共查询到20条相似文献，搜索用时 46 毫秒
1.
In order to research the feasibility of artificial neural network (ANN) in the research of eutrophication of the Bohai Bay in China, an ANN model simulating chlorophyll a, b and c concentrations, concerning temperature, dissolved oxygen, salinity, pH value, chemical oxygen demand (COD), PO43-, NO2-and NO3-factors in the Bohai Bay was presented and validated. After experiencing and training by Matlab, the model′s validation mean square error (MSE) performance is 0.009 985 02. R-squared between estimated and observed concentrations of chlorophyll a, b and c are 0.965 7, 0.998 7 and 0.970 7 respectively, indicating that the estimated value agrees with the observed value well, and the model can be used in the prediction of eutrophication of the Bohai Sea. In order to study the influence of model input factors on chlorophyll concentration (i.e. model outputs), hypothetical scenarios were introduced to show model output responses to variations in input factors. The limitation of temperature, salinity and phosphate that induce red tide in the Bohai Bay was also presented. 相似文献
2.
This research considers the mathematical relationship between concentration of Chla and seven environmental factors, i.e. Lake water temperature (T), Secci-depth (SD), pH, DO, CODMn, Total Nitrogen (TN), Total Phosphorus (TP). Stepwise linear regression of 1997 to 1999 monitoring data at each sampling point of Qiandaohu Lake yielded the multi-variate regression models presented in this paper. The concentration of Chla as simulation for the year 2000 by the regression model was similar to the observed value. The suggested mathematical relationship could be used to predict changes in the lakewater environment at any point in time. The results showed that SD, TP and pH were the most significant factors affecting Chla concentration. 相似文献
3.
This research considers the mathematical relationship between concentration of Chla and seven environmental factors, i.e. Lake water temperature (T), Secci-depth (SD), pH, DO, CODMn, Total Nitrogen (TN), Total Phosphorus (TP).Stepwise linear regression of 1997 to 1999 monitoring data at each sampling point of Qiandaohu Lake yielded the multivariate regression models presented in this paper. The concentration of Chla as simulation for the year 2000 by the regression model was similar to the observed value. The suggested mathematical relationship could be used to predict changes in the lakewater environment at any point in time. The results showed that SD, TP and pH were the most significant factors affecting Chla concentration. 相似文献
4.
农田土壤酶活性生态背景的灰色分析 总被引：1，自引：1，他引：1
苏永春 《常熟理工学院学报》2001,15(2):51-55,58
东北高寒地区麦田土壤酶活性具有明显的季节变化，其中纤维素酶和转化酶的最大值在7月份，脲酶和过氧化氢酶的最大值是在8月份，而脱氢酶的最小低谷值在7月份，用灰色关联分析找出了影响土壤酶活性总体的主要因素为弹尾类动物、活性有机质、土壤pH值和含水量。各种土壤酶分别和4种主要因素之间建立5个灰色数学模型[GM（1，5）]，除脲酶外其它四个数学模型的平均相对误差很小，模型拟合得很好。 相似文献
5.
张沛宇 《天津职业院校联合学报》2013,(11):100-102
在2012年全国大学生数学建模竞赛的C题中,关于脑卒中疾病受环境影响的因素很多同学都按着多元线性回归分析的模型给出了发病率和温度、湿度、气压等外界环境因素的关系,并通过逐步回归分析得出了温度、湿度、气压的关系系数以及他们的权重因子。但通过对发病率和认为温度、湿度、气压等外界环境因素的关系并非简单的线性关系,而是带有交叉项的回归模型,笔者通过非线性回归分析得到了温度、湿度、气压等外界环境因素的关系,并通过F检验,说明系数的误差。并通过预测得出在未来几年的发病率的大概人数,以供医院对医务人员和器械进行配备。 相似文献
6.
