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Identifying the Impact of Preconstruction Elements on Project Time Variances
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作者 Sogol Salary Matthew Reyes 《Journal of Civil Engineering and Architecture》 2025年第1期9-21,共13页
Working toward an efficient duration and timeline for the preconstruction phase should be one of the main objectives for project owners.Failing to plan for and coordinate preconstruction decisions in order to control ... Working toward an efficient duration and timeline for the preconstruction phase should be one of the main objectives for project owners.Failing to plan for and coordinate preconstruction decisions in order to control preconstruction duration and manage time variances can lead to financial insecurities,incomplete contract documents,permitting issues,and unrealistic schedules and resource allocation during this phase.To minimize time variances and ensure a productive decision-making process,project owners should be familiar with critical elements in a project that cause variances in the preconstruction phase timeline.In this study,the impacts of eleven critical preconstruction elements on time variances were analyzed.These eleven preconstruction elements are considered critical in how they impact time variances during the preconstruction phase.They were determined to be critical based either on significantly impacting time variance during the preconstruction phase or believed to be critical from findings from previous studies,however,the findings from this study showed no significant impact on the time variances.In most previous studies focusing on the elements impacting project schedules,data were collected by surveying construction professionals.In this study,objective and quantitative data related to project preconstruction elements were used as opposed to self-reported data.Using the results of this study,project owners and stakeholders will be able to evaluate the critical preconstruction elements impacting the timing of their projects and prioritize decisions related to the critical elements early on during the preconstruction phase. 展开更多
关键词 Preconstruction time variances critical preconstruction elements objective data.
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Estimation of genetic parameters and their sampling variances for quantitative traits in the type 2 modified augmented design 被引量:1
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作者 Frank M.You Qijian Song +4 位作者 Gaofeng Jia Yanzhao Cheng Scott Duguid Helen Booker Sylvie Cloutier 《The Crop Journal》 SCIE CAS CSCD 2016年第2期107-118,共12页
The type 2 modified augmented design(MAD2) is an efficient unreplicated experimental design used for evaluating large numbers of lines in plant breeding and for assessing genetic variation in a population. Statistical... The type 2 modified augmented design(MAD2) is an efficient unreplicated experimental design used for evaluating large numbers of lines in plant breeding and for assessing genetic variation in a population. Statistical methods and data adjustment for soil heterogeneity have been previously described for this design. In the absence of replicated test genotypes in MAD2, their total variance cannot be partitioned into genetic and error components as required to estimate heritability and genetic correlation of quantitative traits, the two conventional genetic parameters used for breeding selection. We propose a method of estimating the error variance of unreplicated genotypes that uses replicated controls, and then of estimating the genetic parameters. Using the Delta method, we also derived formulas for estimating the sampling variances