An Intercomparison of Rules for Testing the Significance of Coupled Modes of Singular Value Decomposition Analysis

This paper clarifies the essence of the significance test of singular value decomposition analysis （SVD）, and investigates four rules for testing the significance of coupled modes of SVD, including parallel analysis, nonparametric bootstrap, random-phase test, and a new rule named modified parallel analysis. A numerical experiment is conducted to quantitatively compare the performance of the four rules in judging whether a coupled mode of SVD is significant as parameters such as the sample size, the number of grid points, and the signal-to-noise ratio vary. The results show that the four rules perform better with lower ratio of the number of grid points to sample size. Modified parallel analysis and nonparametric bootstrap perform best to abandon the spurious coupled modes, but the latter is better than the former to retain the significant coupled modes when the sample size is not much larger than the number of grid points. Parallel analysis and random-phase test are robust to abandon the spurious coupled modes only when either （1） the observations at the grid points are spatially uncorrelated, or （2） the coupled signal is very strong for parallel analysis and is not weak for random-phase test. The reasons affecting the accuracy of the test rules are discussed.

SIGNIFICANCE TEST FOR EMPIRICAL ORTHOGONAL FUNCTION (EOF) ANALYSIS OF METEOROLOGICAL AND OCEANIC DATA

A Monte Carlo experiment was done to create a statistically significant test table for selecting EOF modes whose signals are above the noise level. Numerical analysis showed that it is feasible to choose a shorter data set between temporal and spatial dimensions for conducting an EOF analysis, and thus simplify calculation of the covariance matrix and solution of its eigenvalues and eigenvectors. The experiment showed that the dominant EOF modes remained the same. This approach is more computationally efficient, reducing both computing time and computer memory requirement, while still retaining the dominant signal.

Detecting the Relationship Between Summer Rainfall Anomalies in Eastern China and the SSTA in the Global Domain with a New Significance Test Method

It is suggested that the multiple samples in a correlation map or a set of correlation maps should be examined with significance tests as per the Bernoulli probability model. Therefore, both the contemporaneous and lag correlations of summertime precipitation R in any one of the three regions of Northern China (NC), the Changjiang-Huaihe River Valley (CHRV), and Southern China (SC) with the SSTA in the global domain have been tested in the present article, using our significance test method and the method proposed by Livezey and Chen (1983) respectively. Our results demonstrate that the contemporaneous correlations of summer R in CHRV with the SSTA are larger than those in NC. Significant correlations of SSTA with CHRV R are found to be in some warm SST regions in the tropics, whereas those of SSTA with NC R, which are opposite in sign as compared to the SSTA-CHRV R correlations, are found to be in some regions where the mean SSTs are low. In comparison with the patterns of the contemporaneous correlations, the 1 to 12 month lag correlations between NC R and SSTA, and those between CHRV summer R and SSTA show similar patterns, including the magnitudes and signs, and the spatial distributions of the coefficients. However, the summer rainfall in SC is not well correlated with the SSTA, no matter how long the lag interval is. The results derived from the observations have set up a relationship frame connecting the precipitation anomalies in NC, CHRV, and SC with the SSTA in the global domain, which is critically useful for our understanding and predicting the climate variabilities in different parts of China. Both NC and CHRV summer R are connected with El Nio events, showing a ‘––’pattern in an El Nio year and a ‘+ +’ pattern in the subsequent year.

THE SIGNIFICANCE OF TESTING PREOPERATIVE VISUAL FUNCTION IN CATARACT USING LASER INTERFEROMETRIC VISUAL ACUITY AND ERG

Tests of preoperative visual function and prediction of postoperative E chart visual acuity(ECVA) using laser interferometric visual acuity(LIVA) and electroretinogram(ERG) were performed in 16 cases(19 eyes) of cataract. The results showed that the coincident rate between preoperative LIVA and postoperative ECVA was 63.2%, and there was a parallel correlation between preoperative amplitude of photopic ERG b-wave and postoperative ECVA in 79.0% of the eyes. Comparing these two methods, the test of LIVA ...

