Browsing by Author "Li, Yan"

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An Intelligent Recommender System based on Short-term Risk Prediction for Heart Disease Patients
(2015)
Lafta, Raid
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Zhang, Ji
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Tao, Xiaohui
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Li, Yan
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Tseng, Vincent S.
In this paper, an intelligent recommender system is developed, which uses an innovative time series prediction algorithm to provide recommendations to heart disease patients in the tele-health environment. Based on analytics of each patient\'s medical tests in records, the system provides the patient with decision support for necessity of medical tests. The experimental results show that the proposed system yields satisfactory accuracy in recommendations. The system also offers a promising way for saving the workload for patients and healthcare practitioners in conducting daily medical tests. The research will help reduce the workload and cost in healthcare and help the healthcare industry transform from the traditional scenario to more a personalized paradigm in a tele-health environment.
Detecting small lung tumors in mouse models by refractive-index microradiology
(2011-08-01)
Chien, Chia-Chi
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Zhang, Guilin
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Hwu, Y.
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Liu, Ping
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Yue, Weisheng
Refractive-index (phase-contrast) radiology was able to detect lung tumors less than 1 mm in live mice. Significant micromorphology differences were observed in the microradiographs between normal, inflamed, and lung cancer tissues. This was made possible by the high phase contrast and by the fast image taking that reduces the motion blur. The detection of cancer and inflammation areas by phase contrast microradiology and microtomography was validated by bioluminescence and histopathological analysis. The smallest tumor detected is less than 1 mm(3) with accuracy better than 1 x 10(-3) mm(3). This level of performance is currently suitable for animal studies, while further developments are required for clinical application.
Influences of Nitrogen Doping on the Electrical Characteristics of Indium-Zinc-Oxide Thin Film Transistors
(2016-12)
Han, Yanbing
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Yan, Hai
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Tsai, Yun-Chu
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Li, Yan
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Zhang, Qun
Thin film transistors (TFTs) with nitrogen doped amorphous indium-zinc-oxide (a-IZO:N) as the channel layer were prepared by rf magnetron sputtering with an argon, oxygen, and nitrogen gas mixture at room temperature. XRD measurements confirm the amorphous structure of a-IZO:N thin film and AFM verifies its uniformity. Transmittance curves show that nitrogen doping in a-IZO films can narrow the optical band gap and suppress oxygen vacancies, which is also proved by XPS. When the nitrogen flow rate is 4 SCCM, a-IZO TFTs possess optimized the characteristics, with saturation mobility 24.67 cm(2)V(-1)s(-1), subthreshold swing 0.41 V/decade, on/off ratio 1.7 x 10(9), and threshold voltage -14.46 V. Threshold voltages shift from -22.76 to -9.59 V as the nitrogen flow rate raises from 0 to 6.5 SCCM. The positive gate bias stability and negative bias illumination stability of a-IZO:N TFT are also improved with the nitrogen flow rate of 4 and 2.5 SCCM, respectively.
Numerical Method of Fabric Dynamics Using Front Tracking and Spring Model
(2013-11-01)
Li, Yan
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Chern, I-Liang
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Kim, Joung-Dong
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Li, Xiaolin
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數學建模與科學計算所(含中心)
We use front tracking data structures and functions to model the dynamic evolution of fabric surface. We represent the fabric surface by a triangulated mesh with preset equilibrium side length. The stretching and wrinkling of the surface are modeled by the mass-spring system. The external driving force is added to the fabric motion through the "Impulse method" which computes the velocity of the point mass by superposition of momentum. The mass-spring system is a nonlinear ODE system. Added by the numerical and computational analysis, we show that the spring system has an upper bound of the eigen frequency. We analyzed the system by considering two spring models and we proved in one case that all eigenvalues are imaginary and there exists an upper bound for the eigen-frequency. This upper bound plays an important role in determining the numerical stability and accuracy of the ODE system. Based on this analysis, we analyzed the numerical accuracy and stability of the nonlinear spring mass system for fabric surface and its tangential and normal motion. We used the fourth order Runge-Kutta method to solve the ODE system and showed that the time step is linearly dependent on the mesh size for the system.
Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram
(2017-01)
Doytchinova, Anisiia
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Hassel, Jonathan L.
