分层法车削超大梯形螺纹

石油化工企业有许多大型设备,超大梯形螺纹在设备中经常能用到,超大梯形螺纹车削是车工常见的技术难题,由于车削加工难度较大,对操作者的技能要求较高,因而操作起来较为困难.为了解决此难题,介绍了操作简单、易理解和易掌握的“分层”车削方法.     

基于虚拟加工的数控车削优化探析

随着车削技术的不断进步,人们对于数控车削优化的关注度也逐渐增强。为了做好车削加工过程优化,提升加工效率,就需要了解数控车削加工工艺,文章基于虚拟加工的数控车削优化的实证分析,希望可以对虚拟加工技术和数控车削优化有一个全面的认识与了解,从而为后续的研究奠定基础。     

浅谈钛合金的车削加工特性分析

针对钛合金材料的加工难点,文章进行了车削加工方法的探索和研究。从刀具材料的选择、几何角度的选择以及切削参数的选择上,优选出合理的工艺方案,为今后广泛使用钛合金零部件提供了车削加工依据。     

典型零件车削工艺的分析

锥体螺纹轴和偏心工件是车削常见加工零件,加工这类零件要会分析其结构和加工特点。根据零件的技术要求和结构的复杂程度,掌握其车削加工工艺,才能保证零件的各项技术要求。     

运用宏程序在数控车床上实现环面蜗杆的车削

本文对直廓环面蜗杆的加工方法提出了新的思路和新的方法,就数控车床车削环面蜗杆的关键问题进行了较为全面的分析,并采用宏程序成功实现直廓环面蜗杆在数控车床上的车削加工。     

面向数控车削的CAD/CAM集成应用研究

本文主要分析了数控车削的CAD/CAM集成应用研究中常见的一些管理漏洞和存在问题,阐述了在当前形势下,加强数控车削集成技术运用的重要性,针对目前数控车削系统工作中存在的问题进行研究。笔者通过研究,总结和归纳自身多年工作经验,提出一些加强集成系统应用的对策。希望通过本文的分析能帮助相关企业单位提高工作水平和质量,能更好地应对工作中存在的问题。     

偏心轴类零件的车削加工

偏心轴类零件的车削加工有很多种方法,每种方法有着自身所适合的环境与加工工艺的要求,文章通过对偏心轴类零件车削加工的几种方法的介绍与分析,确定出不同方法所适合的加工条件与要求,从而能更好地针对不同的加工工艺的要求,采用不同的车削加工方法,满足车削加工的需要。     

轴类零件和盘套类零件的车削工艺

一个零件能用不同的加工方法制造,而在一定条件下仅有某一种方法是合理的。本文主要阐述了轴类零件的技术要求、车削加工等车削工艺,盘套类零件的技术要求、内孔加工等车削工艺。     

细长丝杠车削方法的改进

细长丝杠螺纹的大径与其长度之比为1：30及其以上时，称为细长丝杠。由于其长径比较大，在机械加工过程中，机床、刀具等整个工艺系统极易弯曲和振动，加工后不能获得满意的表面粗糙度和几何精度。因此，文章探讨细长丝杠车削改进的方法，以解决细长丝杠的车削难题。     

机器人柔性车削加工单元设计研究

柔性加工是当前机械制造自动化的发展方向,柔性加工单元因特别适合中小企业的需要,其发展潜力和推广空间十分巨大。文章利用自动上下料技术,构建机器人柔性车削加工单元;分析了单元的车削加工工艺流程,并重点描述了单元中的关键设备如机器人、自动上料机、复合手爪及激光测径仪的设计方案。该机器人柔性车削加工单元可广泛应用于轴类零件的自动化生产。     

Multifactor productivity and its determinants: an empirical analysis for Mexican manufacturing

The aim of this paper is twofold. First, we estimate production functions for the Mexican manufacturing sector and for 14 comprehensive groups, allowing us to construct various measures of multifactor productivity. Second, we analyse some of the determinants of productivity growth. We find that, on the one hand, there is a positive relationship between market concentration and technology adoption; on the other hand, both technology adoption and human capital promote productivity, whilst market concentration exerts a negative influence on it. Our results suggest that, once controlling for the effect on technology adoption, more concentration impacts negatively productivity growth.     

低流压高泵效井成因分析及治理措施

低流压、高泵效的油井一方面增加了杆管的疲劳损耗,降低杆管的使用寿命,减短了油井的检泵周期,增加开采成本;另一方面会降低动态控制图合理率,影响油井管理指标,极大影响了油田正常生产与油田生产管理。科学有效地对低流压、高泵效井进行成因分析与制定恰当的治理措施对于油田健康和谐发展具有重要意义。笔者在文中通过对理论泵效公式剖析及实例分析,分析了造成油井低流压高泵效的原因,并在此基础上提出了相应治理措施。     