Improved significance testing of wavelet power spectrum near data boundaries as applied to polar research

When one applies the wavelet transform to analyze finite-length time series, discontinuities at the data boundaries will distort its wavelet power spectrum in some regions which are defined as a wavelength-dependent cone of influence （COI）. In the COI, significance tests are unreliable. At the same time, as many time series are short and noisy, the COI is a serious limitation in wavelet analysis of time series. In this paper, we will give a method to reduce boundary effects and discover significant frequencies in the COI. After that, we will apply our method to analyze Greenland winter temperature and Baltic sea ice. The new method makes use of line removal and odd extension of the time series. This causes the derivative of the series to be continuous （unlike the case for other padding methods）. This will give the most reasonable padding methodology if the time series being analyzed has red noise characteristics.

A New Method of Significance Testing for Correlation-Coefficient Fields and Its Application

Correlation-coefficient fields are widely used in short-term climate prediction research. The most frequently used significance test method for the correlation-coefficient field was proposed by Livezey, in which the number of significantcorrelation lattice(station) points on the correlation coherence map is used as the statistic. However, the method is based on two assumptions:(1) the spatial distribution of the lattice(station) points is uniform;and(2) there is no correlation between the physical quantities in the correlation-coefficient field. However, in reality, the above two assumptions are not valid.Therefore, we designed a more reasonable method for significance testing of the correlation-coefficient field. Specifically, a new statistic, the significant-correlation area, is introduced to eliminate the inhomogeneity of the grid(station)-point distribution, and an empirical Monte Carlo method is employed to eliminate the spatial correlation of the matrix.Subsequently, the new significance test was used for simultaneous correlation-coefficient fields between intensities of the atmospheric activity center in the Northern Hemisphere and temperature/precipitation in China. The results show that the new method is more reasonable than the Livezey method.

Significant Breakthrough in Industrial Test of the "Methanol to Olefins" Process Developed by Dalian Institute of Chemical Physics,Chinese Academy of Sciences

A process of ＂Methanol or Dimethylether to Olefins＂ developed by Dalian Institute of Chemical Physics （DICP）, designated as the DMTO process, has attained great success in industrial scaling up testing. DICP, by collaborating with the Xinxing Coal Chemical Co., Ltd. of Shaanxi Province and the Luoyang Petrochemical Engineering Co. of the SINOPEC Group, operated successfully a 50t（methanol）/d unit for the conversion of methanol to lower olefins, with a methanol conversion of close to 100%, and a selectivity to lower olefins（ethylene, propylene and butylenes） of higher than 90%. On 23rd August, the industrial test project has passed a state appraisal. The experts of the Appraisal Group, headed by Prof. YUAN Qingtang, academician of Chinese Academy of Engineering, drew the conclusions that the DMTO process, by utilizing a proprietary SAPO-34 catalyst system and a recycling fluidized bed reaction system for the production of lower olefins from methanol, is the first unit in the world having a capacity of producing nearly ten thousand tons lower olefins per year. The technological level of the industrial test is at a leading position internationally. This accomplishment will provide a sound base for the subsequent commercialization of the DMTO process.

Detection of Clinically Significant Warm Reactive Anti-A1 in a Post Red Blood Cells Transfusion Patient with Acute Lymphoblastic Leukemia

The purpose of this article is to report that some anti-A1 that react at 37°C are IgG antibodies and are clinically significant, as they can cause the destruction of a proportion of A1 cells in vivo following the transfusion of red blood cells. Therefore, when a serum of an individual contains anti-A1, further testing of the plasma against group A1, A2, and O by referencing red blood cells and individual cells against anti-A1 lectin (Dolichos biflorus lectin) must be performed. Confirming the specificity of anti-A1 by referencing red blood cells is also important in selecting the appropriate blood for transfusion. ABO antibodies are naturally occurring and activate the complement cascade, making them more likely to cause severe transfusion reactions compared to antibodies to other RBC antigens.

