Optical properties of an N-type system in Doppler-broadened multilevel atomic media of the rubidium D2 line

Chen, Yi,Wei, Xiao Gang,Ham, B S IOP Pub 2009 Journal of Physics B: Atomic, Molecular and Optica Vol.42 No.6

<P>We report the observations of Mollow sideband-like transparency windows in a Doppler-broadened four-level N-type system of the rubidium D2 line. A pair of enhanced transparency windows across an electromagnetically induced transparency line centre results from dressed state interactions of two coupling fields. The present observations have potential applications of using the symmetric transparency windows for optical quantum information processing such as multiple optical buffer memories and double slow-light-based enhanced cross-phase modulation. We also discuss the quantum coherent control of absorption cancellation, absorption enhancement and probe gain in a closed N-type four-level model introducing the atom flow rate determined by the population decay rate and control field intensity.</P>

On-chip capacitive sensing and tilting motion estimation of a micro-stage for <i>in situ</i> MEMS gyroscope calibration

Chen, Yi,Aktakka, Ethem Erkan,Woo, Jong-Kwan,Najafi, Khalil,Oldham, Kenn Richard Elsevier 2018 Mechatronics Vol.56 No.-

<P><B>Abstract</B></P> <P>In this paper, we introduce a novel on-chip capacitive sensor design and a motion estimation method for measuring multi-axis out-of-plane tilting motion of a micro-stage that is used for <I>in situ</I> calibration of an integrated MEMS gyroscope. On-chip sensing and motion estimation is critical for this application, since precision in measuring high frequency tilting motion of the micro-stage determines how accurately an on-stage MEMS gyroscope can be calibrated in the field with respect to this motion. To obtain decoupled sensing signals from multi-axis out-of-plane tilting motion, a capacitive sensing layout with high off-axis signal rejection capability is introduced. With the proposed design specifications and range of tilting motion, a dual axis capacitive sensor model is developed, and simulation results show that the sensor is able to reject more than 99.90% of the off-axis signal. The sensor also permits detection of perturbations to stage geometry due to ambient temperature variation through the effects of nonlinear behavior on signal timing. To measure tilting motion with the obtained sensing signal, a motion estimator with extended Kalman Filter (EKF) is also developed. With assistance of a laser Doppler vibrometer (LDV), experiments are performed to identify the parameters of the motion estimator and validate its performance. The experimental results demonstrate a 286 ppm error in scale factor calibration of a commercial MEMS gyroscope by the micro-stage with moderate temperature variation.</P>

Study on the detection behavior of defect-rich single-walled carbon nanotubes toward perchlorate

Chen, Yi,Nguyen, Thuy Hang,Zhang, Shao Lin,Zhang, Z.,Yue, Hongyan,Jian, Jiawen,Yang, Woo-Chul World Scientific Publishing Company 2018 Functional materials letters Vol.11 No.2

<P>Defect-rich single-walled carbon nanotubes (SWCNTs) were prepared by a water vapor flow-assisted chemical vapor deposition process. The correlation between defect density and water flow was quantitively studied using Raman spectrum. The detection capabilities of defective SWCNTs films toward perchlorate anions were investigated. It was found the defect-rich SWCNTs could adsorb more perchlorate anions owing to the strong chemical bonding between anions and defective sites. However, the detective response of defective SWCNTs toward perchlorate was not in compliance with anion adsorption. A tradeoff phenomenon between response and adsorption was found as the defect density of SWCNTs increased. This work is expected to provide a guidance to the future design of SWCNTs based ion detector.</P>

Detuned slow light in the Doppler broadened multi-level D2 line of Rubidium

Chen, Yi,Wei, Xiao Gang,Ham, Byoung S. The Optical Society 2009 Optics express Vol.17 No.3

