediction is vital for any natural hazard risk management plan. The main objective of this study was the development of a multi-hazard susceptibility mapping framework, by combining two natural hazards—flooding and landslides—in the North Central region of Vietnam. This was accomplished using support vector machines, random forest, and AdaBoost. The input data consisted of 4591 flood points, 1315 landslide points, and 13 conditioning factors, split into training (70%), and testing (30%) datasets. The accuracy of the models' predictions was evaluated using the statistical indices root mean square error, area under curve (AUC), mean absolute error, and coefficient of determination. All proposed models were good at predicting multi-hazard susceptibility, with AUC values over 0.95. Among them, the AUC value for the support vector machine model was 0.98 and 0.99 for landslide and flood, respectively. For the random forest model, these values were 0.98 and 0.98, and for AdaBoost, they were 0.99 and 0.99. The multi-hazard maps were built by combining the landslide and flood susceptibility maps. The results showed that approximately 60% of the study area was affected by landslides, 30% by flood, and 8% by both hazards. These results illustrate how North Central is one of the regions of Vietnam that is most severely affected by natural hazards, particularly flooding, and landslides. The proposed models adapt to evaluate multi-hazard susceptibility at different scales, although expert intervention is also required, to optimize the algorithms. Multi-hazard maps can provide a valuable point of reference for decision makers in sustainable land-use planning and infrastructure development in regions faced with multiple hazards, and to prevent and reduce more effectively the frequency of floods and landslides and their damage to human life and property. 相似文献
113.
Anaerobic ammonium oxidation(anammox) is a relatively new pathway within the N cycle discovered in the late 1990 s. This eminent discovery not only modified the classical theory of biological metabolism and matter cycling, but also profoundly influenced our understanding of the energy sources for life. A new member of chemolithoautotrophic microorganisms capable of carbon fixation was found in the vast deep dark ocean. If the discovery of the chemosynthetic ecosystems in the deep-sea hydrothermal vent environments once challenged the old dogma "all living things depend on the sun for growth," the discovery of anammox bacteria that are widespread in anoxic environments fortifies the victory over this dogma. Anammox bacteria catalyze the oxidization of NH_4~+ by using NO_2~- as the terminal electron acceptor to produce N_2. Similar to the denitrifying microorganisms, anammox bacteria play a biogeochemical role of inorganic N removal from the environment. However, unlike heterotrophic denitrifying bacteria, anammox bacteria are chemolithoautotrophs that can generate transmembrane proton motive force, synthesize ATP molecules and further carry out CO_2 fixation through metabolic energy harvested from the anammox process. Although anammox bacteria and the subsequently found ammonia-oxidizing archaea(AOA), another very important group of N cycling microorganisms are both chemolithoautotrophs, AOA use ammonia rather than ammonium as the electron donor and O_2 as the terminal electron acceptor in their energy metabolism. Therefore, the ecological process of AOA mainly takes place in oxic seawater and sediments, while anammox bacteria are widely distributed in anoxic water and sediments, and even in some typical extreme marine environments such as the deep-sea hydrothermal vents and methane seeps. Studies have shown that the anammox process may be responsible for 30%–70% N_2 production in the ocean. In environmental engineering related to nitrogenous wastewater treatment, anammox provides a new technology with low energy consumption, low cost, and high efficiency that can achieve energy saving and emission reduction. However, the discovery of anammox bacteria is actually a hard-won achievement. Early in the 1960 s, the possibility of the anammox biogeochemical process was predicted to exist according to some marine geochemical data. Then in the 1970 s, the existence of anammox bacteria was further predicted via chemical reaction thermodynamic calculations. However, these microorganisms were not found in subsequent decades. What hindered the discovery of anammox bacteria, an important N cycling microbial group widespread in hypoxic and anoxic environments? What are the factors that finally led to their discovery? What are the inspirations that the analyses of these questions can bring to scientific research? This review article will analyze and elucidate the above questions by presenting the fundamental physiological and ecological characteristics of the marine anammox bacteria and the principles of scientific research. 相似文献
114.