一类变系数空间滞后的混合地理加权回归模型

为解决因变量空间滞后存在的局域性问题,对现有常系数空间滞后的混合地理加权回归模型作了具有更广泛形式的拓展,提出一类变系数空间滞后的混合地理加权回归(MGWR-VSLR)模型。MGWR-VSLR模型实现了空间相关性与空间异质性融合,涵盖了绝大多数地理加权回归的模型形式,基于重构参数化方法和似然比检验分别给出模型的系数估计方法与显著性检验以及选取变系数的判别检验。在蒙特卡罗模拟与实际应用中,MGWR-VSLR模型均表现出优异的因变量拟合与预测能力。MGWR-VSLR模型的提出为定量化研究空间效应问题设定适宜的模型形式提供了支撑依据。

P值之争与管理学研究:先验概率的意义

P值之争的本质是人们把统计检验和统计推断混淆,直接用统计检验结果来进行统计推断.这导致许多似是而非的理论被接受.统计检验犯错的是假阳性概率.统计推断犯错的是假阳性之反概率.两种概率之间的数值关系受先验概率影响很大.先验概率越高,利用统计检验的结果进行推断所犯错误概率就越小.如果先验概率很小,即使假阳性概率很小,利用该结果进行推断所犯错误概率也很大.本文以管理学研究为例,提出解决该问题的办法是,通过与现实和与理论的双重对话来掌握先验概率,以提高基于统计检验的结果进行统计推断的可靠性.本文的科学哲学意义是,揭示了科学研究是先验与经验相统一的本质,以及科学研究的不充分决定性的特征.

面向乡村振兴的认养农业发展影响因素——基于咸阳市周边橙种植户的调查

为推进城郊认养农业发展,促进乡村进一步振兴,采用Logistic回归方法,从个人因素、家庭因素、生产因素和环境因素等4个维度对咸阳市周边橙种植户参与认养农业的意愿及影响因素进行研究。结果表明,咸阳周边农户参与认养农业意愿最强烈的影响因素为农户性别、文化程度、是否村干部或合作社成员、是否参与过认养农业、家庭耕地面积、农产品价格波动与滞销情况,均在1%水平上呈现正向显著相关;农户年龄、人口数量、收入来源是否为农业种植、生产对象的需求弹性等因素在5%水平上正向显著相关;家庭收入、市场规模、政策支持、自然灾害和交通便利程度等因素未通过显著性检验。基于实证结果和结合咸阳城郊认养农业发展实际,提出提高农户对认养农业的认知水平,鼓励农户进行规模化、标准化生产,建立专项补贴贷款渠道等措施,从而更好的促进咸阳城郊认养农业发展,加快乡村振兴。

大型地下厂房水压致裂法地应力测量及地应力场反演分析

岩体初始地应力是地下工程研究中的重要内容,依托大型地下厂房工程,采用三维水压致裂法和常规水压致裂法对洞内孔ZK1和地表孔ZK2分别进行地应力测量,获得岩体初始地应力;基于实测数据利用三维数值模拟方法进行地应力场反演计算,获得所需工程区的地应力场分布规律。研究表明:水压致裂法可以有效地获得初始地应力,三维水压致裂法获得的地下应力情况更为准确且可以与垂直孔测试数据互相印证;数值模拟获取的地应力计算值和实测值具有一致性,厂房隧洞布置较为合理且工程区发生岩爆概率较低;现场原位测试结果与回归地应力场分布规律可为工程设计提供有效的科学支撑。

