Collaborative Research: RIPS Type 2: Vulnerability Assessment and Resilient Design of Interdependent Infrastructures

现代基础设施系统，如电网、通信网络和交通网络是相互依赖的，这样一个系统中一个元素的故障可能会导致其他系统中多个元素的故障。这个过程可以在相互依赖的系统之间以级联的方式来回传播，从而导致灾难性的大范围故障。此外，各种各样的人类行为也受到了干扰，比如司机？对僵局的反应，会使级联行为进一步复杂化。需要全新的模型和分析技术来评估和设计有弹性的相互依赖的系统。在这个项目中，一个由来自计算机科学、优化、交通系统、电力工程和社会科学领域的五名研究人员组成的团队将共同努力，更好地理解级联故障现象，为设计有弹性的相互依赖系统开发易于处理的数学模型，并研究创新策略，通过防止级联故障的发生和快速恢复系统运行来增强相互依赖系统的弹性。这项研究将为理解相互依赖系统在中断下的鲁棒性的基本特性奠定基础，从而推动现代复杂网络理论和优化算法的发展。该项目的变革性贡献如下。研究人员将提供第一个能够描述相互依赖系统中级联故障的规模和深度的模型，引入“人类脆弱性”的新概念，并提供基于可服务性识别关键网络元素的第一个模型。研究结果将为公共和私营机构提供及时的支持，以更好地了解级联故障的影响和保护关键要素的影响，并制定政策以增强相互依赖的基础设施系统的复原力。特别是，这些发现可能会使这些管理交通网络和电网的政策选择多样化。研究成果也将丰富网络科学、图论、优化、通信、交通系统、电力工程、社会科学等领域的文献。该项目将涉及各级学生，重点是吸引来自代表性不足群体的学生。现实世界的应用将为本科生和K-12学生提供一个理想的平台，并与从业者和政策制定者接触。通过理论（数学建模和优化）和应用（领域专业知识）方法的结合，该项目将全面调查相互依赖系统中的脆弱性和弹性问题。作为实现这一目标的具体步骤，研究人员将追求五个跨学科的研究任务：1)通过数学量化级联的“深度”和“广度”来分析相互依赖系统中级联失效的机制；2)识别关键元素（节点和/或链接），其移除将导致相互依赖系统的弹性损失最为严重；3)通过网络间链路的最优添加和自适应控制策略来增强相互依赖系统的弹性，以便在系统衰退为全面故障之前快速响应级联行为；4)研究与关键要素相关的“人类脆弱性”，并得出人类脆弱性的度量标准，这些指标将进一步整合到相互依存系统的数学模型中，以改进对关键要素的检测；5)将所提出的严格的数学模型和算法应用于佛罗里达州现实世界中相互依赖的网络，包括电网、通信网络和交通网络，以及人类行为的影响。

Modern infrastructure systems, such as power grids, communication networks, and transportation networks are interdependent in such a way that a failure of an element in one system may cause multiple failures of elements in other systems. This process can propagate back and forth between interdependent systems in a cascading fashion, resulting in a catastrophic widespread failure. In addition, the diverse human behaviors to disruptions, such as drivers? reaction to gridlock, can further complicate the cascading behaviors. Radically new models and analytical techniques are needed to assess and design resilient interdependent systems.In this project, a team of five investigators from the domains of computer science, optimization, transportation systems, power engineering, and social science will work together to gain a better understanding of cascading failure phenomena, develop tractable mathematical models for designing resilient interdependent systems, and investigate innovative strategies to enhance the resilience of interdependent systems by preventing the occurrence of cascading failures and quickly restoring system operations. This research will lay a foundation in understanding the fundamental properties that contribute to the robustness of interdependent systems under disruptions, and thus, advancing the state-of-the-art in modern complex network theory and optimization algorithms. The transformative contributions of the project are as follows. The investigators will offer the first models that can characterize the scale and depth of cascading failures in interdependent systems, introduce the new concept of "human vulnerability", and provide the first model on identifying critical network elements based on serviceability. The findings of the research will provide timely support for public and private agencies to better understand the impacts of cascading failures and the implications of protecting critical elements, and develop policies to enhance the resilience of the interdependent infrastructure systems. In particular, the findings can potentially diversify the choices of these policies for managing transportation networks and power grids. The research results will also enrich the literature in the areas of network science, graph theory, optimization, communications, transportation systems, power engineering, and social science. The project will involve students at all levels, with emphasis on attracting students from underrepresented groups. The real-world applications will offer an ideal platform to engage undergraduate and K-12 students and to reach out to practitioners and policy makers.Via a combination of theoretical (mathematical modeling and optimization) and applied (domain expertise) approaches, this project will comprehensively investigate vulnerability and resilience issues in interdependent systems. As specific steps towards this goal, the investigators will pursue five interdisciplinary research tasks: 1) analyzing the mechanisms of cascading failures in interdependent systems by mathematically quantifying the "depth" and "breadth" of cascades; 2) identifying critical elements (nodes and/or links) whose removal yields the most significant loss of resilience of interdependent systems; 3) enhancing the resilience of interdependent systems via optimal addition of inter-network links and finding adaptive control strategies to rapidly react to the cascading behaviors before the systems decay into full-blown failure; 4) investigating "human vulnerability" associated with critical elements, and deriving metrics of human vulnerability, which will be further integrated into the mathematical models of interdependent systems to refine the detection of critical elements; 5) applying the proposed rigorous mathematical models and algorithms to the real-world interdependent networks in Florida, which consist of power grids, communication networks, and transportation networks, with an impact of human behavior.