of the genetic parameters.Computer simulations indicated that the proposed method for estimating genetic parameters and their sampling variances was feasible and the reliability of the estimates was positively associated with the level of heritability of the trait. A case study of estimating the genetic parameters of three quantitative traits, iodine value, oil content, and linolenic acid content, in a biparental recombinant inbred line population of flax with 243 individuals, was conducted using our statistical models. A joint analysis of data over multiple years and sites was suggested for genetic parameter estimation. A pipeline module using SAS and Perl was developed to facilitate data analysis and appended to the previously developed MAD data analysis pipeline(http://probes.pw.usda.gov/bioinformatics_ tools/MADPipeline/index.html). 展开更多
关键词 Broad-sense HERITABILITY Genetic correlation Sampling variance MODIFIED AUGMENTED DESIGN
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The Environmental Impacts of Informal Economies in China: Inverted U-shaped Relationship and Regional Variances 被引量:3
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作者 YANG Jiangmin TAN Yiming +2 位作者 XUE Desheng HUANG Gengzhi XING Zuge 《Chinese Geographical Science》 SCIE CSCD 2021年第4期585-599,共15页
This paper aims to the debate on the nexus between informal economies and the environment by investigating the long-term dynamic impacts of China’s informal economies on pollution and considering regional differences... This paper aims to the debate on the nexus between informal economies and the environment by investigating the long-term dynamic impacts of China’s informal economies on pollution and considering regional differences in informal economies’ pollution.This paper uses the Multiple Indicators Multiple Causes(MIMIC) model to estimate the size of informal economies and employs econometric models to examine their relationships to pollution based on provincial-level panel data from 2000 to 2017. The results indicate that informal economies’ effects on environmental pollution are not purely positive or negative. Rather, our model indicates that there is an inverted U-shaped relationship between informal economies and pollution in the long run in China;this means that the level of environmental pollution increases at first and then decreases with the growth of informal economies. Further analysis shows that while this inverted, U-shaped relationship is significant in different regions of China, it is affected by different environmental impact factors. The paper concludes by discussing the policy implications for environmental protection and sustainable development. 展开更多
关键词 informal economy POLLUTION environmental Kuznets curve regional variances sustainable development
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Did the Revision of the Japanese Medical Payment System Work Properly?—An Analysis of Averages and Variances of Length of Hospital Stay for Type 2 Diabetes Patients by Individual Hospital 被引量:1
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作者 Kazumitsu Nawata Koichi Kawabuchi 《Health》 CAS 2016年第6期505-517,共13页
