基于多变量校正的MMC快速有限集模型预测控制策略

有限集模型预测控制方法(finite control set model predictive control,FCS-MPC)因其能够实现多目标的控制,在模块化多电平变换器(modular multilevel converter,MMC)中得到广泛应用。随着子模块数量增加,模型预测控制方法计算量呈指数增长,面临计算复杂度高、权重因子难以整定等问题。为了解决上述问题,提出了一种基于多变量校正控制集的MMC模型预测控制策略(multi-variate adjusting set predictive control,MAS-MPC)。该策略基于输出电流与桥臂电压差对子模块投入控制集进行快速校正,通过评估两个成本函数得到最优开关矢量。此外,提出了一种基于分化中项的电容电压平衡方案,可以有效降低排序算法的复杂度。为了验证所提策略的有效性,使用Matlab/Simulink软件平台搭建了10电平的三相MMC系统,并与传统方案进行比较。所提方案在降低输出电流与环流的谐波含量的同时,大幅减少了系统的计算量,使得系统具有更快速的动态响应速度。

近红外光谱法结合多变量校正技术快速分析酒中乙醇含量

提出了将近红外光谱法同多变量校正技术相结合、快速非破坏分析酒中乙醇含量的方法.研究了系列乙醇水溶液的吸收光谱、导数光谱的光谱特征,比较了多元线性回归和主成分回归处理光谱数据的准确程度.

化学计量学中几种常用多变量校正法的应用

作为化学量测的基础理论和方法学，化学计量学的应用非常广泛。尤其在分析检测多组分体系中具有快速、准确、简便的特点。根据近年来的相关文献，LS、PLS、KF及TFA等几种常用的多变量校正法在分析化学等领域具有极其广泛的应用。

航空发动机多变量自校正控制研究

针对航空发动机这一具有耦合和强非线性被控对象,采用基于带遗忘因子的最小二乘参数估计算法的最小方差多变量自校正控制,通过分析保证了闭环系统的可辨识性。仿真结果表明,控制器响应速度快,跟踪精度高,抗干扰和耦合能力强,估计参数能以较快的速度收敛。

多变量自校正前馈PID控制器及其在协调控制中的应用

本文提出一种多变量自校正前馈PID控制器,它不仅可以消除可测外扰的影响,而且可以应用于多变量系统实现解耦控制。电站负荷控制系统的数字仿真表明,该控制器具有良好的控制效果,使负荷控制和汽压控制系统间耦合大大减小。

WCDMA无线传播模型校正

WCDMA采用的是2GHz的频段,与目前GSM采用的900MHz的频段相距甚远,信号的传播方式有了很大的不同。因此,在WCDMA的网络规划中,对无线电波的传播方式重新建模是其规划的基础。传播模型的准确对小区合理规划十分重要。本文利用CW测试获得的数据对我国某市所选的标准传播模型进行了实例校正并介绍了单变量校正法和多变量校正法。

核偏最小二乘特征提取在混合气体FTIR光谱定量分析中的应用

为进一步提高FTIR光谱法实现特征吸收光谱严重重叠的甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷以及正戊烷七组分混合气体定量分析的精度和速度,提出一种核偏最小二乘(Kernel Partial Least Square,KPLS)特征提取耦合支持向量回归机(Support Vector Regression Machine,SVR)的红外光谱定量分析新方法.首先采用KPLS方法对上述七组分混合气体的FTIR光谱进行特征提取,然后将特征提取得到的特征组分作为SVR的输入建立混合气体的定量分析模型.对标准混合气体进行定量分析的结果显示:KPLS-SVR模型的预测精度高于未进行特征提取SVR模型预测的精度,同时预测时间也减少了一半.研究表明,KPLS法可以很好地提取隐含在混合气体FTIR光谱数据与其组分浓度之间的非线性特征并有效地消除光谱数据噪声,大幅度降低数据维数,与SVR耦合可以提高红外光谱分析的精度和速度,是一种有效的红外光谱定量分析方法.

连续小波变换-支持向量回归-紫外分光光度法测定多组分B族维生素含量

提出了连续小波变换-支持向量回归-紫外分光光度法(CWT-SVR-UV)多组分B族维生素含量测定方法.通过对维生素B混合样品测定光谱进行CWT处理,能够扣除光谱背景信号,降低光谱重叠与共线性的影响.将CWT-SVR-UV法用于维生素B1、维生素B2、维生素B3及维生素B6混合组分的同时测定,测定结果相对标准偏差分别为0.9%、1.8%、1.7%和0.5%.与基于原始光谱数据的SVR和偏最小二乘(PLS)建模方法相比较,本文提出的建模测定方法具有更好的预测准确度.