<P>We observed a detuned slow light phenomenon based on electromagnetically induced transparency in (87)Rb D2 line composed of multiple excited-hyperfine states within a Doppler-broadened linewidth. The results show that the maximum group delay of a probe occurs at off-detuned two-photon resonance frequency. The observed detuned group delay is analyzed with numerical calculations for a probe pulse interacting with the neighboring excited-states-modified Doppler broadening atoms for a fixed coupling field. The experimental results are in good agreement with the numerical calculations.</P>

Stabilization of a Scalar Continuous Time Linear System with Unknown Noise Based on Two-stage Event-triggering

Chenyi Wang,Qiang Ling 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.5

This paper aims to ensure the input-to-state stability (ISS) of a continuous-time linear scalar system which suffers from quantization, unknown noise, and network delay. To deal with the unknown noise, we design a dynamic quantization scheme that switches between “zooming-in” and “zooming-out”, and adjusts a “zooming” parameter of finite-level quantizers. Moreover, a two-stage event-triggering scheme is proposed to determine whether to sample the state and whether to transmit the encoded state information. The joint design of the dynamic quantization scheme and the two-stage event-triggering scheme can well counteract the effects of unknown noise and network delay on the desired ISS of the concerned system. Moreover, the proposed schemes can avoid Zeno behavior and do not require any prior bounds on the unknown noise. The effectiveness of the proposed schemes is further verified through simulations.

A clustered sulfonated poly(ether sulfone) based on a new fluorene-based bisphenol monomer

Wang, Chenyi,Shin, Dong Won,Lee, So Young,Kang, Na Rae,Robertson, Gilles P.,Lee, Young Moo,Guiver, Michael D. The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.48

<P>A new fluorene-based bisphenol monomer containing two pendant phenyl groups, 9,9-bis(3-phenyl-4-hydroxy)phenyl-fluorene, was readily synthesized in high yield by a one-step reaction from inexpensive starting materials. A series of poly(ether sulfone)s with clustered sulfonic acid groups was prepared for fuel cell applications by polycondensation of the new monomer with bis(4-hydroxyphenyl)sulfone and bis(4-fluorophenyl)sulfone, followed by sulfonation exclusively on the fluorene rings and pendant phenyl rings, using concentrated sulfuric acid at room temperature. The sulfonated polymers gave tough, flexible, and transparent membranes by solvent casting. The ionic exchange capacity (IEC), water-uptake, dimensional stabilities, mechanical properties, thermal and oxidative stabilities as well as proton conductivities and single fuel cell properties of the membranes were investigated. The membranes with high IEC values show high proton transport properties, and their proton conductivities exhibit lower dependence on relative humidity compared with typical aromatic ion exchange membranes. 4-SPES-38 with an IEC value of 2.23 mequiv. g<SUP>−1</SUP> displays comparable fuel cell performance with Nafion 212 under low humidity conditions.</P> <P>Graphic Abstract</P><P>A new fluorene-based bisphenol monomer with pendant phenyl substituents was prepared by a facile synthetic route, from which clustered sulfonated poly(ether sulfone)s with excellent overall membrane properties were achieved for fuel cell tests. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm34414a'> </P>

