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631.
考虑了影响大气扩散的主要气象因素及其它因素,提出了一个大气SO_2污染预测模型,并运用加权实时最小二乘算法对模型进行实时辨识。这一模型尤其适用于城市及城市中SO_2日均浓度的分区预测,给出了该模型在上海地区应用的结果。 相似文献
632.
为合理确定常熟氟化工项目排污口布置方案,针对长江常熟段水环境特征,尤其是复杂的水地下形和水流流场,建立为较为准确和实用的平面二维水流水质耦合数学模型,应用剖开算子法模拟计算了3套排污方案对重点保护水域影响程序度和范围,并从水流场,水质影响评价,技术经济多角度对方案进行了比较论证,最终推荐污水江中排放的方案,为项目的工程设计和环境管理提供了科学依据。 相似文献
633.
Predicting the Range of Chinese Mitten Crabs in Europe 总被引:1,自引:0,他引:1
LEIF-MATTHIAS HERBORG† DEBORAH A. RUDNICK‡ YANG SILIANG§ DAVID M. LODGE† HUGH J. MacISAAC 《Conservation biology》2007,21(5):1316-1323
Abstract: Ecological niche modeling provides a means for predicting the potential future distribution of a nonindigenous species based on environmental characteristics of the species' native range. We applied this method to the Chinese mitten crab (Eriocheir sinensis) , a catadromous crustacean with a long history of invasion in Europe. We used genetic algorithm for rule-set prediction to predict the potential European distribution of mitten crab based on its distribution in 42 locations in its native Asia. The climatic variables, air temperature, number of days, amount of precipitation, and wetness index, contributed significantly to predictions of native distribution limits. Although the genetic algorithm for rule-set prediction model was developed for the native range, the species' extensive distribution in Europe ( n = 434) allowed independent validation of the predictions. Application of the model to Europe was successful, with 84% of occurrences in regions predicted to be suitable by >80% of the models and <4% of occurrences in areas predicted suitable by <50% of the models (mainly along the northern range). At the watershed scale, areas with established mitten crab populations had significantly higher habitat matching than sites that were not invaded. The independent validation of the Asian-based model by the European distribution revealed that predictions were highly accurate. The model also identified large areas of Europe, particularly along the Mediterranean coast, as vulnerable to future invasion. These predictions can be used to develop strategies to control the spread of mitten crab by preventing introductions into vulnerable areas. 相似文献
634.
Area-Based Refinement for Selection of Reserve Sites with the Benefit-Function Approach 总被引:1,自引:0,他引:1
Abstract: Optimization of resource use is necessary for efficient conservation planning. Many reserve-selection algorithms aim to identify representative but inexpensive networks, which may lead to selecting small sites due to their lower costs and collectively higher species richness. Nevertheless, larger sites would be preferable regarding species' long-term persistence. An area-based refinement can be used to overcome this problem. We used a reserve-planning framework in which continuous benefit functions valued representation (numbers of populations), and differential species weights were based on a species' local rarity and threatened status. We introduced a refinement based on the species-area relationship that provides relatively higher values for larger sites. We applied the proposed method to rich fen vegetation in southern Finland. The species-area refinement resulted in a network of significantly larger sites with minor trade-offs with representation (numbers of populations). Giving endangered species higher weights ensured that the trade-off occurred mostly between site size and representation of low-priority species. We recommend using a species-area refinement for practical, maximum-coverage conservation planning. 相似文献
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提出了一种对多项指标都能普遍适用的区域水资源可持续利用评价模型,将实数编码混沌量子遗传算法应用于区域水资源可持续利用评价模型中参数的优化,并用优化好的模型对区域水资源可持续利用做出评价。通过对中国12个区域实测数据的评价实例研究及与其它评价方法得到的结果进行对比,表明该模型具有实用性和可行性。 相似文献
639.
应用遗传算法建立云杉针叶表面PCDD/Fs光解半衰期的预测模型 总被引:7,自引:1,他引:6
采用量子化学PM3算法计算PCDD/Fs的量子化学参数,应用遗传算法(Genetic Algorithm, GA)对所建模型中的变量进行筛选,建立了能预测吸附到云杉[Picea abies (L.) Karst.]针叶表面的PCDD/Fs光解半衰期(t1/2)的定量结构-性质关系(QSPR)模型,认为影响PCDD/Fs光解速率的主要因素是分子最高占据轨道能(EHOMO)、前线分子轨道能量差(ELUMO-EHOMO)和平均极化率(α).随着EHOMO和α的增大;其lg t1/2值增大,PCDD/Fs的lg t1/2值与其(ELUMO-EHOMO)值呈抛物线关系,当ELUMO-EHOMO=7.847时,lg t1/2有最小值;当ELUMO-EHOMO≤7.847时,lg t1/2值随着ELUMO-EHOMO的增大而减小;当ELUMO-EHOMO≥7.847时,lg t1/2值随着ELUMO-EHOMO的增大而增大. 相似文献
640.
A two-dimensional individual-based model coupled with fish bioenergetics was developed to simulate migration and growth of Japanese sardine (Sardinops melanostictus) in the western North Pacific. In the model, fish movement is controlled by feeding and spawning migrations with passive transport by simulated ocean current. Feeding migration was assumed to be governed by search for local optimal habitats, which is estimated by the spatial distribution of net growth rate of a sardine bioenergetics model. The forage density is one of the most important factors which determines the geographical distributions of Japanese sardine during their feeding migrations. Spawning migration was modeled by an artificial neural network (ANN) with an input layer composed of five neurons that receive environmental information (surface temperature, temperature change experienced, current speed, day length and distance from land). Once the weight of the ANN was determined, the fish movement was solved by combining with the feeding migration model. To obtain the weights of the ANN, three experiments were conducted in which (1) the ANN was trained with back propagation (BP) method with optimum training data, (2) genetic algorithm (GA) was used to adjust the weights and (3) the weights of the ANN were decided by the GA with BP, respectively. BP is a supervised learning technique for training ANNs. GA is a search technique used in computing to find approximate solutions, such as optimization of parameters. Condition factor of sardine in the model is used as a factor of optimization in the GA works. The methods using only BP or GA did not work to search the appropriate weights in the ANN for spawning migration. In the third method, which is a combined approach of GA with BP, the model reproduced the most realistic spawning migration of Japanese sardine. The changes in temperature and day length are important factors for the orientation cues of Japanese sardine according to the sensitivity analysis of the weights of the ANN. 相似文献