Impacts of Disk Rock Sample Geometric Dimensions on Shear Fracture Behavior in a Punch Shear Test

Punch shear tests have been widely used to determine rock shear mechanical properties but without a standard sample geometric dimension suggestion.To investigate the impacts of sample geometric dimensions on shear behaviors in a punch shear test,simulations using Particle Flow Code were carried out.The effects of three geometric dimensions(i.e.,disk diameter,ratio of shear surface diameter to disk diameter,and ratio of disk height to shear surface diameter)were discussed.Variations of shear strength,shear stiffness,and shear dilatancy angles were studied,and the fracture processes and patterns of samples were investigated.Then,normal stress on the shear surface during test was analyzed and a suggested disk geometric dimension was given.Simulation results show that when the ratio of the shear surface diameter to the disk diameter and the ratio of disk height to the shear surface diameter is small enough,the shear strength,shear stiffness,and shear dilatancy angles are extremely sensitive to the three geometric parameters.If the ratio of surface diameter to disk diameter is too large or the ratio of disk height to surface diameter is too small,a part of the sample within the shear surface will fail due to macro tensile cracks,which is characterized by break off.Samples with a greater ratio of disk height to shear surface diameter,namely when the sample is relatively thick,crack from one end to the other while others crack from both ends towards the middle.During test,the actual normal stress on the shear surface is greater than the target value because of the extra compressive stress from the part of sample outside shear surface.

A New Test for Large Dimensional Regression Coefficients

In the article, hypothesis test for coefficients in high dimensional regression models is considered. I develop simultaneous test statistic for the hypothesis test in both linear and partial linear models. The derived test is designed for growing p and fixed n where the conventional F-test is no longer appropriate. The asymptotic distribution of the proposed test statistic under the null hypothesis is obtained.

Experimental validation of a signal-based approach for structural earthquake damage detection using fractal dimension of time frequency feature

This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.

AUTO CAD在确定盒形件毛坯尺寸时的应用

讨论了用 AUTO CAD实现滑移线方法确定盒形件毛坯尺寸的详细过程 ,所得结果正确、可靠。该方法使用简单 ,通用性强 ,对于制定各种形状的盒形件的毛坯尺寸具有很重要的实用价值。

Auto CAD与高级语言标注尺寸的联接及应用

本文主要解决Auto CAD与高级语言标注尺寸的联接及应用问题。实践证明,本联接软件通用性强,是一个非常实用的软件。

一种实用的机械 CAD 工具系统

通过建立机械ＣＡＤ常用符号库（ＳＹＭＬＩＢ），并以ｄＳＡＳＥ构造符合国家标准的公差数据库，在ＡｕｔｏＣＡＤ环境下方便快捷地实现机械图的初始状态、尺寸公差、形位公差、表面粗糙度、各类特性参数表格等常用符号或图形的自动绘制与标注。

用Auto CAD2000进行机械二维图形的设计

叙述了用AutoCAD2 0 0 0进行机械二维图形设计的各种技巧 ,并详细介绍了绘图时的环境设置、图形绘制、标注及绘图输出等。

Auto CAD环境下的尺寸公差自动查询与标注

介绍了AutoCAD环境下机械CAD的尺寸公差自动查询和标注的方法 ,给出按公差与配合的国家标准 (GB180 0 - 180 4 - 79)开发的尺寸公差标注系统实用软件。

Auto CAD环境下尺寸公差自动查询与标注软件的开发

运用VBA语言开发出一套Auto CAD环境下公差自动查询与标注软件,以良好的人机交互界面让用户方便地一次完成查找尺寸公差和标注尺寸公差两项工作,有效提高了绘图效率,在工程绘图中有较大的实用价值。

Auto CAD的标注技巧

本文从实际出发 。

机械CAD中Auto CAD功能的扩展

本文介绍了作者使用Auto CAD软件包过程中,扩展的一套用于该软件包的各种类型的自动标注尺寸函数、粗糙度函数和形位公差函数。这些函数解决了机械CAD中尺寸、粗糙度以及形位公差标注十分繁杂困难的问题,使用十分方便,且类型齐全,在利用AutoCAD作为支撑软件的机械CAD中具有很高的使用价值。

用Auto CAD标注符合国标的标高符号

用Auto CAD来绘制土木工程图,用户必须解决标高符号的标注问题。本文介绍Auto CAD中用带有属性的图块,把标高符号数值定义为可变属性进行插入来标注标高符号的方法,完全符合国家标准。

