Browsing by Author "Tsai, Yu-Shiuan"

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A Multilayer Epidemiological Model Integrating Daily Commuting Network
(2010)
Tsai, Yu-Shiuan
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Huang, Chung-Yuan
;
Wen, Tzai-Hung
;
Sun, Chuen-Tsai
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資訊工程學系
To assess the impacts of various interventions on epidemic dynamics, the authors propose an integrated epidemiological simulation framework called Multilayer Epidemic Dynamics Simulator (MEDSim), which combines four contact structures: within age group, between age groups, daily commute, and nationwide interaction. We use the daily commuting network to simulate outbreak locations and intervention scenarios for the 2009 A/H1N1 influenza epidemic in Taiwan. Our three main findings are: (a) lower transmission rates and earlier intervention activation times did not reduce total numbers of infected cases, but did delay peak times; (b) when transmission rate was decreased by a minimum of 70%, significant slowing-down effects were observed when interventions were activated before the 50th new case (c) peaks times were achieved more quickly when initial outbreaks occurred in urban rather than rural areas. The innovative simulation framework reflects the dynamic processes of epidemics under different intervention scenarios, thus clarifying the effects of complex contact structures on disease transmission dynamics.
A Network-based Simulation Architecture for Studying Epidemic Dynamics
(2010-05-01)
Huang, Chung-Yuan
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Tsai, Yu-Shiuan
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Wen, Tzai-Hung
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資訊工程學系
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Department of Computer Science
Epidemiology instructors are collaborating with computer scientists to construct network-based simulations to recreate infectious disease transmission dynamics and to examine intervention strategy efficacies. Here we propose an architecture based on demographic and geographic properties to support the learning efforts of undergraduate students and novice researchers, and describe our simulations of HIV, SARS, and influenza transmission dynamics in Taiwan. Our findings are offered to support the construction of new network-based epidemic simulations.
Beyond bond links in complex networks:Local bridges, global bridges and silk links
(2019-12-15)
Huang, Chung-Yuan
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Chin, Wei-Chien-Benny
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Fu, Yu-Hsiang
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Tsai, Yu-Shiuan
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資訊工程學系
Many network researchers use intuitive or basic definitions when discussing the importance of strong and weak links and their roles. Others use an approach best described as "if not strong, then weak" to determine the strengths and weaknesses of individual links, thus deemphasizing hierarchical network structures that allow links to express different strength levels. Here we describe our proposal for a hierarchical edge type analysis (HETA) algorithm for determining link types at multiple network hierarchy levels based on the common neighbor concept plus statistical factors such as bond links, kth-layer local bridges, global bridges, and silk links-all generated during long-term network development and evolution processes. Two sets of networks were used to validate our proposed algorithm, one consisting of 16 networks employed in multiple past studies, and one consisting of two types of one-dimensional small-world networks expressing different random rewiring or shortcut addition probabilities. Two applications with potential for developmental contributions are demonstrated: a network fingerprint analysis framework, and a hierarchical network community partition method. (C) 2019 The Authors. Published by Elsevier B.V.
CONSTRUCTION OF LOW-DISTORTED MESSAGE-RICH VIDEOS FOR PERVASIVE COMMUNICATION
(2016-01-01)
You, Zhen-Yu
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Tsai, Yu-Shiuan
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Tsai, Wen-Hsiang
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資訊工程學系
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Department of Computer Science
Many types of multimedia can be used to accommodate information for pervasive communication. Messages may be injected into them by information hiding techniques and extracted for various purposes. Such multimedia with messages embedded are called message-rich multimedia. A new method for creating message-rich videos is proposed in this study for people to exchange messages by display-and-imaging operations. A message is firstly embedded in a given video by a technique of injecting peak values into the DFT spectrum of each video frame. The resulting message-rich video, when displayed on a TV or monitor, is then recorded with a smart-phone camera as another video. The message in the recorded video is finally extracted for visual inspection. This way of message transmission can be used for covert communication, secret message exchanges, etc. Good experimental results show the feasibility of the proposed method.
