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Prof. C. K. Michael Tse

RESEARCH


We believe the surge in intercity travel during the special holiday period in China (about 20 days surrounding the Lunar New Year) was a key drive for the severe outbreaks in multiple regions throughout China. We collected Baidu Migration data from Jan1 to Feb 14, combining with daily infection data for 367 cities in China, and applied a travel-data integrated SEIR model to perform prediction of the severity and peak times of COVID-19 epidemic for all Chinese cities. We performed all data collection, analysis, modeling fitting and prediction of COVID-19 epidemic in China, within two weeks, and published our results on medRxiv.org for public viewing. This work is a collaboration with Dr Choujun Zhan, a former CityU PhD graduate and now professor at South China Normal University.

Link to the article at medRxiv.org [Posted on Feb 20, 2020]
Link to the article at JMIR Public Health and Surveillance [Posted on Mar 25, 2020]


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How efficient are Hong Kong’s public transport systems, as compared to London’s, Paris’s, Beijing’s, Tokyo’s, … and how effective are our resources being used in addressing commuters’ needs?

We developed innovative network-based models that permit effective assessment of the network structure and operation performance of our transport systems. Applications to bus networks, metro networks and others have offered useful insights into the key factors that contribute to an efficient and effective transportation systems that optimize passenger volume and levels of comfort.

Key References:

X. Wu, H. Dong, and C. K. Tse, "A three-layer model for studying metro network dynamics," IEEE Transactions on Systems, Man, and Cybernetics: Systems, to appear.

T. Shanmukhappa, I. W. H. Ho, C. K. Tse, and K. K. Leung, "Recent development in public transport network analysis from the complex network perspective," IEEE Circuits and Systems Magazine, vol. 19, no. 4, pp. 39-65, November 2019.

T. Shanmukhappa, I. W. H. Ho, and C. K. Tse, "Spatial analysis of bus transport networks using network theory," Physica A: Statistical Mechanics and its Applications, vol. 502, pp. 295-314, July 2018.

X. Wu, H. Dong, C. K. Tse, I. W-H. Ho, and F. C. M. Lau, "Analysis of metro network performance from a complex network perspective," Physica A, vol. 492, pp. 553-563, February, 2018.


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New Network-based Models for Power System’s Robustness Assessment and Cascading Failure Simulation

Our model is able to capture the salient characteristics of cascading failure patterns consistent with all historical blackout data. IEEEXplore Innovation Spotlight featured our work in November 2015. 

ieeexplore-spotlight med hr


Key References:

D. Liu, C. K. Tse, and X. Zhang, "Robustness assessment and enhancement of power grids from a complex network's perspective using decision trees," IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 66, no. 5, pp. 833-837, May 2019.

X. Zhang, C. Zhan, and C. K. Tse, "Modeling the dynamics of cascading failures in power systems," IEEE Journal on Emerging and Selected Topics in Circuits and Systems, vol. 6, no. 2, pp. 192-204, June 2017.

X. Zhang, D. Liu, C. Zhan, and C. K. Tse, "Effects of cyber coupling on cascading failures in power systems," IEEE Journal on Emerging and Selected Topics in Circuits and Systems, vol. 6, no. 2, pp. 228-238, June 2017.

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Wireless Power Transfer Applications

Power supplies using remote inductive power transfer have become realistic options for charging moving vehicles and in biomedical uses. The reactive element compensation problem is critical for achieving good efficiency. Our recent work has focused on the basic theory of reactive compensation and efficiency optimization, and application focuses are a charging platform for electric vehicles and LED lighting systems.

Key References:

J. Hou, Q. Chen, Z. Zhang, S-C. Wong, and C. K. Tse, "Analysis of output current characteristics of higher order primary compensation in inductor power transfer systems," IEEE Transactions on Power Electronics, vol. 33, no. 8, pp. 6807-6821, August 2018.

X. Qu, Y. Jing, H. Han, S. C. Wong, and C. K. Tse, "Higher order compensation for inductive-power-transfer converters with constant-voltage or constant-current output combating transformer parameter constraints," IEEE Transactions on Power Electronics, vol. 32, no. 1, pp. 394-405, January 2017. [Best Paper Award (Second Place) 2018]

J. Hou, Q. Chen. X. Ren, X. Ruan, S. C. Wong, and C. K. Tse, "Precise characteristics analysis of series/series-parallel compensated contactless resonant converter," IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 3, no. 1, 101-110, March 2015.