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Yuan, Yuan
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Lin, Hongbo
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Yin, Dechun
BACKGROUND Sympathetic nerve activity is important to cardiac arrhythmogenesis. OBJECTIVE The purpose of this study was to develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. This method (neuECG) can be used to adequately estimate sympathetic tone. METHODS We recorded neuECG signals from the skin of 56 human subjects. The signals were low-pass filtered to show the ECG and high-pass filtered to show nerve activity. Protocol 1 included 12 healthy volunteers who underwent cold water pressor test and Valsalva maneuver. Protocol 2 included 19 inpatients with epilepsy but without known heart diseases monitored for 24 hours. Protocol 3 included 22 patients admitted with electrical storm and monitored for 39.0 +/- 28.2 hours. Protocol 4 included 3 patients who underwent bilateral stellate ganglion blockade with lidocaine injection. RESULTS In patients without heart diseases, spontaneous nerve discharges were frequently observed at baseline and were associated with heart rate acceleration. SKNA recorded from chest leads (V1V6) during cold water pressor test and Valsalva maneuver (protocol 1) was invariably higher than during baseline and recovery periods (P <.001). In protocol 2, the average SKNA correlated with heart rate acceleration (r = 0.73 +/- 0.14, P <.05) and shortening of QT interval (P <.001). Among 146 spontaneous ventricular tachycardia episodes recorded in 9 patients of protocol 3, 106 episodes (73%) were preceded by SKNA within 30 seconds of onset. Protocol 4 showed that bilateral stellate ganglia blockade by lidocaine inhibited SKNA. CONCLUSION SKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating sympathetic tone.
Targeted suppression of vibration in deep hole drilling using magneto-rheological fluid damper
(2014-11-01)
Kong, Lingfei
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Chin, Jih-Hua
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Li, Yan
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Lu, Yanjun
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Li, Pengyang
Under the concept of precision or targeted vibration suppression, a novel approach is developed to reduce the vibration of drilling tool system in deep-hole drilling process. The concept is to suppress the dominant vibration upon its emergence by variable damping or to force the harmful vibration morph into less harmful by different damper position. A magneto-rheological (MR) fluid damper is designed with adjustable damping capability to counteract emerging vibration. A series of experimental investigations are carried out on the BTA deep hole drilling process. The experimental results show that the adjustable MR damping brings down the vibration in all applications with different suppression effect. A relative optimal suppression can always be found. The suppressed vibration experiences a frequency shift which sheds light on the possible avoidance of matching of unwelcome frequency. Different damper locations have different but consistent suppression results which foresee a possibility of forcing the mode of vibration into less harmful one. A potential precision or targeted suppression of vibration upon its emergence is thus possible. (C) 2014 Elsevier B.V. All rights reserved.
Vibration suppression of drilling tool system during deep-hole drilling process using independence mode space control
(2020-04-01)
Kong, Lingfei
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Cao, Shuai
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Chin, Jih-Hua
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Si, Yue
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Miao, Falin
Deep-hole drilling technology is commonly used in the aerospace and automobile industries, for new-energy equipment manufacturing, and in the high-tech industries. While this technology produces high-quality holes, higher quality is pursued. A method to improve the processing quality is to suppress the vibration modes associated with long shafts. This problem was addressed with an aim of real-time application. In addition, a higher goal was set by way of providing a solution (in full) to the associated problem, to shed light on processes that bear similar features in manufacturing and for other industries. An operable control scheme was constructed by transforming the system dynamics to modal space for modal decoupling and truncation. The modal displacement and velocity information estimated by the modal filtering were introduced into the feedback gain matrix. All obstacles in traditional physical space were shunned. A damper/sensor position optimisation algorithm was suggested to minimise the modal spillover and acquire modal orthogonality, which led to a new method that has an edge on all preceding methods because of its stronger ability. A system capable of real-time suppression of modal vibration in a deep-hole drilling tool was built and implemented. Using hole roundness error as the criterium, it was found that further improvement of hole quality was achieved. The idea presented in this work may pave the way for elevating the quality of other manufacturing processes with similar weak stiffness features, such as those seen in long-shaft tools or thin-wall workpieces. The method may also provide a reference for other industries with relevant or comparable problems.