探讨影响滚齿温锻加工质量的因素

影响滚齿温锻加工质量的因素是多方面的,现从齿轮滚刀的选择,滚齿温锻的原理及工艺特点,影响滚齿温锻加工传动精度和接触精度误差的因素及提高滚齿温锻生产率的措施进行了探讨。     

浅谈渐开线齿轮滚刀的基本蜗杆

齿轮是机械传动主要应用零件,在工厂中普遍使用渐开线齿轮滚刀对齿轮进行加工。现通过对滚齿加工过程的实际与理论分析研究探讨渐开线齿轮滚刀基本蜗杆。     

重型卡车传动轴滑动花键磨损试验装置的结构分析与优化设计

根据陕汽重卡提出的大功率重型卡车传动轴试验装置的要求,考虑到国家研发1 000匹马力发动机的技术条件,结合国家汽车行业标准QC/T 523—1999,研发了数控重型卡车传动轴滑动花键磨损试验装置。该装置采用闭环控制,将机械能直接回用设计,以伺服电机和同轴减速机给被测零件在旋转中施加扭矩载荷,以液压缸驱动横向往复滑动。该装置使用方便、试验精度高、节能效果显著。文章介绍了传动轴滑动花键磨损试验方法,给出了试验装置的相关技术参数,并对试验装置的整体结构组成和主要技术内容进行了分析。     

重型卡车传动轴滑动花键磨损试验装置的结构分析与优化设计

根据陕汽重卡提出的大功率重型卡车传动轴试验装置的要求，考虑到国家研发1000匹马力发动机的技术条件，结合国家汽车行业标准QC/T 523-1999，研发了数控重型卡车传动轴滑动花键磨损试验装置。该装置采用闭环控制，将机械能直接回用设计，以伺服电机和同轴减速机给被测零件在旋转中施加扭矩载荷，以液压缸驱动横向往复滑动。该装置使用方便、试验精度高、节能效果显著。文章介绍了传动轴滑动花键磨损试验方法，给出了试验装置的相关技术参数，并对试验装置的整体结构组成和主要技术内容进行了分析。     

抓住功能分析与方案创新——研制“组合式”矩形花键拉刀

<正>我国近四十年来用的20CrmnTi齿轮,这类低碳合金钢材质的花键孔拉削,长期存在不少弊病。从我厂多年来使用五个工具厂家近千支矩形花键拉刀进行拉削的情况来看,拉刀的综合价值偏低,可以归结为三点:一是拉削精度功能差,其产品合格率不足50％;二是拉削速度低(有时不足1米/分);三是使用寿命短,年统计每把拉刀平均切削长度仅100米。     

一种单凹槽端盖式滚珠花键副晃动量的检测方法

文章主要是介绍一种单凹槽端盖式滚珠花键副晃动量的检测方法,通过利用在平台上给固定的花键轴一轴端施加重力,利用不平衡关系通过千分表检测花键轴两端微小的晃动量,并通过实际操作检测证明此方法可精确检测出滚珠花键副的晃动量,并判定是否合格。     

一种单凹槽端盖式滚珠花键副晃动量的检测方法

文章主要是介绍一种单凹槽端盖式滚珠花键副晃动量的检测方法,通过利用在平台上给固定的花键轴一轴端施加重力,利用不平衡关系通过千分表检测花键轴两端微小的晃动量,并通过实际操作检测证明此方法可精确检测出滚珠花键副的晃动量,并判定是否合格。     

2号极压润滑冷却液的研究及其应用

本文论述了２号极压润滑冷却液在Ｙ３８滚齿机上的试验研究及其应用，并对滚刀的耐有度及滚刀使用寿命进行分析，在获得大量可靠数据的基础上取得了令人满意的效果，为２号极压润滑冷却液推广应用提供了可靠的依据。     

宫颈电刀锥切术诊治宫颈病变86例分析

目的 探讨宫颈电刀锥切术在诊治宫颈上皮内瘤变 (CIN)及早期浸润癌中的临床价值.方法 回顾性分析86例患者临床资料,对比阴道镜下宫颈多点活检与宫颈锥切后病理报告.结果 86例宫颈锥切术患者中17例(19.5%)术后病理检查较阴道镜下宫颈多点活检病变级别升高,锥切术后标本中切缘阳性2例(2.3%)均接受了再次手术.结论 宫颈锥切术是宫颈上皮内瘤变的高级确诊手段,阴道镜下宫颈多点活检不能代替宫颈锥切术.     

塑料模具异形镶件的机械综合加工工艺改进及探讨

随着消费者对塑料制件的外观美观性和质量要求等不断提升,一些异形镶件塑料加工产品成为内高端塑料加工产品的必要技术部分,通过使用有效的模具,设计制造出不同的异形镶件,提升塑料之间的复杂度和美观性。就目前塑料模具异性镶件加工现状来看,其中也存在一定的工艺技术难点,本文介绍了塑料膜具异形镶件的基本技术应用,分析目前塑料模具异形镶件加工中存在的主要问题,探究机械综合加工工艺改进在异形镶件中的有效应用。     

汽车花键轴间隙测控系统的设计与分析

对花键轴间隙测控系统的设计原理以及结合比例极限分析法在花键轴角度间隙分析中的应用进行研究,从快速、精确的角度出发,论述花键轴间隙测控系统的总体设计方案、软件系统构成的特点以及关键算法。     

Asymptotics and smoothing parameter selection for penalized spline regression with various loss functions

Penalized splines are used in various types of regression analyses, including non‐parametric quantile, robust and the usual mean regression. In this paper, we focus on the penalized spline estimator with general convex loss functions. By specifying the loss function, we can obtain the mean estimator, quantile estimator and robust estimator. We will first study the asymptotic properties of penalized splines. Specifically, we will show the asymptotic bias and variance as well as the asymptotic normality of the estimator. Next, we will discuss smoothing parameter selection for the minimization of the mean integrated squares error. The new smoothing parameter can be expressed uniquely using the asymptotic bias and variance of the penalized spline estimator. To validate the new smoothing parameter selection method, we will provide a simulation. The simulation results show that the consistency of the estimator with the proposed smoothing parameter selection method can be confirmed and that the proposed estimator has better behavior than the estimator with generalized approximate cross‐validation. A real data example is also addressed.     

