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Chen, Yuanfeng,Geng, Di,Lin, Tengda,Mativenga, Mallory,Jang, Jin IEEE 2016 IEEE electron device letters Vol.37 No.7
<P>As clock signals are usually supplied by external rigid ICs, they may limit mechanical flexibility of devices fabricated on plastic. Reported in this letter is a full-swing clock generating circuit that is integrated on a plastic substrate. The clock signal is generated by a 13-stages ring oscillator (RO), which is implemented by n-type-only dual-gate amorphousindium-gallium-zinc-oxide thin-film transistors. By combining bootstrapping and pseudo-CMOS inverting, an output peak-peak voltage (Vp-p) that reaches the supply voltage (V-DD) and a high speed, reaching an output frequency of 360 kHz, are achieved. In addition, a phase modulating capacitor is implemented in the RO to increase the high voltage level holding time and the addition of a buffer in the circuit is also studied for the achievement of two antiphase outputs.</P>
High-Speed Pseudo-CMOS Circuits Using Bulk Accumulation a-IGZO TFTs
Yuanfeng Chen,Di Geng,Mativenga, Mallory,Hyoungsik Nam,Jin Jang IEEE 2015 IEEE electron device letters Vol.36 No.2
<P>We propose a way to achieve high-speed circuits with dual-gate (DG) bulk-accumulation back-channeletched (BCE) amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) using the pseudo-CMOS structure. The DG BCE a-IGZO TFTs exhibit field-effect mobility (μ<SUB>FE</SUB>), threshold voltage (Vth), and subthreshold swing of 30 ± 3 cm<SUP>2</SUP>/Vs, 2 ± 0.5 V, and 120 ± 30 mV/decade, respectively. For input voltage (V<SUB>DD</SUB>) of 20 V, seven-stage pseudo-CMOS ring oscillators implemented with the BCE bulk-accumulation a-IGZO TFTs show oscillation frequency of 6.51 MHz, which corresponds to a propagation delay time of 11 ns/stage and is faster than the 17 ns/stage delay of the fastest single-gate-driven ratioed coplanar a-IGZO TFT circuits.</P>
Yuanfeng Wu,Enwei Chen,Neil S Ferguson,Yuteng He,Haozheng Wei,Yimin Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
The axially moving string model is widely used in engineering applications and is of great significance in research. To suppress transverse vibration and facilitate energy dissipation of the axially moving string with nonclassical boundaries, a bi-objective optimization model and methodology are proposed for its boundary parameters’ design. First, an approximate numerical model for an axially moving string with a nonclassical boundary is established, which is based on the finite element method (FEM) and Newmark-beta method. Then, a biobjective model is proposed, including the average transverse vibration and the average system energy in a single traveling wave period, and a particle swarm optimization (BOPSO) algorithm is established for optimization. Finally, the proposed optimization model is applied in a numerical example, and the results are compared with NSGA-II, a multi-objective cuckoo search algorithm (MOCSA), and multi-objective flower pollination algorithm (MOFPA) to verify the feasibility of the proposed methodology.
CNN-based damage identification method of tied-arch bridge using spatial-spectral information
Yuanfeng Duan,Qianyi Chen,Hongmei Zhang,Chung Bang Yun,Sikai Wu,Qi Zhu 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.5
In the structural health monitoring field, damage detection has been commonly carried out based on the structural model and the engineering features related to the model. However, the extracted features are often subjected to various errors, which makes the pattern recognition for damage detection still challenging. In this study, an automated damage identification method is presented for hanger cables in a tied-arch bridge using a convolutional neural network (CNN). Raw measurement data for Fourier amplitude spectra (FAS) of acceleration responses are used without a complex data pre-processing for modal identification. A CNN is a kind of deep neural network that typically consists of convolution, pooling, and fully-connected layers. A numerical simulation study was performed for multiple damage detection in the hangers using ambient wind vibration data on the bridge deck. The results show that the current CNN using FAS data performs better under various damage states than the CNN using time-history data and the traditional neural network using FAS. Robustness of the present CNN has been proven under various observational noise levels and wind speeds.