We evaluated the effects of the 2010 revision of the medical payment system on the length of stay (LOS). In this analysis, we assessed not only the average length of stay (ALOS), but also variance of LOS at individual... We evaluated the effects of the 2010 revision of the medical payment system on the length of stay (LOS). In this analysis, we assessed not only the average length of stay (ALOS), but also variance of LOS at individual hospitals. We used a dataset of 18,641 type 2 diabetes patients collected from 51 general hospitals. The variables found to affect LOS were age, comorbidities, complications, acute hospitalization, introduced by other hospitals, winter, one-week hospitalization, specific hospitalization period, and principal diseases coded E11.5, E11.6 and E11.7. Although the effect was marginal, the 2010 revision did reduce ALOS, and the reduction was larger as ALOS became longer. On the other hand, we did not find that the variance of LOS within hospitals became smaller. The results of the study suggest that new incentives and assistance to hospitals to help them make efficient use of medical information are needed. 展开更多
关键词 Type 2 Diabetes Length of Hospital Stay Analysis of variances
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Robust Variance Components Estimation in the PERG Mixed Distributions of Empirical Variances—PEROBVC Method
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作者 Perović Gligorije 《Open Journal of Statistics》 2020年第4期640-650,共11页
A mixed distribution of empirical variances, composed of two distributions the basic and contaminating ones, and referred to as PERG mixed distribution of empirical variances, is considered. In the paper a robust inve... A mixed distribution of empirical variances, composed of two distributions the basic and contaminating ones, and referred to as PERG mixed distribution of empirical variances, is considered. In the paper a robust inverse problem solution is given, namely a (new) robust method for estimation of variances of both distributions—PEROBVC Method, as well as the estimates for the numbers of observations for both distributions and, in this way also the estimate of contamination degree. 展开更多
关键词 Non-Homogeneous Sets of Empirical variances PERG Mixed Distribution of Empirical variances Robust variance Components Estimation—PEROBVC Method
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Research on a Monte Carlo global variance reduction method based on an automatic importance sampling method 被引量:1
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作者 Yi-Sheng Hao Zhen Wu +3 位作者 Shen-Shen Gao Rui Qiu Hui Zhang Jun-Li Li 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第5期200-215,共16页
Global variance reduction is a bottleneck in Monte Carlo shielding calculations.The global variance reduction problem requires that the statistical error of the entire space is uniform.This study proposed a grid-AIS m... Global variance reduction is a bottleneck in Monte Carlo shielding calculations.The global variance reduction problem requires that the statistical error of the entire space is uniform.This study proposed a grid-AIS method for the global variance reduction problem based on the AIS method,which was implemented in the Monte Carlo program MCShield.The proposed method was validated using the VENUS-Ⅲ international benchmark problem and a self-shielding calculation example.The results from the VENUS-Ⅲ benchmark problem showed that the grid-AIS method achieved a significant reduction in the variance of the statistical errors of the MESH grids,decreasing from 1.08×10^(-2) to 3.84×10^(-3),representing a 64.00% reduction.This demonstrates that the grid-AIS method is effective in addressing global issues.The results of the selfshielding calculation demonstrate that the grid-AIS method produced accurate computational results.Moreover,the grid-AIS method exhibited a computational efficiency approximately one order of magnitude higher than that of the AIS method and approximately two orders of magnitude higher than that of the conventional Monte Carlo method. 展开更多
关键词 Monte Carlo Global variance reduction Reactor shielding Automatic importance sampling
