In smart city services, information systems can provide efficient and effective support during an emergency, and an emergency management system can make use of any available infrastructure network, such as the Internet of Things. However, ordinary communication infrastructures can be prone to disruptions or even failures during emergencies. Hence, it is necessary to present a fallback system in case of such failures. In this article, we propose such a fallback design for emergency management that relies on short-range multihop wireless communications. Specifically, we model the crowd by a multihop ad hoc network consisting of nodes (i.e., civilians with smartphones or wearable devices) that are capable of short-range communications, and address the problem of how to “diffuse” the crowd in an efficient and distributed fashion. The problem is subdivided into crowd density computation and crowd diffusion. We treat the area as a grid that is divided into square cells. Crowd density computation is to compute the density of each cell, for which we present efficient distributed algorithms that compute the density of each grid cell exactly. With the computed densities, crowd diffusion is to design a load-balancing strategy (to direct local movements of individual civilians) such that in a short time the nodes/civilians will become evenly distributed over the entire area. We present a distributed diffusion algorithm that has good performance. We conduct extensive simulations to evaluate the proposed algorithms, and the results corroborate our theoretical analyses.

中文翻译：

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通过物联网进行人群密度计算和扩散


在智慧城市服务中，信息系统可以在紧急情况下提供高效、有效的支持，应急管理系统可以利用任何可用的基础设施网络，例如物联网。然而，普通通信基础设施在紧急情况下很容易出现中断甚至故障。因此，有必要在发生此类故障时提供后备系统。在本文中，我们提出了一种依赖短程多跳无线通信的应急管理后备设计。具体来说，我们通过多跳自组织网络对人群进行建模，该网络由能够进行短距离通信的节点（即拥有智能手机或可穿戴设备的平民）组成，并解决如何以高效且有效的方式“分散”人群的问题。分布式时尚。该问题分为人群密度计算和人群扩散问题。我们将该区域视为划分为方形单元的网格。人群密度计算是计算每个网格单元的密度，为此我们提出了高效的分布式算法来精确计算每个网格单元的密度。根据计算出的密度，人群扩散是为了设计负载平衡策略（引导个体平民的局部移动），使得节点/平民在短时间内均匀分布在整个区域。我们提出了一种具有良好性能的分布式扩散算法。我们进行了广泛的模拟来评估所提出的算法，结果证实了我们的理论分析。