Dynamic output-feedback-based H_~ design for networked control systems with multipath packet dropouts

Tang, Z.,Park, J.H.,Lee, T.H. Elsevier [etc.] 2016 Applied Mathematics and Computation Vol.275 No.-

<P>This paper is devoted to the stability of networked control system with time-varying delays. A dynamic output feedback controller is designed to realize H-infinity control of the networked system with the H-infinity performance attenuation level gamma. Since the frequent occurrence of packet dropouts and communication delays which all could degrade the performance of system or even cause system instability, we consider the networked control system with both input and output packet dropouts and bidirectional time-varying communication delays. Some sufficient conditions are obtained to grantee asymptotic stability of the system in view of Schur complement and singular values decomposition of matrix. Afterwards, intensive analysis is carried out to present the existence of admissible dynamic output feedback controller by applying an appropriate weighting method which introduces slack matrices variables. What is more, a numerical example is presented to illustrate the validity of theoretical analysis. (C) 2015 Elsevier Inc. All rights reserved.</P>

China Spallation Neutron Source: Accelerator Design Iterations and R&D Status

J. Wei,C.-D. Deng,C.-H. Wang,C.-T. Shi,H. Sun,H.-F. Ouyang,H.-M. Qu,H.-Y. Dong,J. Li,J. Zhang,J.-S. Cao,J.-Y. Tang,L. Dong,L.-L. Wang,Q. Qin,Q.-B. Wang,S. Wang,S.-N. Fu,S.-X Fang,T. -G. Xu,W. Kang,Y.- 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I

The China Spallation Neutron Source (CSNS) is a high-power, accelerator-based project currently under preparation. The accelerator complex consists of an H$^-$ ion source, an H$^-$ linac, a rapid-cycling proton synchrotron, and the transport lines. During the past year, the design of most accelerator systems went through major iterations, and initial research and developments was started on the prototyping of several key components.

Environmentally friendly and non-polluting solvent pretreatment of palm samples for polyphenol analysis using choline chloride deep eutectic solvents

Fu, N.,Lv, R.,Guo, Z.,Guo, Y.,You, X.,Tang, B.,Han, D.,Yan, H.,Row, K.H. Elsevier 2017 Journal of chromatography Vol.1492 No.-

<P>In this work, choline chloride (ChCI) deep eutectic solvents (DESs) were evaluated for the pretreatment of palm samples in the analysis of polyphenols, such as protocatechuic acid, catechins, epicatechin, and caffeic acid. During the enrichment step of the pretreatment, eight DESs comprising ChCI with ethylene glycol (EG), glycerol (Gly), xylitol (Xyl), phenol (Ph), formic acid (FA), citric acid (CiA), oxalic acid (OA), or malonic acid (MA), were prepared and applied to the reflux extraction of polyphenols from palm samples. All the DESs exhibited higher polyphenol extraction efficiency than methanol, and the highest extraction efficiency was obtained using ChCI-FA (1:1, mole ratio). For the purification step of the pretreatment, eight ChCI DES-modified adsorbents were prepared by hydrothermal polymerization and packed into solid phase extraction (SPE) cartridges, and ChCI-Urea, ChCI-Gly, ChCI-FA, and water, were used as eluents. The ChCI DES-modified adsorbents were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, and Brunauer-Emmett-Teller surface analysis, and the polyphenols were analyzed by mass spectrometry and high-performance liquid chromatographultraviolet detection. The highest purification efficiency was obtained using the ChCI-Ph DES-modified adsorbent as the SPE packing material and ChCI-Urea-H2O (1:1:5, mole ratio), ChCI-Gly (1:1, mole ratio), ChCI-FA-H2O (1:1:5, mole ratio), and H2O as the eluents. Compared to conventional purification processes that employ commercial C-18 or C-8 SPE columns with organic solvents as eluents, the ChCI DES-based SPE purification process successfully avoided the use of expensive commercial SPE columns and organic solvents. Furthermore, it isolated a larger amount of the target compounds under the same experimental conditions, and could be applied over five cycles with good reversibility. This work indicates that DESs as green solvents have great potential for the totally green pretreatment of samples during the enrichment and purification processes. (C) 2017 Elsevier B.V. All rights reserved.</P>

Multi-stage approach for structural damage identification using particle swarm optimization

Tang, H.,Zhang, W.,Xie, L.,Xue, S. Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.11 No.1

An efficient methodology using static test data and changes in natural frequencies is proposed to identify the damages in structural systems. The methodology consists of two main stages. In the first stage, the Damage Signal Match (DSM) technique is employed to quickly identify the most potentially damaged elements so as to reduce the number of the solution space (solution parameters). In the second stage, a particle swarm optimization (PSO) approach is presented to accurately determine the actual damage extents using the first stage results. One numerical case study by using a planar truss and one experimental case study by using a full-scale steel truss structure are used to verify the proposed hybrid method. The identification results show that the proposed methodology can identify the location and severity of damage with a reasonable level of accuracy, even when practical considerations limit the number of measurements to only a few for a complex structure.