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Correction of Left Ventricular Doppler Echocardiographic Measurements for Physiological Variances Using a Novel Optimized Multivariable Allometric Model in Healthy Chinese Han Adults
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作者 Guihua Yao Xiangyun Chen +12 位作者 Wenjing Yang Qing Zhang Jing Liu Huan Liang Hui Sun Yao Xu Li Wang Jinfeng Xu Cheng Zhang Fengrong Sun Mei Zhang Xueying Zeng Yun Zhang 《Engineering》 SCIE EI CAS 2022年第9期115-122,共8页
Most left ventricular(LV)Doppler measurements vary significantly with age and gender,making it necessary to correct them for physiological variances.We aimed to verify the hypothesis that different Doppler measurement... Most left ventricular(LV)Doppler measurements vary significantly with age and gender,making it necessary to correct them for physiological variances.We aimed to verify the hypothesis that different Doppler measurements correlate nonlinearly with different biometric variables raised to different scaling factors and exponents.In this work,a total of 23 LV Doppler parameters were measured in 1224 healthy Chinese adults.An optimized multivariable allometric model(OMAM)and scaling equations were developed in 70%of the subjects(group A),and the reliability of the model and equations was verified using the remaining 30%of the subjects(group B)as well as 183 overweight subjects(group C).The single-variable isometric model(SVIM)with body surface area(BSA)as a scaling variable was used for comparison.Before correction,all 23 LV Doppler parameters correlated significantly with one or more of the biometric variables.In group B,gender differences were found in 47.8%(11/23)of the parameters and were eliminated in 81.8%(9/11)of the parameters after correction with OMAM.The successful correction rate with OMAM was 100%(23/23)in group B and 82.6%(19/23)in group C.New reference values for corrected Doppler measurements independent of biometric variables were established.The SVIM with BSA successfully corrected none of the 23 parameters.In conclusion,different LV Doppler parameters allometrically correlated with one or more of the biometric variables.The novel OMAM developed in this study successfully corrected the effects of the physiological variances of most biometric variables on Doppler measurements in healthy and overweight subjects,and was found to be far superior to the SVIM.However,whether the OMAM equations can be applied to other ethnicities,obese subjects,and pathological conditions requires further investigation. 展开更多
关键词 Doppler echocardiography Physiological variance Allometric model Normal reference values
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The Genetic Variances for the Phytic Acid and Inorganic Phosphorus Contents of Elite Inbred Lines in Tropical Maize
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作者 P. Na Chiangmai P. Yodmingkhwan +1 位作者 P. Nilprapruck C. Aekatasanawan 《Journal of Agricultural Science and Technology(A)》 2011年第8期1326-1328,共3页
The study aimed to determine the genetic variances of phytic acid (myo-inositol 1,2,3,4,5,6 hexakis-dihydrogen phosphate) (PA) and inorganic phosphorus contents (InP) in grains of tropical maize (Zea mays L.).... The study aimed to determine the genetic variances of phytic acid (myo-inositol 1,2,3,4,5,6 hexakis-dihydrogen phosphate) (PA) and inorganic phosphorus contents (InP) in grains of tropical maize (Zea mays L.). The understanding of genetic variances in PA and InP in tropical maize would be useful for breeding management in tropical region. A total of 16 Ki inbred lines and 26 new inbred lines of tropical maize were planted in Completely Randomized Design (CRD) on the dry season 2008 at lnseechandrastitya Institute for Crops Research and Development, Thailand. The results showed that genotypic differences were highly significant (P 〈 0.01) for InP in both sources of germplasm, but genotype effect only was found significant in new inbred lines for PA content. The values for broad sense heritability (h2b) was generally lower on PA in maize grains compared with InP both in Ki and new inbred lines [h^2b of PA: 2.42 (Ki), 14.18 (commercial hybrid extracted); h^2b of InP: 32 (Ki) and 29.53 (commercial hybrid extracted)]. 展开更多
