Browsing by Author "Chen, Yi-Ting"

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800V Ultra-High-Voltage Start-up Mechanism for Pre-regulator in Power Factor Correction (PFC) Controller
(2011)
Chen, Chi-Lin
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Tsai, Jen-Chieh
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Chen, Yi-Ting
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Ni, Chia-Lung
;
Chen, Chun-Yen
The on-chip 800V ultra-high-voltage (UHV) start-up mechanism was introduced in this paper. Using the UHV start-up mechanism can minimize the current leakage at the AC input and remove the need of external start-up resistor and capacitor. As a result, the standby current can be decreased to improve the efficiency of AC-DC systems. Furthermore, the zero current detection (ZCD) circuit was used here to ensure the work of the pre-regulator. An inductance coil will detect the primary inductance current and reflect the voltage, which is detected by ZCD circuit to provide the energy to the pre-regulator. The test circuit fabricated in TSMC 800V UHV process can show the highly-integrated PFC controller. Experimental results demonstrate low THD of 8%, which results in high PF of 99%. Certainly, high efficiency of 95% can be ensured at the output power of 50W.
92% High Efficiency and Low Current Mismatch Interleaving Power Factor Correction Controller With Variable Sampling Slope and Automatic Loading Detection Techniques
(2013-11-01)
Su, Yi-Ping
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Chen, Chun-Yen
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Ni, Chia-Lung
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Kang, Yu-Chai
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Chen, Yi-Ting
This paper proposes the dual nondeadtime variable sampling slope technique to carry out precise phase sensing and suppress phase error in interleaving power factor correction (PFC) controller over a whole ac switching cycle for low current mismatch. Furthermore, the proposed automatic loading detection (ALD) technique can keep efficiency higher than 92% over a wide load range due to accurately controlling the ON/OFF of dual phases. The test circuit fabricated in the TSMC 0.5-mu m 800-V UHV process shows that the highly integrated interleaving PFC can deliver a high power of 180 W and a high efficiency of 95% at an output power of 180 W.
acPad: Enhancing Channel Utilization for 802.11ac Using Packet Padding
(2017-01-01)
Lin, Chi-Han
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Chen, Yi-Ting
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Lin, Kate Ching-Ju
;
Chen, Wen-Tsuen
;
資訊工程學系
Multi-User Multiple Input Multiple Output (MU-MIMO) enables a multi-antenna access point (AP) to serve multiple users simultaneously, and has been adopted as the IEEE 802.11ac standard. While several PHY-MAC designs have recently been proposed to improve the throughput performance of a MU-MIMO WLAN, they, however, usually assume that all the concurrent streams are of roughly equal length. In reality, users usually have frames with heterogeneous lengths even after aggregation, leading to different lengths of transmission time. Hence, the concurrent transmission opportunities might not always be fully utilized when some streams finish earlier than the others in a transmission opportunity (TXOP). To resolve this inefficiency, this paper presents acPad, a PHY-MAC design that adds additional frames to fill up the idle channel time and better utilize the spatial multiplexing gain. Our acPad identifies proper users as the padding so as to improve the padding gain, while preventing this padding from harming all the ongoing streams. Our evaluation via large-scale trace-driven simulations demonstrates that acPad improves the throughput by up to 2.83x, or by 1.36x on average, as compared to the conventional 802.11ac.
Automatic Loading Detection (ALD) Technique for 92% High Efficiency Interleaving Power Factor Correction (PFC) Over a Wide Output Power of 180W
(2012)
Tsai, Jen-Chive
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Chen, Chun-Yen
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Chen, Yi-Ting
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Ni, Chia-Lung
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Su, Yi-Ping
the proposed automatic loading detection (ALD) technique keeps high efficiency in interleaving power factor correction (PFC) over a wide load range. With the advantages of small input/output filter and output ripple in the interleaving mechanism, the improved efficiency by the ALD technique at light loads due to reduced switching loss can be widely used in the adapter of portable electronics. The ALD technique can calculate the power by the detection of peak input voltage to reduce the switching loss since the slave channel can be completely turned off for power saving at light loads. Therefore, the boundary control mode (BCM) control can simultaneously provide high power and keep high conversion efficiency both at light and heavy loads. The highly integrated PFC controller fabricated in TSMC 800V UHV process shows high efficiency of 92% over a wide output power of 180 W.
