智能制造背景下数控技术专业人才培养模式改革的思考

智能制造是我国制造业转型升级的发展方向,但是,目前我国高职院校培养的数控技术技能人才还不能适应智能制造岗位的需求,企业迫切需要高职院校加快数控技术专业人才培养模式改革。高职院校中的学生技能单一、师资力量薄弱、实训设备落后等问题亟待解决。高职院校需要准确定位数控技术专业人才培养目标,重新构建数控技术专业课程体系,完善数控技术专业实训条件,建设数控技术专业“双师型”教学团队,加强校企合作,推动“1+X”试点工作等。     

一维六方准晶中正方形孔边双裂纹的反平面问题

本文通过引入合适的保角映射函数,充分利用复变函数方法和解析函数理论,研究一维六方准晶中正方形孔边两不对称裂纹的反平面问题。在孔周及裂纹面为自由表面的假设下,结合数值保角映射函数和复变函数中的Cauchy积分公式,得到声子场和相位子场耦合作用下复势函数的近似解,并且给出裂纹尖端应力强度因子和能量释放率的显示表达式。数值算例讨论裂纹长度和正方形边长对场强度因子的影响规律。     

黄土泥岩接触面滑坡工程防护的数值模拟

以晋陕蒙接壤区黄土泥岩接触地带滑坡为工程研究背景,分析研究黄土泥岩接触面滑坡的工程防护。通过室内试验确定了黄土的基本物理力学参数。利用FLAC2D数值软件,对地区常见的挡墙和锚索工程防护措施,针对坡脚为15°和25°的滑坡模型进行了工程防护的数值模拟,对比其防护效果,并给出工程建议。     

低码率TCMDS／SSMA系统在衰落信道下的性能

将高效网格编码调制（ＴＣＭ）应用于室内慢衰落信道下的直接序列扩频多址（ＤＳ／ＳＳＭＡ）系统中，提出了一种分析ＴＣＭＤＳ／ＳＳＭＡ系统性能的方法。理论分析和模拟表明，在系统用户数、用户信源比特速率和伪码周期相同的前提下，通过消除并行路径和增大最短错误分支长度等适当编码方法，采用低码率ＴＣＭ的ＤＳ／ＳＳＭＡ系统较与Ｕｎｇｅｒｂｏｅｃｋ型ＴＣＭ相结合的ＤＳ／ＳＳＭＡ系统具有更好的性能。     

相关瑞利衰落信道上自适应MQAM的性能分析

采用L条支路最大比合并分集接收的相关瑞利衰落信道容量,推导恒定发射功率自适应M进制正交幅度调制的频谱效率,并将它们与独立同分布瑞利衰落信道理论容量进行比较。数值结果阐明相关性和天线设置对瑞利衰落信道容量和自适应M进制正交幅度调制性能的影响。     

Numerical Method for Reliability Analysis of Phased-Mission System Using Markov Chains

This article presents a numerical method for solving continuous time Markov chain (CTMC) model for reliability evaluation of phased-mission system. The method generates infinitesimal matrix based on the statistical independence of subsystem failure and repair process. The infinitesimal generator matrix is stored by the use of sparse matrix-compressed storage schemes, and the transient solution of the CTMC model is obtained by using three methods including the uniformization method, forward Euler method, and Runge-Kutta method, which take advantage of the sparseness of the infinitesimal generator matrix. An example PMS is used to compare the preconditioning methods for sparse matrix and numerical methods. Experiment results show that compressed row storage scheme (CRS) saves more storage than other storage formats, and uniformization method combined with CRS achieves the best efficiency and accuracy.     

Efficient survey sampling of households via Gaussian quadrature

Summary.  The collection of data through surveys is a costly and time-consuming process, particularly when complex economic data are involved. The paper presents an efficient approach, based on Gaussian quadrature, to survey sampling when some information is available about the target population. Using household data from Mozambique, we demonstrate that Gaussian quadrature subsamples, based on relatively easy to observe household characteristics such as size and educational attainment of members, generate better estimates of the moments of household expenditure than random samples of equal size.     

The random intrinsic fast initial response of one-sided CUSUM charts

This article analyses the performance of a one-sided cumulative sum (CUSUM) chart that is initialized using a random starting point following the natural or intrinsic probability distribution of the CUSUM statistic. By definition, this probability distribution remains stable as the chart is used. The probability that the chart starts at zero according to this intrinsic distribution is always smaller than one, which confers on the chart a fast initial response feature. The article provides a fast and accurate algorithm to compute the in-control and out-of-control average run lengths and run-length probability distributions for one-sided CUSUM charts initialized using this random intrinsic fast initial response (RIFIR) scheme. The algorithm also computes the intrinsic distribution of the CUSUM statistic and random samples extracted from this distribution. Most importantly, no matter how the chart was initialized, if no level shifts and no alarms have occurred before time τ?>?0, the distribution of the run length remaining after τ is provided by this algorithm very accurately, provided that τ is not too small.     

Probabilities of Failure in Mixed Acceptance Sampling Schemes

Mixed acceptance sampling schemes are commonly used for consumer protection. In a typical application, a sample is taken from a product lot and tested to check that the average value of the sample is not less than the labelled net content, and that there is no 'unreasonable' deficiency in any individual item. Exact and approximate expressions are obtained for the probabilities of failure or success under such schemes and under a variety of conditions.     

Generalized Estimating Equations to Binary Probit Model

Inference in generalized linear mixed models with multivariate random effects is often made cumbersome by the high-dimensional intractable integrals involved in the marginal likelihood. This article presents an inferential methodology based on the generalized estimating equations for the probit latent traits models. This method belonging to the broad class of semi parametric approaches involves marginal joint moments of order 1 and 2, which has analytical expression. The different results are illustrated with a simulation study.