关键词 Phytic acid inorganic phosphorus Zea mays HERITABILITY genetic variances
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Dependence of epoch-wise two-way nested ANOVA estimates of variances of unmodeled effects present in relative GPS positioning on satellite elevation cutoff angle and PDOP mask
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作者 Darko Andic Radovan Durovic 《Geodesy and Geodynamics》 CSCD 2022年第5期473-491,共19页
Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning i... Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning is presented herein.Data used for this study refer to the winter and summer periods of the years with minimal(2008)and maximal(2013)solar activity.These data were collected every 30 s in static mode,at two permanent GPS stations located in Montenegro,establishing a mediumdistance(116-km-long)baseline with a height difference of approximately 760 m between its endpoints.The study showed that changing satellite elevation cutoff angle,with a fixed PDOP mask,affects epochwise two-way nested ANOVA estimates of variances related to the‘far-field’multipath(considered as the nested factor herein)and the combined unmodeled effect of tropospheric and ionospheric refraction(considered as the nesting factor herein).However,changing of PDOP mask,with a fixed satellite elevation cutoff angle,doesn’t affect epoch-wise two-way nested ANOVA estimate of variance of the combined unmodeled effect of tropospheric and ionospheric refraction,but,generally,affects the estimate of variance of the‘far-field’multipath(possibly mixed with a part of a‘shorter-term’ionospheric refraction),which is especially pronounced for the summer period.It should also be noted that there is a significant influence of satellite elevation cutoff angle change on both epoch-wise horizontal and vertical position accuracy,only for the summer period,especially in the presence of maximal solar activity,while there is no significant impact of PDOP mask change on epoch-wise positional accuracy. 展开更多
关键词 Unmodeled effects in relative GPS positioning 2-way nested ANOVA Epoch-wise variance components Satellite elevation cutoff angle change PDOP mask change
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Robust Sequential Covariance Intersection Fusion Kalman Filtering over Multi-agent Sensor Networks with Measurement Delays and Uncertain Noise Variances 被引量:4
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作者 QI Wen-Juan ZHANG Peng DENG Zi-Li 《自动化学报》 EI CSCD 北大核心 2014年第11期2632-2642,共11页
关键词 KALMAN滤波 传感器网络 测量不确定 噪声方差 网络延迟 多代理 卡尔曼滤波器 协方差
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远隔缺血后适应治疗对急性缺血性卒中超时间窗患者临床预后的影响:一项随机对照试验
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作者 袁丹 王莹 +4 位作者 王英鹏 许莉 薛佳 程晶晶 王海鹏 《中国全科医学》 CAS 北大核心 2025年第2期169-174,共6页