Boundary Conduction Mode Controlled Power Factor Corrector With Line Voltage Recovery and Total Harmonic Distortion Improvement Techniques
(2014-07-01)
Su, Yi-Ping
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Ni, Chia-Lung
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Chen, Chun-Yen
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Chen, Yi-Ting
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Tsai, Jen-Chieh
The proposed line voltage recovery (LVR) and the total harmonic distortion improvement (THDI) technique improve power factor (PF) and total harmonic distortion (THD) over a wide line voltage range in boundary conduction mode controlled power factor corrector (PFC). The LVR detects the input line root-mean-square voltage to generate the digital equivalent code to the THDI for optimizing the THD by tuning the on-time value at different line voltages. In addition, the LVR and the THDI provide a feedforward path to reduce the ripple of the feedback voltage for further improving the THD. Therefore, the PFC controller can keep high PF and low THD over a wide line voltage. Experimental results demonstrate that the peak PF value is 0.998 and the minimum THD is 1.7% by the test circuit fabricated in a TSMC 800-V ultrahigh-voltage process with the universal line voltage range of 90-264 V.
Coherent quality management for big data systems: a dynamic approach for stochastic time consistency
(2019-06-01)
Chen, Yi-Ting
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Sun, Edward W.
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Lin, Yi-Bing
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資訊工程學系
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Department of Computer Science
Big data systems for reinforcement learning have often exhibited problems (e.g., failures or errors) when their components involve stochastic nature with the continuous control actions of reliability and quality. The complexity of big data systems and their stochastic features raise the challenge of uncertainty. This article proposes a dynamic coherent quality measure focusing on an axiomatic framework by characterizing the probability of critical errors that can be used to evaluate if the conveyed information of big data interacts efficiently with the integrated system (i.e., system of systems) to achieve desired performance. Herein, we consider two new measures that compute the higher-than-expected error,that is, the tail error and its conditional expectation of the excessive error (conditional tail error)as a quality measure of a big data system. We illustrate several properties (that suffice stochastic time-invariance) of the proposed dynamic coherent quality measure for a big data system. We apply the proposed measures in an empirical study with three wavelet-based big data systems in monitoring and forecasting electricity demand to conduct the reliability and quality management in terms of minimizing decision-making errors. Performance of using our approach in the assessment illustrates its superiority and confirms the efficiency and robustness of the proposed method.
Enhanced hydrogen generation from formic acid by a biomimetic ruthenium complex with a covalently bonded phosphine ligand
(2017-04-13)
Chen, Mei-Hua
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Lin, Jia-Hoa
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Li, Chuen-Ru
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Gliniak, Jacek
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Chang, Chin-Hao
A series of [Ru-2(CO)(5)(mu-SCH2CH2CH2S)PXS] complexes (Ru-2-S-2-PXS, X = phosphine ligands, S = 1-8) have been synthesized and evaluated for their photocatalytic H-2 generation efficiencies from formic acid decomposition. The [Ru-2(CO)(5)(mu-SCH2CH2CH2S)P(o-C6H4CH3)(3)] (Ru-2-S-2-PX4) catalyst + P(CH3)(3) ligand exhibited a high turnover frequency of 15,840h(-1) and turnover number of 24,536. A mechanistic investigation of the Ru-2-S-2-PX4 + FA/TEA catalyzed photocatalytic H-2 generation reaction using ATR-IR, EI-MS, and NMR techniques suggested that when Ru2-S2-PX4 was photoirradiated, the P(o-C6H4CH3)(3) was dissociated from the complex to form a new species, [Ru-2(CO)(5)(mu-SCH2CH2CH2S)]* (I). The free P(o-C6H4CH3)(3) then