改进的冗余捷联惯组故障检测与隔离主成分析法

针对冗余捷联惯组故障检测问题,提出了一种改进的主成分析(Principal Component Analysis Algorithm,PCA)算法。思路是将PCA方法和奇偶空间方法的优点结合,通过PCA方法分析影响故障的主要因素,奇偶向量运算消除载体机动影响,并对奇偶矢量进行滤波。仿真结果表明随着滤波器的作用,能够检测到的故障幅值降低,提高故障检测的灵敏度。所提出的理论及方法可行,为箭载冗余惯组故障检测与隔离提供一种理论参考。

粒子群算法与主成分析法在支持向量机回归预测中的应用研究

提出在支持向量机回归预测中采用粒子群算法优化参数和主成分析降维的方法,通过算例分析表明,此法能够显著提高预测的精度。

基于主成分分析法和熵值法结合的供应商评价研究

供应商评价是预防供应中断发生的有效措施,从供应商风险评价的角度讨论了供应中断风险管理中供应商选择的重要性,建立了供应中断风险下供应商评价的指标体系,在此基础上,结合主成分法与熵值法计算供应商的得分并进行排序,最终得到供应商的优劣等级,为供应商的选择提供理论依据。

我国上市公司MBO的绩效研究——基于主成分分析法

本文以1998年～2002年间我国上市公司中实施MBO的三十家公司为样本,选用七类十七个财务指标,采用主成分分析法,对上市公司实施MBO前后的综合绩效变化做了实证分析研究。结果表明,MBO并未从根本改善我国上市公司的整体绩效和经营成长质量。文章同时还对其成因作了定性分析,并得出在目前股权非全流通、相关措施并不完善的情况下,不鼓励上市公司实行MBO的结论。

基于主成分分析法的渠道混凝土衬砌最佳切缝时间研究

本文采用主成分分析法和线性回归方法,结合影响切缝时间的各个因素,确定最佳切缝时间的主要影响因素,得出最佳切缝时间与其主要影响因素之间的关系式为Y赞=37.887-5.270X1-5.633X2+2.821X3。

探索主成分分析法构建公立医院财务风险预警模型

目的:对公立医院财务风险预警模型中采用主成分分析法进行构建的作用及效果进行分析研究。方法:采用主成分分析法对公立医院的相关财务风险指标进行处理,并构建出财务预警的综合评价模型,通过样本医院相关数据对这一模型加以验证评价。结果:财务风险预警模型的准确度较高,存在实际应用价值。结论:以主成分分析法进行公立医院的财务风险预警模型构建,对于准确判断公立医院的财务状况,有效识别医院中潜在的财务风险有较好的帮助。

主成份分析法在食品业经营决策中的应用研究

在激烈的市场竞争中,面对众多的食品种类和众多的消费者群,食品业能否做出正确的经营决策,关键在于是否取得了真实可靠的数据并采用了科学的定量分析方法。主成份分析法在这方面应发挥其有力的作用。

基于稀疏主成分的股票指数追踪研究

本文将追踪误差定义为股票投资组合收益率与所追踪指数的基准收益率之差,分别在无交易费用和有交易费用的情况下,建立追踪误差极小化的股票指数预测模型.首先采用稀疏主成分分析法对沪深300以及香港恒生的股票进行选择,然后根据所选择的股票样本求解股票指数预测模型.数值实验表明基于稀疏主成分的股票指数追踪模型具有稀疏性、可解释性及较好的样本外追踪误差的优点.

基于AHM-CRITIC组合赋权贝叶斯的南湾水库水质评价与影响因素分析

针对传统贝叶斯模型将各评价因子“等权重”、忽略了各评价因子对水质贡献差异性的问题,在传统贝叶斯模型的基础上引入AHM-CRITIC组合赋权,构建基于AHM-CRITIC组合赋权的贝叶斯水质评价模型,并基于南湾水库2012—2020年库区断面和主要入库支流逐月水质实测数据,定量分析南湾湖水质与主要入库支流水质类别,并与其他方法进行对比分析。研究发现:①2012—2015年,南湾湖水质基本维持Ⅲ类标准,2016—2020年,偶有时段不满足Ⅲ类标准,甚至出现Ⅳ类水,董家河断面水质较差,小浉河断面、谭家河断面、五道河断面、席家河断面等水质较好;②组合赋权贝叶斯水质评价模型与单因子指数法和改进内梅罗指数法的结果更吻合,克服了主观赋权贝叶斯法的缺点。说明该模型能更真实反映南湾湖水质,可为同类水质评价提供技术依据。