背景急性缺血性卒中(AIS)高发,及时恢复脑血流是治疗的关键,超时间窗就诊患者无更多促进脑血流恢复的治疗手段。研究远隔缺血后适应(RIPostC)治疗对AIS超时间窗就诊患者的临床疗效、并发症和预后,具有重要的临床意义。目的探究RIPostC... 背景急性缺血性卒中(AIS)高发,及时恢复脑血流是治疗的关键,超时间窗就诊患者无更多促进脑血流恢复的治疗手段。研究远隔缺血后适应(RIPostC)治疗对AIS超时间窗就诊患者的临床疗效、并发症和预后,具有重要的临床意义。目的探究RIPostC治疗对AIS超时间窗患者干预的影响,为超时间窗就诊的AIS患者寻求安全、有效的脑血流恢复治疗方式。方法本研究采用随机、分组、安慰剂对照法进行试验。选取2021-09-02—2022-08-31于北京航天总医院神经内科病房住院治疗的超溶栓时间窗(发病时间>6 h)的AIS患者为研究对象。依据随机数字表法将患者分为对照组和试验组。试验期+随访期共90 d,均使用同等的一般治疗、脑血管病常规治疗,试验组在此基础上给予RIPostC治疗14 d(28次),对照组给予模拟的RIPostC治疗14 d(28次)。在干预前和干预后30 d、干预后90 d,采用改良Rankin量表(mRS)、美国国立卫生研究院卒中量表(NIHSS)评估两组患者神经功能,简易精神状态检查量表(MMSE)、蒙特利尔认知评估量表(MoCA)评估患者认知功能,工具性日常生活能力量表(IADL)评估日常生活能力,焦虑自评量表(SAS)、抑郁自评量表(SDS)评估精神状态,经颅多普勒超声(TCD)评估脑血流速度,以白介素(IL)-6反映炎症情况。结果122例患者中,最终完成试验及随访99例,其中试验组49例,对照组50例。两组患者性别、年龄、基础疾病(高血压、糖尿病、冠心病)及基线NIHSS评分比较,差异无统计学意义(P>0.05)。重复测量方差分析结果示,时间与组别对MMSE、MoCA、mRS、NIHSS、脑血流速度、IL-6存在交互作用(P<0.05),时间和组别对MMSE、MoCA、NIHSS、脑血流速度、IL-6主效应显著(P<0.05),时间对mRS、SAS、SDS、IADL主效应显著(P<0.05)。试验组干预后30、90 d MMSE、MoCA评分及脑血流速度均高于对照组,mRS、NIHSS评分均低于对照组(P<0.05);试验组干预后30、90 d SDS、IADL评分低于对照组(P<0.05);试验组干预后30 d SAS评分高于对照组,IL-6低于对照组(P<0.05)。99例患者中共有23例患者发生不良反应,其中试验组17例,对照组6例,两组皮肤瘀点、头晕、心慌、胸闷发生率比较,差异无统计学意义(P>0.05);对照组患者皮肤瘀斑发生率[4.00%(2/50)与12.24%(6/49)]、总不良反应发生率[12.00%(6/50)与34.69%(17/49)]低于试验组(P<0.05)。结论RIPostC治疗可降低AIS患者的炎症反应,对神经功能、认知功能抑郁情绪及颅内血流速度可起到积极的改善效果。 展开更多
关键词 急性缺血性卒中 远隔缺血后适应 超时间窗 炎症反应 随机对照试验 重复测量方差分析
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Logistic混沌映射与差分进化改进人工蜂群优化水下定位
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作者 陈嘉兴 刘扬 +1 位作者 刘晓茜 刘志华 《工程科学与技术》 北大核心 2025年第1期57-67,共11页
水下节点定位时通常采用距离估算法,在节点之间利用点到点的距离来估计或基于角度估计来完成节点定位。然而,这种算法存在较大的定位误差。为了提升定位的精确度,引入了人工蜂群(ABC)优化算法,该算法通过将节点定位结果优化问题转化为... 水下节点定位时通常采用距离估算法,在节点之间利用点到点的距离来估计或基于角度估计来完成节点定位。然而,这种算法存在较大的定位误差。为了提升定位的精确度,引入了人工蜂群(ABC)优化算法,该算法通过将节点定位结果优化问题转化为对节点目标函数的优化问题,有效地提高了水下节点的定位精度。尽管如此,ABC算法在迭代过程中仍存在收敛速度慢、易陷入局部最优的问题。针对这些问题,提出了一种通过Logistic混沌映射与差分进化改进的人工蜂群优化水下定位算法(improved artificial bee colony optimization underwater localization algorithm by Logistic chaos mapping and differential evolution,LDIABC)。首先,在算法种群初始化阶段,引入了Logistic混沌映射,利用该映射函数产生的混沌序列代替随机数生成器,从而使种群在初始化分布时蜜源位置更均匀,并从理论上证明了Logistic混沌序列的互异性,从而避免由于种群分布过于密集导致算法在迭代过程中陷入局部最优;其次,提出了适应度方差这一标准来验证在算法迭代过程中未陷入局部最优,进一步证明其有效性;然后,在引领蜂搜索阶段,基于差分进化的变异策略,提出了权重因子改进引领蜂邻域搜索方式,提高了引领蜂的全局搜索效率,加快了算法的收敛速度。仿真实验表明,LDIABC算法能够有效避免传统ABC算法收敛速度慢和易陷入局部最优的问题。相较于Tent-IABC算法、ELOABC算法、CODEGWO算法以及SAPSO算法,LDIABC算法在收敛速度和节点定位成功率上均有显著提升,并且优化定位精度分别提升了6.36%、13.33%、14.16%和16.88%。这些结果证明LDIABC算法能够有效提升水下节点定位精度,具有良好的优化效果。 展开更多
关键词 人工蜂群优化 水下定位 LOGISTIC混沌映射 适应度方差 权重因子
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以碳酸钾为沉淀剂制备碳酸锂及其反应结晶条件优化
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作者 张志强 覃冬兰 +2 位作者 王佳琴 成春春 周娜 《化工矿物与加工》 2025年第1期8-16,共9页
碳酸钠生产过程中会产生大量的碳排放以及废水、废渣,可能会对环境造成危害。本文以碳酸钾代替碳酸钠作为制备碳酸锂的沉淀剂,并在反应结晶过程中加入超声波以控制碳酸锂不产生大的团聚体,采用响应面法优化主要的反应结晶条件,对碳酸锂... 碳酸钠生产过程中会产生大量的碳排放以及废水、废渣,可能会对环境造成危害。本文以碳酸钾代替碳酸钠作为制备碳酸锂的沉淀剂,并在反应结晶过程中加入超声波以控制碳酸锂不产生大的团聚体,采用响应面法优化主要的反应结晶条件,对碳酸锂中的钾含量、粒径D_(50)进行了方差分析,结果表明:钾含量拟合模型显著(P=0.0002,F=24.47),模型的拟合系数为0.9692、修正拟合系数为=0.9296、预测拟合系数为0.8751,满足方差分析要求;粒径D_(50)拟合模型显著(P=0.0002,F=24.91),拟合系数为=0.9697,修正拟合系数R^(2)=0.9308,预测拟合系数为0.7472,满足方差分析要求。碳酸锂中钾含量主要影响因素是温度,反应结晶温度与超声功率有明显的交互作用;碳酸锂粒径D_(50)主要影响因素是温度和超声功率,但是各个因素之间的交互作用不明显。对最优条件进行验证,碳酸锂中钾含量平均值为0.899 mg/g碳酸锂、D_(50)为17.346μm、平均收率为86.91%,预测值与试验值较为接近。 展开更多
关键词 碳酸锂 碳酸钾 响应面法 超声波 粒径分布 方差分析 钾含量
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Variance Type of Capsule Morphological Characters in Platycodon grandiflorum Population 被引量:6
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作者 金江山 严一字 +2 位作者 李斗哲 朴锦 王丽丽 《Agricultural Science & Technology》 CAS 2009年第5期140-142,共3页
