悬臂式开卷机四棱锥套的分析与改进

本文主要研究悬臂式开卷机四棱锥套的结构及受力,分析失效原因,利用Solid Works软件对开卷机卷筒的两个主要零件(卷筒四棱锥套和扇形板)建模仿真,进行有限元分析,并提出改进方案。     

提高矿山测量验收精度的改进方法和措施分析

矿山测量作为矿山生产建设的基础,即对矿山生产过程开展地质测量来实现矿山作业的顺利推进以及资源的有效开发。本文结合新疆地区铝土矿开采的实际情况,简要探究如何实现露天矿山验收测量精度的提高。     

一种新型开卷机卷筒设计及应用

当前开卷机的结构为十字头拉板式,无法安装轴承和与拉杆连接,本文针对现有的开卷机存在的缺点,设计了一种拆卸方便、快速的开卷机卷筒。结果表明拆卸时只需抽出、插入销即可完成拉杆和旋转液压缸的离合,快捷方便,具有较好的经济效益。     

矿井测量中测量精度控制与优化

矿井测量工作是煤矿生产建设的基础性工作,在对矿井的设计、矿井的基础建设以及煤矿的生产作业都起着至关主要的作用。在矿井的测量工作中,对测量精度控制和优化的好坏将决定着煤矿企业的发展。本文首先介绍矿井测量工作中影响测量精度的因素,然后重点分析探讨测量精度的控制和优化。     

RTK测量精度分析

GPSRTK作为21世纪的一项高新技术,因其定位精度高、测量速度快、劳动强度低等特点被广泛应用。本文就是从GP—SRTK的基本原理出发,分析测量误差因素,探讨RTK在控制测量中的应用特点及精度大小。通过GPSRTK实际观测作业得到工程实践数据,再用GPSRTK实际测量的数据与常规控制测量得到的数据进行比较,分析了GPSRTK的测量精度,检验RTK是否可以满足控制测量精度要求,精度可靠程度如何。     

浅谈煤矿测量精度的提高

精准的煤矿测量保证了煤矿企业的安全生产和运营,是煤矿开采工作的重点项目之一,相关方面的研究受到了人们的广泛关注。本文在对现代煤矿测量技术作出论述的同时就提高煤矿测量精度的措施进行了探讨和分析。     

基于重卷机组的开卷取恒张力控制系统

本文以宝钢五冷轧冷卷准备机组为工程实例,介绍了基于西门子传动工艺控制板T400的开卷取恒张力控制系统,并对其中的关键技术进行了深入分析。     

关于大尺寸长度测量修正值

用钢卷尺测量大尺寸长度分为平测和悬测两种情况。测量修正值的大小与所用的钢卷尺和两端的水平张拉力关系极大,测量修正时一定要保证卷尺和张拉力都要符合标准的规定。     

热轧生产线生产热轧板卷的板型改善研究

文章全面分析当前热轧生产线生产热轧板卷的板型构造,深入研究轧后板形和横向厚差、板形控制等技术上的精准参数,从而更好地实现板形控制技术。     

浅述基坑变形测量方法及观测精度、频次的确定

基坑变形测量多为对基坑顶部进行水平位移观测,测量方法有视准线法、小角度法、极坐标法等。一般取观测中误差不大于允许变形值的1/10~1/20为变形观测的精度。变形观测频次的确定本着实用原则,既要能正确反映变形点的变化过程,又不得漏掉变化时刻。     

在储量核实中勘探线剖面测量应注意事项探讨

地质剖面测量贯穿于矿产普查与勘探的各个阶段,在储量核实的过程中,地质剖面测量占据着不可取代的地位。剖面测量工作是开展其他地质工作的基础,开展剖面测量工作要适应地质要求、注重经济实用,更重要的是要增加高科技含量。在测量的过程中,要合理地选择测量方法,尽量削弱误差带来的影响,进而提高工作效率。     

基于地形图量测的架空送电线路平断面图制作方法

纸质版1∶10000地形图经过扫描数字化,利用Hough变换直线检测算法提取其方里格网点的图像坐标,分别与格网点的理论坐标组成同名点对,利用仿射变换原理对其进行几何纠正后,可用于架空送电线路初步设计阶段平断面的制作。     

Information precision and asymptotic efficiency of industrial markets

I present a strategic model of a bilateral oligopoly with asymmetric information to examine (i) the validity of the conjecture of price-taking behavior in such markets as the number of agents becomes large and (ii) the effect of the rate that individual information precision decreases with increased number of agents on convergence to price-taking and efficiency. I show that with downstream competition, increasing the number of sellers may make all participants price-takers in the limit, but increasing the number of buyers may not. When the total precision of information in the market is high, price-taking and full social efficiency is achieved in the limit with large numbers of buyers and sellers. However, if the total precision of information in the market is poor, price-taking conjecture may fail and large inefficiencies, including full inefficiency, can occur in the limiting outcome. The rate of decrease of individual information precision with increased number of agents determines the rate of convergence to efficiency, and the convergence is slower than that predicted by single-unit auction models in the literature. I also demonstrate that when the number of sellers or both the number of buyers and the sellers go to infinity, price-taking and information aggregation tend to go together. When the number of buyers goes to infinity, however, information can get aggregated when the agents do not become price-takers in the limit. Albeit, in the latter case, the aggregated information is masked by the noise in the sellers’ signals and the cost variability.     

下动式折弯机几何精度调整

文章以AMADA公司生产的RG系列折弯机为例,介绍下动式折弯机几何精度调整的方法,为同类设备精度调整提供了参考。     

Random group effects and the precision of regression estimates

When explanatory variable data in a regression model are drawn from a population with grouped structure, the regression errors are often correlated within groups. Error component and random coefficient regression models are considered as models of the intraclass correlation. This paper analyzes several empirical examples to investigate the applicability of random effects models and the consequences of inappropriately using ordinary least squares (OLS) estimation in the presence of random group effects. The principal findings are that the assumption of independent errors is usually incorrect and the unadjusted OLS standard errors often have a substantial downward bias, suggesting a considerable danger of spurious regression.     

High precision registration of complicated longitudinal and cross-sectional data

In the article are given examples showing how, by using musical notation in registering (complicated) developments, considerably more qualitative variables may be taken into account than we were used to; furthermore, the temporal element may be represented with a degree of precision that corresponds to our needs. In case of cross-sectional data modifications of musical notation may be used. However, we have to recognize that there are also variables, maybe important ones, that — for several reasons — cannot be registered with a very high precision. Other complications are hinted at. The method described is rather a working method by means of which to improve the basis for a further quantitative analysis than a method suitable for showing final research results.     

Meanings of measurement

Abstract

In public domains, performances – also in ambiguous fields like policing – are controlled, by making them transparent, by comparing them, and by linking them to targets. Although this ‘numerical capture' of complex phenomena has been heavily criticized, management by measurement is blossoming and in specific cases, measurements like crime monitoring have played a role in reducing crime. The question, however, is whether such improvements are caused by distinctive measurement methods, or by ‘something else'. This paper will analyze how one particular measurement method, the so-called Rotterdam ‘Safety Index', contributed to safety policies. It will show how this dubious instrument is made meaningful; how, indeed, ‘something else' is at work. Political and administrative key players made certain moves in order to ‘link', ‘store', and ‘advocate' the Safety Index. These acts, moreover, occurred amidst distinctive socio-political conditions. Because of ‘acts in context', the Index became a workable tool, producing tangible effects.