Effects of friend-making resources/costs and remembering on acquaintance networks
(2010-02-01)
Huang, Chung-Yuan
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Tsai, Yu-Shiuan
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資訊工程學系
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Department of Computer Science
We consider two overlooked yet important factors that affect acquaintance network evolution and formation-friend-making resources and remembering-and propose a bottom-up, network-oriented simulation model based on three rules representing human social interactions. Our proposed model reproduces many topological features of real-world acquaintance networks, including a small-world phenomenon and a sharply peaked connectivity distribution feature that mixes power-law and exponential distribution types. We believe that this is an improvement over fieldwork sampling methods that fail to capture acquaintance network node connectivity distributions. Our model may produce valuable results for sociologists working with social opinion formation and epidemiologists studying epidemic dynamics. (C) 2009 Elsevier B.V. All rights reserved.
Influences of Resource Limitations and Transmission Costs on Epidemic Simulations and Critical Thresholds in Scale-Free Networks
(2009-03-01)
Huang, Chung-Yuan
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Tsai, Yu-Shiuan
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Sun, Chuen-Tsai
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Hsieh, Ji-Lung
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Cheng, Chia-Ying
Critical thresholds represent one of the most important diffusion indicators of epidemic outbreaks. However, we believe that recent studies have overemphasized ways that the power-law connectivity distribution features of social networks affect epidemic dynamics and critical thresholds. As a result, two important factors have been overlooked: resource limitations and transmission costs associated with social interactions and daily contact. Here we present our results from the simultaneous application of mean-field theory and an agent-based network simulation approach for analyzing the effects of resources and costs on epidemic dynamics and critical thresholds. Our main findings are: (a) a significant critical threshold does exist when resources and costs are taken into consideration, and it has a lower bound whenever contagion events occur in scale-free networks; (b) when transmission costs increase or individual resources decrease, critical contagion thresholds in scale-free networks grow linearly and steady density curves shrink linearly;(c) regardless of whether the resources of individuals obey delta, uniform, or normal distributions, they have the same critical thresholds and epidemic dynamics as long as the average value of usable resources remains the same across different scale-free networks; and (d) the spread of epidemics in scale-free networks remains controllable as long as resources are properly restricted and intervention strategy investments are significantly increased.
Integrating epidemic dynamics with daily commuting networks: building a multilayer framework to assess influenza A (H1N1) intervention policies
(2011-05-01)
Tsai, Yu-Shiuan
;
Huang, Chung-Yuan
;
Wen, Tzai-Hung
;
Sun, Chuen-Tsai
;
Yen, Muh-Yong
We describe an innovative simulation framework that combines daily commuting network data with a commonly used population-based transmission model to assess the impacts of various interventions on epidemic dynamics in Taiwan. Called the Multilayer Epidemic Dynamics Simulator (MEDSim), our proposed framework has four contact structures: within age group, between age groups, daily commute, and nationwide interaction. To test model flexibility and generalizability, we simulated outbreak locations and intervention scenarios for the 2009 swine-origin influenza A (H1N1) epidemic. Our results indicate that lower transmission rates and earlier intervention activation times did not reduce total numbers of infected cases, but did delay peak times. When the transmission rate was decreased by a minimum of 70%, significant epidemic peak delays were observed when interventions were activated before new case number 50; no significant effects were noted when the transmission rate was decreased by less than 30%. Observed peaks occurred more quickly when initial outbreaks took place in urban rather than rural areas. According to our results, the MEDSim provides insights that reflect the dynamic processes of epidemics under different intervention scenarios, thus clarifying the effects of complex contact structures on disease transmission dynamics.
Response to Wilson's note on 'Influences of resource limitations and transmission costs on epidemic simulations and critical thresholds in scale-free networks'
(2011-03-01)
Tsai, Yu-Shiuan
;
Sun, Chuen-Tsai
;
Huang, Chung-Yuan
;
資訊工程學系
;
Department of Computer Science
James R. Wilson points out what he describes as flaws in our proof in 'Influences of Resource Limitations and Transmission Costs on Epidemic Simulations and Critical Thresholds in Scale-free Networks' (Simulation 85(3): 205-219) and offers an alternative steady-state behavior derivation based on our epidemic simulation model. In this response we will explain our definitions for the terms used in our paper and the derivation process for our analysis, then compare and contrast our mathematical model with that proposed by Wilson. We suggest that more compartmental models can be used to support our argument that increasing transmission costs or decreasing individual resources increases the critical threshold of a contagion event in a scale-free network.