[ Objective] The aim was to study variance type of capsule morphological characters in Platycodon grandiflorum population, and provide some theoretical basis for seeking to genetic markers which can differentiate diff... [ Objective] The aim was to study variance type of capsule morphological characters in Platycodon grandiflorum population, and provide some theoretical basis for seeking to genetic markers which can differentiate different P. grandiflorum and breeding new varieties. [ Method] According to shape morphological characters of capsule from the same population of perennial purple P. gandiflorum, seven types of distinct di- versity capsule were selected, variance analysis and multiple comparison on the length, diameter, length/diameter of the different types of capsule were carried out. [ Result] There is unicolor and bicolor, even trichrome, among main color was brown and purple. Capsule shape was main cone, furthermore, containing long roller type, spheroidicity and sphericity. [ Conclusion] P. gandiflorum capsule was divided into long form, short form and middle type from length/diameter size in perennial culture P. gandiflorum population. 展开更多
关键词 Platycodon grandiflorum population CAPSULE variance type
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免疫细胞与膝骨关节炎之间因果作用:一项两样本双向孟德尔随机化分析 被引量:2
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作者 吴广涛 秦刚 +4 位作者 何凯毅 范以东 李威材 朱宝刚 曹英 《中国组织工程研究》 CAS 北大核心 2025年第5期1081-1090,共10页
背景:膝骨关节炎是一种常见的关节软骨及周围组织损伤的慢性炎症性疾病,而免疫细胞在膝骨关节炎免疫炎症反应中起到重要作用,但其中的具体机制仍有待深入研究。目的:采用孟德尔随机化方法来评估731种免疫细胞表型与膝骨关节炎风险之间... 背景:膝骨关节炎是一种常见的关节软骨及周围组织损伤的慢性炎症性疾病,而免疫细胞在膝骨关节炎免疫炎症反应中起到重要作用,但其中的具体机制仍有待深入研究。目的:采用孟德尔随机化方法来评估731种免疫细胞表型与膝骨关节炎风险之间的潜在因果关系。方法:使用全基因组关联分析(GWAS)目录中公开获取731种免疫细胞表型的全基因组关联分析统计数据(从GCST0001391到GCST0002121)和IEUGWAS数据库中膝骨关节炎的全基因组关联分析数据(ebi-a-GCST007090)。采用逆方差加权法、MR-Egger回归法、加权中位数法、加权模型法和简单模型法来研究免疫细胞与膝骨关节炎之间的因果关系。敏感性分析用于检验孟德尔随机化分析结果是否可靠,然后以同样方法进行反向孟德尔随机化分析。结果与结论:①正向分析结果表明,共有4种免疫细胞表型与膝骨关节炎有显著的因果关系(FDR<0.20),其中B细胞中的CD27 on CD24+CD27+(OR=1.026,P=0.00026,Pfdr=0.18)、髓系细胞中的CD33 on CD33dim HLA DR-(OR=1.014,P=0.00050,Pfdr=0.18)以及Treg细胞中的CD45RA+CD28-CD8br%CD8br(OR=1.001,P=0.00078,Pfdr=0.18)与膝骨关节炎风险呈直接的正向因果关联;单核细胞中PDL-1 on monocyte(OR=0.952,P=0.00098,Pfdr=0.18)与膝骨关节炎风险呈直接的负向因果关联。②反向分析结果表明,当膝骨关节炎作为暴露数据时,与731种免疫细胞表型均不具有显著因果关系(FDR<0.20)。③敏感性分析结果显示:双向孟德尔随机化的Cochran’s Q检验和MR-Egger回归法结果P值均大于0.05,表明免疫细胞表型与膝骨关节炎之间的因果效应分析不存在显著的异质性和多效性。④上述结果证实,CD27 on CD24+CD27+,CD33 on CD33dim HLA DR-,CD45RA+CD28-CD8br%CD8br以及PDL-1 on monocyte免疫细胞表型与膝骨关节炎之间可能具有较为显著的潜在因果关系,这为研究膝骨关节炎的生物学机制及探索膝骨关节炎的早期防治提供有价值的线索,也为干预性药物的开发提供了新的方向。 展开更多
关键词 骨关节炎 膝骨关节炎 免疫机制 免疫细胞 孟德尔随机化 因果关系 全基因组关联分析 逆方差加权法 敏感性分析
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基于mean-variance的服务集群负载均衡方法 被引量:7
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作者 包晓安 魏雪 +2 位作者 陈磊 胡国亨 张娜 《电信科学》 北大核心 2017年第1期1-8,共8页
大量并发请求任务进行分配时,负载调度机制是通过最小化响应时间及最大化节点利用率实现网络中节点的负载均衡,在基于遗传算法的负载均衡算法中,适应度函数设计对服务集群负载均衡效率产生重要的影响。对此提出了一种基于mean-variance... 大量并发请求任务进行分配时,负载调度机制是通过最小化响应时间及最大化节点利用率实现网络中节点的负载均衡,在基于遗传算法的负载均衡算法中,适应度函数设计对服务集群负载均衡效率产生重要的影响。对此提出了一种基于mean-variance的服务集群负载均衡方法对适应度函数进行优化,采用投资组合选择模型mean-variance进行最小化响应时间,以得到每个服务器资源利用率的权重,从而获得最优的分配组合,进而提高适应度函数的准确性和有效性。在不同服务环境下与其他模型进行比较,仿真结果表明,本文的负载均衡算法在节点利用率和响应时间方面使服务集群得到了更好的均衡。 展开更多
关键词 负载均衡 mean-variance模型 遗传算法 负载调度
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FUZZY WITHIN-CLASS MATRIX PRINCIPAL COMPONENT ANALYSIS AND ITS APPLICATION TO FACE RECOGNITION 被引量:3
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作者 朱玉莲 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2008年第2期141-147,共7页
Matrix principal component analysis (MatPCA), as an effective feature extraction method, can deal with the matrix pattern and the vector pattern. However, like PCA, MatPCA does not use the class information of sampl... Matrix principal component analysis (MatPCA), as an effective feature extraction method, can deal with the matrix pattern and the vector pattern. However, like PCA, MatPCA does not use the class information of samples. As a result, the extracted features cannot provide enough useful information for distinguishing pat- tern from one another, and further resulting in degradation of classification performance. To