Jishan Hu
Hong Kong University of Science and Technology
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Publication
Featured researches published by Jishan Hu.
Studies in Applied Mathematics | 2000
Jishan Hu; Min Yan
We provide an algorithm to convert integrable equations to regular systems near noncharacteristic, movable singularity manifolds of solutions. We illustrate how the algorithm is equivalent to the Painleve test. We also use the algorithm to prove the convergence of the Laurent series obtained from the Painleve test.
Indoor and Built Environment | 2004
Christopher Yu Hang Chao; Jishan Hu
An enthalpy and carbon dioxide level based demand control ventilation (EDCV) algorithm has been developed. This takes into account both the indoor occupancy level and the energy content of the fresh air and return air while controlling the fresh air supply. It has been applied under various operating conditions to ensure that the most effective control strategy was used. A back propagation (BP) neural network was used to tune the proportional, integral and differential (PID) parameters in order to obtain a good control performance. Experiments were conducted in a mediumsized lecture theatre to verify the performance of the developed EDCV algorithm in a real application. The results showed that acceptable indoor air quality could be obtained with less energy consumption. Under the optimum experimental conditions, about 15.4% of the total cooling energy was saved. The control performance was found to be good with the PID parameters tuned via the neural network
Nonlinearity | 1999
Jishan Hu; Min Yan
We use the Lorenz system, the Rikitake model and the nonlinear Schrodinger equation to demonstrate that for completely integrable systems, there exist what we call regular mirror systems near movable singularities. The method for finding the mirror systems is very similar to the original Weiss et als (1983 J. Math. Phys. 24 522-6) version of the Painleve test. It tests the complete integrability and gives a systematic and conceptual proof that the formal Laurent series generated by the Painleve test are convergent.
Journal of Mathematical Physics | 1991
Jishan Hu; Martin D. Kruskal
This paper generalizes the Pokrovskii-Khalatnikov method to calculate the actual behavior of the reflection coefficient for singular problems, which vanishes to all orders in the small parameter e. Two different classes of reflection coefficient problems are considered.
Journal of Mathematical Physics | 1991
Harry Gingold; Jishan Hu
In this paper the generalized Liouville–Green approximation is used to study the wave reflection with a turning point at infinity. The method provided here unifies the work by many authors in finding the nontrivial behavior of the reflection coefficient for high‐energy particles above barrier in the semiclassical limit.
Complex Variables and Elliptic Equations | 2012
Ovidiu Calin; Der-Chen Chang; Jishan Hu; Yutian Li
Formulas for heat kernels are found for degenerate elliptic operators by finding the probability density of the associated Ito diffusion. The formulas involve an integral of a product between a volume function and an exponential term.
Physica D: Nonlinear Phenomena | 2001
Jishan Hu; Min Yan; Tat Leung 余達良 Yee
We demonstrate, through various examples of Hamiltonian systems, that symplectic structures have been encoded into the Painleve test. Each principal balance in the Painleve test induces a mirror transformation that regularizes movable singularities. Moreover, for finite-dimensional Hamiltonian systems, the mirror transformations are canonical.
Applicable Analysis | 2009
Der-Chen Chang; Ting-Hui Chang; Jishan Hu
In this article, we use Hamiltonian and Lagrangian formalisms to give a detailed discussion of sub-Riemannian geometry, which arose from the sub-Laplacian on the product of Heisenberg groups. In particular, we calculate the sub-Riemannian distances along the geodesics. We also find the complex action function and the volume element on the product group. Using this action function and the volume element, we obtain the fundamental solution and the heat kernel for the operator .
Hvac&r Research | 2008
Jishan Hu; Christopher Yu Hang Chao
In this study, the feasibility of using a micro LiBr/water-based absorption heat pump system embedded in protective clothing used in hazardous environments is explored and the characteristics of various microelectromechanical-system-based components are reviewed. The pump is identified as a key part of optimizing the performance of the system. An electroosmotic (EO) micro pump is suggested due to its higher flow rate together with many other advantages. A fabrication process of the EO micro pump was developed and various prototypes of the EO pump were fabricated using standard microfabrication technology. Experiments were conducted to study the performance of the EO micro pump. The results show that a thinner pump offers a higher pressure capacity but a lower flow rate. Higher electric field strength results in an enhanced pressure capacity and flow rate. The flow rate increases at higher temperatures. The effect of the ionic concentration on pumping performance is weak even if the flow rate and pressure capacity are enhanced to some extent. Ethanol was also explored, and it was found that both the flow rate and the pressure are lower when water is used as the working liquid. The information from these results is valuable for use in the subsequent design of the overall micro heat pump system. A thermodynamic analysis using the EO pump information shows that the energy density of the micro heat pump system can be as high as 2.6 W/g and is feasible for use in protective clothing aiming at a total cooling load of about 300 W. The EO pump has been found to contribute about 45% of the total mass of the micro heat pump system.
Journal D Analyse Mathematique | 2003
Jishan Hu; Min Yan
We present a direct and elementary proof that all the solutions of the Painlevé Equations I, II and IV are meromorphic functions on the whole complex plane. The proof uses some ideas from the existing proofs but applies the ideas in a different setting.