attacks a second molecule of Ru-2-S-2-PX4 to form Ru-2-S-2-(PX4)(2) and release of free CO, which is then combined with species I to form Ru-2-S-2. Subsequent attachment of formate ion to species Ru-2-S-2-PX4, Ru-2-S-2, and Ru-2-S-2-(PX4)(2) to form [Ru-2(CO)(5)(mu-SCH(2)CH(2)CH(2)SA]-HC00(-) (II), Ru-2-S-2-HCOO- (II') and Ru-2-S-2-PX4-HCOO- (II"), respectively. Rearrangement of complex II (or II' or II") and evolution of CO2 generate a transient complex [Ru-2(CO)(5)(mu-SCH2CH2CH2S)H (III), which then undergoes a protonation process to yield complex [Ru-2(CO)(5)(mu-SCH2CH2CH2S)H-2] (IV). Release of H-2 and re-incorporation of the formate anion as well as evolution of CO2 regenerates the active complex III and the cycle begins again. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
FDoF: Enhancing Channel Utilization for 802.11ac
(2018-02-01)
Lin, Chi-Han
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Chen, Yi-Ting
;
Lin, Kate Ching-Ju
;
Chen, Wen-Tsuen
;
資訊工程學系
Multi-user multiple input multiple output (MU-MIMO) enables a multi-antenna access point to serve multiple users simultaneously, and has been adopted as the IEEE 802.11ac standard. While several PHY-MAC designs have recently been proposed to improve the throughput performance of a MU-MIMO WLAN, they, however, usually assume that all the concurrent streams are of roughly equal length. In reality, users usually have frames with heterogeneous lengths even after aggregation, leading to different lengths of a transmission time. Hence, the concurrent transmission opportunities might not always be fully utilized when some streams finish earlier than the others in a transmission opportunity. To resolve this inefficiency, this paper presents full degree-of-freedom (FDoF), a PHY-MAC design that exploits a novel power allocation scheme to reduce the idle channel time and further leverages frame padding to better utilize the spatial multiplexing gain. Unlike traditional MIMO power allocation, which aims at maximizing the theoretical sum-rate, FDoF's power allocation explicitly considers heterogeneous frame lengths and minimizes the channel time required to finish concurrent frames, as a result improving the effective throughput. FDoF's padding protocol then identifies proper users to reuse the remaining idle channel time, while preventing this padding from harming all the ongoing streams. Our evaluation via large-scale trace-driven simulations demonstrates that FDoF's improves the throughput by up to 2.83x, or by 1.36x on average, as compared to the conventional 802.11ac. By combining FDoF's power allocation with frame padding, the average throughput gain can be further increased to 1.75x.
Generalized optimal wavelet decomposing algorithm for big financial data
(2015-07-01)
Sun, Edward W.
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Chen, Yi-Ting
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Yu, Min-Teh
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資訊工程學系
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Department of Computer Science
Using big financial data for the price dynamics of U.S. equities, we investigate the impact that market microstructure noise has on modeling volatility of the returns. Based on wavelet transforms (DWT and MODWT) for decomposing the systematic pattern and noise, we propose a new wavelet-based methodology (named GOWDA, i.e., the generalized optimal wavelet decomposition algorithm) that allows us to deconstruct price series into the true efficient price and microstructure noise, particularly for the noise that induces the phase transition behaviors. This approach optimally determines the wavelet function, level of decomposition, and threshold rule by using a multivariate score function that minimizes the overall approximation error in data reconstruction. The data decomposition method enables us to estimate and forecast the volatility in a more efficient way than the traditional methods proposed in the literature. Through the proposed method we illustrate our simulation and empirical results of improving the estimation and forecasting performance. (C) 2015 Elsevier B.V. All rights reserved.
Growth competition between layer-type and porous-type Cu3Sn in microbumps
(2017-12-01)
Chu, David T.