目的:探索凤尾草多糖最佳提取工艺件。方法:采用酶水解法提取凤尾草多糖,在缓冲溶液用量、p H、时间、温度、以及酶的浓度这五个单因素试验基础上,结合正交试验探究最佳复合酶的配比,并对各因素进行二项式拟合,应用效应面法优化凤尾草多糖的提取条件。结果:凤尾草多糖最佳提取工艺为:缓冲溶液量为凤尾草质量的21.81倍,p H为4.71,时间为2.0 h,温度为48.88℃,纤维素酶用量为凤尾草质量的0.30%,果胶酶用量为凤尾草质量的0.40%,木瓜蛋白酶量是凤尾草质量的0.30%。结论:此方法提取的凤尾草多糖含量为10.43%。 相似文献
7.
Hg0 absorption in potassium persulfate solution 总被引：1，自引：0，他引：1
The aqueous phase oxidation of gaseous elemental mercury （Hg^0） by potassium persulfate （KPS） catalyzed by Ag^＋ was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption （CVAA） and ion chromatograph （IC）, respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate （SN）, temperature, Hg^0 concentration in the reactor inlet and tertiary butanol （TBA）, free radical scavenger, on the removal efficiency of Hg^0 were studied. The results showed that the removal efficiency of Hg^0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg^0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg^0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed. 相似文献
8.
郑钦华 《宁德师专学报(自然科学版)》2013,25(3):248-255
根据2009年和2010年4～10月份对三沙湾海域生态环境调查,共鉴定浮游植物118种,其中硅藻门有36属93种,甲藻门12属25种,主要的优势种为中肋骨条藻（Skeletonema costatttm）、诺氏海链藻（Thalassiosira cordenskiotdi）、具槽直链藻（Melosira sulcata）、旋链角毛藻（Chaetoceros curvisetus）、冕孢角毛藻（Chaetocerossub secttmdus）、柔弱拟菱形藻（Pseudo—nitzschia delicatissma）及东海原甲藻（Prorocentrum donghaiense）．回归相关性分析表明,湾内浮游植物的分布季节和丰度受到多种环境理化因子的影响,水体pH、DO、COD、Chl—a对赤潮发生期间环境状况及赤潮的发生和发展具有明显的指示作用;尤其在6～8月间与赤潮生物细胞数之间存在显著性相关关系． 相似文献
9.
INTRODUCTION Nitrate contamination in groundwater and sur-face water has become an increasingly serious envi-ronmental problem. Anthropogenic sources such asnitrogen fertilizers, animal wastes, and septic systemsaccount for most nitrate contamination of ground-water. Nitrate itself is relatively non-toxic. However,it can be microbially reduced to nitrite, which posesseveral health threats to humans including methemo-glo-binemia, liver damage and cancers. Nitrate out-flow onto shallow cont… 相似文献
10.
盖清霞 《青岛教育学院学报》2014,(5):20-24
莱州湾是渤海的三大海湾之一。从古至今,莱州湾的鲐鱼资源变动就十分明显,显著特征是时有时无。其主要原因为鲐鱼不适宜在浑浊的海水里生存。黄土高原的水土流失导致了黄河泥沙含量的提高,而黄河注入到渤海中则影响了莱州湾海水的透明度。近几十年来,莱州湾还受到了沿岸的工业污染和地上河流的陆源污染,这使得莱州湾的海洋环境更加恶化。现如今,多种因素交织导致鲐鱼基本上在莱州湾消失了。 相似文献
11.
探讨了交联魔芋葡甘聚糖和交联魔芋葡甘聚糖固化单宁微球的制备条件,进一步研究了新制的吸附剂一交联魔芋葡甘聚糖固化单宁微球对Sc^3＋的吸附性能,研究了时间、pH、温度和Sc^3＋的浓度等因素对材料吸附Sc^3＋的影响。结果表明：交联魔芋葡甘聚糖固化单宁微球对Sc^3＋的吸附在8h左右基本达到平衡,pH低于6．50时,Sc^3＋的平衡吸附量随pH和温度的升高而升高,50℃下,在HAc—NaAc介质中,当Sc^3＋的质量浓度为50mg／L,pH为6．39时,吸附容量达到886μg／g． 相似文献
12.
