Analysis on mass flow rate of R22 and R407C through coiled adiabatic capillary tubes with GA and PSO optimized BP networks

Guobing Zhou,Yuchen Zhou 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

R22 and R407C mass flow rates through straight and coiled adiabatic capillary tubes are analyzed with three ANN models, i.e., the feed forward network with back propagation (BP) algorithm, GA-BP (genetic algorithm optimized BP network) and PSO-BP (BP algorithm combined with particle swarm optimization). The modelled outputs by these ANN methods are compared with experimental data. The results showed that the predicted mass flow rates with the three models of BP, GA-BP and PSO-BP agree quite well with the experimental data with the mean relative error of 3.82 %, 3.14 % and 2.3 % for R22, and 3.17 %, 2.66 % and 2.46 % for R407C, respectively. PSO-BP network is then employed to predict the coiling effect of capillary tubes on the mass flow rate. It is shown that the mass flow rates with coiled diameter between 0.04 m and 0.6 m are about 4 %-13 % lower than that of the straight capillary tube.

Synthesis and characterization of thieno-isoindigo derivative-based near-infrared conjugated polymer for ambipolar field-effect transistors and photothermal conversion

Zhang, Guobing,Dai, Yanrong,Wang, Dong,Liu, Yu,Lu, Hongbo,Qiu, Longzhen,Cho, Kilwon Elsevier 2017 Dyes and pigments Vol.147 No.-

<P><B>Abstract</B></P> <P>A new thieno-isoindigo derivative, (3<I>E</I>,7<I>E</I>)-3,7-bis(4-(2-decyltetradecyl)-4<I>H</I>-thieno[3,2-<I>b</I>]pyrrole-5,6-dione)-5,7-dihydropyrrolo[2,3-<I>f</I>]indole-2,6(1<I>H</I>,3<I>H</I>)-dione (<B>BTPDI</B>), was designed and synthesized. A donor−acceptor conjugated polymer (<B>PBTPDI-TT</B>) was also synthesized with this new unit as the acceptor and thieno[3,2-<I>b</I>]thiophene as the donor. The microstructure, photophysical, electrochemical, field-effect properties and photothermal performances were investigated. The polymer showed a broad absorption spectrum that spanned across the near-infrared (NIR) region (780–1300 nm), with a very low bandgap (∼0.95 eV), deep lowest unoccupied molecular orbital, and suitable highest occupied molecular orbital levels. As a result, the polymer-based organic field-effect transistors showed highly balanced hole and electron transport characteristics with a hole mobility of 0.027 cm<SUP>2</SUP> V<SUP>−1</SUP>s<SUP>−1</SUP> and an electron mobility of 0.022 cm<SUP>2</SUP> V<SUP>−1</SUP>s<SUP>−1</SUP>. The polymer nanoparticles showed good reusability under NIR (980 nm) irradiation and could also effectively convert NIR light to heat at an excellent efficiency of 20.3%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new thieno-isoindigo derivative dye and its polymer were designed and synthesized. </LI> <LI> The polymer showed ultra broad absorption spectra that spanned across the near-infrared region and remarkably low bandgap. </LI> <LI> The new polymer showed highly balanced hole and electron transport characteristics. </LI> <LI> Polymer nanoparticles showed excellent photothermal conversion efficiency under 980 nm irradiation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fused Heptacyclic-Based Acceptor-Donor-Acceptor Small Molecules: N-Substitution toward High-Performance Solution-Processable Field-Effect Transistors

Zhang, Guobing,Zhao, Yao,Kang, Boseok,Park, Sangsik,Ruan, Jiufu,Lu, Hongbo,Qiu, Longzhen,Ding, Yunsheng,Cho, Kilwon American Chemical Society 2019 Chemistry of materials Vol.31 No.6

<P>Although various donor-acceptor (D-A) small molecules with high power conversion efficiency have been reported, D-A small molecules with high field-effect mobility are still rare. In this work, two new A-D-A small molecules with a rigid indacenodithieno[3,2-<I>b</I>]thiophene (<B>IDTT</B>) moiety as the central core and both ends capped with strong electron-withdrawing indole-2,3-dione (<B>IDD</B>) and N-substituted pyrrolo[2,3-<I>b</I>]pyridine-2,3-dione (<B>IDD-N</B>) were synthesized and characterized for applications in solution-processable organic field-effect transistors (OFETs). A N atom was introduced to the <B>IDD</B> units to enhance the planarity and structural ordering by noncovalent interactions, leading to a dramatic effect on the small molecule. The unsubstituted small molecule (<B>IDTT-IDD</B>) did not show any field-effect performance, whereas an encouraging hole mobility of 7.7 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> with an average mobility of 6.1 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> was obtained for solution-processable OFETs based on the N-substituted one (<B>IDTT-IDD-N</B>). This work provided a simple and effective molecular strategy for the design of D-A small molecules for high-performance solution-processable OFETs.</P> [FIG OMISSION]</BR>