一种自商图与压缩感知相结合的人脸识别算法

鉴于SRC人脸识别方法在实际运用中遇到的高维、光照变化问题,该文提出了Q_SRC解决方法,即在基于稀疏表示算法的基础上,利用自商图提取光照不变量,通过主成分析法将图像数据进行降维处理,实现了在实际环境中的人脸识别。实验结果表明,Q_SRC提高了识别率。

中国工业行业科技原创力的区域差异研究——基于31省市数据的实证分析

在经济全球化加速发展和科技创新突飞猛进的背景下,不断提升我国工业行业的科技原创力水平,是促进我国产业技术水平发展、实现产业结构升级优化与产业国际竞争力提升的必然选择。利用主成分分析法对中国工业行业科技原创力进行的区域差异分析,可以说明在我国三大区域间及三大区域内部各省区间,均存在较为明显的工业行业科技原创力发展水平差异。通过构建包含"创新主体—创新行为—创新环境"三要素在内的分析框架,则可以进一步说明其产生原因。

投资者情绪对股价崩盘的影响——分析师的中介效应

本文选取2008-2016年沪深两市A股的公司样本,通过投资者情绪指数的构建证实了投资者情绪和股价崩盘风险的正相关关系,即越高涨的投资者情绪越容易引发下一期股价崩盘。进一步地,从不同产权性质出发,我们发现相对于国有上市公司,投资者情绪与股价崩盘风险的正相关关系在非国有企业中更显著。此外,研究表明证券分析师在投资者情绪对上市公司未来股价崩盘风险的影响中起到了中介作用。上述研究对于监管部门防范股价崩盘风险和营造良好市场氛围都具有重要的现实意义。

基于注意力机制的Bi-LSTM风机叶片结冰故障检测

采用一种基于注意力机制的双向长短时记忆网络的深度学习结冰检测模型,引入欠采样和主成分析法方法对数据进行数据平衡以及降维处理,同时解决数据不平衡和数据冗余等造成的模型泛化能力差和检测精度低的问题。该模型在数据采集与监视控制系统的风场数据集上进行验证,其相关评价指标性能都有所提升,验证结果表明模型能有效检测风机叶片的结冰故障,对于风机的维护具有重要的参考意义。

基于混合型专家系统的资信评估系统模型设计与实现

文章探讨将人工神经网络与专家系统结合应用于商业银行企业信用评估 ,并以一个混合型专家系统ECAMES(EnterpriseCreditAssessmentMixedExpertSystem)为例 ,阐述了混合型专家系统模型的设计与实现。

Spatial and Temporal Differences of Urban Land Comprehensive Carrying Capacity in Guangxi

The comprehensive carrying capacity of urban land can reflect the re- source level, economic scale, social development and environmental pressure of ur- ban land carrying. The assessment indicator system of urban land comprehensive carrying capacity was constructed from the 4 aspects of resource, economy, society, environment, and principal component analysis and cluster analysis were used to evaluate the urban land comprehensive carrying capacity of Guangxi and the 14 cities in 2005-2014, and analyzed its spatial and temporal characteristics as well as the driving forces, with the aim to provide references for improving the urban land comprehensive carrying capacity. The results showed that, the overall urban land comprehensive carrying capacity in Guangxi increased in 2005-2014, and there were significant differences in the land comprehensive carrying capacities among the cities in Guangxi in 2005-2014, in which Liuzhou, Guilin, Nanning belonged to the regions with the highest carrying capacity, while Beihai, Yulin, Wutong belonged to the regions with high carrying capacity, and the carrying capacities of the other cities changed with the changes of time. The economic development degree was an important factor influencing urban land comprehensive carrying capacity, but could not directly represent the urban land comprehensive carrying capacity level.

