Evaluation of empirical estimation of uniaxial compressive strength of rock using measurements from index and physical tests

The uniaxial compressive strength(UCS) of rock is an important parameter required for design and analysis of rock structures,and rock mass classification.Uniaxial compression test is the direct method to obtain the UCS values.However,these tests are generally tedious,time-consuming,expensive,and sometimes impossible to perform due to difficult rock conditions.Therefore,several empirical equations have been developed to estimate the UCS from results of index and physical tests of rock.Nevertheless,numerous empirical models available in the literature often make it difficult for mining engineers to decide which empirical equation provides the most reliable estimate of UCS.This study evaluates estimation of UCS of rocks from several empirical equations.The study uses data of point load strength(Is(50)),Schmidt rebound hardness(SRH),block punch index(BPI),effective porosity(n) and density(ρ)as inputs to empirically estimate the UCS.The estimated UCS values from empirical equations are compared with experimentally obtained or measured UCS values,using statistical analyses.It shows that the reliability of UCS estimated from empirical equations depends on the quality of data used to develop the equations,type of input data used in the equations,and the quality of input data from index or physical tests.The results show that the point load strength(Is(50)) is the most reliable index for estimating UCS among the five types of tests evaluated.Because of type-specific nature of rock,restricting the use of empirical equations to the similar rock types for which they are developed is one of the measures to ensure satisfactory prediction performance of empirical equations.

EMPIRICAL BAYES TEST PROBLEMS OF VARIANCE COMPONENTS IN RANDOM EFFECTS MODEL

Bayes decision rule of variance components for one-way random effects model is derived and empirical Bayes (EB) decision rules are constructed by kernel estimation method. Under suitable conditions, it is shown that the proposed EB decision rules are asymptotically optimal with convergence rates near O(n-1/2). Finally, an example concerning the main result is given.

One-sided empirical Bayes test for location parameter in Gamma distribution

In this paper, we devote to constructing the one-sided empirical Bayes(EB) test for the location parameter in the Gamma distribution by nonparametric method. Under some mild conditions, we prove that the EB test is asymptotically optimal with the rate of the order O(n^(-δs/(2s+1))), where 1/2 ≤ δ < 1 and s > 1 is a given natural number. An example is also given to illustrate that the conditions of the main theorems are easily satisfied.

Comparison between empirical prokinetics, Helicobacter test-and-treat and empirical endoscopy in primary-care patients presenting with dyspepsia: A one-year study

瞄准：调查最佳的策略在主要照顾对待消化不良的病人。方法：介绍给主要照顾门诊病人诊所的消化不良的病人随机被分到：(1 ) 实验内视镜检查法，(2 ) H pylori test-and-treat，并且(3 ) 实验专业版有 cisapride 的运动治疗。如果病人们在 2 wk 以后仍然保持征兆，早内视镜检查法被安排。症状严厉， quality-of-life (SF-36 ) 以及耐心的偏爱和满足被估计。所有病人由 wk 经历了内视镜检查法 6。病人们被跟随在上面为一年。结果：二百和三十四个病人被招募(163 女、吝啬的年龄 49 ) 。46% 是 H pylori 积极。测试的 26% H pylori 和运动病人显示出的 25% 实验专业版在 wk 的没有改进 2 后续和需要的早内视镜检查法。收到实验 cisapride 的 15% 病人对治疗作出回应很好，但是消化性溃疡是最后的诊断。症状分辨率和 quality-of-life 在这些组之中是类似的。为三策略的费用是每病人的 HK 美元 4343，美元 1771 和美元 1750。66% 病人喜欢有早内视镜检查法。结论：三策略是同等地有效的。实验专业版运动治疗是最不昂贵的，但是消化性溃疡可以与这治疗被错过。H pylori test-and-treat 是最划算的选择。

Empirical Bayes Test for Two-parameter Exponential Distribution under Type-Ⅱ Censored Samples

The empirical Bayes test problem is considered for scale parameter of twoparameter exponential distribution under type-II censored data.By using wavelets estimation method,the EB test function is constructed,of which the asymptotic optimality and convergence rates are obtained.Finally,an example concerning the main result is given.

