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Valley V² Control Technique for Switching Converters with Fast Transient Response
Guohua Zhou,Jianping Xu,Jin Sha,Yanyan Jin 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Valley V² control technique for switching converters is proposed in this paper. By utilizing output voltage ripple as pulse-width modulation ramp and valley voltage of output voltage ripple as additional control variable, valley V² control technique provides faster load transient response than conventional current-mode control techniques. Steady-state and transient performances of switching converters with valley V² control, peak V² control, and current-mode control are compared and verified by experimental results.
Guohua Sheng,Shengji Jin,Lintao Ma,Quan Bai,Chao Xu,Xiaoyu Wang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1
The concept of seismic robustness is proposed by combining the concept of seismic performance and structural robustness. The existing qualitative, quantitative and evaluation methods of seismic robustness are all direct researched on the whole structure, and the influence mechanism of its internal components on the overall seismic robustness is still unclear. It is very important to establish a clear relationship between component design and structural seismic robustness for the structural design, reinforcement design and final evaluation of structural seismic robustness. Based on this, taking the column as the starting point, a quantitative method for the seismic robustness of RC frame by the seismic robustness index is proposed, which takes into account the resistance vulnerability of column and influence of column on the storey drift ratios (SDRs). In which, the resistance vulnerability is represented by the defined control vulnerability coefficient Pimax, and the influence on the SDRs are represented by the storey drift ratio importance coefficients (SDRCs) . The method not only reflects the essential mechanical properties of the column, but also reflects the effects brought about by different SALs. The feasibility of the method is demonstrated by numerical examples of two types of failures (assuming single column and two columns failure), and four optimization design proposals are proposed for it. The analysis shows that of the target columns to the floor where the target columns located are obviously greater than those on the remaining floors of the target frame. The seismic robustness index R decreases sharply with the increase of the seismic action level (SAL). R is different compare single column failure with two columns failure under 4 SALs. The most effective way to improve the R of the frame under a certain SAL is to retrofit its control column.
Xie Guohua,Dong ping,Chen Hui,Xu Ling,Liu Yi,Ma Yanhui,Zheng Yingxia,Yang Junyao,Zhou Yunlan,Chen Lei,Shen Lisong 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-
ATF3 has been reported to be dysregulated in various cancers and involved in various steps of tumorigenesis. However, the mechanisms underlying the abnormal expression of ATF3 and its biological function in gastric cancer (GC) have not been well investigated. Here, we report ATF3 as one of the key regulators of GC development and progression. Patients with low ATF3 expression had shorter survival and a poorer prognosis. In vitro and in vivo assays investigating ATF3 alterations revealed a complex integrated phenotype that affects cell growth and migration. Strikingly, high-throughput sequencing and microarray analysis of cells with ATF3 silencing or of ATF3-low GC tissues indicated alterations in the Wnt signaling pathway, focal adhesions and adherens junctions. Mechanistically, the expression of β-catenin and cell migration inducing hyaluronidase 1 (CEMIP) was significantly upregulated in GC cells with downregulated ATF3, which was synergistically repressed by the β-catenin/TCF3 signaling axis and noncoding RNA miR-17-5p and HOXA11-AS. In addition, we found that WDR5 expression was promoted by TCF3 and is involved in miR-17-5p and HOXA11-AS activation in GC cells. Taken together, our findings revealed the mechanism of ATF3 downregulation and its biological role in regulating the expression of Wnt signaling-related genes during GC progression, suggesting new informative biomarkers of malignancy and therapeutic directions for GC patients.
