Application of cross validation techniques for modelling construction costs during the very early design stage

Building client/owners need estimates of likely construction costs for budgeting purposes early in the procurement process when little detailed design information is available beyond the type, size and location of the facility. One of the more sophisticated techniques available for this purpose is the storey enclosure method, developed by James in 1954. This uses the basic physical measurements of the building envelope, together with an arbitrary set of multipliers, or weights, to forecast tender/bid prices. Although seldom used in practice, James succeeded in showing his method to be capable of significantly outperforming alternative approaches.

The research reported in this paper aimed firstly to reassess James’ claims with new data and secondly to advance his method by using regression techniques to obtain the weights involved. Based on data from 138 completed Hong Kong projects for four types of building, two types of regression models were developed. This involved the use of sophisticated features such as leave-one-out cross validation to simulate the way in which forecasts are produced in practice and a dual stepwise selection strategy that enhances the chance of identifying the best model. An algorithm was also designed to select the appropriate parametric and non-parametric tests for objective and rigorous model evaluation against alternatives.

The results indicate that, contrary to James’ claim, both his original method and the two regression-based alternatives are not significantly better or worse than other models. Surprisingly, the widely used floor area model was found to under-perform in terms of consistency for offices and private housing. For private housing in particular, it was felt that the storey enclosure method was likely to offer good prospects of improvement on those methods currently in use in practice.     

对沈大高速公路服务区考察的思考

通过对建筑实例的考察详细地表述了沈大高速公路在改扩建过程中对服务区规划设计、单体建筑为适应未来新的发展趋势而重新定位的实践,尤其在功能拓展、地域个性化风格形式和管理模式的合理定位问题上引发了今后对高速路服务区设计的思考。     

以昆明为例谈如何构建和谐街道景观

对城市街道的功能和街道景观的不和谐因素进行了论述，阐明街道景观设计中需要和谐化的设计，并归纳、提炼出构建“和谐”街道景观的原则和方法。     

对郑州市城市规划与城市发展的几点看法

通过对郑州市城市发展现状和城市规划的认识，经过分析，提出了几条有关郑州市城市规划、域市发展方向和城市建设的建议，对郑州市城市特色和城市人口发展也提出了一些看法。     

平面交叉口交通控制与管理不安全因素分析

在现场调查分析交通标志、标线、信号设置存在问题,视距不良、交叉路口交通组织和渠化不当等的基础上,总结了公路平面交叉口在交通控制与管理方面常见的9个不安全因素。运用事故折减系数(CRF)统计数据分析了不安全因素引起事故的可能性,采用汽车碰撞理论分析与专家调查结合的方法,进行各事故类型的严重性分析,进一步确定了各不安全因素的危险性指数,得到其危险性排序,为交叉口安全诊断和安全保障研究提供了依据。     

上海海港新城自行车交通规划探讨

虽然我国城市自行车道路一直在演变中改善,但是自行车交通与城市交通系统运行效率仍有待提高。在遵循可达性、空间分离、道路容量适中的原则下,芦潮港新城规划中提出了设置双向自行车专用道的非对称道路断面的设想。     

城市道路路边停车设置方法研究

静态交通同动态交通一样是城市道路交通的一部分,静态交通不仅是交通问题,而且是一个土地利用问题,城市土地有限,不可能满足静态交通需求,还需要在不影响动态交通情况下,设置路边停车,才能即满足停车需求。本文从研究路边停车设置着手,提出了路边停车设置条件和方法,以规范路边停车设置和管理,改善道路交通秩序,充分利用道路空间,缓解城市道路交通拥挤程度。     

以弗莱堡市为例看当今欧洲城市新区发展趋势

通过对德国弗莱堡市在不同历史阶段的城市发展分析,展现了欧洲城市的几个典型阶段的发展特征及其空间构成特点;并以此为背景来分析建于20世纪90年代的城市新区Rieselfeld的设计思想、建设阶段和城市空间及建筑单体构成特色。     

大城市快速交通对周边小城镇发展规划的影响--以武汉市横店街规划为例

交通问题源于人类克服空间障碍的实践.管子云:山川涸落,天气上,地气下,万事交通.交通的发展促进着社会的进步和发展,交通的发展水平往往成为一个国家或地区进步的标志.快速干道作为现代交通建设不可或缺的重要组成部分,在城市和区域发展中越来越凸显其不可忽略的指导性作用.在带动大城市地区周边小城镇发展的同时也对其规划发展形成难以逾越的障碍.进而进一步影响大城市的扩张.     

基于Elman经网络的深基坑变形智能监测

Elman神经网络是一种典型的动态递归神经网络，它既可以学习空域模式，又可以学习时域模式，能使训练好的网络具有非线性和动态特性。文章采用11个输入单元和1个输出单元Elman神经网络。利用Maflab提供的神经网络工具箱编写了Elman神经网络程序，可以通过几种监测数据来推测另一种监测数据。最后以一幢超高层建筑的深基坑工程为例．说明了Elman神经网络方法用于深基坑变形的预测具有较好的可靠性，通过不断加入新的数据，Elman神经网络程序所能判断的数据类型和精度均不断提高。