谈钢筋优化下料降低成本

钢筋作为建筑结构的灵魂和骨架,具有单价高、用量多的特点,在土建中占到30%-40%的造价,所以钢筋的成本控制成为了一种非常有效的管理手段。在成本管理过程中,钢筋下料的控制对企业降本增效起着决定性作用。文章通过线性规划方法在钢筋下料中的应用,以达到提高经济效益的目的。     

氧乙炔焰切割输油管线的操作技术

采油厂的输油管线在长期的使用过程中,由于腐蚀、老化等原因,易出现穿孔、管壁变薄等各种情况,针对输油管线内部残留油气等可燃物、残余压力,在施工条件复杂时容易发生事故的特点,利用改进氧乙炔焰切割工艺,提高输油管线维修和更换工作的安全性和工作效率。     

CAXA软件在数控线切割实践教学中的应用

本文以CAXA软件作为数控线切割教学平台,阐述了CAXA软件在线切割绘图编辑以及零件加工中的应用,改变了传统的教学模式,使教学效果显著提高。数控线切割实训,旨在提高工科院校学生的实践能力、自主创新能力。     

纵轴式掘进机截割头运动参数对截割载荷的影响分析

对影响纵轴式掘进机截割载荷的运动参数进行了分析,在ANSYS中建立了纵轴式掘进机截割头截割煤岩的有限元模型,并基于LS-DYNA对其截割过程进行了仿真分析,获得了截割载荷随时间的动态变化曲线。针对截割过程中对截割载荷影响较大的运动参数,包括截割头钻进速度、摆动速度和转速等对截割载荷的影响进行了比较分析。仿真结果表明,截割载荷随截割头钻进和摆动速度的增大而增加,随截割头转速的增大有所降低。分析结果为合理选取截割头运动参数及提高截割头的截割性能提供了理论依据。     

Fair and square: Cake-cutting in two dimensions

We consider the classic problem of fairly dividing a heterogeneous good (“cake”) among several agents with different valuations. Classic cake-cutting procedures either allocate each agent a collection of disconnected pieces, or assume that the cake is a one-dimensional interval. In practice, however, the two-dimensional shape of the allotted pieces is important. In particular, when building a house or designing an advertisement in printed or electronic media, squares are more usable than long and narrow rectangles. We thus introduce and study the problem of fair two-dimensional division wherein the allotted pieces must be of some restricted two-dimensional geometric shape(s), particularly squares and fat rectangles. Adding such geometric constraints re-opens most questions and challenges related to cake-cutting. Indeed, even the most elementary fairness criterion–proportionality–can no longer be guaranteed. In this paper we thus examine the level of proportionality that can be guaranteed, providing both impossibility results and constructive division procedures.     

浅谈PASSIM机组水松纸切割系统的常见故障与排除

本文详细的介绍了帕西姆(PASSIM)机组的水松纸切割原理,在日常生产过程中产生水松纸切割故障的原因、解决方法及预防措施。     

抚育采伐作业对保留木的影响

抚育采伐的目的是在未成熟的林分中,为了给保留木创造良好的生长条件,通过采伐部分林木的手段,改善林内光照条件,为保留木增加营养面积,同时进行人工选择,提高林木产品产量,所以抚育采伐对采伐木和保留木都必须有严格的选木要求。没有正确的选木就没有林木的优质丰产,就不能实现间伐的既定目的。     

风机盘管冷凝水盘加工工艺研究

本文对风机盘管冷凝水盘的加工工艺方案进行了系统研究,创新地提出了包括盘体钣金件分步拉伸工艺方案、海绵滚压成型工艺方案、海绵电热切割工艺方案等一整套加工工艺方案。工艺方案经实践证明切实可靠,研究结果对冷凝水盘的生产具有重要的实际指导意义。     

渝怀线贺家田车站深孔松动控制爆破方案

文章介绍渝怀线贺家田车站深孔松动控制爆破施工，并对邻近障碍物的高边坡路堑石方爆破施工及防护进行探讨，为同类工程施工提供经验。     

Automatic Editing for Business Surveys: An Assessment of Selected Algorithms

Statistical offices are responsible for publishing accurate statistical information about many different aspects of society. This task is complicated considerably by the fact that data collected by statistical offices generally contain errors. These errors have to be corrected before reliable statistical information can be published. This correction process is referred to as statistical data editing. Traditionally, data editing was mainly an interactive activity with the aim to correct all data in every detail. For that reason the data editing process was both expensive and time-consuming. To improve the efficiency of the editing process it can be partly automated. One often divides the statistical data editing process into the error localisation step and the imputation step. In this article we restrict ourselves to discussing the former step, and provide an assessment, based on personal experience, of several selected algorithms for automatically solving the error localisation problem for numerical (continuous) data. Our article can be seen as an extension of the overview article by Liepins, Garfinkel & Kunnathur (1982). All algorithms we discuss are based on the (generalised) Fellegi–Holt paradigm that says that the data of a record should be made to satisfy all edits by changing the fewest possible (weighted) number of fields. The error localisation problem may have several optimal solutions for a record. In contrast to what is common in the literature, most of the algorithms we describe aim to find all optimal solutions rather than just one. As numerical data mostly occur in business surveys, the described algorithms are mainly suitable for business surveys and less so for social surveys. For four algorithms we compare the computing times on six realistic data sets as well as their complexity.