A theoretical study on fullerene-dizincocene hybrids
Gao, Guohua,Xu, Xiang,Kang, Hong Seok Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of computational chemistry Vol.30 No.6
<P>Using the density functional theory, we investigated the possible formation of fullerene-dizincocene hybrids, specifically C<SUB>60</SUB>*-Zn-Zn-Cp*, C<SUB>60</SUB>*-Zn-Zn-C<SUB>60</SUB>*, C<SUB>70</SUB>*-Zn-Zn-Cp*, and C<SUB>70</SUB>*-Zn-Zn-C<SUB>70</SUB>*, where C<SUB>60</SUB>*, Cp*, and C<SUB>70</SUB>* represent C<SUB>60</SUB>(CH<SUB>3</SUB>)<SUB>5</SUB>, C<SUB>5</SUB>(CH<SUB>3</SUB>)<SUB>5</SUB>, and C<SUB>70</SUB>(CH<SUB>3</SUB>)<SUB>5</SUB> radicals. Our calculation shows that these hybrids have HOMO-LUMO gaps which are larger than has been experimentally identified for C<SUB>60</SUB>*-Fe-Cp. In addition, the strength of the Zn&n.bond;Zn bonds is similar to that in Cp*-Zn-Zn-Cp* which was also synthesized recently. Furthermore, heterohybrids, C<SUB>60</SUB>*-Zn-Zn-Cp* and C<SUB>70</SUB>*-Zn-Zn-Cp* are expected to exist in equilibria with homohybrids, C<SUB>60</SUB>*-Zn-Zn-C<SUB>60</SUB>* and C<SUB>70</SUB>*-Zn-Zn-C<SUB>70</SUB>*, in which heterohybrids are much more favored. On the other hand, another hybrid involving Sc<SUB>3</SUB>N@C<SUB>68</SUB> as a fullerene unit is not highly probable. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/01928651-2009-30-6-JCC21121-gra001.gif' alt='wiley_img/01928651-2009-30-6-JCC21121-gra001'> </P>
Hao Xu,GUOHUA LUO 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-
This review gives a summary on heterogeneous non-mercury catalysts for acetylene hydrochlorination process. First, various catalysts are classified and their performances are compared. Next, studies on catalytic performance by theoretical characterizations and molecule level simulations are introduced. Then, efforts for industrial scaling up and corresponding long-term plant trial results are presented to show enormous potential of state-of-the-art catalysts. Finally, the crucial engineering issues for future industrialization process including kinetic study, reactor design & simulation and material recycling process are proposed. Based on promising achievements, we believe that extensive industrial application of non-mercury catalysts for acetylene hydrochlorination will soon become reality.
Shuhan Zhou,Guohua Zhou,Shaohuan Zeng,Shungang Xu,Taiqiang Cao 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
The flyback converter, which can be regarded as a nonlinear time-varying system, has complex dynamics and nonlinearbehaviors. These phenomena can affect the stability of the converter. To simplify the modeling process and retain theinformation of the output capacitor branch, a special sampled-data model of a peak current-mode (PCM) controlled flybackconverter is established in this paper. Based on this, its dynamic behaviors are analyzed, which provides guidance for designingthe circuit parameters of the converter. With the critical stability boundary equation derived by a Jacobian matrix, the stableoperation range with a varied output capacitor, proportional coefficient of error the amplifier, input voltage, reference voltageand slope of the compensation ramp of a PCM controlled flyback converter are investigated in detail. Research results show thatthe duty ratio should be less than 0.5 for a PCM controlled flyback converter without ramp compensation to operate in a stablestate. The stability regions in the parameter space between the output capacitor and the proportional coefficient of the erroramplifier are enlarged by increasing the input voltage or by decreasing the reference voltage. Furthermore, the rampcompensation also can extend to the stable region. Finally, time-domain simulations and experimental results are presented toverify the theoretical analysis results.
Zhiyuan Hu,Guohua Xu,Yongjie Shi 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.4
Rotors with active flap control have considerable potential in reducing vibration and noise and improving aerodynamic performance. However, due to the movement of the flap, there are unavoidable gaps between the components that will lead to significant changes in the aerodynamic characteristics. Moreover, considering the difficulties in motion modeling and the accuracy of the simulation of the flow field in such a narrow gap, carrying out related research is challenging; thus, there has been inadequate targeted research, and that which does exist requires supplementation. To carry out this challenging flow field simulation, the overset assembly algorithm proposed by the author in previous research is adopted in the present study. It is used to successfully assemble the narrow gap, and the accuracy of the simulation is fully verified by comparing the results with the actual experimental results and a grid study. Furthermore, to compensate for the lack of research and experiments on the gap effect, cases considering a complete range of gap widths from an absence of a gap to a width of 10% of the chord length are set up and carried out under the following three case groups: steady cases with a fixed trailing-edge deflection angle, unsteady cases in which only the trailing-edge flap is flapping, and full-motion cases characterized by the periodic flap of the main airfoil and the trailing-edge flap. The results show that the gap increases the drag of the trailing-edge flap and decreases aerodynamic efficiency, especially at low speeds and high angles of attack. Nevertheless, when the gap is unavoidable, there is a range of the gap width that makes unapparent the decrease of aerodynamic efficiency. Moreover, the decrease of aerodynamic efficiency can be reduced as much as possible by a well-designed gap region geometry to ensure that the airfoil and the trailing-edge flap fit together when moving.