中国终身教育教授者教授能力教育要求分析

JIA CHENYI,임명희 한국아시아학회 2023 아시아연구 Vol.26 No.2

The purpose of this study is to improve and strengthen the teaching capabilities of Chinese lifelong education instructors by identifying the importance and current level of teaching capabilities recognized by lifelong education instructors and ranking educational needs. To this end, a survey of 259 Chinese lifelong education instructors was conducted for four weeks from October 1, 2022. As a result of this study, a difference test between the important level of teaching competency and the current level was conducted to determine the priority according to the teaching competency education needs of lifelong education instructors. As a result of the analysis, there was a statistically significant difference in the difference between the important level and the current level in teaching competency. Program development capabilities, self-management capabilities, learner progress management capabilities, teaching method development capabilities, learning resource and information collection capabilities, course planning capabilities, learning counseling and consulting capabilities, integration of learning content, concentration development capabilities, and motivation capabilities. In the Focus model, a total of 10 items were derived from teaching method development, curriculum preparation, motivation, teaching media utilization, communication, ice breaking, self-management, learner progress management, concentration, learning counseling, and consulting. Borich's demand priority detailed competencies and The Focus for Focus model HH were seven top priority detailed competencies: teaching method development, course preparation, motivation, self-management, learner progress management, concentration development, learning counseling, and consulting. It is important to prepare a plan based on the analysis of instructors' educational needs because the teaching competency for lifelong education instructors to play a successful role as instructors plays an important role in learners' learning outcomes and learners' learning satisfaction. Therefore, when conducting a curriculum to strengthen instructor capabilities in lifelong education institutions, it is necessary to strengthen the curriculum design according to the needs of instructors. This study is meaningful in that it confirmed the educational needs of lifelong education instructors for teaching competency through a multi-layered method and derived what the priority of teaching competency is.

Human Gestures and Five Elements with Kinect-based Interactive Installation in Modern New Media Art

Qin Chenyi,Jongwon Choi 중앙대학교 영상콘텐츠융합연구소 2021 TechArt :Journal of Arts and Imaging Science Vol.8 No.3

Poly(arylene ether sulfone) proton exchange membranes with flexible acid side chains

Wang, Chenyi,Shin, Dong Won,Lee, So Young,Kang, Na Rae,Lee, Young Moo,Guiver, Michael D. Elsevier 2012 Journal of membrane science Vol.405 No.-

<P><B>Graphical abstract</B></P><P><ce:figure id='fig0005'></ce:figure></P><P><B>Highlights</B></P><P>► Poly(arylene ether sulfone) PEMs with two or four flexible sulfobutyl groups. ► Excellent balance between proton conductivity and dimensional swelling. ► Nanophase separated morphology with interconnected hydrophilic clusters of 1–3nm. ► Better conductivity-swelling behavior compared with analogous poly(arylene ether sulfone)s with inflexible side-chain sulfonic acid.</P> <P><B>Abstract</B></P><P>New monomers containing two or four pendent methoxyphenyl groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxyphenyl groups (2-MPAES-<I>xx</I> and 4-MPAES-<I>xx</I>) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy group to the reactive hydroxyl group, the respective side chain-type sulfonated copolymers (2-SPAES-<I>xx</I> and 4-SPAES-<I>xx</I>) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl groups had high proton conductivities in the range of 0.108–0.258S/cm for 2-SPAES-<I>xx</I> and 0.135–0.194S/cm for 4-SPAES-<I>xx</I> at 80°C, respectively. The methanol permeabilities of these membranes were in the range of 1.59×10<SUP>−7</SUP>–4.69×10<SUP>−7</SUP>cm<SUP>2</SUP>/s, which is much lower than Nafion<SUP>®</SUP> (15.5×10<SUP>−7</SUP>cm<SUP>2</SUP>/s). 2-SPAES-<I>xx</I> and 4-SPAES-<I>xx</I> display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications.</P>

Improving the Self-adaptive Rate Control to Wireless Multicast for Virtual Environment

Liu Li,Chen Hong-qian,ChenYi,YaoChun-Lian 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.11

Distributed virtual environment requires high stability and low delay to support real-time data transmission for large number of users. In wireless network-based virtual environment, traditional transmission protocol fails to meet the requirements of virtual environment due to variety of nodes distribution, complexity, and difference of bandwidth. Based on our research of rate control for distributed virtual environment, we hereby propose a bandwidth self-adaptive rate control algorithm based on layers of interest. According to effective bandwidth of proxy gateway in distributed virtual environment, this method solving the problem of time inconsistency between publishers and subscribers, constraining occupied bandwidth within the range of effective bandwidth of gateways. Our experiments prove that this algorithm can solve the problem that users’needs of interactive with each other very frequently in wireless network virtual environment. The algorithm automatically match data transmission based on bandwidth and the received datagram is smooth and much more stable. The prime performances meet our expected research objectives.