Empirical Analysis of Object-Oriented Design Metrics for Predicting Unit Testing Effort of Classes

In this paper, we investigate empirically the relationship between object-oriented design metrics and testability of classes. We address testability from the point of view of unit testing effort. We collected data from three open source Java software systems for which JUnit test cases exist. To capture the testing effort of classes, we used metrics to quantify the corresponding JUnit test cases. Classes were classified, according to the required unit testing effort, in two categories: high and low. In order to evaluate the relationship between object-oriented design metrics and unit testing effort of classes, we used logistic regression methods. We used the univariate logistic regression analysis to evaluate the individual effect of each metric on the unit testing effort of classes. The multivariate logistic regression analysis was used to explore the combined effect of the metrics. The performance of the prediction models was evaluated using Receiver Operating Characteristic analysis. The results indicate that: 1) complexity, size, cohesion and (to some extent) coupling were found significant predictors of the unit testing effort of classes and 2) multivariate regression models based on object-oriented design metrics are able to accurately predict the unit testing effort of classes.

基于PSM-DID实证分析的PPP项目实施对医疗设施供给效率的影响研究

PPP医疗卫生项目的实施对于推动医疗卫生事业改革以及完善我国政府公共投资事业具有重要意义。通过采用PSM-DID方法,对PPP项目中的医疗设施供给效率进行实证检验,研究发现:从全国性来看,PPP项目的推广应用可以显著提升医疗设施供给的效率;从异质性分析来看,东部、中部和西部地区的PPP项目推广应用对医疗设施供给效率的影响存在着一定的差异性。针对西部地区,可以侧重扩大PPP医疗卫生项目建设的规模及覆盖区域和范围;针对东部和中部地区,可以侧重加大PPP医疗卫生项目的质量、服务水平和效率提升,注重医疗卫生服务的多样化发展和优质医疗服务资源的提供。

Convergence Rate of Empirical Bayes Test for the Parameter of the Truncated-type Distribution Families

In this paper, we construct the empirical B ay es test (EBT) for the parameter of the truncated-type distribution families. It is found that the proposed test is asymptotically optimal. The convergence rate of the EBT is given.

NON-DESTRUCTIVE PAVEMENT LAYER THICKNESS MEASUREMENT USING EMPIRICAL MODE DECOMPOSITION WITH GPR

Ground Penetrating Radar(GPR) is an effective Non-Destructive Testing(NDT) technique for highway pavement surveys, which is able to acquire continuous pavement data compared with traditional core drilling method. In this study, we proposed an accurate and efficient method to estimate the thickness of each pavement layer using an air-coupled GPR system. For this work, the main difficulties are estimating each pavement layer's time delay and dielectric constant. We first give the basic signal model for pavement evaluation, and then present an Intrinsic Mode Functions(IMFs) product detector to determine each pavement layer's time delay. This method is based on Empirical Mode Decomposition(EMD), which is an adaptive signal decomposition procedure and proved to be suitable for suppressing noises in GPR signal. The dielectric constant was determined by metal reflection measurement. The laboratory and highway experiments illustrate that the proposed thickness estimation method yields reasonable result, thus meets the requirements of practical highway pavement survey with massive GPR data.

In-Tunnel Blast Pressure Empirical Formulas for Detonations External, Internal and at the Tunnel Entrance

In order to define the loading on protective doors of an underground tunnel, the exact knowledge of the blast propagation through tunnels is needed. Thirty-three scale high-explosive tests are conducted to obtain in-tunnel blast pressure for detonations external, internal and at the tunnel entrance. The cross section of the concrete model tunnel is 0.67 m2. Explosive charges of TNT, ranging in mass from 400 g to 4 600 g, are detonated at various positions along the central axis of the model tunnel. Blast gages are flush-installed in the interior surface of the tunnel to record side-on blast pressure as it propagates down the tunnel. The engineering empirical formulas for predicting blast peak pressure are evaluated, and are found to be reasonably accurate for in-tunnel pressure prediction.

