论文标题
城市的机械类似物
Mechanical Analog for Cities
论文作者
论文摘要
由于越来越多的需求,需要对遭受危害的城市的动态和反应发展进行定量的,基于科学的预测理解,在本文中,我们应用了统计力学和微笑学的概念来为具有预测能力的城市开发机械类似物。我们设想一个城市是一个矩阵,在该矩阵中,人们(手机用户)受到城市的经济和其他相关激励措施的驱动,同时使用其基础设施网络的收集方式相似,而热驱动的布朗尼探测粒子也在复杂的粘弹性材料中移动。从GPS位置数据计算数千个手机用户的平均值位移(集合平均值),以建立蠕变合规性和由此产生的脉冲响应功能。这些时间响应函数的推导允许合成简单的机械类似物,这些类似物在正常条件下令人满意地模拟了城市的行为。我们的研究集中于预测城市对急性冲击(压力整个城市区域的自然危害)的反应,这些响应距离有有限的持续时间;我们表明,我们得出的城市的固体机械类似物预测,城市立即恢复为事实的响应,表明它们本质上是弹性的。我们的发现与2021年2月在北美冬季风暴之后的达拉斯大都会(Dallas Metroplex)的记录反应非常吻合,这在我们拥有可靠的GPS位置数据的时候发生。
Motivated from the increasing need to develop a quantitative, science-based, predictive understanding of the dynamics and response of cities when subjected to hazards, in this paper we apply concepts from statistical mechanics and microrheology to develop mechanical analogs for cities with predictive capabilities. We envision a city to be a matrix where people (cell-phone users) are driven by the economy of the city and other associated incentives while using the collection of its infrastructure networks in a similar way that thermally driven Brownian probe particles are moving within a complex viscoelastic material. Mean-square displacements (ensemble averages) of thousands of cell-phone users are computed from GPS location data to establish the creep compliance and the resulting impulse response function of a city. The derivation of these time-response functions allows the synthesis of simple mechanical analogs that model satisfactorily the behavior of the city under normal conditions. Our study concentrates on predicting the response of cities to acute shocks (natural hazards that stress the entire urban area) that are approximated with a rectangular pulse with finite duration; and we show that the solid-like mechanical analogs for cities that we derived predict that cities revert immediately to their pre-event response suggesting that they are inherently resilient. Our findings are in remarkable good agreement with the recorded response of the Dallas metroplex following the February 2021 North American winter storm which happened at a time for which we have dependable GPS location data.