连栽桉树人工林土壤理化性质的主分量分析

利用主分量分析法对连栽桉树人工林土壤的理化性质进行分析,确定了影响连栽桉树人工林土壤肥力的主分量因子,并通过连栽桉树人工林主分量因子对不同代次的桉树人工林土壤肥力变化进行了分析。结果表明,各代次桉树人工林0—20cm和20—40cm的土壤主分量影响因子基本相同,由土壤的物理性质和N,P,K这3大营养元素构成的第一主分量是影响桉树人工林土壤综合肥力的最主要影响因子;桉树人工林在经过3代连栽后,林地土壤的综合肥力较第1、第2代桉树人工林土壤的综合肥力明显下降。研究结果表明,保持连栽桉树人工林地良好的土壤通气透水性和提高土壤N,P,K养分含量对保持桉树人工林的可持续发展具有重要的意义。     

基于主成分-聚类分析的崩岗侵蚀强度评价

为了研究湖北省通城县杨垄小流域崩岗群的崩岗侵蚀强度,提高评估的可靠性,使用RTK测量崩岗,获取崩岗面积、主沟坡降、内部平均坡度等11个参数,将其作为崩岗侵蚀强度分析的评价因子,通过主成分分析提取了崩岗侵蚀强度参数的4个主成分因子,得出选择的16个崩岗侵蚀强度。结果表明:杨垄小流域不同崩岗侵蚀强度分为3类:2号,5号,10号,11号为高度侵蚀;8号,15号,16号为中度侵蚀;其余为轻度侵蚀;小流域的中高度侵蚀型崩岗面积占崩岗群总面积的2/3以上,侵蚀面积较大。依据分类结果,可针对不同崩岗存在的风险因素制定对应的风险控制方案和措施,有利于崩岗的防治。     

基于主成分分析的哈尔滨市土地生态安全评价

土地生态安全关系到一个区域整体生态环境的可持续发展。按照哈尔滨市土地资源现状,从自然、经济、社会三个方面选取与土地生态安全关系密切的21个指标,构建评价指标体系。运用主成分分析方法,对2001—2008年哈尔滨市土地生态安全状况进行分析,最后设定安全阈值,并进行初步探讨。结果表明:2001—2008年哈尔滨市土地生态安全状况呈波动变化的递减发展趋势,但总体处于较安全水平。具体来说哈尔滨市土地生态安全变化水平可分为几个变化阶段,2002年前处于较安全水平;2003年处于生态安全拐点,随后至2007年安全水平不断下降,期间虽2005年有小幅上升,但变化总趋势递减,直至2008年稍有好转处于较安全水平。土地生态安全处于连续波动状态,近些年有不安全趋势。     

基于主成分分析的蓝莓果实质地品质评价

为完善蓝莓果实质地品质评价体系,应用物性分析仪整果穿刺和质地多面分析法对22个蓝莓品种的果实质地品质进行测定,分析各质地参数间的相关性,并采用主成分分析法建立蓝莓果实质地品质优劣评价模型,对22个蓝莓品种的果实质地品质进行综合评价。结果表明,代表蓝莓果实质地品质的10个质地参数均存在品种间差异,其中品种间果皮破裂距离、果皮脆性、果皮韧性、果实硬度、粘附性、咀嚼性和回复性差异较大,果皮强度、弹性和内聚性差异较小。蓝莓果皮破裂距离与果皮强度、果皮韧性呈极显著正相关,果皮脆性与果皮韧性、果皮破裂距离呈极显著负相关,果实硬度与果实弹性呈显著负相关,咀嚼性与果实硬度、粘附性、弹性呈显著正相关,回复性与内聚性呈极显著正相关。采用主成分分析法建立了蓝莓果实质地品质综合评价指数模型,筛选出综合评价蓝莓果实质地品质的核心指标:果实硬度、果皮脆性和果实回复性。果实质地品质优良的参评蓝莓品种依次为大粒蓝金、克瑞顿、布莱登、陶柔、夏普蓝、莱格西、奥尼尔、泽西、米德、双迪。本研究结果为高品质蓝莓品种选育和良种采后储运、加工及销售提供了重要参考。     

基于主分量的神经网络气温预报模型

根据山西省6个有代表性的气象观测站1951-2000年的气象资料,以降水量、气温为预报因子,以太原市最冷月平均气温为预报量,采用人工神经网络与主分量分析相结合的方法,建立了太原最冷月平均气温预报模型。该模型对1960-1990年的历史样本拟合的平均相对误差为3.6%,对1991-2000年独立样本的预报准确率达90%,说明该模型可使预报泛化能力显著提高,对农业防灾减灾有较大作用。     

宁夏引黄灌区农村信息化主成分分析

对宁夏扬黄灌区2007年农村传统信息化与其他影响因子之间利用主成分法进行分析,得出以下结论：影响宁夏灌区传统农村信息化有4个主成分,分别为及时信息因子、网络信息因子、通讯信息因子和人际交往因子。各主成分方差贡献率分别为33．4216％、31．6659％、16．5499％和7．6844％,累积贡献率达89．3281％,代表了农村信息化指标89．3281％的信息。     