基于Voronoi图的空间点事件统计聚类方法

挖掘地理空间数据中点事件聚集模式对于揭示流行疾病、犯罪分布热点区域及城市基础设施空间分布格局等具有重要意义。针对不同形状、密度和大小的显著空间点聚集模式的识别,目前以空间扫描统计为代表的方法虽然可以对空间点聚类的显著性进行统计推断,减少虚假聚类结果,但其主要用于识别球形或椭圆形状的聚簇,对于沿着街道或河道分布的任意形状、不同密度的显著空间点聚簇识别还存在局限。因此,本研究提出一种基于Voronoi图的空间点聚集模式统计挖掘方法。首先,采用Voronoi图来度量空间点分布的聚集性,将空间点聚类问题转化为热点区域探测问题;其次,结合局部Gi*统计量探测统计上显著的空间点聚簇;最后,通过模拟数据和真实犯罪事件数据进行实验与对比分析。结果表明:本方法能够有效探测任意形状的空间点聚类,并对空间点簇的显著性进行统计判别,识别显著的空间点簇,减少随机噪声点的干扰;聚类识别结果优于现有代表性方法,如DBSCAN算法、空间扫描统计方法等。

钢混组合梁斜拉桥非对称张拉施工控制的拉索索力统计敏感性分析

针对非对称张拉施工斜拉桥存在的主梁和桥塔线形控制难题,以某大跨度钢混组合梁斜拉桥施工控制为例,开展了拉索索力统计敏感性分析研究。以斜拉索索力为设计参数,综合采用均匀试验和正交试验设计方法以及多元线性回归和极差分析显著性检验方法,对成桥和施工阶段主梁和桥塔截面的内力、位移进行统计敏感性分析。结果表明:提出的索力统计敏感性分析方法可准确获得成桥和施工阶段的敏感性索力参数;对于成桥阶段,S10、MS10、S9号斜拉索索力为结构线形的敏感性参数;非对称张拉施工时,S10、MS10、S9、MS9、S8、MS8、S5、MS5号斜拉索索力为影响主梁和塔顶截面位移的敏感性参数;若采用对称张拉施工,S10、MS10、S8、MS8、S9、MS9、S7、MS7号斜拉索索力则为影响主梁和塔顶截面位移的敏感性参数。

基于灰色关联分析的纵扭超声辅助对电火花微孔加工影响评价

TC4钛合金是航空航天领域经常加工的材料,由于其难切削的特点通常使用电火花进行加工,但存在加工效率与废屑排除的问题。纵扭超声振动可以有效优化如上弊端,但目前没有严谨定量的科学分析证明纵扭超声辅助对电火花加工的优化程度。因此提出纵扭超声辅助电火花放电能量模型,阐明放电机制以及放电能量的影响因素;设置单因素试验和正交试验,通过显著性T检验探索纵扭超声振动对电火花加工的影响程度,通过建立灰色关联分析模型分析电参数的影响权重并选出最优参数组,最后通过打孔试验验证了选优结果的正确性。研究结果表明:峰值电流和脉冲宽度对加工效率和质量的影响较为明显,引入纵扭超声振动明显改善了电火花加工性能,最优峰值电流从2 A提升至3 A,脉冲宽度从125μs提升至150μs,材料去除率提升了83.8%,相对电极损耗率、孔锥度和表面粗糙度分别降低了33.7%、22.3%和16.4%。

矸石粉基胶结充填材料析水特性试验研究

为了探明矸石粉基胶结充填材料的析水特性,运用正交试验设计了以矸石粉、高水材料、水泥、粉煤灰为组合的胶结充填材料,采用极差分析、方差分析等方法,研究了矸石粉基质量浓度(A)、水泥含量(B)、粉煤灰含量(C)、高水材料含量(D)4个因素对胶结材料的析水率的影响情况;得到各因素对矸石粉基胶结充填材料析水特性影响的拟合公式。结果表明:基于极差分析的矸石粉基胶结充填材料的析水率影响程度为D>A>B>C,基于方差分析的材料析水率影响程度为D>B>A>C,析水率随着矸石粉浆质量分数的升高呈现下降趋势,随着水泥含量的增加则呈现先减少后增大再减少的趋势,随着粉煤灰质量增加呈现先减少后平稳的趋势,随着高水的增加呈现下降的趋势;高水含量对材料析水率的影响程度最大,矸石粉基质量分数与水泥质量对材料析水率影响相当,粉煤灰含量对材料析水率影响较小。