Wan-min Ni Jian-ying Zhang Teng-da Ding R. Jan Stevenson Yin-mei Zhu 《浙江大学学报(A卷英文版)》2012,13(4):311-322
Understanding the pattern of phytoplankton and their dependence on water quality variables, can help the management of eutrophic
lakes. The aim of this study was to determine water quality and environmental factors associated with cyanobacteria dominance
and microcystin production in Qingshan Lake, a subtropical lake located in the headwater of the Taihu watershed, China. Water
samples collected monthly from 10 study sites in Qingshan Lake were analyzed for the species distributions of freshwater algae
and physico-chemical parameters including total nitrogen (TN), ammonia (NH4
+-N), nitrate (NO3
−-N), total phosphorus (TP), and chlorophyll a (Chl-a) from June, 2008 to May, 2009. Qingshan Lake was found to be eutrophic,
based on the calculated trophic state index (TSI). The average TN of 4.33 mg/L during the study period exceeded the Surface
Water Quality Standards of China. TP was significantly correlated with relative abundance of cyanobacteria and Microcystis biovolume, indicating its important role in regulating cyanobacteria. Microcystis, Anabaena, and Oscillatoria were dominant cyanobacteria in Qingshan Lake from June to November, 2008. Cyanobacteria dominance was regulated by water
temperature and TP. Principal component analysis further indicated that microcystin production was most affected by water
temperature, TP, and cyanobacteria biomass. Results suggest that the control of TP in summer can mitigate cyanobacteria dominance
and microcystin production in Qingshan Lake, and close monitoring should be undertaken in summer. 相似文献
13.
根据2005年5月的南水北调中线水源区调查资料,对其粪大肠菌群及异养细菌的丰度和分布进行了研究,并分析了其与环境因子的相关关系。结果表明,南水北调中线水源区粪大肠菌群数量分布主要受陆源性物质的支配,呈现近岸高,库心未被检出的特征;而异养细菌分布特征为近岸比库心较多。粪大肠杆菌和异养细菌的分布与NH3-N、TN、Chla呈正相关,与TP、COD、T和pH关联性不明显,与BOD、SD呈负相关关系。 相似文献
14.
探索了新型吸附材料交联羧甲基葡甘聚糖（CCMKGM）微球的制备条件,研究了交联羧甲基葡甘聚糖微球材料对Sc^3＋的吸附特性,分别考察了时间、pH、温度、Sc^3＋的浓度对微球材料吸附Sc^3＋的影响;同时测定了微球材料的洗脱与再生性能.结果表明：pH和温度对交联羧甲基葡甘聚糖微球吸附Sc^3＋有明显的影响,Sc^3＋的平衡吸附量随pH和温度的升高而升高.在50℃下,HAc-NaAc介质中,Sc^3＋质量浓度为400mg/L,pH为6.40时,吸附容量达到92.9mg/g,CCMKGM对Sc^3＋的吸附在9h左右基本达到平衡.再生CCMKGM效果与原CCMKGM基本一致。 相似文献
15.
采用二次回归正交旋转组合设计方法对大豆渣吸附Cu^2＋的五个因素进行优化,建立了浓度（X1）、加入量（X2）、pH（X3）、温度（X4）、时间（X5）对吸附率（Y）的回归数学模型：Y=73．58219＋5．50153X1＋4．61857X2＋19．47253X3＋5．84406X4＋3．62286X5—4．77678X1^2-2．69559X2^2-6．6478X3^2＋2．78751X4^2-4．53383X5^2＋0．14936X1X3—0．37914X1X4—0．12638X1X5＋0．26425X2X3＋1．02252X2X4—0．56296X2X5—3．55009X3X4—0．3102X3X,-0．33318X4X5。得出各因素对大豆渣吸附Cu^2＋影响顺序为：pH〉温度〉浓度〉加入量〉时间。从模型可知,在浓度、加入量,pH、温度、时间为40mg／L、0．1g、8、60℃、4h时,大豆渣对Cu^2＋吸附率最高可达98．82％,验证值为97．98％,与理论值基本一致。 相似文献
16.