Modelling the spatiotemporal distribution of the incidence of resident foreign population

Many European countries have recently experienced a substantial increase in the proportion of immigrants in their populations. The incidence of resident foreigners calculated at a national level does not provide information on the local spatial and temporal distribution of the phenomenon. This information may be of crucial importance for planning local policies. In this article, we suggest a tool for practitioners to provide spatiotemporal maps representing the local distribution of the incidence of resident foreigners in the territory, and changes in spatial trends over time. We illustrate this with Italian data at a municipal level, for the period 2003–2008. To account for spatiotemporal interactions in the data, we propose using a generalized additive model incorporating a smoother of the time and space dimensions. Specifically, we set up a tensor product smoother combining a cubic regression spline basis for time and a soap film spline basis for space. This approach provides a consistent framework to produce spatiotemporal maps which could be effectively used by policy makers to decide the allocation of economic resources at a local level.     

基于C语言对三次样条函数的求解及程序

在解三次样条函数时,最后都要归结为求解三对角型方程组。根据此类方程组的特点,该文介绍了一种追赶法,推导了使用这种方法的消元过程和回代过程,并给出了求解此类方程组的通用C语言程序,大大地节省了计算机工作量和计算机存贮单元。     

Time Series Modelling of Daily Tax Revenues

We provide a detailed discussion of time series modelling of daily data in general and daily tax revenues in particular. The main feature of the daily tax revenue series is the pattern within calendar months. Standard time series methods for seasonal adjustment and forecasting cannot be used since the number of banking days per calendar month varies and because there are two levels of seasonality: between months and within months. We propose a daily time series model based on unobserved components that allows for the classic decomposition into trend, seasonal plus irregular, but it also includes components for intra-monthly, trading-day and length-of-month effects. Such components typically rely on stochastic cubic spline, polynomial and dummy variable functions. State space techniques are used for the recursive computation of the likelihood and forecasts functions with special allowance for irregular spacing. The model is operational for daily forecasting at the Dutch Ministry of Finance. We present the model specification and discuss estimation and forecasting results up to December 1999. A comparative forecast evaluation is also presented.     

Optimal design of nonlinear experiments with parameter constraints

The nonlinear regression model with N observations y _i=η(x _i,θ) +ε_i, and with the parameter θ subject to q nonlinear constraints C _j (θ)=0; j=1, …,q, is considered. As an example, the spline regression with unknown nodes is taken. Expressions for the variances (variance matrices) of the LSE are discussed. Because of the complexity of these expressions, and the singularity of the variance matrix of the LSE for θ, the optimality criteria and their properties, in particular the convexity and the equivalence theorem are considered from different aspects. Also the possibility of restriction to designs with limited values of measures of nonlinearity is mentioned. Research supported by the VEGA-grant of the Slovak grant agency No. 1/7295/20.     

圆锥螺纹量规中径测量方法探讨

在汽车行业对圆锥螺纹量规质量要求不断提升的同时，对测量准确度也提出了进一步的要求。本文分析了圆锥螺纹塞规几种测量方法的优缺点，着重探讨了用万能工具显微镜测量圆锥螺纹中径方法以及用螺纹塞规检验螺纹环规方法。     

减量训练和停训对大鼠坐骨神经超微结构的影响

研究大负荷运动损伤后减量训练和停训大鼠坐骨神经超微结构的变化。方法:建立动物运动损伤模型及减量训练和停训模型。利用透射电子显微镜观察各组大鼠坐骨神经超微结构的变化。结果:①大负荷运动组坐骨神经超微结构严重损伤。②减量训练组坐骨神经超微结构基本恢复正常,新生神经纤维产生。③停训组部分髓鞘结构基本完整,但仍有灶状髓鞘脱失和崩解。结论:减量训练更有利于损伤坐骨神经组织结构的修复。     

车削圆柱中消除回转体锥度的创新方法

本文阐述了在车削加工专业的实习教学中,圆柱工件表面易产生锥度的原因,消除锥度的传统方法,在车工教学实践中发现的新方法可以方便、有效地消除锥度,具有实用性强的良好效果。通过介绍一种极为方便简捷的操作方法,采用运动合成原理,解决了普通或数控车床加工圆柱体过程中产生锥度的问题。     

Additive cubic spline regression with Dirichlet process mixture errors

The goal of this article is to develop a flexible Bayesian analysis of regression models for continuous and categorical outcomes. In the models we study, covariate (or regression) effects are modeled additively by cubic splines, and the error distribution (that of the latent outcomes in the case of categorical data) is modeled as a Dirichlet process mixture. We employ a relatively unexplored but attractive basis in which the spline coefficients are the unknown function ordinates at the knots. We exploit this feature to develop a proper prior distribution on the coefficients that involves the first and second differences of the ordinates, quantities about which one may have prior knowledge. We also discuss the problem of comparing models with different numbers of knots or different error distributions through marginal likelihoods and Bayes factors which are computed within the framework of Chib (1995) as extended to DPM models by Basu and Chib (2003). The techniques are illustrated with simulated and real data.