Project Report

Research OutcomesDue to the possibility of failure, partial failure, and maintenance, many real-world systems such as internet, telephone, and transportation networks may be characterized as stochastic-flow networks (SFN), which exhibit multiple levels of performance. This infrastructure serves as the foundation of many services such as electronic commerce, air traffic control, and emergency response systems. The increase in the number and sophistication of services hosted by these platforms has rendered society heavily dependent on the performance and reliability of the networks that support these services. Given the business and mission-critical nature of many of these services, methods to predict network performance and reliability are essential. Mathematical models to assess these metrics offer quantitative guidance to improve networks so that users can be confident critical services will be available when called upon. As a 2011 NSF East Asia and Pacific Summer Institutes (EAPSI) Graduate Student Fellow, Lance Fiondella traveled to Taipei, Taiwan for eight weeks to conduct collaborative research in the Laboratory of Network Reliability & Service Science, directed by Professor Yi-Kuei Lin, Chair of the Department of Industrial Management at the National Taiwan University of Science and Technology and a 2008 recipient of the National Science Council (NSC) Outstanding Research Award. Professor Lin closely supervised his full time PhD student Ping-Chen Chang and Lance as they worked together to construct a stochastic-flow network model to analyze the performance of a computer network, where the failure of the physical lines comprising the edges of the network can experience correlated failures. Correlation poses a serious threat to many engineered systems because the simultaneous failure of multiple components can dangerously degrade performance and reliability. One commonly occurring example of a correlated failure specific to communication networks is a backhoe cutting several physical lines as it digs up the ground to perform work on buried pipes or cables. Other, potentially disastrous, examples include earthquakes and hurricanes that simultaneously damage many arcs and nodes of a network, suggesting that correlated failures between edges and nodes may occur. The technique developed by the researchers quantifies the probability that a given amount of data can be sent from a source to destination through this network. This probability that the network satisfies a specified level of demand is referred to as the system reliability. Experimental results demonstrated that correlation can produce a significantly negative impact on reliability, especially when there is a high level of network demand. The models developed, thus, capture the influence of correlation on system reliability and offer a method to measure the utility of reducing the possibility of correlated failures through strategies such as physically shielding vulnerable portions of the network. The approach should also prove effective for conducting tradeoff studies to compare alternative network topologies, thereby identifying designs that will be more resilient to correlated failures. This research provides the mathematical tools needed to guide design studies that will ultimately benefit society through more robust networks, which will directly contribute to disaster management efforts and homeland security for the international community. Cultural Learning In addition to the long-term collaborations forged between participants and their host researchers, the group of twenty-five American students who travelled together to Taiwan was greeted by an energetic group of students from the National Tsing Hua University. The team of Taiwanese students hosted a weeklong orientation program, which provided elementary Chinese language training and a calligraphy class, a tour of the Ying-ge Ceramics Museum, a highly informative lecture on the indigenous tribes of the island, and a trip to a local Hakka village, where visitors prepared their own dinner the old-fashioned way. Modern Taiwan was also presented, including a visit to HsinChu Science Park, the nation’s Silicon Valley, and a visit to Taipei 101 the second tallest building in the world. Additional cultural experiences included a visit to the National Palace Museum and the Mengjia Longshan Temple. The seven week stay in southern Taipei also afforded the opportunity for weekend excursions to visit the National Museum of History and surrounding botanical gardens, a flower market, the Chiang Kai-Shek and Sun Yat-sen Memorial Halls, the Museum of Fine Arts and the Museum of Jade Art, the Confucius and Bao-an temples as well as temples along the Xianji Yan and Jiantan Shan Hiking Trails. The beauty and wisdom imparted by these visits solidified the belief that international collaboration among scientists is an essential diplomatic function key to the peaceful development of society. Last Modified: 09/14/2011 Submitted by: Lance N Fiondella PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH Yi-Kuei Lin, Ping-Chen Chang, and Lance Fiondella, A study of correlated failures on the network reliability of power transmission systems, International Journal of Electrical Power & Energy Systems, 43(1), pp. 954-960, December 2012.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Fiondella Lance N
United States
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