A bis(2-oxoindolin-3-ylidene)-benzodifuran-dione containing copolymer for high-mobility ambipolar transistors

Zhang, Guobing,Li, Peng,Tang, Longxiang,Ma, Jingxuan,Wang, Xianghua,Lu, Hongbo,Kang, Boseok,Cho, Kilwon,Qiu, Longzhen The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.24

<P>A bis(2-oxoindolin-3-ylidene)-benzodifuran-dione (BIBDF)-based low band gap polymer (PBIBDF-BT), containing a solubilizing alkyl chain bithiophene unit as a donor, has been synthesized. The polymer with a low-lying LUMO/HOMO energy level (−4.03/−5.55 eV) exhibits efficient ambipolar charge transport. The electron and hole mobilities are as high as 1.08 and 0.30 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively.</P> <P>Graphic Abstract</P><P>The PBIBDF-BT polymer exhibits high ambipolar charge transport with electron and hole mobilities as high as 1.08 and 0.30 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc48695h'> </P>

LCL APF based on fractional-order fast repetitive control strategy

Pan, Guobing,Gong, Fei,Jin, Libing,Wu, Hao,Chen, Sihan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.10

The LCL type active power filter (APF) with a traditional repetitive controller has drawbacks in terms of poor dynamic performance, large steady-state error, and difficult digital implementation. A fast repetitive control (RC) algorithm was proposed in this paper in an effort to improve the APF dynamic performance without worsening its stability. To eliminate the non-integer delay of the traditional RC, a fractional-order RC algorithm based on the Lagrangian Interpolation was developed. The proposed fast fractional-order RC (FFORC) strategy only needs 1/6 delay time when compared to the traditional RC. In addition, it can track the error signal quickly and obtain a higher steady-state accuracy. Furthermore, the double current loops control method with grid side current and inverter side current feedback is proposed to achieve active damping of the resonance peak of the LCL filter, which ensures that the APF system is stable. Simulation and experimental results are presented to verify the performance of the dynamic response and steady-state accuracy of the proposed FFORC strategy.

Phase lag compensation for improving the stability of LCL‑type converters under weak grid condition

Jianfeng Wang,Guobing Pan,Jing Ouyang,Chengyao Liu,Yinghao Zhou,Gong Fei 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5

LCL-type converters are widely used in the sustainable energy generation system due to their flexible current control strategies and high efficiency. The LCL filter has a resonance peak, which needs to be handled appropriately; otherwise, it causes system instability. Single-loop feedback control strategy is very popular at present; it does not require additional sensors to measure the state variables for active damping. Under weak grid condition, the resonance peak of LCL filter shifts to the left evidently and greatly reduces the stability margin; thus, maintaining the stability of single-loop control is a challenging task. This paper presents an improved grid current feedback (GCF) single-loop control strategy, which is designed to raise the stability margin of system to adapt weak grid condition. Low pass filter controller is used for phase lag compensation. A phase margin design method is proposed to ensure system stability, and the corresponding discrete method in z-domain has been proposed in detail. Experiments performed on a three-phase converter platform are finally presented to verify the effectiveness of the proposed phase lag compensation for GCF control strategy.

Analytical Approximation Algorithm for the Inverse of the Power of the Incomplete Gamma Function Based on Extreme Value Theory

( Shanshan Wu ),( Guobing Hu ),( Li Yang ),( Bin Gu ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.12

This study proposes an analytical approximation algorithm based on extreme value theory (EVT) for the inverse of the power of the incomplete Gamma function. First, the Gumbel function is used to approximate the power of the incomplete Gamma function, and the corresponding inverse problem is transformed into the inversion of an exponential function. Then, using the tail equivalence theorem, the normalized coefficient of the general Weibull distribution function is employed to replace the normalized coefficient of the random variable following a Gamma distribution, and the approximate closed form solution is obtained. The effects of equation parameters on the algorithm performance are evaluated through simulation analysis under various conditions, and the performance of this algorithm is compared to those of the Newton iterative algorithm and other existing approximate analytical algorithms. The proposed algorithm exhibits good approximation performance under appropriate parameter settings. Finally, the performance of this method is evaluated by calculating the thresholds of space-time block coding and space-frequency block coding pattern recognition in multiple-input and multiple-output orthogonal frequency division multiplexing. The analytical approximation method can be applied to other related situations involving the maximum statistics of independent and identically distributed random variables following Gamma distributions.