北方粳稻耐盐碱相关性状主成分分析及综合评价

为建立北方粳稻耐盐碱综合评价指标体系,筛选适宜苏打盐碱地种植的水稻种质资源,本研究采用混合盐碱胁迫处理,测定了50份北方粳稻材料的28项表型指标,以各单项指标耐盐碱系数作为评价水稻耐盐碱性依据,利用相关分析、主成分分析及聚类分析方法综合评价其耐盐碱相关性。结果表明,利用主成分分析将盐碱胁迫下28个单项指标转化为8个相互独立的综合指标,累积贡献率达80.665%。依据参试材料耐盐碱综合评价值进行聚类分析,将50个参试材料划分强耐盐碱型、耐盐碱型、中间型和盐碱敏感型四类。强耐盐碱类型包括松98-131、SR-824-14、长白9号3个材料,D值分别为0.68、0.63、0.61。回归分析和相关分析表明,结实率、产量、生物量、经济系数、根直径、分蘖期叶面积和齐穗期干物重对耐盐碱性影响显著,可作为水稻耐盐碱鉴定的综合指标。本研究结果为水稻耐盐碱育种提供了技术和种质资源支撑。     

基于主成分分析和RBF神经网络的水电工程造价估算研究

建立了基于主成分分析和RBF神经网络的水电工程造价估算模型,并运用MTLAB语言程序将其实现。实例表明,该方法可以使工程项目初期造价估算更合理、准确,给企业和决策者提供一种智能的估价方法。     

Analysis of Phosphate Rock Dissolution Determining Factors Using Principal Component Analysis in Some Acid Indonesian Soils

Abstract

Dissolution of phosphate rock (PR) materials and its subsequent phosphorus (P) availability to plants depend upon soil characteristics, PR characteristics, type of crops, and environmental conditions. Agronomic effectiveness of the PR sources has frequently been investigated in the field or in the greenhouse. This is time consuming and not cost‐effective. Therefore, identification of the soil characteristics influencing the dissolution of PR is very important for direct application of P sources. The principal component analysis was used to summarize the characteristics of acid soils in an incubation system into a number of factors that may affect PR dissolution. Three major factors were selected in this study: 1) soil texture, 2) soil acidity, and 3) fertilization. Using the scores of the individual factors as independent variables, a stepwise regression analysis was performed to derive a PR dissolution function. The coefficient of determination (R²) reached 0.91**, and the magnitude of the different factors affect PR dissolution following the order of soil texture (54%)>soil acidity (43%)>fertilizer (3%). Fertilizer was not significant as a PR dissolution factor.     

主成分分析在河流水质综合评价中的应用

采用主成分分析法（PCA）,对大沽夹河流域水质进行了定量化综合评价。结果表明:流域水质具有明显的区域差异,在14个典型监测断面中,福山水闸下和新夹河桥2个监测断面水质污染较为严重,宫家岛等4个断面水质较好,其余断面水质良好。就全流域而言,水质污染程度不是很严重,基本满足功能区的要求。     

不同生长阶段墨瑞鳕脂肪酸组成及主成分分析

为比较不同生长阶段墨瑞鳕肌肉中脂肪酸组成的变化,本研究通过气相色谱技术测定墨瑞鳕幼鱼、成鱼、亲鱼肌肉中脂肪酸含量,并对脂肪酸组成进行主成分分析。结果表明,3个不同生长阶段墨瑞鳕的不饱和脂肪酸(UFA)总量分别为52.2%、58.2%、60.1%;在高度不饱和脂肪酸(HUFA)中DHA含量均最高。随着鱼体生长,墨瑞鳕棕榈油酸、油酸、亚油酸、亚麻酸含量均呈上升趋势,从高到低依次为亲鱼>成鱼>幼鱼;肉豆蔻酸、花生一烯酸、花生四烯酸、EPA、DHA含量呈下降趋势,从高到低依次为幼鱼>成鱼>亲鱼;UFA总量和单不饱和脂肪酸(MUFA)含量呈上升趋势,从高到低依次为亲鱼>成鱼>幼鱼;多不饱和脂肪酸(PUFA)总量和必需脂肪酸(EFA)总量含量呈先升后降趋势,从高到低依次为成鱼>亲鱼>幼鱼。墨瑞鳕不同生长阶段脂肪酸含量大部分存在显著差异,特别是幼鱼与成鱼的脂肪酸含量(除二十碳三烯酸外)均存在显著差异;肉豆蔻酸、花生一烯酸、花生四烯酸、EPA和DHA等5种脂肪酸是墨瑞鳕的主要特征脂肪酸,这5种主要特征脂肪酸之间均互呈强正相关。随着墨瑞鳕的生长发育应及时提...     

