滚齿加工误差分析与检验组(之二)Ⅱ.齿轮的径向误差与检验项目

本文是“滚齿加工误差分析与检验组”一文的第二部分。这部分的主要内容是分析与研究滚齿加工时产生径向误差(亦称几何偏心)的原因,径向误差的合成方法、特征,径向误差与检验项目的关系、数学模型、几何意义。     

滚齿加工误差分析与检验组(之三)Ⅲ、齿轮的切向误差与检验项目

本文是“滚齿加工误差分析与检验组”一文的第三部分。这部分的主要内容是分析与研究滚齿加工时产生切向误差(亦称运动偏心)的原因,切向误差的特征,切向误差与检验项目的关系、数学模型等。     

滚齿加工误差分析与检验组(之七) Ⅶ.轴向误差与检验项目

本文是“滚齿加工误差分析与检验组”一文的第七部分。这部分的主要内容是论述轴向误差的产生原因,数学模型以及轴向误差与第Ⅲ公差组之间的关系。     

滚齿加工误差分析与检验组(之六)——Ⅵ.机床周期误差刀具误差及齿形误差

本文是“滚齿加工误差分析与检验组”一文的第六部分。这部分的主要内容是论述机床周期误差、刀具误差对齿形误差的影响,导出了有关计算的数学模型以及与第Ⅱ公差组的关系。     

滚齿加工误差分析与检验组(之四) Ⅳ.偏心误差的合成与补偿

本文是“滚齿加工误差分析与检验组”一文的第四部分。这部分的主要内容是分析与研究滚齿加工时既有几何偏心又有运动偏心的情况下应如何考虑其合成与补偿方法、数学模型和几何意义。通过补偿,可以减少加工误差(偏心误差)对齿轮加工精度的影响。     

滚齿加工误差分析与检验组(之五) Ⅴ.公差组及检验项目

本文是“滚齿加工误差分析与检验组”一文的第五部分。这部分的主要内容是论述齿轮新标准中的公差组与检验项目之间的关系:第Ⅰ公差组与几何偏心及运动偏心之间的关系。     

回转支承滚齿加工质量提升方案

回转支承中外齿式齿轮目前主要采用滚齿的加工方式。根据现行回转支承相关行业标准中齿轮的技术要求,分析齿轮的加工工艺,提出回转支承中提升外齿式齿轮加工质量的有效措施。     

用微小分齿误差法滚切大质数斜齿轮

本文介绍了滚动大质数齿轮的运动调整,微小分齿误差法的基本原理及减小分齿误差的方法,并作了应用举例。     

在无差动装置的滚齿机上滚切斜齿圆柱齿轮

斜齿圆柱齿轮的轮齿一般多在有差动装置的滚齿机上切制。下面要讨论的是,在无差动装置的滚齿机上如何切制斜齿圆柱齿轮。 在无差动装置的滚齿机(如广东顺德机床厂曾生产的Y35型)上滚切斜齿圆柱齿轮,机床无须作任何改动,也不需增加任何附件,只是分齿挂轮的计算与滚切直齿时不同。现以Y35型滚齿机(无差动装置)为例,介绍分齿挂轮的计算方法。 1.滚切直齿时分齿挂轮的计算 Y35型滚齿机滚切直齿圆柱齿轮时,分齿挂轮a、b、c、d的计算公式如下:     

改造滚齿机实现直齿锥齿轮滚切加工

设备修理时,经常要更换直齿锥齿轮,但锥齿轮要在专用机床刨齿机上加工。而一般厂家无此设备,通常在铣床上用成形法加工,精度及表面粗糙度很难达到要求;有时用成形法铣削加工的成形模数铣刀又不齐全,使锥齿轮的加工根本无法进行。为此,结合设备大修理,对普通旧Y38-1滚齿机应用数控技术实施技术改造,在不影响原使用性能的前提下,可实现直齿锥齿轮的滚切加工,解决了设备维修中锥齿轮加工的难题。 一、滚齿机滚切锥齿轮原理 图1中ω_刀为齿轮滚刀的回转速度,ν_刀为齿轮滚刀的垂直     