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Our Universal Growth Equation describes how user population of products and services, membership subscriptions, even your publications and citations, grow as time goes

We derive from first principle a growth equation that fits all data of growing user population, such as Facebook signups, electronic products, services, app downloads, and virtually everything that grows as time goes, like the number of papers you publish and the number of times your papers get cited. If x(t) is the quantity of the item you are interested in, it will grow according to


where c1 and c2 are growth parameters corresponding to peer influence and personal decision, respectively, and N is the total potential user population. The basis of our theory is a network of people who make decision on whether to sign up for a service or use a product according to the individuals’ independent judgement as well as peer influence. Statistical analysis is used to derive the above growth equation.

Key References:

C. Zhan and C. K. Tse, "A network model for growth of markets having hierarchical dependence," IEEE Transactions on Network Science and Engineering, vol. 6, no. 3, pp. 198–209, July 2019. [Link to IEEEXplore]

C. Zhan and C.K. Tse, "A universal model for growth of user population of products and services," Network Science,  vol. 4, no. 4, pp. 491-507, December 2016. [Link to Online Journal Viewing]

C. Zhan and C.K. Tse, "A network model for growth of publications and citations,” Journal of Complex Networks, Advance Access, doi: 10.1093/comnet/cnw019, August 2016 [Link to Online Journal Viewing]

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Network Research in Finance

Network of World’s Stock Markets:  Nodes are stock indices of different countries. A link indicates that the two connected markets are correlated in the sense that the time series of the pair of indices over 2005-2007 have a Pearson correlation of over 85%.

Key References:

C. K. Tse, J. Liu, and F. C. M. Lau, “A network perspective of stock markets,” Journal of Empirical Finance, vol. 17, no. 4, pp. 659-667, September 2010. [Download]

J. Liu, C. K. Tse, and K. He, “Fierce stock market fluctuation disrupts scalefree distribution,” Quantitative Finance, vol. 11, no. 6, pp. 817-823, June 2011. [Download]

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Nonlinear Phenomena in Renewable Energy Systems and Grid-Connected Power Converter Systems: Interactions, Stability and Design [Awarded Best Paper (Second Place) by IEEE Transactions on Power Electronics 2015]

Our latest initiative in power electronics research has been motivated by the recent development of energy systems which emphasizes the integration of the various renewable sources with the power grid and other distribution infra-structures. The new development has spawned new interests and serious concerns about stability and the impacts of interactions of a large number of systems through the distribution network. Moreover, renewable sources are also subject to fluctuation of availability, e.g., solar, wind, tidal, etc. The systems are therefore expected to be multi-structural and operating with multi-operating modes. Our research focus is on the complex behavior of such systems interacting via a common distribution network. 

Key References:

M. Huang, Y. Peng, C. K. Tse, Y. Liu, J. Sun, and X. Zha, "Bifurcation and large-signal stability analysis of three-phase voltage source converter under grid voltage dips," IEEE Transactions on Power Electronics, vol. 32, no. 11, pp. 8868-8879, November 2017.

C. Wan, M. Huang, C. K. Tse, and X. Ruan, "Effects of interaction of power converters coupled via power grid: a design-oriented study," IEEE Transactions on Power Electronics, vol. 30, no. 7, pp. 3589-3600, July 2015. [Best Paper Award (Second Place) 2016]

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LED Drivers (Gold Medals at International Exhibition of Inventions, Geneva 2013 and 2009)

A novel two-level current driving method has been developed for LED lamps. The driver takes advantage of the intrinsic characteristic of LEDs to improve the luminous level by around 15%. The idea is to adjust the two ends of the PWM current such that throughout the linear control range, the luminous level of the LEDs is always higher than the usual PWM driven LEDs.

Key References:

X. Qu, S. C. Wong, and C. K. Tse, "A current balancing scheme with high luminous efficacy for high power LED lighting," IEEE Transactions on Power Electronics, vol. 29, no. 6, pp. 2649-2654, June 2014.

S. K. Ng, K. H. Loo, S. K. Ip, Y. M. Lai, K.T. Mok, and C. K. Tse, "Sequential variable bi-level driving approach suitable for use in high color precision LED display panels," IEEE Transactions on Industrial Electronics, vol. 59, no. 12, pp. 4637-4645, December 2012.