A New Dynamic Transmission-Mode Selection Scheme for AMC/HARQ-Based Wireless Networks

( Xiaohui Ma ),( Guobing Li ),( Guomei Zhang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.11

In this paper, we study the cross-layer design for the AMC/HARQ-based wireless networks, and propose a new dynamic transmission-mode selection scheme to improve system spectrum efficiency. In the proposed scheme, dynamic thresholds for transmission-mode selection in each packet transmission and retransmission are jointly designed under the constraint of the overall packet error rate. Comparing with the existing schemes, the proposed scheme is inclined to apply higher modulation order at the first several (re)transmissions, which corresponds to higher-rate transmission modes thus higher average system spectrum efficiency. We also extend the cross-layer design to MIMO (Multi-input Multi-output) communication scenarios. Numerical results show that the proposed new dynamic transmission-mode selection scheme generally achieves higher average spectrum efficiency than the conventional and existing cross-layer design.

Modulation Recognition of BPSK/QPSK Signals based on Features in the Graph Domain

Li Yang,Guobing Hu,Xiaoyang Xu,Pinjiao Zhao 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.11

The performance of existing recognition algorithms for binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) signals degrade under conditions of low signal-to-noise ratios (SNR). Hence, a novel recognition algorithm based on features in the graph domain is proposed in this study. First, the power spectrum of the squared candidate signal is truncated by a rectangular window. Thereafter, the graph representation of the truncated spectrum is obtained via normalization, quantization, and edge construction. Based on the analysis of the connectivity difference of the graphs under different hypotheses, the sum of degree (SD) of the graphs is utilized as a discriminate feature to classify BPSK and QPSK signals. Moreover, we prove that the SD is a Schur-concave function with respect to the probability vector of the vertices (PVV). Extensive simulations confirm the effectiveness of the proposed algorithm, and its superiority to the listed model-driven-based (MDB) algorithms in terms of recognition performance under low SNRs and computational complexity. As it is confirmed that the proposed method reduces the computational complexity of existing graph-based algorithms, it can be applied in modulation recognition of radar or communication signals in real-time processing, and does not require any prior knowledge about the training sets, channel coefficients, or noise power.

Portal pressure gradient and serum albumin: A simple combined parameter associated with the appearance of ascites in decompensated cirrhosis treated with transjugular intrahepatic portosystemic shunt

Dongmei Zhao,Guobing Zhang,Mingquan Wang,Chaoxue Zhang,Jiabin Li 대한간학회 2019 Clinical and Molecular Hepatology(대한간학회지) Vol.25 No.2

Background/Aims: In recent years, greater assessment accuracy after transjugular intrahepatic portosystemic shunt (TIPS) to ascertain prognosis has become important in decompensated cirrhosis due to portal hypertension. The aim of this study was to assess the ratio of the portal pressure gradient (PPG) pre-TIPS (pre-PPG) to albumin (PPA), which influence ascites formation in cirrhotic patients in the 6-months after TIPS placement, and is a metric introduced in our study. Methods: This was a retrospective cohort study of 58 patients with decompensated cirrhosis admitted to an academic hospital for the purpose of TIPS placement. We collected the following data: demographics, laboratory measures, and PPG during the TIPS procedure. Then we analyzed the association between the above data and ascites formation post- TIPS in cirrhosis patients. Results: Twenty-two patients with ascites and 28 without ascites were evaluated. Univariate and binary logistic regression analysis were adjusted for the following variables: to determine prognosis; Child-Pugh scores, lymphocyte count, platelet count, hemoglobin level, albumin level and pre-PPG or PPA. The outcome showed that PPA was better than pre-PPG and albumin for predicting ascites according to area under receiver operating characteristic curves and a statistical model that also showed PPA’s influence 6-months post-TIPS. Conclusions: The combined measurement of pre-PPG and albumin, defined as PPA, may provide a better way to predict post-TIPS ascites in decompensated cirrhosis, which underlines the need for a large clinical trial in the future.