重庆市区域物流与区域经济互动机理研究

中央直辖市的设立,开辟了重庆发展的新天地。区域物流在促进地区经济发展的过程中起着举足轻重的作用。为了验证重庆区域物流与区域经济增长的互动关系,作者以统计分析为基础,建立数量模型来分析重庆区域物流与区域经济的内在联系,最后证实重庆区域物流可以促进该区域经济的发展;另一方面随着经济不断增长和对物流固定资产投资的不断增加,也可以加快区域物流产值的迅速提升。     

Measurement of technical efficiency in farrow-to-finish swine production using multi-activity network data envelopment analysis: evidence from Taiwan

This study aims to propose a dynamic multi-activity network data development analysis (DMNDEA) model to measure the technical efficiency of farrow-to-finish swine production in Taiwan. Production phases are explicitly divided into two activities; namely, the breed-to-farrow phase and the wean-to-finish phase. By using this model, the problem of shared inputs and dynamic intermediates among activities that characterize pig production are taken into account in an integrated framework, simultaneously with the consideration of non-zero slack, allowing us to examine aspects of production in a more comprehensive and factual manner. For the empirical results based on sample data from 2006 to 2007, it is shown that the overall technical inefficiencies obtained from DMNDEA are not obviously different from those obtained using a traditional one-stage model. However, the DMNDEA results explicitly show us that the sources of inefficiency for each farm are different. Furthermore, second-stage bootstrapping regression results reveal that the determinants of efficiency for each production phase are not the same, indicating the need to identify the influential factors for each production phase separately.     

平面误差测量数据的计算机辅助分析软件开发

平面度误差测量中常采用旋转法处理数据,使之符合最小条件,从而计算出平面度误差,但手工处理过程复杂,工作量大。使用自主开发的计算机辅助分析软件,不仅可以提高运算速度,而且可以通过CAD图形分析模块的分析,给生产加工提出指导性的意见。     

基因的法律地位研究

随着人类基因图组的公布,世界进入基因时代。科技的进步是把"双刃剑",我们一方面在享受基因技术给我们带来的利益,另一方面也生活在基因风险带来的困惑当中。如何确定基因的法律地位从而对其进行有效规制和保护,显得尤其重要。针对基因的性质和法律地位,文章从基因与基因信息入手,从而分析出基因之中存在的法律关系与利益,确定其法律地位。     

Regional Production and Cost Minimization in the Republics of the Former Soviet Union

After the disintegration of the Soviet Union, the problems encountered early in the reforms made it obvious that understanding the system and structure of the economy during the Soviet period was crucial for predictions and recommendations. The present study analyzes the production of the republics of the former Soviet Union, by grouping them into the regions defined by common geographical and historical conditions, and by estimation of cost functions that represent the two major theories of international trade: the Heckscher-Ohlin and Ricardo-Viner models. The estimated parameters of the cost functions allow us to draw conclusions about the achievement of cost minimization and to calculate the elasticities that represent the comparative statics of both models. As a result of the analysis, it is demonstrated that the achievement of the cost-minimization goal depends on local conditions.     

The joint impact of labour policies and the “Great Recession” on unemployment in Europe

The paper consists of an empirical analysis of the separate as well as joint impacts on total and youth unemployment of indicators of labour market policies on the one hand, and the financial crisis associated with the “Great Recession” on the other. In particular, we investigate labour market data in the past two decades for the Enlarged Europe and adopt a variable accounting for the idiosyncratic severity shock of the crisis. This time-varying and country-specific crisis variable enables us to test empirically and in a novel way the joint impact of labour market policies and the economic crisis on labour market dynamics even when accounting for common macro shocks.     

SUBSTITUTION ELASTICITIES IN A CONSTANT ELASTICITY OF SUBSTITUTION FRAMEWORK – EMPIRICAL ESTIMATES USING NONLINEAR LEAST SQUARES

Elasticities are key parameters for any economic analysis. Using the World-Input–Output Database, we estimate substitution elasticities for a three-level nested constant elasticity of substitution KLEM production structure using up to date nonlinear least squares estimation procedures. This allows us for the first time to use one coherent data set for the estimation process. Furthermore, it gives us the opportunity to derive elasticities from the same data which researchers can use to calibrate their models. On the basis of our estimations, we demonstrate that the practice of using Cobb–Douglas or Leontief production functions in economic models must be rejected for the majority of sectors. We provide a comprehensive set of estimated substitution elasticities covering a wide range of sectors. Our results suggest that no substantial change in input substitutability takes place during the time period we consider. Moreover, there is no substantial variation in substitution elasticities across regions.     

The Measurement of Consumption Efficiency Considering the Discrete Choice of Consumers

In this study we propose a mathematical definition of the consumption efficiency of multi-attribute products in the price–quality space. A new model, the discrete Range Adjusted Measure (RAM) model, is suggested as an empirical tool to measure the level of consumption efficiency. We further discuss the effect of consumption efficiency on the innovation incentive. Empirical work is made for the mobile phone market. We expect that the consumption efficiency concept will contribute to the extension of the traditional framework of production efficiency analysis on the one hand and to the understanding of the nature of innovation in a technology-intensive market on the other hand.JEL Classification: C67, D11, D12, D21