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Chu, Yi-Cheng
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Lin, Jie-An
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Chen, Yi-Ting
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Wang, Chun-Chieh
Experimental study of growth competition between the co-existing layer-type and porous-type Cu3Sn in solder microbumps of Cu/SnAg/Cu is reported. The thickness of the SnAg solder is about 14 pm and the Cu column on both sides is 20 pm. Upon wetting-reflow, the solder is reacted completely to form Cu Sn iptermetallic compounds in a multi-layered structure of Cu/Cu3Sn/Cu6Sn5/Cu3Sn/Cu. Upon further annealing at 220 degrees C and 260 C, we obtain Cu/Cu3Sn/porous Cu3Sn/Cu3Sn/Cu, in which both types of Cu3Sn co-exist and form an interface. In the layer-type growth, we assume Cu to be the dominant diffusing species, coming from the Cu column. The Cu reacts with Cu6Sn5 to grow the Cu3Sn layer. In the porous-type growth, we assume Sn to be the dominant diffusing species, coming from the depletion of Sn in Cu6Sn5. The depleted Cu6Sn5 transforms to the porous-type Cu3Sn. At the same time, the Sn diffuses to the side-wall of Cu column to form a coating of Cu3Sn. Experimental observations of 3-dimensional distribution of voids in the porous-type Cu3Sn are performed by synchrotron radiation tomography; the voids are interconnected for the out-diffusion of Sn. The competing growth between the layer-type and the porous-type Cu3Sn is analyzed. (C) 2017 Elsevier Ltd. All rights reserved.
High-PF and Ultra-Low-THD Power Factor Correction Controller by Sinusoidal-Wave Synthesis and Optimized THD Control
(2013)
Chang, Chih-Wei
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Ni, Chia-Lung
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Tsai, Jen-Chieh
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Chen, Yi-Ting
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Chen, Chun-Yen
the proposed sinusoidal-wave synthesis (SWS) and the optimized THD control (OTC) improve power factor (PF) and total harmonic distortion (THD) over a wide line voltage range. The SWS detects the input line root-mean-square (rms) voltage to generate the digital equivalent code to the OTC for optimizing the THD by tuning the on-time value. Besides, the SWS and the OTC provide a feedforward path to reduce the ripple of the feedback voltage for further improving the THD. Therefore, the PFC converter can keep high PF and low THD over a wide line voltage. Experimental results demonstrate the PF is higher than 0.99 and the THD is 1.7% at V-AC of 90 - 110V by the test circuit fabricated in TSMC 800V UHV process.
High-Rate Hydrogen Generation by Direct Sunlight Irradiation with a Triruthenium Complex
(2019-02-04)
Wu, Tung-Kung
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Chen, Yi-Ting
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Peng, Chun-Sheng
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Lin, Jia-Hoa
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Gliniak, Jacek
Herein we report a biomimetic triruthenium catalyst that, when under direct sunlight irradiation, facilitates high-rate H-2 production from formic acid (FA) dehydrogenation. The system consists of 2 mu mol of catalyst and 6 mu mol of tri-o-tolylphosphine in 1 mL of dimethylformamide (DMF) and 4 mL of FA/triethylamine (TEA; 5:2). With 0.4 mM catalyst loaded, a high turnover frequency of 1.15 X 10(6) h(-1) was detected when under direct sunlight irradiation. In an experiment with 0.2 mM catalyst loaded, more than 140 L of H-2 (280 L of H-2 + CO2) was produced, and a turnover number of approximately 2.78 X 10(6) was obtained within 5 h without decline in H-2 generation activity, making it suitable for high-rate H-2 production.
Improving model performance with the integrated wavelet denoising method
(2015-09-01)
Chen, Yi-Ting
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Sun, Edward W.
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Yu, Min-Teh
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交大名義發表
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National Chiao Tung University
Intelligent pattern recognition imposes new challenges in high-frequency financial data mining due to its irregularities and roughness. Based on the wavelet transform for decomposing systematic patterns and noise, in this paper we propose a new integrated wavelet denoising method, named smoothness-oriented wavelet denoising algorithm (SOWDA), that optimally determines the wavelet function, maximal level of decomposition, and the threshold rule by using a smoothness score function that simultaneously detects the global and local extrema. We discuss the properties of our method and propose a new evaluation procedure to show its robustness. In addition, we apply this method both in simulation and empirical investigation. Both the simulation results based on three typical stylized features of financial data and the empirical results in analyzing high-frequency financial data from Frankfurt Stock Exchange confirm that SOWDA significantly (based on the RMSE comparison) improves the performance of classical econometric models after denoising the data with the discrete wavelet transform (DWT) and maximal overlap discrete wavelet transform (MODWT) methods.