fullly use class in- formation of samples, a novel method, called the fuzzy within-class MatPCA (F-WMatPCA)is proposed. F-WMatPCA utilizes the fuzzy K-nearest neighbor method(FKNN) to fuzzify the class membership degrees of a training sample and then performs fuzzy MatPCA within these patterns having the same class label. Due to more class information is used in feature extraction, F-WMatPCA can intuitively improve the classification perfor- mance. Experimental results in face databases and some benchmark datasets show that F-WMatPCA is effective and competitive than MatPCA. The experimental analysis on face image databases indicates that F-WMatPCA im- proves the recognition accuracy and is more stable and robust in performing classification than the existing method of fuzzy-based F-Fisherfaces. 展开更多
关键词 face recognition principal component analysis (PCA) matrix pattern PCA(MatPCA) fuzzy K-nearest neighbor(FKNN) fuzzy within-class MatPCA(F-WMatPCA)
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肥胖与普通男性跨越不同高度障碍动态稳定性的差异
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作者 张文丽 赵子麒 +2 位作者 梁雷超 汤运启 王勇 《中国组织工程研究》 CAS 北大核心 2025年第11期2319-2326,共8页
背景:肥胖对步行时的动态平衡产生负面影响,而跨越障碍是较为日常的功能活动,对控制身体姿势的稳定性要求更高。目的:探讨肥胖男性与普通男性动态稳定性的差异,采用相对更具挑战性的跨越障碍对肥胖男性的平衡能力进行评估。方法:招募24... 背景:肥胖对步行时的动态平衡产生负面影响,而跨越障碍是较为日常的功能活动,对控制身体姿势的稳定性要求更高。目的:探讨肥胖男性与普通男性动态稳定性的差异,采用相对更具挑战性的跨越障碍对肥胖男性的平衡能力进行评估。方法:招募24名男性青年,肥胖组与普通组(非肥胖组)各12名,分别以随机顺序完成平地行走和不同高度(4,11,15 cm)障碍物的跨越测试。使用Qualisys运动捕捉系统与Kistler测力台采集运动学与动力学数据。采用双因素(2组别*4动作类型)重复测量方差分析,对各指标进行统计分析。结果与结论:①肥胖组比普通组步速更低(P<0.05),跨越11 cm与15 cm障碍时第一单支撑期占比减小,第二双支撑期占比增加(P<0.05);②在平地行走时,普通组的内外方向动态稳度大于肥胖组(P<0.05);③在跨越4 cm障碍时,肥胖组前后方向动态稳度低于普通组(P<0.05);④在跨越11 cm障碍时,两组前后方向动态稳度无显著性差异(P>0.05),而内外方向差异有显著性意义(P<0.05);⑤在跨越15 cm障碍时,肥胖组动态稳度低于普通组(P<0.05);⑥提示肥胖使人体在跨越障碍过程中对身体的控制能力下降,动态稳定性降低,发生跌倒的风险较普通人群更高;此外,相较于平地行走,跨越障碍时肥胖组稳定性下降较普通人群更为显著。 展开更多
关键词 肥胖 跨越障碍 动态稳度 平衡 姿势控制 稳定性 跌倒 双因素重复测量方差分析
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务农还是务工:农业保险背景下农户就业选择
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作者 张鹏峰 顾海英 《农业技术经济》 北大核心 2025年第1期95-110,共16页
与务工相比,农业生产具有较强的农业风险属性,直接导致务农收入不稳定,农业保险能有效缓解农业收入的剧烈波动,改变农户对农业收入的预期。基于“均值—方差效用模型”,本文从理论层面分析了农业保险背景下农户的就业选择。理论分析结... 与务工相比,农业生产具有较强的农业风险属性,直接导致务农收入不稳定,农业保险能有效缓解农业收入的剧烈波动,改变农户对农业收入的预期。基于“均值—方差效用模型”,本文从理论层面分析了农业保险背景下农户的就业选择。理论分析结果表明,政策性农业保险降低了农业收入的波动程度,农户会调整务农与务工之间的劳动时间分配比例,增加种植规模,减少务工时间。论文采用2020年中国乡村振兴综合调查(CRRS)数据,实证分析了农业保险对农户就业选择的影响。研究表明,农业保险导致农户农业种植面积和务农时间显著增加,务农收入提高;农业保险还导致农户家庭成员务工比例下降,务工时间和务工收入显著减少。本文为农业保险对农户就业选择的影响提供了理论支持和经验证据,也为以政策性农业保险为代表的支农惠农措施提供了政策启示。 展开更多
关键词 农业保险 就业选择 均值—方差效用模型
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关节镜下Wafer术治疗尺骨撞击综合征20例临床疗效
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作者 李远 银毅 +4 位作者 李清山 何克 冷雨 孙官军 彭旭 《安徽医药》 CAS 2025年第1期87-90,I0005,共5页
目的探讨关节镜下Wafer术治疗腕关节尺骨撞击综合征(UIS)的早期疗效。方法回顾性分析2019年8月至2022年9月遂宁市中心医院收治20例尺骨阳性变异(UV)≤4 mm的UIS病人,均行关节镜下Wafer术治疗,术后行规范的康复性锻炼。男9例,女11例,年... 目的探讨关节镜下Wafer术治疗腕关节尺骨撞击综合征(UIS)的早期疗效。方法回顾性分析2019年8月至2022年9月遂宁市中心医院收治20例尺骨阳性变异(UV)≤4 mm的UIS病人,均行关节镜下Wafer术治疗,术后行规范的康复性锻炼。男9例,女11例,年龄范围18~76岁,病程范围6~24个月。术前尺骨撞击试验、尺腕压力试验及Press test均为阳性。术前腕关节掌屈、背伸、尺偏、桡偏角度分别为(54.2±3.8)°、(61.1±4.3)°、(15.8±4.6)°、(13.0±2.7)°,疼痛视觉模拟评分法(VAS)、Mayo腕关节评分、上肢功能评分表(DASH)评分、握力、UV程度分别为(6.2±1.1)分、(53.5±9.1)分、(45.9±5.8)分、(60.5±9.3)N,(3.5±1.5)mm。结果病人切口均Ⅰ期愈合,无腕关节僵硬及感染等并发症发生。病人均获随访,随访时间范围为12~24个月。末次随访时腕关节掌屈、背伸分别为(54.7±4.1)°、(61.7±4.6)°,与术前比较均差异无统计学意义(P>0.05);尺偏、桡偏角度分别为(34.4±5.3)°、(15.6±3.5)°,与术前比较均差异有统计学意义(P<0.05);VAS、Mayo腕关节评分、DASH评分、握力、UI分别为(1.6±0.6)分、(81.0±8.3)分、(15.7±4.2)分、(80.8±8.7)N,(0.8±0.8)mm,上述指标与术前比较均差异有统计学意义(P<0.05)。结论关节镜下Wafer手术治疗UV≤4 mm的UIS病人疗效确切,可有效缓解疼痛,改善腕关节功能,值得临床应用及推广。 展开更多
关键词 腕关节 关节镜检查 Wafer术 尺骨撞击综合征 尺骨阳性变异 尺骨撞击试验 尺腕压力试验
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