Maximum Entropy Empirical Likelihood Methods Based on Bivariate Laplace Transforms and Moment Generating Functions

Maximum Entropy Empirical Likelihood (MEEL) methods are extended to bivariate distributions with closed form expressions for their bivariate Laplace transforms (BLT) or moment generating functions (BMGF) without closed form expressions for their bivariate density functions which make the implementation of the likelihood methods difficult. These distributions are often encountered in joint modeling in actuarial science and finance. Moment conditions to implement MEEL methods are given and a bivariate Laplace transform power mixture (BLTPM) is also introduced, the new operator generalizes the existing univariate one in the literature. Many new bivariate distributions including infinitely divisible(ID) distributions with closed form expressions for their BLT can be created using this operator and MEEL methods can also be applied to these bivariate distributions.

Goodness-of-Fit Test for Non-Stationary and Strongly Dependent Samples

In this article we improve a goodness-of-fit test, of the Kolmogorov-Smirnov type, for equally distributed- but not stationary-strongly dependent data. The test is based on the asymptotic behavior of the empirical process, which is much more complex than in the classical case. Applications to simulated data and discussion of the obtained results are provided. This is, to the best of our knowledge, the first result providing a general goodness of fit test for non-weakly dependent data.

大跨度单层柔性光伏支架结构气动阻尼的试验研究

大跨光伏支架结构轻柔,在风荷载作用下易产生显著气动效应。为研究该类结构的气动阻尼特征,对不同风速和张力工况下两种典型倾角(0°和10°)的大跨度柔性光伏支架结构开展气弹风洞试验。基于气弹模型风洞试验结果,分别利用经验小波变换(empirical wavelet transform,EWT)和变分模态分解(variational modal decomposition,VMD)结合改进的随机减量方法(random decrement technique,RDT)识别得到了柔性光伏支架结构在不同风速风向、组件倾角和拉索预张力下的气动阻尼比。研究结果表明,气动阻尼对风向角的变化较为敏感。当组件倾斜铺设时(10°倾角),大跨光伏结构气动阻尼在180°迎风向时会出现负值。张力增加可能导致高风速下平铺组件的气动阻尼比显著降低。气动阻尼比随风速的增加整体呈减小趋势,低风速下基本为正值,而高风速下可能出现负气动阻尼。不同方法识别出的气动阻尼比结果存在一定的差异,但反映出的气动阻尼的变化特征具有一致性。

基于新课标的中小学生计算思维量表构建研究

对学生计算思维的培养已成为数字时代的核心议题,科学、精准的评价则是培养学生计算思维能力的基础。然而,针对义务教育阶段学生的计算思维测评,目前国内尚无依托相关课程标准制定的本土化的、权威的量表。为此,研究首次依托《义务教育信息科技课程标准(2022年版)》(以下简称“新课标”)中的计算思维定义及培养要求,共以12920名(N1=1029,N2=1458,N3=10433)小学生和初中生为研究样本,运用收敛混合方法构建一个面向我国教育实际的、经严格论证的中小学生计算思维量表。结果显示:经过两轮的收敛混合分析,修改后的计算思维量表共包含5个因子及15个题项,具有良好的内容效度;经过大样本实证检验分析,量表具有良好的信效度,且具有跨性别、年级和地区测量等值性,可以用来测量中小学生的计算思维水平。

冻结重塑黏土分数阶蠕变本构模型分析

人工冻土的蠕变特性受温度场、水分场、应力场的相互影响,而传统的岩土本构模型未能考虑温度、含水率等因素。为了表达冻土介于理想固体和理想流体之间的某种“勾兑效应”,基于岩土的经验模型,将分数阶导数理论引入其中,建立受水、热、力三场耦合影响的人工冻土分数阶蠕变模型。将西安某煤矿黏土重塑并进行不同温度、含水率的单轴抗压和单轴蠕变试验,得到温度和含水率对冻结重塑黏土强度特性和蠕变特性的影响规律。分析冻结重塑黏土在不同负温、含水率及两种应力等级下的蠕变曲线,得到lg t-lgε曲线的线性关系,进而得出冻结重塑黏土分数阶蠕变模型相关参数与温度、含水率的函数关系。对比分数阶冻土蠕变模型试验值与计算值,发现该模型能够很好地反映冻土在不同应力等级下其蠕变随温度和含水率的变化规律,对指导寒区冻土工程设计与施工具有重要意义。