Haokun Chen,Shumei Zhong,Liuling Wu,Yuanfeng Sha,Qiang Qin,Qi Qi Pang,Jia-Le Song 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
Understand the dietary conditions of freshmen in a medical university, and explore the correlation between their dietary patterns and physical fitness levels. A dietary frequency survey was carried out among 2125 freshmen to evaluate their nutrient intake. Factor analysis was performed to extract common factors and determine dietary patterns. According to the "National Standards for Students" Physical health", the freshmen were tested for physical fitness, and the correlation analysis was conducted between the results of physical fitness score and dietary patterns. Four dietary patterns were identified by factor analysis, which were healthy dietary pattern (HDP), high fat and high sugar pattern (HFP/HSP), preserved food pattern and trace element pattern (TEP). Spearman rank correlation analysis showed the HDP and TEP were significantly positively correlated with the fitness test scores (r=0.064,0.062, p< 0.01), while the HFP and HSP was significantly negatively correlated (r=-0.057,p<0.01). Our results suggest that a healthy diet was associated with improved physical fitness performance, while a high intake of fatty and sweetened foods was associated with the opposite.
A Multicast Routing Algorithm Based on Prior Objective Nodes
Weijun Yang,Xiaodong Wang,Yuanfeng Chen 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.10
The minimum Steiner tree problem is an NP-complete problem in multicast routing algorithms. In this paper, an improved algorithm called the prior nodes minimum cost path heuristic (PNMPH) algorithm is presented according to the shortage of the minimum cost path heuristic (MPH) algorithm, in which some paths that pass through prior destination nodes are selected first. It partly shares links in the network and decreases the cost of the multicast routing tree. It is also closer to the optimal solution with the time complexity O(n3). The simulation results on the existing networks show that the cost of the PNMPH algorithm is lower than that of the MPH algorithm in the case of more than 90%.
Seok-Jeong Song,Yuanfeng Chen,Jin Jang,Hyoungsik Nam IEEE 2015 Journal of display technology Vol.11 No.3
<P>This paper describes a new simultaneous emission AMOLED pixel circuit to achieve high brightness. Unlike the previous simultaneous emission scheme, the proposed one allows the programming operation to take place at the same time with the emission of OLEDs, which leads to high brightness. The proposed hybrid pixel circuit consists of programming and driving parts. The programming part compensates for the threshold voltage variation by means of a voltage programming scheme and the driving part is updated from the programming part through the internal current programming scheme. The SPICE simulation ensures that the proposed scheme dramatically reduces the average current error to 1.5% and 4.0% as to the threshold voltage variations of ±0.2 V and ±0.5 V, respectively. In addition, because approximately the whole frame time can be secured for the emission period, the output luminance loss is alleviated substantially compared with the previous method.</P>
Effect of Bulk-Accumulation on Switching Speed of Dual-Gate a-IGZO TFT-Based Circuits
Xiuling Li,Di Geng,Mativenga, Mallory,Yuanfeng Chen,Jin Jang IEEE 2014 IEEE electron device letters Vol.35 No.12
<P>The effect of bulk accumulation on switching speed of dual-gate amorphous indium-gallium-zinc-oxide thin-film transistor (TFT)-based circuits is investigated. Given that bulk accumulation is achieved by synchronized driving of the top gate (TG) and bottom gate, it can be modulated by varying the length of the TG (L<SUB>TG</SUB>) for fixed source-drain distance (L). It is confirmed from fabricated ring oscillators that switching speed increases with increasing L<SUB>TG</SUB> for fixed L, verifying that bulk accumulation improves switching speed. However, switching speed drops dramatically when the TG overlaps the source/drain electrodes due to additional parasitic capacitance. TFT-circuits with the longest, but nonoverlapping TGs are demonstrated to exhibit the fastest switching speed; operation frequency exceeding 2.63 MHz for input voltage V<SUB>DD</SUB> of 20 V, which is also the fastest among all inverted staggered amorphous-oxide-semiconductor TFT-based circuits.</P>