Pre-Flooding Island Formation in Distribution Systems Resolving Local Critical Infrastructures Interdependency

Author(s):  
Mahdi Bahrami ◽  
Mehdi Vakilian ◽  
Hossein Farzin ◽  
Matti Lehtonen
2017 ◽  
Vol 34 (5) ◽  
pp. 720-732 ◽  
Author(s):  
Indra Gunawan ◽  
Frank Schultmann ◽  
Seyed Ashkan Zarghami

Purpose The purpose of this paper is to review the different interpretations of four key performance indicators of water distribution networks (WDNs): reliability, resilience, redundancy and robustness. It then addresses a range of metrics which have been developed to assess the performance of critical infrastructures, in particular WDNs. Design/methodology/approach The paper provides a comprehensive review and categorization of performance indicators of WDNs. The main focus is on papers addressing performance indicators of water distribution systems, additionally papers on application of complex system approach to critical infrastructures are also included. Findings Due to this complexity, a wide range of interpretation of WDNs performance indicators exists in the literature. This represents a significant impediment toward universally accepted interpretation of these indicators Accurate assessment of WDNs’ performance depends on clear definition of system performance indicators as well as accurate quantifying of these indicators. The application of 18 metrics as a basis for assessing the system performance have been reviewed in this paper and none are particularly significant as standalone values. Combination of these indicators are required to accurately indicate the performance of WDNs. Originality/value The authors believe that this paper can be a valuable source of information for academic researchers and practitioners and suggests a roadmap for future works.


Author(s):  
Louise K. Comfort

Managing critical infrastructures presents a specific set of challenges to crisis managers. These systems include electrical power; communications; transportation; and water, wastewater, and gas line distribution systems. Such infrastructures undergird the continued operation of communities in a modern society. Designed for efficiency, these technical systems operate interdependently, which makes them vulnerable to the stress of extreme events. Changes in population, demographics, land use, and economic and social conditions of communities exposed to hazards have significantly increased the number of people dependent on critical infrastructures in regions at risk. Although advances in science, technology, and engineering have introduced new possibilities for the redesign, maintenance, and retrofit of built infrastructure to withstand extreme events, the complexity of the task has exceeded the capacity of most public and private agencies to anticipate the potential risk and make investments needed to upgrade infrastructures before damage occurs. A mix of public and private ownership of infrastructure systems further complicates the task of ensuring public safety and security in crisis. Public agencies cannot protect communities alone. FEMA has developed a “whole of nation” approach to strengthen cross-jurisdictional linkages with state, county, and municipal emergency managers as well as private and nonprofit organizations. Computational modeling facilitates the exploration of alternative approaches to managing risk generated among a range of actors, interdependent infrastructures, and types of hazard events. Advanced uses of sensors, telemetry, and graphic display of changing performance for critical infrastructure provide timely, accurate information to reduce uncertainty in crisis events. Such technologies enable crisis managers to track more accurately the impact of extreme events on the populations and infrastructures of communities at risk, and to anticipate more reliably the likely consequences of future hazardous events. A basic shift has occurred in the assessment of risk. The focus is no longer on calculating the damage from past events, but on anticipating and reducing the consequences of future hazards, based on sound, scientific evidence as well as local experience and knowledge. Recognizing communities as complex, adaptive systems, crisis managers strive to create a continual learning process that enables residents to monitor their changing environment, use systematically collected data as the basis for analysis and change, and modify policies and practice based on valid evidence from actual environments at risk. Visualization constitutes a key component of collective learning. In complex settings, people comprehend visual images more readily than written or aural directions. Using graphic technologies to display emerging risk at multiple levels simultaneously provides an effective means to guide particular decisions at intermediate (meso) and local levels of operation. For communities seeking to reduce risk, investment in information technologies to enable rapid, community-wide access to interactive communication constitutes a major step toward building capacity not only for managing risk to critical infrastructure but also in maintaining continuity of operations for the whole community in extreme events.


Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.


WRPMD'99 ◽  
1999 ◽  
Author(s):  
P. Costa ◽  
A. Esposito ◽  
C. Gualtieri ◽  
D. Pianese ◽  
G. Pulci Doria ◽  
...  

Author(s):  
Mietek A. Brdys ◽  
Kazimierz Duzinkiewicz ◽  
Michal Grochowski ◽  
Tomasz Rutkowski

Author(s):  
Denys Popelysh ◽  
Yurii Seluk ◽  
Sergyi Tomchuk

This article discusses the question of the possibility of improving the roll stability of partially filled tank vehicles while braking. We consider the dangers associated with partially filled tank vehicles. We give examples of the severe consequences of road traffic accidents that have occurred with tank vehicles carrying dangerous goods. We conducted an analysis of the dynamic processes of fluid flow in the tank and their influence on the basic parameters of the stability of vehicle. When transporting a partially filled tank due to the comparability of the mass of the empty tank with the mass of the fluid being transported, the dynamic qualities of the vehicle change so that they differ significantly from the dynamic characteristics of other vehicles. Due to large displacements of the center of mass of cargo in the tank there are additional loads that act vehicle and significantly reduce the course stability and the drivability. We consider the dynamics of liquid sloshing in moving containers, and give examples of building a mechanical model of an oscillating fluid in a tank and a mathematical model of a vehicle with a tank. We also considered the method of improving the vehicle’s stability, which is based on the prediction of the moment of action and the nature of the dynamic processes of liquid cargo and the implementation of preventive actions by executive mechanisms. Modern automated control systems (anti-lock brake system, anti-slip control systems, stabilization systems, braking forces distribution systems, floor level systems, etc.) use a certain list of elements for collecting necessary parameters and actuators for their work. This gives the ability to influence the course stability properties without interfering with the design of the vehicle only by making changes to the software of these systems. Keywords: tank vehicle, roll stability, mathematical model, vehicle control systems.


2020 ◽  
Vol 140 (6) ◽  
pp. 456-464
Author(s):  
Naoto Yorino ◽  
Tsubasa Watakabe ◽  
Ahmed Bedawy Khalifa ◽  
Yutaka Sasaki ◽  
Yoshifumi Zoka

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