Urban land use,mobility and theory of science: exploring the potential for critical realism in empirical research

Academic discussion where the adequacy of positions within theory of science is illustrated by means of examples from empirical research studies seems to be an area of neglect. The purpose of this paper is to contribute to such a debate, using examples from investigations into the relationship between urban structure and travel behaviour. The main research question of these investigations was whether, and to what extent, urban structural conditions are influencing residents' transportation activity. In other words, is there a causal relationship between urban structure and travel behaviour? Furthermore, we asked whether results from studies of the relationship between land use and transport can provide a basis for predictions about the likely consequences of alternative land-use strategies. The methodology and empirical findings of the studies are discussed in the light of the theory of science position labelled ‘critical realism’, in an attempt to relate theory of science to empirical research, but also in order to contribute to the discussion of the usefulness of this specific approach. Copyright © 2002 John Wiley & Sons, Ltd.     

不同场地条件下水下隧道周围土体位移变化的数值分析

以拟建的哈尔滨松花江隧道为背景,考虑土体—衬砌的材料非线性特性和相互作用,按平面应变假定,建立在不同场地条件下的若干接近实际的有限元计算模型,应用有限元计算软件ANSYS进行数值分析,得出不同场地条件下隧道周围土体位移的分布规律,遴选出了影响水下隧道周围土体变形的部分关键因素,为合理确定隧道覆土层安全厚度提供了一定的理论依据。     

Employing the shared socioeconomic pathways to predict CO2 emissions

Predicting CO₂ emissions is of significant interest to policymakers and scholars alike. The following article contributes to earlier work by using the recently released “shared socioeconomic pathways” (SSPs) to empirically model CO₂ emissions in the future. To this end, I employ in-sample and out-of-sample techniques to assess the prediction accuracy of the underlying model, before forecasting countries’ emission rates until 2100. This article makes three central contributions to the literature. First, as one of the first studies, I improve upon the Representative Concentration Pathways (RCPs) by incorporating the SSPs, which did not exist when the RCPs have been released. Second, I calculate predictions and forecasts for a global sample in 1960–2100, which circumvents issues of limited time periods and sample selection bias in previous research. Third, I thoroughly assess the prediction accuracy of the model, which contributes to providing a guideline for prediction exercises in general using in-sample and out-of-sample approaches. This research presents findings that crucially inform scholars and policymakers, especially in light of the prominent 2 °C goal: none of the five SSP scenarios is likely to be linked to emission patterns that would suggest achieving the 2 °C goal is realistic.     

多因素耦合条件下硫化矿自燃神经网络动态预测模型研究

硫化矿石自燃是多种因素、多场耦合综合作用的结果,是一典型的非线性问题。笔者应用人工神经网络技术,以Matlab软件为平台,通过现场调查和理论分析,建立了矿石含硫量、通风强度、环境温度3因素与硫化矿石自燃之间的预测模型;通过数据样本学习与部分现场监测数据相结合进行模拟,研究表明预测数据与实测结果基本吻合,误差控制在10%以内,取得了较好的效果。该研究为预防硫化矿石自燃提供一个新的思路和方法,具有一定的理论意义和应用价值。     

元胞自动机在矿山地质灾害预测中的应用

本文根据复杂性科学理论,论证了地质灾害系统是一个复杂大系统。元胞自动机（Cellular Automata,CA）是一种重要的复杂性科学研究工具,本文阐述了元胞自动机的基本原理和方法,总结了其基本特点,认为元胞自动机在安全科学与技术领域有着广阔的应用前景,并探讨了其在滑波预测、地下水渗透、岩爆预测等几种矿山地质灾害预测中的应用。     

突变级数法在采空区塌陷预测中的应用

基于突变级数理论,分析影响采空区稳定性的因素(包括采空区体积率、距地表的垂深、地质构造复杂程度、煤层倾角、覆盖层厚度、覆盖层类型等),研究采空区塌陷的预测方法.对各影响因素进行排序并确定各因素指标体系,得到各样本的突变级数,从而对采空区稳定性进行预测.实例验证表明,突变级数法的判断结果符合实际,与神经网络分级法的判断结果一致.可见,基于突变级数理论的采空区塌陷预测方法具有科学性和有效性.     

基于熵权的隧道塌方风险非线性模糊评判方法

隧道塌方风险分析是隧道设计和安全施工的重要环节。首先选取隧道塌方风险评价指标并建立评价指标风险分级标准,在深入分析新奥法隧道施工风险影响因素的基础上,根据隧道塌方风险影响因素具有模糊不确定性和层次性的特点建立隧道塌方风险的模糊综合评判模型。其次,通过研究各因素评价指标取值方法及隶属度函数选取原则,建立评价指标隶属度确定方法。然后针对不同专家工程经验及认知的不同,引入群组决策的思想,基于信息熵理论建立评价指标的权重计算方法。考虑到影响因素对隧道塌方风险影响具有非线性特征,引入非线性模糊运算方法,从而最终建立基于熵权的隧道塌方风险非线性模糊评判方法。最后通过工程实例分析表明了方法的可行性与合理性。     

基于重构相空间充填体变形规律的灰色预测研究

尾砂胶结充填体是非线性力学介质,其变形是能量耗散的复杂过程,必须研究其内在变形规律,才能正确预测采矿过程中充填体的稳定性.对不同配比的尾砂胶结充填体进行力学试验,得出了其应力-应变规律,对安庆铜矿高阶段充填体变形进行了监测.采用自适应滤波原理,研究基于重构相空间的测量数据去噪处理方法.用灰色理论研究充填体变形在相空间中相点距离的演变规律,建立了重构相空间的灰色预测模型.为减小预测误差,对预测结果采用残差模型修正.应用建立的模型,对安庆铜矿高阶段充填体变形进行分析,确定了采场合理回采周期.结果表明,充填体变形具有非线性混沌特性,不同配比的充填体表现出不同的非线性动力学行为,重构相空间能充分展示充填体变形的内在规律.     

基于GA-ELM的冲击地压危险性预测研究

为提高冲击地压预测的效率和准确率,在分析冲击地压影响因素的基础上,提出了一种将遗传算法(GA)与极限学习机(ELM)相结合的冲击地压预测的新方法。为了避免ELM受输入权值矩阵和隐含层偏差随机性的影响,算法采用GA对ELM的输入权值矩阵和隐含层偏差进行优化,建立GA-ELM冲击地压预测模型。利用某矿冲击地压统计数据对该模型进行了实例分析,将ELM、SVM和BP算法预测结果与该模型进行了对比分析。结果表明:GA-ELM模型具有较高的预测精度,可以相对准确、有效地对冲击地压发生的可能性进行预测。     

张集矿综采工作面瓦斯治理措施及效果分析

张集矿属于煤与瓦斯突出矿井,针对目前所开采的17266工作面地质构造条件复杂、瓦斯涌出量大、处于突出危险区等瓦斯治理难题,采取"风排瓦斯、高抽巷穿层钻孔抽采、运输巷、回风巷顺层钻孔抽采和上隅角埋管抽采"等瓦斯综合治理措施,用分源预测法得出工作面绝对瓦斯涌出量为30.3 m3/min。结果表明,工作面的主要瓦斯涌出来源为本煤层瓦斯涌出。工作面风排瓦斯量11.0 m3/min,工作面瓦斯抽采率达63.0%以上。