城市流动性的量化与诊断——基于网络地图数据和可达性模型的方法研究

城市流动性问题的科学诊断能够帮助城市规划在解决城市问题特别是交通问题时更好地对症下药。现有的针对城市可达性或流动性的模型由于受到数据来源和运算条件的限制,更多停留在静态分析和局部分析的层面,缺乏对城市整体流动性的量化描述。研究利用互联网数据和算法程序,提出了覆盖城市所有节点两两之间可达关系的城市流动性标准模型,并在此基础上建立以城市中心、最近商业中心、最近公园以及对外交通设施节点为参照的参照系模型。最后以上海市中心城区为例,运用参照系模型和网络地图数据对城市的整体流动性以及其空间布局情况进行了分析诊断,揭示了上海中心城区在整体可达性上存在的内高外低、东西差异、指状放射等结构特征,并指出了流动性需要改进的主要节点。     

基于演化博弈的建筑工人流动行为研究

建筑劳务市场处于不完全信息条件下,建筑工人流动与用工企业挽留呈现动态博弈关系。运用演化博弈论的思想和方法,构建演化博弈模型,分析不同条件下演化稳定策略,探索用工单位的挽留措施对建筑工人流动行为的影响。结果表明,目前用工模式下,用工单位是否采取挽留措施,建筑工人均会选择流动。政府作为第三方,应该积极推动目前用工模式改革,引导建筑工人有序流动。     

The Tyranny of Small Decisions. Unsustainable Cities and Local Day-to-Day Transport Planning

Though new goals for sustainable cities and transport systems have been developed, decisions and planning at a local level often fail to achieve these ambitions. The purpose of this article is to analyse the factors in local decision-making and planning practice that conduce to urban sprawl and increased car traffic. The article analyses how the conscious application of so-called “day-to-day decision-making and planning”, results in a diminution of planning's role as a strategic tool, in concealment of the environmental impact of increased traffic, in the deprioritization of environmental goals in favour of growth, and in the “tyranny of small decisions”, where the need to make many individual decisions distracts from the achievement of sustainable city and transport systems. Day-to-day decision-making and planning are analysed and described in a case study centring on retail trade on the outskirts of the Swedish town of Örebro.     

浅析伊东丰雄对于“流动性”的转变

在当下电子信息迅猛发展的时代,信息技术已经逐渐成为了人们生活当中不可或缺的一个重要部分,同时也影响着人们的生存观念和生活方式,进而对建筑的设计也产生了不小的影响和冲击。以日本建筑师伊东丰雄获得普利茨克奖为契机,在对伊东丰雄以往作品进行回顾和探讨的同时,从大家所熟悉的空间流动性为线索来解析在伊东丰雄的建筑中所包含的不同寻常的特质以及这种特质的转变。通过对建筑流动性转变的浅析,再次解读伊东在对于建筑创作的过程当中与同僚的不同之处。     

钢管柱柱芯混凝土顶升施工技术

分析了钢管柱混凝土施工的难点和特点,决定采用泵送顶升浇筑法进行混凝土施工。对高流态自密实混凝土进行了试配并通过具体实践,决定采用一次顶升施工工艺,混凝土质量满足要求。     

可液化地基单桩基础离心机模型试验的三维数值分析

文章通过三维水土耦合动-静一体有限元程序DBLEAVES对饱和砂土地基（Dr=40%）单桩基础的离心机模型试验进行模型试验相对应的原型三维有限元数值模拟和分析。对比分析小震（峰值加速度0.08g）和大震（峰值加速度0.47g）情况下的土体加速度、超静孔隙水压、沉降位移以及桩身弯矩等变化规律。其中,地基土的性质采用应力诱导各向异性的交变移动弹塑性模型模拟,基桩采用弹性梁单元模型模拟。结果表明：①超静孔隙水压会“隔断”振动波的传递,当土体接近完全液化时,土表面峰值加速度会明显小于输入波峰值加速度,而当超静孔隙水压比较小时,土表面加速度相对于输入波则可能会放大;②地震时所达到的最大超静孔隙水压比是地基土沉降量的主要因素之一,且一大部分沉降发生在震后的孔压消散期;③数值模拟与模型试验结果的对比分析表明,交变移动模型可以较好地反映土体在交变荷载下的动力响应特性,验证了所采用的DBLEAVES程序和有限元方法的有效性。     

Migration and occupational careers: The static and dynamic urban wage premium by education and city size

Using matched employer-employee full population data on regional migrants in Sweden, this paper addresses the question whether the urban wage premium, and ‘thick’ labour market matching effects, are to be found across all educational groups, and whether the population threshold for these types of effects varies by educational category. Estimating initial wages, average wage level and wage growth 2001-2009, we find similar wage premiums for all workers in the three largest metropolitan areas, but that there are distinct population thresholds for these type of effects, regardless of educational background. However, job search behaviour as explaining dynamic effects over time seems to pertain mostly to those with higher education.     

Aggregate effects and measuring regional dynamics

Empirical models of regional adjustment often control for aggregate effects when estimating the impact of region-specific shocks on local economies. It is, however, difficult to filter out the effects of aggregate shocks—such as oil shocks, uncertainty shocks, or national recessions—because the incidence of these shocks varies across space and time. We propose an improved econometric method to control for this form of spatiotemporal heterogeneity, thereby yielding more accurate estimation of the effects of local shocks on regional economies. Applying the method to US states, we find that labour demand shocks are mostly absorbed through changes in participation; the migration response to these shocks is limited; and recoveries are highly protracted     

建筑业劳务工人职业流动对工人技术水平的影响及对策研究

在我国建筑业,劳务工人的频繁流动使其缺乏连续、逐步提高的技术训练,直接导致这一群体的技术水平和能力难以有效提高。通过主体仿真技术建立建筑业劳务工人职业流动的仿真模型,并引入学习曲线对建筑业劳务工人的技术水平进行模拟,发现存在劳务工人职业流动频繁、用工成本飙升和劳务工人技术水平提升缓慢的现象,其根本原因在于劳务工人的自利倾向、低流动成本和用工单位的相互竞价。仿真实验还研究了技术准入对策和技术激励对策在引导劳务工人的自利倾向、增加劳务工人的流动成本两方面的作用。相应对策的仿真实验表明,技术准入和技术激励两种对策均能有效解决以上问题,其中技术激励的正面作用远大于其导致的成本增加,使激励变得更加重要。     

Thermodynamic and diffusion kinetic studies of the Fe-Co system

The phase equilibria, thermodynamic properties and diffusion mobilities of the Fe-Co system were carefully assessed through the CALPHAD methods. As an indispensable tool, the first-principles calculations were carried out to study the magnetic moments and the enthalpies of mixing of the bcc_A2, bcc_B2, fcc_A1 and hcp_A3 phases as well as the point defect types of the bcc_B2 phase. In order to verify the heat capacities reported in the literature, new measurements were conducted in a high-temperature calorimetric apparatus using the three-dimensional calorimetric method. Because of the revision of the thermodynamic parameters in the present work, the diffusion mobilities for the fcc_A1 phase were reassessed. The diffusion mobilities for the bcc_A2 phase were established for the first time based on the experimental diffusion coefficients. For the low-temperature bcc_B2 phase, the diffusion couple experiments conducted in the present work show that the diffusion process is sluggish and the interdiffusion coefficients are difficult to determine. Therefore the tracer diffusivities of Co and Fe in the Fe-Co alloys were used to assess the diffusion mobilities for the bcc_B2 phase, while the composition-distance profile of one diffusion couple was served as a validation of its diffusion mobilities.