This study examines the roles of the multi-physics approach in accounting for model errors for typhoon forecasts with the local ensemble transform Kalman filter (LETKF). Experiments with forecasts of Typhoon Conson (2010) using the weather research and forecasting (WRF) model show that use of the WRF’s multiple physical parameterization schemes to represent the model uncertainties can help the LETKF provide better forecasts of Typhoon Conson in terms of the forecast errors, the ensemble spread, the root mean square errors, the cross-correlation between mass and wind field as well as the coherent structure of the ensemble spread along the storm center. Sensitivity experiments with the WRF model show that the optimum number of the multi-physics ensemble is roughly equal to the number of combinations of different physics schemes assigned in the multi-physics ensemble. Additional idealized experiments with the Lorenz 40-variable model to isolate the dual roles of the multi-physics ensemble in correcting model errors and expanding the local ensemble space show that the multi-physics approach appears to be more essential in augmenting the local rank representation of the LETKF algorithm rather than directly accounting for model errors during the early cycles. The results in this study suggest that the multi-physics approach is a good option for short-range forecast applications with full physics models in which the spinup of the ensemble Kalman filter may take too long for the ensemble spread to capture efficiently model errors and cross-correlations among model variables. 相似文献
115.
116.
《工程测量学》双语教学的实践与评估 总被引:2,自引:0,他引:2
介绍工程测量学双语教学的具体实践过程,对工程测量学双语教学模式及教学效果进行了问卷调查、评估与分析,提出工程测量学双语教学存在的问题和应采取的改进措施。 相似文献
117.
118.
Yuling Zhang Hong Qian Jiali Wang Chaoqun Si Zhiyu Chen Jiangyan Dang Zhenyi Zhang 《Environmental Earth Sciences》2017,76(2):90
The objective of this paper was to investigate a petroleum-contaminated groundwater site in northeast China. Based on the monitoring and analysis of environmental characteristics of groundwater slightly contaminated with petroleum, microbes were added into the petroleum-contaminated groundwater via single-well and multiple-well models to enhance bioremediation. The effect of enhanced bioremediation was monitored and analyzed, and variations in the environmental characteristics of groundwater containing total petroleum hydrocarbons (TPH) were identified to provide a scientific basis for controlling and remediating petroleum-contaminated groundwater. Findings confirmed that this site was slightly contaminated and TPH levels exhibited a slight decreasing trend. After enhanced remediation, the microbial degradation effect was large, and the TPH concentration significantly reduced. In particular, near the wells treated by bioremediation, the amounts of electron acceptors, such as NO3 ?, Fe3+, and SO4 2?, markedly decreased. The product of the microbial degradation process, HCO3 ?, gradually increased in the treated wells. Activities of the enzyme catechol 1, 2-dioxygenase decreased, while those of catalase increased. Reductions in pH, from 7.4 to 6.1, were recorded, and the groundwater environment became further deoxidized. 相似文献
119.
利用试验资料,对蒸散面积2 m2和4 m2两种尺寸蒸渗计测量蒸散量的差异及原因进行了研究。结果表明:2 m2蒸渗计与4 m2蒸渗计所测蒸散量具有很好的一致性,但2 m2蒸渗计所测蒸散量总体要略偏大,日蒸散量平均偏大4%,月蒸散量平均偏大10%,年蒸散量相对偏大5%;典型天气条件下,2 m2蒸渗计和4 m2蒸渗计所测蒸散量的日变化过程基本相同,小时蒸散量的差异表现为晴天时白天显著偏大、夜晚略有偏小,阴天时白天略偏大、夜晚较接近,雨天时白天、夜晚均非常接近的特征。晴天和阴天时,2 m2蒸渗计比4 m2蒸渗计测量日蒸散量分别偏大1.78 mm和0.12 mm,雨天时偏小0.11 mm;2 m2蒸渗计比4 m2蒸渗计测量蒸散量总体偏大的原因,主要是2 m2蒸渗计土壤温度显著高于4 m2蒸渗计和建造时间不同导致土体内部土壤湿度产生差异。 相似文献
120.
????XPL????Ч?????????HPL??VPL??????????????????м?????????????????????HPL??VPL??????????????HPL??VPL?????????С??9 m??12 m?????????12 m??20 m????????????????????????????????????? 相似文献