Interaction Between DEHP and Particulate in a Eutrophic Lake 总被引：2，自引：0，他引：2
Characteristics of interaction between di-2-ethylhexyl phthalate(DEHP) and particulate in a eutrophic lake were studied in this paper. DEHP concentrations ranged from 89.9 to 247 μg/L with an average value of 146 μg/L in subsurface water (SSW) samples, and from 82.0 to 390 μg/L with an average value of 211 μg/L in water surface microlayer (SM) samples. The results indicate that there was only a weak correlation between the DEHP concentrations and suspended particulate material(SPM) concentrations in both SSW and SM,while the significant correlation between DEHP concentrations and chlorophyll a concentrations was found,which suggestes that DEHP was principally bound to phytoplankton in the eutrophic lake. Correlation between DEHP concentrations and total phosphor (TP) concentrations was also found in this investigation. Enrichment factors (EF) of DEHP in SM were in the range of 0.85 to 2.12 with an average value of 1.35..DEHP EFs were significantly related to the enrichment of chlorophyll a in SM. The results suggest that the enrichment of DEHP in SM of this eutrophic lake was mainly due to DEHP accumulation in phytoplankton and was controlled by distribution of phytoplankton between SM and SSW. 相似文献
17.
Engineeringrisk analysis is an integrated margin-al science, which has been rapidly developed in thepast two decades. It includes a series of methods toanalyze different problems induced by various uncer-tainties. Project risk assessment involves risk identifi-cation, risk estimation and risk evaluation, etc[1].Recently, researchers have been paying more andmore attention to the development of the quantitativerisk analysis methods[2], especially to the evaluationmethods of risk probability.Som… 相似文献
18.
在室温条件下,对不同浓度的食盐(NaCl)和蔗糖(C12H22O11)溶液在超声光栅中形成的光栅光谱进行测量,并运用线性回归方法详细研究了超声波声速与溶液浓度的关系。两种溶液中的测量数据显示,在溶液达到饱和前超声波声速随溶液浓度的增加单调递增,显现出良好的线性关系;达到饱和后超声波声速则为常数。线性拟合表明,两种溶液中声速相对浓度的线性关系成立的置信概率都很高。从影响超声波传播速度最主要的因素——分子或离子浓度分析解释了NaCl溶液中,线性关系更为完美、溶液浓度的改变对超声波声速的影响也更加剧烈的原因。 相似文献
19.
以硅酸钠为硅源原位生成SiO2增强橡胶 总被引：1，自引：0，他引：1
陈海燕 《泰州职业技术学院学报》2006,6(6):55-59
采用溶胶-凝胶技术，以硅酸钠为原料制得活性硅醇的THF溶液，再与天然橡胶及少量偶联剂混合，原位生成二氧化硅（SiO2）增强橡胶。论述了在酸性条件下制备特性聚硅酸的最佳反应条件，对温度，pH值及硅酸钠浓度的影响进行了研究。同时用热重分析（TG）测试材料的热性能，电子拉力机测量SiO2含量对材料的力学性能的影响。为弹性体杂化材料的制备提供了一种更具实用价值的新方法。 相似文献
20.
Allelopathic effects of submerged macrophytes against algae are affected by many environmental factors which can only be measured one by one by traditional methods. Box-Behnken design of response surface methodology was used to optimize three environmental factors(temperature, light intensity and total dissolved solids) of allelopathic effects of Potamogeton pectinatus against Microcystis aeruginosa at the same time. By solving the regression equation and analyzing the response surface contour plots, the optimal conditions of the relatively inhibitory rate of Microcystis aeruginosa were that the temperature was 23℃, the light intensity was 2,700,lx and the total dissolved solids were 4,415,mg/L. Under these conditions, the optimal value of relatively inhibitory rate of Microcystis aeruginosa was 81.9%. According to validation experiments, the results of analysis indicated that the experimental values fitted well with the predicted ones. 相似文献