基于主成分分析法的枫香耐铅性及土壤修复潜力研究

探究枫香(Liquidambarformosana Hance)对铅污染土壤的修复作用,为缓解土壤铅危害和枫香在重金属污染地推广种植提供科学参考,以1年生枫香幼苗为试材,设置6个Pb2+浓度(分别为0,100,300,500,800,1000 mg/kg)对各Pb2+浓度环境下枫香幼苗的生理特性和积累特性进行研究,并采...     

Combined Use of Principal Component Analysis (PCA) and Chemical Mass Balance (CMB) for Source Identification and Source Apportionment in Air Pollution Modeling Studies

Chemical mass balance (CMB) and principal component analysis (PCA) are used together for source identification and source apportionment in this air pollution modeling study. Source profile sets, each of which contains five source profiles based on ten pollutant species, were generated using a computer program. Another algorithm was implemented to produce ten random data sets, which was composed of 100 simulated measurement results for all of ten pollutant species. Ten source profile sets were selected. Five of them contained sources of dissimilar characteristics, whereas the other five were chosen from those of similar emission profiles. Ten simulated data sets for each source profile set were used in the analyses. PCA was applied to all simulated data sets; a number of principal factors were extracted and interpreted. The identified sources for each data set were used in fitting with CMB analyses, and source contributions were estimated. The performance of PCA–CMB combination was evaluated in the aspect of percent variance explained, percent apportionment, R ², and χ ². PCA was able to explain 89.6% to 100% of the variance within the data sets used. Two to five sources were extracted depending on the characteristics of source profile sets used. CMB was found to be successful in the aspect of percent apportionment since 95.4% to 100% of mass concentrations were apportioned. The values of R ² and χ ² were found out to range from 0.981 to 1.000 and from 0.000 to 29.947, respectively. Evaluating overall results from the analyses, PCA–CMB combination produced satisfactory results in the aspect of source identification and source apportionment.     

基于主成分分析法的红枣1年生枝条抗寒性研究

以6个红枣品种临泽小枣、俊优2号、脆枣、骏枣、爆米花和子弹头的1年生枝条为试材,测定相对电导率、可溶性糖、可溶性蛋白、丙二醛、游离脯氨酸含量等指标,研究其在低温处理下的生理变化特征,并用主成分分析法对其抗寒性进行综合评价.结果表明,6个品种枣树的半致死温度值(LT50)为-23.73～-16.06℃,俊优2号的最低、子...     

Starch Pasting and Textural Attributes of Elbow Macaroni as Impacted by Dough Moisture,Dough Mixing Time,and Macaroni Cooking Time

The effects of dough moisture, mixing time, and cooking time on uncooked and cooked elbow macaroni by means of starch pasting and macaroni textural characteristics were investigated. In conventional elbow macaroni production, cooking time was found to have significant contributions to cooked macaroni starch pasting properties, indicating that degree of starch cook dependent on cooking time was the main influence on cooked macaroni starch pasting phenomena. Dough moisture also showed some significant (P < 0.05) relationships with cooked macaroni starch pasting properties; however, mixing time did not show significant effect. Cooked macaroni starch pasting properties showed significantly (P < 0.05) high correlations with cooked macaroni firmness and stickiness. Cooking time was the only major variable contributing to variations in cooked elbow macaroni starch and consequently in pasting and texture characteristics. Cooking time was highly related to firmness and stickiness of cooked elbow macaroni (P < 0.0001, R² = 0.8148; P < 0.0001, R² = 0.6215, respectively). In addition, dough moisture had a slight significant (P < 0.05) effect on cooked elbow macaroni firmness and stickiness. Cooked elbow macaroni firmness and stickiness were found to be highly correlated (P = 0.0001, R² = 0.8459). Increases in firmness increased cooked elbow macaroni stickiness. As a result, when elbow macaroni was cooked for shorter times, firmer and stickier macaroni was obtained.     

基于主成分分析法的煤矸石山植被水土保持功能评价

运用主成分分析方法对抚顺西排土场植被水土保持功能进行评价,遴选植被冠层截留量、植被冠层高度,乔灌郁闭度、基部盖度、枯枝落叶层截留量、枯枝落叶层厚度和有效根密度7个指标建立评价体系.选取5种植被为研究对象,选择栽植后恢复3 a和恢复5 a的植被分别进行研究.对各植被水土保持功能指标进行计算和比较,运用SPSS 13.0统计软件得出各植被水土保持功能的综合值.结果为恢复3 a的植被水土保持功能排序为沙棘、紫穗槐、刺槐、小叶杨、油松;恢复5 a的植被水土保持功能排名为刺槐、沙棘、紫穗槐、小叶杨、油松.研究表明:灌木在植被恢复早期所具有的水土保持功能较好.随着恢复时间的增加,阔叶乔木的水土保持功能逐渐增强.建议煤矸石山生态修复中采取阔叶乔木和灌木混交的模式.