考虑截面规则性的柱状节理岩体变形及强度特性研究

柱状节理岩体的复杂结构使其现场力学参数的确定存在困难,可靠地估计柱状节理岩体强度及变形特性对工程安全至关重要。结合Voronoi图形及3D打印技术制作不规则柱状节理岩体光敏树脂模具,并制备了具有不同倾角的规则及不规则柱状节理岩体试样。基于开展的单轴压缩试验结果,分析不同截面柱状节理岩体的变形及强度特性差异。根据试样最终破坏形态,揭示柱状节理岩体破坏模式及机制。结合已有研究结果,描述节理面材料对柱状节理岩体破坏形态及强度的影响。基于传统节理系数方法,提出了更能反映柱状节理岩体柱体结构特征的修正节理系数方法。采用修正节理系数法建立规则及不规则柱状节理岩体试验结果与现场变形及强度参数间的经验关系,将所提出计算公式应用于白鹤滩水电站工程,预测结果与现场实测值及RMR法(RMR为岩石质量评分指标)、Q法(Q为岩体质量指标)的预测值进行比较。结果表明,对于现场变形和强度参数,所提出的修正节理系数法的预测结果与现场实测结果较为吻合。

经验知识监督的RC墩柱力学性能神经网络分析方法

基于试验或数值模拟的单一墩柱力学性能分析方法难以兼顾计算精度和效率,纯数据驱动的分析方法存在可解释性差和对数据依赖性强等问题。为此,本文通过研究钢筋混凝土(RC)墩柱力学性能试验数据、经验知识和机器学习的融合机制,提出了经验知识监督的RC墩柱力学性能神经网络(knowledge-guided neural network,KGNN)分析方法。首先,建立了包含761组RC墩柱拟静力试验样本的数据库;随后,基于经验知识分析了RC墩柱主要特征对其力学性能的影响规律,构建了相应的数学表征方法;最后,将RC墩柱试验数据及经验知识融入人工神经网络架构和训练过程,建立了高精度、可解释、可通用且不依赖大量训练数据的RC墩柱力学性能KGNN分析模型。本文提出的KGNN分析方法与纯数据驱动神经网络(BPNN)的结果对比表明:BPNN在测试集上表现更好,在分析墩柱承载力时均方根误差(E)和拟合系数(R^(2))分别为0.070和0.978,KGNN模型的E和R^(2)分别为0.108和0.942;但由于BPNN所预测的墩柱特征对承载力的影响规律与经验知识并不吻合,即未能准确反映墩柱特征与其力学性能间的关系,BPNN模型发生了过拟合;而KGNN方法不仅可以快速准确获得RC墩柱力学性能,且预测规律与经验知识吻合较好,具有更高的可靠性和实用性。因此,融合试验数据与经验知识的神经网络有望成为一种新的RC结构力学性能分析方法。

青海省多年地表感热通量的时空变化特征

选取青海省35个气象站观测数据,基于CHEN-WENG感热系数方案,计算了1980—2017年青海省地表感热通量。利用小波分析、Mann-Kendall突变检验和经验正交函数法(Empirical Orthogonal Function,EOF),对感热通量的时空变化特征及其影响因子进行分析。结果表明:(1)1980年以来,青海省全年和各季节感热通量总体上均呈上升趋势,并具有28 a的主周期和约18 a的副周期,冬季的周期变化较为复杂;(2)全年和各季节感热通量与地气温差存在显著相关性,2004—2017年受地气温差增大的影响上升;(3)全年、春季和秋季感热通量与风速存在显著相关性,1980—2004年受风速减小的影响感热通量下降;(4)夏季降水与感热通量呈显著负相关;(5)从空间上看,全年以及春季感热通量呈现出显著的东西分异,秋、冬季表现出一定程度的南北分异。