本征拉曼光谱血液分析技术研究

本文介绍了一种基于拉曼光谱分析与漫反射光谱光度测试相结合的本征拉曼光谱光度测试验血分析技术,这是一种快速的,经皮肤的非入侵式验血技术,在血糖监测等重症护理,现场快速验血等领域有着广阔的应用前景。

多组分烷烃混合气体FTIR光谱定量分析新方法

提出一种核偏最小二乘(KPLS)特征提取耦合支持向量回归机(SVR)的新方法,用于实现气测录井中傅立叶变换红外(FTIR)光谱法对甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷以及正戊烷7种组分混合气体的定量分析。采用KPLS方法对光谱数据进行特征提取,将得到的特征组分作为SVR的输入建立7组分气体的定量分析模型。对相同混合气体进行定量分析,结果显示,采用KPLS特征提取后,SVR模型对7种组分气体的预测均方根误差(RMSEP)分别为0.116、0.079、0.104、0.092、0.108、0.029和0.016,均小于线性偏最小二乘法(LPLS)、LPLS-SVR、KPLSR以及SVR模型的RMSEP。结果表明,KPLS-SVR法可以更好地提取隐含在混合气体FTIR光谱数据与其组分浓度之间的非线性特征,并有效地消除光谱数据噪声,大幅度降低数据维数,是一种有效的气测录井烷烃混合气体定量分析方法。

主成分回归滴定分析糖蜜中多组分有机酸

针对计算滴定分析问题,在滴定体系中以pH2.0为参考基准,滴定至特定pH值所消耗滴定剂增量为测量指标,构建了多组分有机酸的pH谱。以主成分回归法对含有乙酸、乳酸、草酸、琥珀酸、柠檬酸和乌头酸等6组分有机酸体系进行主成分拟合,结果表明,性质相似的柠檬酸和乌头酸的拟合预测能力较差,但其总量可得到较好的预测结果。方法对以上6种有机酸及柠檬酸和乌头酸总量的相对预测均方根误差分别为5.80%、8.88%、7.40%、5.55%、12.32%、15.25%和3.16%。应用该法对2种糖蜜中有机酸进行了分析并与离子色谱分析结果作了对照。

AMD进展与C反应蛋白、白介素6及其他心血管生物标记间的前瞻性研究

Background: Age-related macular degeneration (AMD) and cardiovascular disease share common risk factors. Inflammatory biomarkers, including C-reactive protein (CRP),interleukin 6 (IL- 6), soluble tumor necrosis factor alpha receptor 2, soluble intercellular and vascular adhesion molecules (intercellular adhesion molecule 1 and vascular cell adhesion molecule 1), and lipid biomarkers, including lipoprotein(a) and apolipoprotein B, have all been associated with cardiovascular disease. We previously found an association betweenAMD and CRP in a cross-sectional analysis, but the prospective relationships between AMD, CRP, and the other cardiovascular disease markers are unknown. Objective: To test the hypothesis that baseline cardiovascular disease biomarkers are associated with subsequent increased risk for progression ofAMD.Design, Setting, and Participants: This prospective cohort study involved 251 participants aged 60 years and older who had some sign of nonexudative AMD and visual acuity of 20/200 or better in at least one eye at baseline. The AMD status was assessed by standardized grading of fundus photographs, and stored fasting blood specimens obtained at baseline were analyzed for levels of the various biomarkers. The average follow-up time was 4.6 years. Main Outcome Measures: Relationship between biomarkers and incidence rates of progression of AMD. Results: Comparing the highest quartile with the lowest quartile, CRP was associated with progression of AMD, with a multivariate adjusted relative risk (RR) of 2.10 (95% confidence interval (CI), 1.06- 4.18; P for trend, .046) controlling for body mass index, smoking, and other cardiovascular variables and a multivariate adjusted RR of 2.02 (95% CI, 1.00- 4.04; P for trend, .06) controlling additionally for antioxidant nutrients. Interleukin 6 was also related to progression of AMD, with a multivariate adjusted RR of 1.81 (95% CI, 0.97- 3.36; P for trend, .03). Comparing the highest quartile with the lowest quartile, the effect estimates for vascular cell adhesion molecule 1 (multivariate adjusted RR, 1.94) and apolipo-proteinB (adjusted RR, 1.39) were in the positive direction but were not statistically significant (P for trend, .08 and .24, respectively). The CRP and IL- 6 levels were both significantly related to higher body mass index and current smoking. Conclusions: Higher levels of the systemic inflammatory markers CRP and IL- 6 are independently associated with progression of AMD.