浅谈Auto CAD尺寸设置

在工程制图中,不同场合需要的标注方式是多种多样的,即便是同一个直径标注,也有多种表现方式。在Auto CAD中,可设置多个不同的尺寸样式(大样式),配以不同的样式名,而每一个大样式又可分别针对不同类型的尺寸(半径、直径、线形、角度)进一步设置。

High-dimensional proportionality test of two covariance matrices and its application to gene expression data

With the development of modern science and technology, more and more high-dimensionaldata appear in the application fields. Since the high dimension can potentially increase the com-plexity of the covariance structure, comparing the covariance matrices among populations isstrongly motivated in high-dimensional data analysis. In this article, we consider the proportion-ality test of two high-dimensional covariance matrices, where the data dimension is potentiallymuch larger than the sample sizes, or even larger than the squares of the sample sizes. We devisea novel high-dimensional spatial rank test that has much-improved power than many exist-ing popular tests, especially for the data generated from some heavy-tailed distributions. Theasymptotic normality of the proposed test statistics is established under the family of ellipticallysymmetric distributions, which is a more general distribution family than the normal distribu-tion family, including numerous commonly used heavy-tailed distributions. Extensive numericalexperiments demonstrate the superiority of the proposed test in terms of both empirical sizeand power. Then, a real data analysis demonstrates the practicability of the proposed test forhigh-dimensional gene expression data.

基于Auto CAD的正等轴测图的绘制与标注

Auto CAD既可以用三维建模的方式绘制三维实体,也可以用绘制轴测图的方法在二维平面内展示三维形体。文章阐述基于Auto CAD绘图环境下平面体与曲面体正等轴测图的绘制方法,及其文字与尺寸标注方法与技巧。

Robust U-type test for high dimensional regression coefficients using refitted cross-validation variance estimation

This paper aims to develop a new robust U-type test for high dimensional regression coefficients using the estimated U-statistic of order two and refitted cross-validation error variance estimation. It is proved that the limiting null distribution of the proposed new test is normal under two kinds of ordinary models.We further study the local power of the proposed test and compare with other competitive tests for high dimensional data. The idea of refitted cross-validation approach is utilized to reduce the bias of sample variance in the estimation of the test statistic. Our theoretical results indicate that the proposed test can have even more substantial power gain than the test by Zhong and Chen(2011) when testing a hypothesis with outlying observations and heavy tailed distributions. We assess the finite-sample performance of the proposed test by examining its size and power via Monte Carlo studies. We also illustrate the application of the proposed test by an empirical analysis of a real data example.

Heart-Rate Analysis of Healthy and Insomnia Groups with Detrended Fractal Dimension Feature in Edge

Insomnia,whether situational or chronic,affects over a third of the general population in today’s society.However,given the lack of non-contact and non-inductive quantitative evaluation approaches,most insomniacs are often unrecognized and untreated.Although Polysomnographic(PSG)is considered as one of the assessment methods,it is poorly tolerated and expensive.In this paper,with the recent development of Internet-of-Things devices and edge computing techniques,we propose a detrended fractal dimension(DFD)feature for the analysis of heart-rate signals,which can be easily acquired by many wearables,of good sleepers and insomniacs.This feature was derived by calculating the fractal dimension(FD)of detrended signals.For the trend component removal,we improved the null space pursuit algorithm and proposed an adaptive trend extraction algorithm.The experimental results demonstrated the efficacy of the proposed DFD index through numerical statistics and significance testing for healthy and insomnia groups,which renders it a potential biomarker for insomnia assessment and management.

Sufficient dimension reduction in the presence of controlling variables

We are concerned with partial dimension reduction for the conditional mean function in the presence of controlling variables.We suggest a profile least squares approach to perform partial dimension reduction for a general class of semi-parametric models.The asymptotic properties of the resulting estimates for the central partial mean subspace and the mean function are provided.In addition,a Wald-type test is proposed to evaluate a linear hypothesis of the central partial mean subspace,and a generalized likelihood ratio test is constructed to check whether the nonparametric mean function has a specific parametric form.These tests can be used to evaluate whether there exist interactions between the covariates and the controlling variables,and if any,in what form.A Bayesian information criterion(BIC)-type criterion is applied to determine the structural dimension of the central partial mean subspace.Its consistency is also established.Numerical studies through simulations and real data examples are conducted to demonstrate the power and utility of the proposed semi-parametric approaches.