食品中菌落总数纸片法的方法验证及结果分析

目的:探究三种厂家的测试片的纸片法在食品菌落总数测定中的一致性,分析比较不同厂家测试片的实际应用效果,为食品检测机构提供参考依据。方法:采用GB 4789.2-2022《食品安全国家标准食品微生物学检验菌落总数测定》对三种厂家的菌落总数测试片,通过纸片法和倾注法对标准菌株菌悬液、人工污染样品进行菌落总数检测,运用统计学分析确定两种方法之间检测结果的显著性和相关性。结果 经统计学分析,两种方法在标准菌株菌悬液和人工污染样品检测结果之间无显著性差异(P>0.05),两种方法的检测结果相关性非常好(R2>0.996)。结论:三种厂家的菌落总数测试片法与倾注法的检测结果一致,菌落总数测试片更加快速、简便,减少检测流程,提高检测效率。不同厂家的测试片存在一定差异,实验室可根据样品特性选择合适的测试片。

土壤检测及其对环境保护的意义探究

土壤是生态环境系统的重要组成部分,社会经济发展、产业建设、日常生活等均与土壤密切相关。加大对土壤的检测力度,能够掌握土壤的真实情况,采取有效措施改善土壤,保护生态环境,促进人们生活水平提高、工业生产的稳定发展。本文研究了土壤检测的工具方法、流程,阐述了土壤检测对环境保护的意义,提出了加强土壤检测助力环境保护的措施,以供借鉴。

无创DNA检查在单项超声软指标异常胎儿染色体筛查中的临床意义

目的:探究无创DNA检查(non-invasive DNA,NIPT)在单项超声软指标(ultrasound soft index,USM)异常胎儿染色体筛查中的临床意义。方法:选取2022年1月至2023年8月于郑州四六〇医院进行NIPT的174例单项USM阳性孕妇进行回顾性研究,分析其USM及NIPT结果,以临床最终结果为“金标准”,分析NIPT诊断结果及诊断效能,进一步分析不同检查结果的妊娠结局情况。结果:174例单项USM异常孕妇中,NIPT提示161例低风险,13例高风险,提示高风险包括2例性染色体数目异常,18-三体、13-三体各1例,21-三体9例;核型分析检测提示9例21-三体,1例47、XYY,18-三体、13-三体各1例,其中1例NIPT提示性染色体数目异常,患者核型分析检测结果提示正常;NIPT诊断灵敏度为85.71%,准确度为98.28%,漏诊率为15.38%;NIPT提示161例低风险,另有1位NIPT提示高风险患者经核型分析结果显示其染色体未出现明显异常现象,共计162例,其中18例在其他医院分娩,4例患者失访,其他孕妇均在郑州四六〇医院妇产科行产检、分娩,随访结果显示新生儿无明显异常;NIPT提示14例高风险孕妇中,XYY染色体数目异常、核型正常孕妇选择足月分娩,21-三体、13-三体、18-三体核型异常孕妇均选择引产。结论:NIPT在单项USM异常孕妇中具有较高的诊断灵敏度、准确度,漏诊率相对较低,可为临床及时筛查单项USM异常孕妇胎儿异常,降低流产风险提供可靠依据。

京津冀地区近50 a降水时空变化分析

为了明确京津冀地区近年来降水时空变化特征,使用线性回归、空间插值以及M-K显著性检验、相关性分析、小波分析等方法,结合地区DEM数据,对近50 a降水逐日、逐月数据进行处理分析。结果显示,京津冀地区年降水量呈不显著增加趋势,且存在平均周期约20 a的周期性变化;年降水的不稳定性在增强,除春季外,其余季节降水的不稳定性均在增强;夏季降水与年降水具有最强的相关性;年降水量呈现自东南沿海向西北内陆递减规律,春季、秋季、冬季降水呈现两侧多、中间少的特征,夏季降水与年降水分布特征一致;绝大部分地区年降水量呈增加趋势,增幅的空间分布与年降水量的空间分布趋势相反,夏季降水与年降水在空间上仍然具有最高的一致性。