超重和肥胖的不同指标与动脉粥样硬化患病之间的关系:Dallas心脏研究

目的:本研究拟在大规模人群队列中评估超重和肥胖的不同指标与动脉粥样硬化患病之间的关系。背景:虽然肥胖与心血管性死亡有关,但是尚不清楚这种关系是否由增加的动脉粥样硬化负荷所介导。方法:使用来自Dallas心脏研究的资料,作者评估了性别特异性的肥胖指标犤即体重指数(BMI)、腰围(WC)、腰臀比(WHR)犦与动脉粥样硬化患病之间的关系,

男子饮酒与缺血性卒中的风险:饮酒方式与普通饮料的作用

Brookline Ave nue, Boston, MA 02215, United States] Background: The association of light to moderate alcohol consumption with ris k for ischemic stroke remains controversial, as do the roles of beverage type an d drinking pattern. Objective: To assess the association of drinking patterns an d beverage type with risk for ischemic stroke among men. Design: Prospective coh ort study. Setting: United States. Participants: 38156 male health professionals who were free of known cardiovascular disease or cancer at baseline in 1986. Me asurements: With a semi quantitative food frequency questionnaire, the autho rs individually ascertained consumption of regular and light beer, red and white wine, and liquor every 4 years. Alcohol consumption was categorized as light (0 .1 to 9.9 g/d, or < 1 drink daily), moderate (10.0 to 29.9 g/d, or 1 to 2 drinks daily), and heavier (≥ 30.0 g/d, or ≥ 3 drinks daily). Results: During a foll ow up period of 14 years, 412 cases of incident ischemic stroke were documente d. Compared with abstainers, light drinkers had a multivariate adjusted relati ve risk of 0.99 (95% CI, 0.72 to 1.37), moderate drinkers had a multivariate adjusted relative risk of 1.26 (CI, 0.90 to 1.76), and heavier drinkers had a m ultivariate adjusted relative risk of 1.42 (CI, 0.97 to 2.09; P =0.01 for tren d). Consumption of 10.0 to 29.9 g of alcohol per day on 3 to 4 days per week app eared to be associated with the lowest risk (relative risk, 0.68 [CI, 0.44 to 1. 05]). Red wine consumption was inversely associated with risk in a graded manner (P = 0.02 for trend), but other beverages were not. The apparently higher risk for ischemic stroke with heavier alcohol use appeared to be most pronounced for the embolic subtype. Limitations: This study had limited power to examine specif ic drinking patterns and heavy drinking and could not assess risk for hemorrhagi c stroke. Conclusions: In this sample of male health professionals, light and mo derate average alcohol use was generally not associated with an increased risk f or ischemic stroke, although drinking pattern and beverage type modified this re lation. Intake of more than 2 drinks per day may be associated with a higher ris k for ischemic stroke.

ESC2016:贫血是ST段抬高型心肌梗死患者不良预后的标志

2016年8月27—31日,欧洲心脏病学会年会(ESC2016)将在意大利罗马盛大召开。来自葡萄牙Garcia de Orta医院的Caldeira博士在本次会上发表了有关贫血对ST段抬高型心肌梗死患者预后影响的研究,研究指出,贫血是ST段抬高型心肌梗死患者不良预后的标志。该研究纳入3339名行直接经皮冠状动脉介入治疗(PCI)的ST段抬高型心肌梗死患者,贫血定义为男性血红蛋白<13g/dl,女性<12g/dl,并将血红蛋白10g/dl作为轻度及中重度划分界限。研究终点为院内病死率、严重出血和心血管再入院率。

确定性多变量自校正控制的稳定性、收敛性和鲁棒性

本文用基于传递函数概念的虚拟等价系统方法统一分析各种类型的多变量确定性自校正控制系统的稳定性、收敛性和鲁棒性,分别针对参数估计收敛到真值、参数估计收敛到非真值以及参数估计不收敛的3种情况给出若干定理、推论和注释.在各个判据的基础上,进一步深化对确定性多变量自校正控制系统的理解.所得结论说明:参数估计的收敛性不是确定性多变量自校正控制系统稳定和收敛的必要条件;系统自身的反馈信息对确定性多变量自校正控制是充分的,即外加激励信号不是必要的.