Adaptive partitioning PCA model for improving fault detection and isolation

In chemical process, a large number of measured and manipulated variables are highly correlated. Principal component analysis(PCA) is widely applied as a dimension reduction technique for capturing strong correlation underlying in the process measurements. However, it is difficult for PCA based fault detection results to be interpreted physically and to provide support for isolation. Some approaches incorporating process knowledge are developed, but the information is always shortage and deficient in practice. Therefore, this work proposes an adaptive partitioning PCA algorithm entirely based on operation data. The process feature space is partitioned into several sub-feature spaces. Constructed sub-block models can not only reflect the local behavior of process change, namely to grasp the intrinsic local information underlying the process changes, but also improve the fault detection and isolation through the combination of local fault detection results and reduction of smearing effect.The method is demonstrated in TE process, and the results show that the new method is much better in fault detection and isolation compared to conventional PCA method.

Seasonal variation in fatty acid composition of seston and the copepod Calanus sinicus(Brodsky,1962)in Jiaozhou Bay and its trophic implications

The fatty acid compositions of seston and Calanus sinicus were investigated to study trophic relationships in Jiaozhou Bay. Principal component analysis was carried out to ordinate the fatty acid patterns of seston in stations and months. The results showed that diatoms were most abundant in the phytoplankton at station A5 （located in the northwest of the bay： 36~9＇N, 120~20＇E） and least abundant at station D7 （located outside of the bay： 35~59＇N, 120~26＇E）. By contrast, dinoflagellates were most abundant at station D7 and least abundant at station A5. According to the annual variations of 16：1 （o7 and 18：4（o3/ 16：1（o7, diatoms flourished mainly in spring and summer, while dinoflagellates bloomed exclusively in summer. A distinctive feature of the fatty acid composition of C. sinicus was the prevalence of 20：5o3 and 22：6（o3. The higher content of 16：1（o7 over 18：4（o3 in females indicated that diatoms contributed more than dinoflagellates to the diet of C. sinicus. The feeding intensity of C. sinicus on diatoms was higher in spring and autumn than in other seasons. The herbivorous indicators 20：1 and 22：1 were comparatively low, suggesting that besides phytoplankton, C. sinicus might feed on a wider range of particles including organic detritus, bacteria and small copepods.

Epiphytic orchids and their ecological niche under anthropogenic influence in central Himalayas,Nepal

The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） What is the ecological niche of the different epiphytic orchid species？ （2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.

Tolerance to Iron-Deficiency Stress of Three Apple Rootstock Species in Hydroponic System

[Objective] Iron deficiency is one of the most important crop element deficiencies in the Loess Plateau of northwestern China. The selection for crop cultivars that are tolerant to low iron levels could be one of the approaches to solving the problem and improving crop production. [Method] Three major apple root stock species （Malus prunifolia, Malus sieversii and Malus baccata） were selected to evaluate their tolerance to iron defciency in hydroponic system. A 3×2 factorial pot experiment was conducted with three replicates in a greenhouse at Gansu Agricultural University, Lanzhou, China. [Result] The SOD, POD and CAT activities in roots and stems of the 3 root stock species in Fe-defcient Hoagland solution decreased, however Malus sieversii got the less reduction and had better root architecture and growth than the other species. The aboveground biomass, plant height, chlorophyll content, total root length and lateral root number were correlated positively with iron-defciency stress tolerance. The species’ tolerance to iron-defciency from high to low was M. sieversii’s〉M. baccata’s〉M. prunifolia’s. Moreover, the improvement of some morphological features such as root length, above-ground biomass, plant height and lateral root number in apple could be conducive to breeding cultivars with tolerance to iron-defciency stress. [Conclusion] Malus sieversii had better tolerance to iron-defciency stress than the others in this study.

Comprehensive Evaluation on Urban Sustainable Development of Harbin City in Northeast China

It is an effective way in realizing urban coordinated and sustainable development to establish a series of in- dicators and to evaluate urban environmental and socioeconomic development. According to the characteristics of Harbin City in Northeast China, an indicator system including five subsystems and 37 indicators was established for comprehensive evaluation on urban sustainable development. The development indexes of all urban subsystems and complex system were calculated quantitatively using the comprehensively integrated methods composed of Principle Component Analysis, Analytic Hierarchy Process and weighed index method, and then the comprehensive level of ur- ban sustainable development and the degree of urban interior coordination were analyzed. The results indicated that 1) the overall urban development presented an uptrend, however, the interior development was not well balanced from 1996 to 2006; 2) the development in each subsystem presented a strong fluctuation; and 3) the development in re- sources subsystem showed a downtrend. Based on those results, the suggestions of urban sustainable development were put forward at the end.