Interaural Coherence Induced Ideal Binary Mask for Binaural Speech Separation and Dereverberation
(2016-01-01)
Chen, Yi-Ting
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Chen, Tzu-Hao
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Huang, Mao-Chang
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Chi, Tai-Shih
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電機工程學系
We have proposed a spatial-cue based binaural noise reduction algorithm for hearing aids. However, in that algorithm, decision parameters are empirically selected. In this paper, we extend the work and propose a supervised classification algorithm for binaural speech enhancement/separation and dereverberation using a modified ideal binary mask (mIBM) as the training target and simple neural networks (NNs) as classifiers. The low complexity of the simple NNs makes the proposed algorithm practical for binaural hearing aids. The interaural time difference (ITD) and the interaural level difference (ILD) of each T-F unit are extracted as the basic binaural features. For the purpose of dereverberation, the interaural coherence (IC) is also considered when building the target mIBM and training the NNs. For separation evaluations, our method yields comparable performance to a more complicated benchmark system, which cannot de-reverb the signal. For concurrent separation and dereverberation, our method offers 4 to 5 dB improvement on the frequencyweighted segmental speech-to-noise ratio (SNRfw) over unprocessed speech.
iVRNote: Design, Creation and Evaluation of an Interactive Note-Taking Interface for Study and Reflection in VR Learning Environments
(2019-01-01)
Chen, Yi-Ting
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Hsu, Chi-Hsuan
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Chung, Chih-Han
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Wang, Yu-Shuen
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Babu, Sabarish V.
In this contribution, we design, implement and evaluate the pedagogical benefits of a novel interactive note taking interface (iVRNote) in VR for the purpose of learning and reflection lectures. In future VR learning environments, students would have challenges in taking notes when they wear a head mounted display (HMD). To solve this problem, we installed a digital tablet on the desk and provided several tools in VR to facilitate the learning experience. Specifically, we track the stylus' position and orientation in the physical world and then render a virtual stylus in VR. In other words, when students see a virtual stylus somewhere on the desk, they can reach out with their hand for the physical stylus. The information provided will also enable them to know where they will draw or write before the stylus touches the tablet. Since the presented iVRNote featuring our note taking system is a digital environment, we also enable students save efforts in taking extensive notes by providing several functions, such as post-editing and picture taking, so that they can pay more attention to lectures in VR. We also record the time of each stroke on the note to help students review a lecture. They can select a part of their note to revisit the corresponding segment in a virtual online lecture. Figures and the accompanying video demonstrate the feasibility of the presented iVRNote system. To evaluate the system, we conducted a user study with 20 participants to assess the preference and pedagogical benefits of the iVRNote interface. The feedback provided by the participants were overall positive and indicated that the iVRNote interface could be potentially effective in VR learning experiences.
Jump Detection and Noise Separation by a Singular Wavelet Method for Predictive Analytics of High-Frequency Data
(2019-08-01)
Chen, Yi-Ting
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Lai, Wan-Ni
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Sun, Edward W.
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資訊學院
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College of Computer Science
High-frequency data is a big data in finance in which a large amount of intra-day transactions arriving irregularly in financial markets are recorded. Given the high frequency and irregularity, such data require efficient tools to filter out the noise (i.e. jumps) arising from the anomaly, irregularity, and heterogeneity of financial markets. In this article, we use a recurrently adaptive separation algorithm, which is based on the maximal overlap discrete wavelet transform (MODWT) and that can effectively: (1) identify the time-variant jumps, (2) extract the time-consistent patterns from the noise (jumps), and (3) denoise the marginal perturbations. In addition, the proposed algorithm enables reinforcement learning to optimize a multiple-criteria decision or convex programming when reconstructing the wavelet-denoised data. Using simulated data, we show the proposed approach can perform efficiently in comparison with other conventional methods documented in the literature. We also apply our method in an empirical study by using high-frequency data from the US stock market and confirm that the proposed method can significantly improve the accuracy of predictive analytics models for financial market returns.