女性中等量酒精摄入对认知功能的影响

BACKGROUND: The adverse effects of excess alcohol intake on cognitive function are well established, but the effect of moderate consumption is uncertain. METHODS: Between 1995 and 2001, we evaluated cognitive function in 12,480 participants in the Nurses’ Health Study who were 70 to 81 years old, with follow- up assessments in 11,102 two years later. The level of alcohol consumption was ascertained regularly beginning in 1980. We calculated multivariate- adjusted mean cognitive scores and multivariate- adjusted risks of cognitive impairment (defined as the lowest 10 percent of the scores) and a substantial decline in cognitive function over time (defined as a change that was in the worst 10 percent of the distribution of the decline). We also stratified analyses according to the apolipoprotein E genotype in a subgroup of women. RESULTS: After multivariate adjustment, moderate drinkers (those who consumed less than 15.0 g of alcohol per day [about one drink]) had better mean cognitive scores than nondrinkers. Among moderate drinkers, as compared with nondrinkers, the relative risk of impairment was 0.77 on our test of general cognition (95 percent confidence interval, 0.67 to 0.88) and 0.81 on the basis of a global cognitive score combining the results of all tests (95 percent confidence interval, 0.70 to 0.93). The results for cognitive decline were similar; for example, on our test of general cognition, the relative risk of a substantial decline in performance over a two- year period was 0.85 (95 percent confidence interval, 0.74 to 0.98) among moderate drinkers, as compared with nondrinkers. There were no significant associations between higher levels of drinking (15.0 to 30.0 g per day) and the risk of cognitive impairment or decline. There were no significant differences in risks according to the beverage (e.g., wine or beer) and no interaction with the apolipoprotein E genotype. CONCLUSIONS: Our data suggest that in women, up to one drink per day does not impair cognitive function and may actually decrease the risk of cognitive decline.

再灌注治疗时代入院血糖与无糖尿病的心肌梗死患者的不良结局

目的:在接受现代治疗的非糖尿病患者中,探讨入院血糖水平与血糖范围较大的急性心肌梗死后患者不良结局的相关性。

胎盘早剥的危险因素:早产胎膜早破、子宫内感染和羊水过少

OBJECTIVE: To examine whether preterm premature rupture of membranes (PROM), intrauterine infection, and oligohydramnios are risk factors for placental abruption. METHODS: Data for this retrospective cohort study were derived from the 1988 National Maternal and Infant Health Survey (N=11,777). Association between abruption and these clinical risk factors was expressed as relative risk (RR) and 95%confidence interval (CI), with multivariate adjustment for potential confounders. RESULTS: The overall incidence of abruption was 0.87%. The risk of abruption was 3.58-fold higher (95%CI 1.74-7.39)among women with preterm PROM (2.29%) compared with women with intact membranes (0.86%). The rates of abruption among women with and without intrauterine infection were 4.81%and 0.83%, respectively (RR 9.71, 95%CI 3.23-29.17). However, oligohydramnios was not associated with abruption (1.46%compared with 0.87%; RR 2.09, 95%CI 0.92-5.31). Compared with women with intact membranes, the RR for abruption among preterm PROM and whose membranes were ruptured for 24-47 hours and 48 hours or more before delivery, respectively, were 2.37 (95%CI 0.99-9.09), and 9.87 (95%CI 3.57-27.82). When preterm PROM was accompanied by intrauterine infections, the RR for abruption was 9.03 (95%CI 2.80-29.15) compared with women with intact membranes and no infections. Similarly, preterm PROM accompanied by oligohydramnios conferred over a 7.17-fold risk (95%CI 1.35-38.10) for abruption compared with women with neither of these 2 conditions. CONCLUSION: Women presenting with preterm PROM are at increased risk of developing abruption, with the risk being higher either in the presence of intrauterine infections or oligohydramnios. Physicians managing patients with preterm PROM should be aware that these patients are at increased risk of developing abruption after 24 hours following preterm PROM.