我国资信评级业发展的现状及趋势

资信评级是社会信用体系的主题内容之一,而社会信用体系是现代市场经济运行的基础。面对正在蓬勃发展的资信评级市场,本文就其发展现状和未来趋势做较为深入地分析和阐述。     

The Role of Planning and Workplace Support in Returning to Work after Maternity Leave

The paper reports a longitudinal study of the post‐pregnancy work outcomes for full‐time working women who were pregnant with their first baby. Regression analyses revealed that women who did not return to work as intended were differentiated from those who did return to work by the amount of planning they had done in pregnancy, as well as having lower pre‐natal income and less anti‐cipated support within the workplace. Almost one third of those who returned to work part‐time reported reduced job status. The study shows the importance of workplace planning and support in return to work after maternity leave.     

The intertemporal stability of the concentration-margins relationship in Dutch and U.S. manufacturing

Factors influencing price-cost margins are investigated using a rich panel data base of the Dutch manufacturing sector. Attention is devoted to the intertemporal stability of the relationship explaining price-cost margins and to a comparison with U.S. results. Our results indicate that isolated cross-section analyses can be misleading. Evidence is provided for similarities and dissimilarities between the U.S. and the Netherlands when explaining price-cost margins. Dutch margins are influenced by industry-specific factors such as sales changes, import competition, capital intensity and operating expenses. Domestic seller concentration, aggregate capacity utilization and export intensity play no distinct roles.This research was sponsored in part by the Economics Research Foundation, which is part of the Netherlands Organization for Scientific Research. We wish to thank H. W. de Jong, Leo Sleuwaegen, David Audretsch and Aad Kleijweg for their useful comments.     

Introduction: Deregulation and Reform of Housing and Housing Finance Markets: Recent Lessons from Western and Central Europe

Recent years have seen the emergence of substantial scholarly research devoted to cross-national comparisons of real estate markets and financial institutions. In part, these analyses evaluate real estate market efficiency and the distributional outcomes associated with diverse institutions and economies. Further, these analyses draw from the experience of different markets and institutions in a normative sense, so as to help facilitate the development of appropriate real estate market mechanisms and policy in emerging market economies.     

The impact of survey characteristics on the measurement of food consumption

Survey characteristics affect the quality of the measurement of food consumption within households; thus, it is important to identify best practices for designing surveys that collect food data. This paper analyses the impact of survey characteristics on the measurement of food consumption from a sample of 81 national surveys. Results highlight regularities that can inform best practices in designing surveys and promoting the use of the data for multiple purposes. Surveys focused on food acquisition collect higher food quantities compared to those that target food consumption. Surveys based on recall interviews collect higher food quantities compared to those based on diaries, but the difference decreases with long reference periods. The use of standard units of measurement as well as the consideration of partakers in meals and of seasonality generates significant differences in the survey results. The impact of the different survey characteristics carries substantive implications when food consumption data are employed for assessing food security conditions. The results are part of a wider work program aimed at improving the quality of household survey data. More evidence is needed, ideally through coordinated sets of analyses and experiments in different contexts. Additionally, survey characteristics must be complemented by effective field work in order to generate high quality data. Towards this end, statistical capacity development is crucial to promote better data and more evidence-based decision making.     

The impact of interfirm relationships on investment: Evidence from the Polish dairy sector

Financial constraints and credit market imperfections are a major constraint on investment, growth and poverty reduction in transition and developing countries. This paper analyses the impact on investments of financial assistance programs as part of interfirm relationships. Our empirical evidence is based on a two-stage survey methodology. Qualitative evidence on dairy companies’ assistance programs was gathered in the first stage through in-depth interviews at the level of the dairy companies. Quantitative data on 290 milk producing rural households in Poland was collected through a random survey in the second stage. The empirical analysis shows that dairy companies have played an important role in financial assistance, in particular for dairy-specific investments. In addition, they had an important indirect impact on farm activities and investments through feed supply and loan guarantee programs.     

对国外石油化工行业的考察与思考

介绍了国外石油化工行业的发展趋势和主营业务的发展方向，以及国外公司在保持公司核心竞争力上所采取的战略。通过对跨国石油公司在公司的发展定位，组织结构的设置，生产与经营管理，面临的环保挑战等方面分析，提出中国石油化工企业参与国际竞争应改进的几个方面。