Topology and parameters recognition of uncertain complex networks via nonidentical adaptive synchronization

Tang, Z.,Park, J. H.,Lee, T. H. Springer Science + Business Media 2016 Nonlinear dynamics Vol.85 No.4

<P>Topology plays an essential role in chaotic behaviors and evolution performances of a complex dynamical network. In this paper, recognition issue for unknown system parameters and topology of uncertain general complex dynamical networks with nonlinear couplings and time-varying delay is investigated through generalized outer synchronization. Firstly, the unknown system parameters and topology in master network are successfully estimated by a slave network. Secondly, the unknown system parameters of both two networks and the unknown topology of the master network are effectively evaluated in view of generalized outer synchronization based on an adaptive feedback control strategy. Two situations of parameters and topologies recognition are efficiently verified by illustrative numerical simulations.</P>

Polymerdimethylsiloxane surface treatment with an atmospheric pressure helium plasma jet driven by unipolar nanosecond pulses

Tang T.Y.,Lee H.,Kim H.S.,Kim G.H.,Lee B.,Kim H.J.,Lee H.J. 한국물리학회 2021 Current Applied Physics Vol.29 No.-

A nanosecond-pulse power source transfers energy to electrons of atmospheric pressure discharges in a nanosecond-scale rising time and shows different plasma chemistry than a slowly varying sinusoidal discharge. We report how the operation parameters, such as applied voltage, pulse duration, and repetition frequency, affect the discharge characteristics and the surface property of polydimethylsiloxane (PDMS). The applied voltage controls the energy delivery per a pulse cycle, and the repetition frequency dominantly affects the plasma density in a long-term operation. The water contact angle, the optical emission spectroscopy, and the atomic force microscope diagnostics on the PDMS are presented. While the polarity of the nano pulse bias changes the emission length of the plasma jet, the hydrophilicity is not affected by it because the chemical reactions by radicals are more dominant than the physical reactions of charged particles on PDMS.

Carbon nanotube-clamped metal atomic chain

Tang, D.-M.,Yin, L.-C.,Li, F.,Liu, C.,Yu, W.-J.,Hou, P.-X.,Wu, B.,Lee, Y.-H.,Ma, X.-L.,Cheng, H.-M. National Academy of Sciences 2010 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.107 No.20

Inductances of a Superconducting Magnet for Cyclotron K120

H. M. Tang,김동락,최연석,이병섭,양형석,김유석 한국초전도.저온공학회 2008 한국초전도저온공학회논문지 Vol.10 No.4

The design of a superconducting magnet system producing very high magnetic field is underway at Korea Basic Science Institute (KBSI) to accelerate three kinds of carbon irons (C+2, C+4, C+6) to 120 MeV. A quarter-scaled prototype will be manufactured in order to confirm the feasibility of our design. Magnet Inductances in the system have a great influence on the current ramping rates and contribute to the stored energy, which are usually considered to be unfavorable in magnet operation. The modeling and simulation scheme of a prototype superconducting magnet for the cyclotron K120 is described in this paper. The inductances are calculated by a numerical method with and without iron yokes, respectively. These calculation results will be used as engineering design details such as a current ramping rate and a quench protection design.

Very small “window of opportunity” for generating CO oxidation-active Au_<i>n</i> on TiO₂

Tang, X.,Schneider, J.,Dollinger, A.,Luo, Y.,Wö,rz, A. S.,Judai, K.,Abbet, S.,Kim, Y. D.,Gantefö,r, G. F.,Fairbrother, D. H.,Heiz, U.,Bowen, K. H.,Proch, S. The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.14

<P>Recent research in heterogeneous catalysis, especially on size-selected model systems under UHV conditions and also in realistic catalytic environments, has proved that it is necessary to think in terms of the exact number of atoms when it comes to catalyst design. This is of utmost importance if the amount of noble metal, gold in particular, is to be reduced for practical reactions like CO oxidation. Here it is shown that on TiO<SUB>2</SUB> only Au<SUB>6</SUB> and Au<SUB>7</SUB> clusters are active for CO oxidation which holds for the single crystal, thin films, and titania clusters deposited on HOPG. Size-selected cluster deposition and TPD methods have been employed to investigate the CO oxidation activity of Au<SUB><I>n</I></SUB>/TiO<SUB>2</SUB> systems which are compared to recent results reported by Lee <I>et al.</I> to form a consistent picture in which only two species can be regarded as “active”. The efficiency of investigated Au<SUB><I>n</I></SUB>/(TiO<SUB>2</SUB>)<SUB>93</SUB>/HOPG composite materials is attributed to carbon-assisted oxygen spillover from gold to support particles and across grain boundaries.</P> <P>Graphic Abstract</P><P>The probability of creating CO oxidation-active species on TiO<SUB>2</SUB> is very small since only Au<SUB>6</SUB> and Au<SUB>7</SUB> are catalytically active. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp00160e'> </P>

Multi-stage approach for structural damage identification using particle swarm optimization

H. Tang,W. Zhang,L. Xie,S. Xue 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.1

An efficient methodology using static test data and changes in natural frequencies is proposed to identify the damages in structural systems. The methodology consists of two main stages. In the first stage, the Damage Signal Match (DSM) technique is employed to quickly identify the most potentially damaged elements so as to reduce the number of the solution space (solution parameters). In the second stage, a particle swarm optimization (PSO) approach is presented to accurately determine the actual damage extents using the first stage results. One numerical case study by using a planar truss and one experimental case study by using a full-scale steel truss structure are used to verify the proposed hybrid method. The identification results show that the proposed methodology can identify the location and severity of damage with a reasonable level of accuracy, even when practical considerations limit the number of measurements to only a few for a complex structure.