Analysis of Power System Resilience Subject to Extreme Events

The purpose of this study is to increase the understanding of power system resilience through pattern recognition of disaster-induced system disruption. This study consists of analyzing power system failure and recovery patterns in a post-extreme event environment to determine relevant pattern characteristics relating to power system resilience. Specifically, the methodology of this study consists of (1) collecting and processing data from power system failures induced by natural disasters categorized by power companies, states, counties, and natural disaster occurrence.; (2) developing failure and recovery curves for the collected data; (3) investigating and establishing statistical distribution models that correlate to the goodness of fit for plotted curves best characterizing the system behaviour for each extreme external occurrence; and (4) creating a quantitative algorithm for specifying the resilience of such engineered systems. The resultant algorithm will assist in answering questions about the resiliency of power systems. Since modern society relies extensively on power systems to survive, this increased insight into power system resilience will provide better situational awareness for stakeholders during future decision-making discussions regarding power system construction.https://ecommons.udayton.edu/stander_posters/4205/thumbnail.jp

The AMSC network control system

The American Mobile Satellite Corporation (AMSC) is going to construct, launch, and operate a satellite system in order to provide mobile satellite services to the United States. AMSC is going to build, own, and operate a Network Control System (NCS) for managing the communications usage of the satellites, and to control circuit switched access between mobile earth terminals and feeder-link earth stations. An overview of the major NCS functional and performance requirements, the control system physical architecture, and the logical architecture is provided

A distributed fault-detection and diagnosis system using on-line parameter estimation

The development of a model-based fault-detection and diagnosis system (FDD) is reviewed. The system can be used as an integral part of an intelligent control system. It determines the faults of a system from comparison of the measurements of the system with a priori information represented by the model of the system. The method of modeling a complex system is described and a description of diagnosis models which include process faults is presented. There are three distinct classes of fault modes covered by the system performance model equation: actuator faults, sensor faults, and performance degradation. A system equation for a complete model that describes all three classes of faults is given. The strategy for detecting the fault and estimating the fault parameters using a distributed on-line parameter identification scheme is presented. A two-step approach is proposed. The first step is composed of a group of hypothesis testing modules, (HTM) in parallel processing to test each class of faults. The second step is the fault diagnosis module which checks all the information obtained from the HTM level, isolates the fault, and determines its magnitude. The proposed FDD system was demonstrated by applying it to detect actuator and sensor faults added to a simulation of the Space Shuttle Main Engine. The simulation results show that the proposed FDD system can adequately detect the faults and estimate their magnitudes

Perspectives on the use of rule-based control

Issues regarding the application of artificial intelligence techniques to real-time control are discussed. Advantages associated with knowledge-based programming are discussed. A proposed rule-based control technique is summarized and applied to the problem of automated aircraft emergency procedure execution. Although emergency procedures are by definition predominately procedural, their numerous evaluation and decision points make a declarative representation of the knowledge they encode highly attractive, resulting in an organized and easily maintained software hierarchy. Simulation results demonstrate that real-time performance can be obtained using a microprocessor-based controller. It is concluded that a rule-based control system design approach may prove more useful than conventional methods under certain circumstances, and that declarative rules with embedded procedural code provide a sound basis for the construction of complex, yet economical, control systems

Environmental Control and Life Support Integration Strategy for 6-Crew Operations

The International Space Station (ISS) crew complement has increased in size from 3 to 6 crew members. In order to support this increase in crew on ISS, the United States on-orbit Segment (USOS) has been outfitted with a suite of regenerative Environmental Control and Life Support (ECLS) hardware including an Oxygen Generation System (OGS), Waste and Hygiene Compartment (WHC), and a Water Recovery System (WRS). The WRS includes the Urine Processor Assembly (UPA) and the Water Processor Assembly (WPA). With this additional life support hardware, the ISS has achieved full redundancy in its on-orbit life support system between the t OS and Russian Segment (RS). The additional redundancy created by the Regenerative ECLS hardware creates the opportunity for independent support capabilities between segments, and for the first time since the start of ISS, the necessity to revise Life Support strategy agreements. Independent operating strategies coupled with the loss of the Space Shuttle supply and return capabilities in 2010 offer new and unique challenges. This paper will discuss the evolution of the ISS Life Support hardware strategy in support of 6-Crew on ISS, as well as the continued work that is necessary to ensure the support of crew and ISS Program objectives through the life of statio

