荷载形状对钢桥面铺装力学响应的影响

针对轮胎接地形状的不规则性,构造理想传力垫层、运用三维有限元接触分析方法分析了矩形、椭圆、长圆3种简化荷载形状在具有不同单轮横向宽度及两轮中心距时铺装层的力学响应。结果表明单轮横向宽度与两轮中心距对横向拉应变有较大影响,而矩形形状荷载计算结果较椭圆和长圆形状荷载小。与实测数据的对比分析表明:以往计算采用的单轮横向宽度偏小,长圆荷载的计算结果与实测值更接近,在用简化矩形均布荷载分析钢桥面铺装力学响应时,单轮横向宽度与两轮中心距应该尽量按实际情况选取,并进行荷载形状修正。     

3 S技术在公路勘察设计中的应用

3S(GPS、RS、GIS)及其集成技术在公路勘察设计中的应用,使公路勘察设计实现内外业一体化、自动化、设计方案最优化成为可能,结合工程实际分别简要介绍了3S及其集成技术在公路勘察设计中的应用。     

石砌U型高桥台破坏机理及加固改进对策研究

石砌U型高桥台是西部山区公路建设中广泛采用的结构形式,也是一个受力复杂的砌体结构,在填土荷载和车辆荷载作用下经常发生局部开裂破坏,其破坏机理尚不清楚,为了研究其破坏机理并解决局部开裂破坏问题,本文采用常规U型桥台及钢筋混凝土圈梁及倒角加固改进后的10∶1模型进行试验研究,并进行了三维有限元分析。通过试验及计算结果,基本摸清了其破坏机理,并验证所采用的改进方法简单可靠。     

地铁民用通信建设相关问题考虑

本文主要对地铁民用通信建设规划和实施时的一些关键问题作个简单分析，并就建设中遇到的实际问题作主要说明．     

船体三维建模技术研究

研究在Pro/E环境下船体三维建模的过程和方法,以“通达2号轮”为例进行建模设计,着重研究了船体构件的创建以及装配过程,对生产过程进行数值模拟,建立船舶特征参数化图库以提高建模的效率。     

Two- or three-layered box-models versus fine 3D models for coastal ecological modelling? A comparative study in the English Channel (Western Europe)

The general trend in ecosystem modelling is to improve the spatial resolution by shifting from rough box-models to fine 3D models. Despite the continuous speeding-up of computing, 3D models involving numerous state variables may remain intractable, especially for parameter calibration, when processes with long half-life periods (i.e, from years to decades) are introduced, such as the behaviour of organic matter in sediment and population dynamics of benthic species. In these cases, a first approach can be provided by fast-running box-models, if they take into account the most crucial hydrodynamic properties of the system. In a macrotidal shelf sea such as the English Channel, the long-term horizontal transport can be summarized by the tidal residual circulation, and the vertical stratification can be sketched by a two- or three-layered integral model.This paper compares the results obtained in the English Channel area by the same biogeochemical equations of pelagic primary production, coupled to 1) a two-layered box-model 2) a three-layered box-model (i.e., with an intermediate cline layer between surface and bottom ones) and 3) a fine-gridded 3D model. Comparison is focused firstly on thermal stratification and summer dinoflagellate blooms in the north-western Channel and secondly on the haline stratification and the sequence of blooms obtained in the eutrophicated Seine river plume. Comparison shows that box-models act as low-pass filters which reproduce correctly the weekly mean time-course, but greatly reduce the variance locally observed in a tide-oscillating plume region. As far as global characteristics are concerned, such as the annual primary production, or the percentage of variation in annual production after reducing the nutrient loadings, the box and 3D models gave very similar results. This conclusion reinforces the usefulness of using box-models as a first approach in long-term processes, for which a long transient phase is expected before reaching the annual periodic solution.     

工程造价实行"三控"制度的探讨

对工程项目的规划、设计、施工等阶段影响工程造价的因素,进行了分析;对工程项目各阶段实行工程造价控制的主要措施,进行了初步探讨。     

基于S3C2410TK开发平台的嵌入式导航系统应用研究

随着嵌入式设备的日臻完善，导航系统正逐渐向小型化、专业化方向发展。文章介绍了SAMSUNG公司推出的基于ARM920T内核的S3C2410TK硬件开发平台．讨论了以EVC＋＋4．O为系统软件开发工具，实现对城区GIS的GPS导航。重点介绍了多线程技术，电子地图的读取和显示等关键技术。     

电弧喷涂工艺参数对3Cr13涂层性能稳定性的影响

采用正交设计方法研究了电弧喷涂工艺参数对 3Cr13涂层结合强度和耐磨性的影响。试验结果表明 :影响涂层性能稳定性的工艺参数主要是电弧电流 ,其次是喷涂距离。按涂层结合强度和按磨损失重确定的空气压力与电弧电压两个因素的主次排列顺序不同。当电弧电流一定时 ,喷涂距离过大或过小都不利于涂层性能的稳定性 ,且喷涂距离和空气压力为反向组合时涂层性能稳定性最差。涂层中的孔隙率和氧化物的数量是造成涂层性能变化波动的主要原因 ,采用较大的电弧电流可减少涂层中的孔隙率和氧化物数量 ,有利于涂层的致密性增强 ,涂层强度高 ,耐磨性也好。     

进口A333Gr.3低温钢焊接工艺评定及现场焊接

分析了进口低温不锈钢A333Gr.3的焊接性,通过分别采用焊后热处理和焊后不进行热处理两种方案进行焊接工艺评定试验,制定了合理的低温甲醇洗涤装置主蒸汽管现场焊接工艺参数及工艺措施。试验结果表明:该钢的焊接性良好,焊后不进行热处理更有利于提高焊接接头的低温韧性。