数控折弯机的使用技巧

随着通信、医疗、数控等行业需求的增加,钣金制造业不断扩大,对钣金加工设备的要求越来越高,每个企业都希望扩大设备的功能与加工范围,以便提高加工能力,提高生产效率。本文以数控折弯机的日常使用为基础,详细描述了数控折弯机的使用技巧,并以实际加工为例,简述了数控折弯机的功能扩展,为充分发挥数控折弯机使用效率提供了新的思路。     

基于校园已有建筑物沉降监测网的水准测量一体化教学模式与实现

《建筑工程测量》是实践性很强的一门课程,积极探索教学新模式,将工程项目融入课程教学工程中,将教学内容模块化,营造工程项目的真实场景,教学过程模拟施工现场开展,营造工程项目工作流程。本文将《建筑工程测量》中水准测量的教学内容模块化,与建筑物的沉降观测进行项目一体化教学,保证了"理论与实践,实践与项目"相结合。     

Minimum Moment Method for Resource Leveling Using Entropy Maximization

The minimum moment method for resource leveling is revisited and restated as an entropy-maximization problem. The minimum moment method assumes that the moment of the daily resource demands about the horizontal axis of a project’s resource histogram is a good measure of the resource utilization and that the optimal resource allocation exists when the total moment is at a minimum, thus when the resource histogram is of rectangular shape. The entropy-maximization method proposed in this paper makes use of the general theory of entropy and two of its principal properties (subadditivity and maximality) to revisit the minimum moment method for resource leveling. The entropy-maximization method presented allows for activity stretching and provides resource allocation solutions that show improvement over previous approaches. A case study is also presented that validates the results.     

库尔勒市区GPS高程与水准高程的比较分析

介绍了利用GPS测定地面点高程的基本原理,将库尔勒市区GPS E级网的GPS高程与水准高程进行了比较分析,讨论了GPS高程的拟合方法和所能达到的精度.     

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According to the elastic- plastic bending theory, the straightening reduction could be calculated by the curvature integral method. The 3D dynamic finite element model of bimetal composite plate was established during straightening process. And then the change rules of longitudinal displacement of composite plate and the influence on the residual stress of composite plate under different reduction procedures during straightening process were analyzed by simulation. The results show that the part of the initial wave shape can be eliminated in initial pass time, and the crown of straightened plates can be largely reduced after properly increasing the subsequent inflection during the straightening process, residual stress of the plate is small and uniformly distributed. The flatness of straightened composite plate is complied with the national standards.     

Application of atomic force microscopy and scaling analysis of images to predict the effect of current density, temperature and leveling agent on the morphology of electrolytically produced copper

Atomic force microscopy (AFM) was used to study the morphology of electrodeposited Cu at current densities from 183 to 253 A m⁻². Digital image analysis was employed to parameterize the morphological information encoded in AFM images and to extract information concerning the mechanism of the electrodeposition reaction. It has been shown how the limiting roughness, δ, the critical scaling length, L_c and the aspect ratio, 4δ/L_c, vary as a function of the deposition time and electrodeposition conditions, such as temperature, current density and the amount of organic additives. It has been demonstrated how laboratory experiments of short duration and the scaling analysis of AFM images can be used to predict roughness of the metal sample after 2 weeks of industrial electrorefining.     

Study on a clamping device of leveling equipment mounted on jacket

This paper proposes a novel clamping device for leveling equipment mounted on offshore oil platform jacket,which solves the problem of leveling equipment clamping lifting force of more than 2000 tons.The main features are that lifting force transmits to clamp claw through wedge force amplifier,embed the teeth of claw into the pile,and the embedded depth increases with the lifting force,resulting in a gravitational self-locking function.This theoretical model of clamping device was established,and the force and material characteristic were analyzed,and the feasibility of the theoretical model was verified by thin shell elastic-plastic stability theory and thin-walled structures theory.An experimental prototype of clamping device was produced to test gravity self-locking function and bearable leveling force.Compared with the theoretical model and the experimental results,it proved that the embedded clamping devices have gravitational self-locking function and can meet the need of actual leveling equipment.     

Persistent Scatterers Interferometry detects and measures ground subsidence in Lisbon

Results from the application of Persistent Scatterers Interferometry in Lisbon Metropolitan Area revealed two previously unknown subsiding urban areas: one (Laranjeiras) is located in the center of Lisbon; another (Vialonga) is to be found toward the North, in an industrial region crossed by Lisbon's main highway and railway lines. The two subsiding sectors are bordered by sharp velocity gradients, and the subsidence pattern appears partially delimited by mapped geologic faults. Surface geology and urbanization alone are unable to explain the phenomena. In the Vialonga area, the historical record of water pore pressure shows a clear decline of the levels (up to 65 m in 27 years), providing evidence of over-exploitation of groundwater resources. Limited information from wells drilled inside and outside the subsidence area points to a spatial correlation between the subsidence and the water pressure levels, and suggests that faults could be acting as hydraulic barriers in the aquifer system. The surface subsidence detected is probably caused by compaction of a clay-rich Oligocene-aged aquitard, led by over-exploitation of adjacent aquifers. The same Oligocene aquitard layer is present in the Laranjeiras area, immediately bellow a multi-layered sand-clay-limestone Miocene aquifer, but further work is needed to diagnose the possibility of over-exploitation of groundwater here. In this work we were able to independently confirm the PSI results, by comparing autonomous PSI results processed for the same geographical areas, and by comparing PSI with leveling and continuous GPS derived subsidence velocities, whose close match provided further ground validation of the space-borne PSI technique.     

一种利用精密全站仪实施跨江水准测量的方法

在跨江水准测量原理基础上,提出一种利用精密全站仪实施大跨距跨江水准测量的方法,并结合长江隧道工程介绍了具体的作业方法和量测结果。通过实际量测结果分析证明,该方法可以消除球气差影响。     

红外电磁波三角高程代替等级水准可行性研究

本文从一个测站所能达到的精度出发．用与水准测量类比的方法研究证实了红外电磁波三角高程在一定条件下是可以代替四等水准测量的．