Assessing catchment scale flood resilience of urban areas using a grid cell based metric

This is the final version. Available on open access from Elsevier via the DOI in this recordUrban flooding has become a global issue due to climate change, urbanization and limitation in the capacity of urban drainage infrastructures. To tackle the growing threats, it is crucial to understand urban surface flood resilience, i.e., how urban drainage catchments can resist against and recover from flooding. This study proposes a grid cell based resilience metric to assess urban surface flood resilience at the urban drainage catchment scale. The new metric is defined as the ratio of the number of unflooded grid cells to the total grid cell number in an urban drainage catchment. A two-dimensional Cellular Automata based model CADDIES is used to simulate urban surface flooding. This methodology is demonstrated using a case study in Dalian, China, which is divided into 31 urban drainage catchments for flood resilience analysis. Results show the high resolution resilience assessment identifies vulnerable catchments and helps develop effective adaptation strategies to enhance urban surface flood resilience. Comparison of the new metric with an existing metric reveals that new metric has the advantage of fully reflecting the changing process of system performance. Effectiveness of adaptation strategies for enhancing urban surface flood resilience is discussed for different catchments. This study provides a new way to characterize urban flood resilience and an in-depth understanding of flood resilience for urban drainage catchments of different characteristics, and thus help develop effective intervention strategies for sustainable sponge city development.Engineering and Physical Sciences Research Council (EPSRC)China Scholarship Counci

A global analysis approach for investigating structural resilience in urban drainage systems

Copyright © 2015 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Water Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Water Research (2015), DOI: 10.1016/j.watres.2015.05.030Building resilience in urban drainage systems requires consideration of a wide range of threats that contribute to urban flooding. Existing hydraulic reliability based approaches have focused on quantifying functional failure caused by extreme rainfall or increase in dry weather flows that lead to hydraulic overloading of the system. Such approaches however, do not fully explore the full system failure scenario space due to exclusion of crucial threats such as equipment malfunction, pipe collapse and blockage that can also lead to urban flooding. In this research, a new analytical approach based on global resilience analysis is investigated and applied to systematically evaluate the performance of an urban drainage system when subjected to a wide range of structural failure scenarios resulting from random cumulative link failure. Link failure envelopes, which represent the resulting loss of system functionality (impacts) are determined by computing the upper and lower limits of the simulation results for total flood volume (failure magnitude) and average flood duration (failure duration) at each link failure level. A new resilience index that combines the failure magnitude and duration into a single metric is applied to quantify system residual functionality at each considered link failure level. With this approach, resilience has been tested and characterized for an existing urban drainage system in Kampala city, Uganda. In addition, the effectiveness of potential adaptation strategies in enhancing its resilience to cumulative link failure has been tested.UK Commonwealth PhD scholarshipEngineering & Physical Sciences Research Council (ESPRC) - Safe & SuRe research fellowshi

Organizational Resilience: A Dynamic Capability of Complex Systems

In recent years, the concept of organizational resilience has largely attracted the interest of academicians and practitioners alike. A fair number of researches have been conducted on developing the concept of organizational resilience. However, there seems to be a lack of consensus over its conceptualization mainly because the concept itself is prodigious and is used in a variety of disciplines. Furthermore, research within the domain of organizational resilience has been outcome oriented; however, questions addressing the drivers of resilience are yet to be answered. On the other hand, research within the domain of dynamic capabilities view have long been criticized as tautological, resistant to operationalization, and lacking the unification of thought. However, there exists a sufficient degree of conceptual similitude between the two concepts, mainly due to their epistemological similarities grounded within the theoretical assumptions of chaotic systems, environmental dynamism, and systems thinking. Incorporating both perspectives in parallel for understanding the theoretical connections can lead to clarifications at an ontological level. Therefore, this paper attempts to propose a holistic model of organizational resilience by incorporating a lens metaphor of dynamic capabilities view. This paper is divided into four sections. The first section of this paper lays down the multidisciplinary discourses within the realm of organizational resilience. The second section highlights the management discourse about the conceptualization of organizational resilience. The third section of this paper uses a lens metaphor of dynamic capabilities view in an attempt to add depth to the concept of organizational resilience. The fourth and the final section attempts to propose the drivers of organizational resilience from a strategic viewpoint