Machine learning with parallel neural networks for analyzing and forecasting electricity demand
(2020-08-01)
Chen, Yi-Ting
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Sun, Edward W.
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Lin, Yi-Bing
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資訊工程學系
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Department of Computer Science
Traditional methods applied in electricity demand forecasting have been challenged by the course of dimensionality arisen with a growing number of distributed or decentralized energy systems are employing. Without manually operated data preprocessing, classic models are not well-calibrated for their robustness when dealing with the disruptive elements (e.g., demand changes in holidays and extreme weather). Based on the application of big data driven analytics, we propose a novel machine learning method originating from the parallel neural networks for robust monitoring and forecasting power demand to enhance supervisory control and data acquisition for new industrial tendency such as Industry 4.0 and Energy IoT. Through our approach, we generalize the implementation of machine learning by using classic feed-forward neural networks, for parallelization in order to let the proposed method achieve superior performance when dealing with high dimensionality and disruptiveness. With the high-frequency data of consumption in Australia from January 2009 to December 2015, the overall empirical results confirm that our proposed method performs significantly better for dynamic monitoring and forecasting of power demand comparing with the classic methods.
Merging anomalous data usage in wireless mobile telecommunications: Business analytics with a strategy-focused data-driven approach for sustainability
(2020-03-16)
Chen, Yi-Ting
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Sun, Edward W.
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Lin, Yi-Bing
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資訊工程學系
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Department of Computer Science
Mobile internet usage has exploded with the mass popularity of smartphones that offer more convenient and efficient ways of doing anything from watching movies, playing games, and streaming music. Understanding the patterns of data usage is thus essential for strategy-focused data-driven business analytics. However, data usage has several unique stylized facts (such as high dimensionality, heteroscedasticity, and sparsity) due to a great variety of user behaviour. To manage these facts, we propose a novel density-based subspace clustering approach (i.e., a three-stage iterative optimization procedure) for intelligent segmentation of consumer data usage/demand. We discuss the characteristics of the proposed method and illustrate its performance in both simulation with synthetic data and business analytics with real data. In a field experiment of wireless mobile telecommunications for data-driven strategic design and managerial implementation, we show that our method is adequate for business analytics and plausible for sustainability in search of business value. (C) 2019 Published by Elsevier B.V.
Perturbation On-time (POT) Control and Inhibit Time Control (ITC) in Suppression of THD of Power Factor Correction (PFC) Design
(2011)
Tsai, Jen-Chieh
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Chen, Chi-Lin
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Chen, Yi-Ting
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Ni, Chia-Lung
;
Chen, Chun-Yen
The paper presented the perturbation on-time (POT) control technique to suppress the total harmonic distortion (THD) to improve the performance of the power factor correction (PFC) in the AC-DC converter. Simultaneously, it can improve the efficiency through the proposed inhibit time control (ITC) mechanism at low AC input voltage. The test circuit fabricated in TSMC 800V UHV process can show the highly-integrated PFC controller. Experimental results demonstrate low THD of 8%, which results in high PF of 99%. Besides, high efficiency of 95% can be ensured at the output power of 90W.
Perturbation On-Time (POT) Technique in Power Factor Correction (PFC) Controller for Low Total Harmonic Distortion and High Power Factor
(2013-01-01)
Tsai, Jen-Chieh
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Chen, Chi-Lin
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Chen, Yi-Ting
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Ni, Chia-Lung
;
Chen, Chun-Yen
The proposed perturbation on-time technique suppresses total harmonic distortion (THD) and, thus, improves the power factor in the power factor correction (PFC) controller. Besides, the adaptive control of the minimum off time by the proposed inhibit time control can improve efficiency even at low ac input voltage. Therefore, highly integrated PFC converter fabricated in the TSMC 800-V ultrahigh voltage process can achieve low THD of 6%, high PF of 99%, and high efficiency of 95% at the output power of 90 W.