Simulation of Grid-Connected Solar Micro-inverter Based on Fuzzy PI Controller

Weiliang Liu,Changliang Liu,Huichao Zhang,Yongjun Lin,Liangyu Ma 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

Grid-connected solar micro-inverter is a highly nonlinear and time-varying system, so it is difficult to achieve good control effect using traditional PI controller. In this paper, small signal analysis model of micro-inverter is established, grid-connected current control strategy composed of fuzzy PI controller and grid voltage feed-forward is put forward, and the initial parameters of PI controller is optimized using the genetic algorithm. Simulation results show that the control strategy has the virtues of good robustness, small dynamic deviation, and could reduce the harmonic content of grid-connected current.

Effects of aromatic cycle oils on performance of residue hydrotreating

Yongjun Liu,Yu Zou 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.11

Hydrotreating, as an important pretreatment process of residue catalytic cracking, is used to eliminate metals,S and N contaminants and partly process asphaltene from streams so that the products can be efficiently processed in downstream conversion units. We investigated the effects of aromatic additives on residue hydrtreating (RHT) by adding various types and contents of high aromatic cycle oils into atmosphere residue (AR). The aromatic additives modify the colloidal structure of asphaltene in AR and improve the liberation of heteroatomic compounds bound in nucleus. Therefore, the amount of carbon residue in blending oils decreases and the removal efficiency of Ni, V, S and N increases obviously. The increase of conversion is greater for nitrogen than for sulfur, and hydrodevanadium reveals a distinct advantage over hydrodenickel. However, excessive amount of light cycle oil (more than 20% wt) is not helpful for removing the Ni and V since a little of metalloporphyrins stubbornly bond with the superstructure of nucleus.

Unified calculation model for the longitudinal fundamental frequency of continuous rigid frame bridge

Yongjun Zhou,Yu Zha,Jiang Liu,Yuan Jing 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.3

The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier’s height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.

A recyclable Pd colloidal catalyst for liquid phase hydrogenation of a-pinene

Yongjun Yang,Xianxiang Liu,Dulin Yin,Zehui Zhang,Dichen Lei,Jing Yang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-

A recyclable Pd colloidal catalyst was found to be effective for the liquid phase hydrogenation of apinene. Under optimal conditions, a-pinene conversion of 99.4% and cis-pinane selectivity of 81.3% were obtained. Furthermore, the Pd colloidal catalyst could be recovered conveniently and reused for eight runs without significant loss of the catalytic activity and selectivity.

Analytical model for the basement wall horizontally supported by flexible floor diaphragms

Yongjun Lin,Xianzhao Zhang,Kaiqi Liu,Wenqiang Xu 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.5

Subterranean floors are treated as the rigid lateral support in the current practice for the basement wall design. The structural performance of the basement wall will be influenced by the floor openings, which are inevitable to satisfy building functional requirements. An analytical model for the basement wall being presented is able to analyze the effect of such opening quantitatively. The magnitude of the horizontal support stiffness is determined based on deformation analysis of the diaphragm opening area. Idealized models of the basement wall are continuous beams with various degrees of indeterminacy. The force method is used to deduce the functions for internal forces acting towards the basement wall. The proposed analytical model is verified with results derived by finite element analyses through consideration of various factors, including various numbers of stories, combinations of beam-slab sections, and percentages of floor opening dimensions. The maximum deviations on critical design sections for all prototype basement structures are less than 15.99%. Comparisons with conventional rigid support models are also performed, providing an estimation of the effect of the opening on the mechanical behavior of the basement wall.

Functional Conservation of an AGAMOUS Orthologous Gene Controlling Reproductive Organ Development in the Gymnosperm Species Taxus chinensis var. mairei

Yongjun Fei,Zhi-Xiong Liu,Hai-Yan Xiong,Lai-Yun Li 한국식물학회 2018 Journal of Plant Biology Vol.61 No.1

Arabidopsis AGAMOUS (AG) has roles in specifying reproductive organ (stamens and carpels) identity, floral meristem determinacy, and repression of A-function. To investigate possible roles of AG orthologous genes in gymnosperm species and evolution of C function, we isolated and identified AG orthologous gene TcAG from Taxus chinensis var. mairei (family Taxaceae, order Coniferales), a member of the last divergant lineage from higher Conifer that sisters to Gnetales. Sequence alignment and phylogenetic analysis grouped TcAG into the gymnosperm AG lineage. TcAG was expressed in both developing male and female cones, but there was no expression in juvenile leaves. Ectopic expression of TcAG in an Arabidopsis ag mutant produced flowers with the third whorl petaloid stamen and fourth whorl normal carpel, but failed to convert first whorl sepals into carpeloid organs and second whorl petals into stamenoid organs. A 35S::TcAG transgenic Arabidopsis ag mutant had very early flowering, and produced a misshapen inflorescence with a shortened floral axis. Our results suggest that establishment of the complete C-function occurred gradually during AG lineage evolution even in gymnosperms.

Study on the thermoelectric properties of porous Bi-Te films deposited using thermal evaporation on AAO template

Shiying Liu,GUOJIAN LI,Mingdi Lan,Yongjun Piao,Yanan Zhang,QIANG WANG 한국물리학회 2020 Current Applied Physics Vol.20 No.3

The application of thermoelectric films is limited to retain the temperature gradient. In this study, the Bi-Te films are deposited on the AAO template with a pore size of 100 nm using thermal evaporation. The results show that the conductive types of the Bi-Te film are tuned by source temperature. The power factor of the p-type porous film decreases 36% by comparing to that of the p-type nonporous film (1020 μW/mK2 at 250 °C). Meanwhile, the temperature difference in the porous device is maintained and is approximately 5.0 °C. Thus, the maximum output power is achieved in the porous device (about 25 pW), which is 5 times higher than that of the nonporous device. This provides a method to improve the conversion efficiency of thermoelectric film device by maintaining the temperature difference by using porous structure.

Novel integrative soft computing for daily pan evaporation modeling

LiLi Liu,Yongjun Zhu,Yu Zhang,Peng Wang,Loke Kok Foong 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.4

Regarding the high significance of correct pan evaporation modeling, this study introduces two novel neurometaheuristic approaches to improve the accuracy of prediction for this parameter. Vortex search algorithms (VSA), sunflower optimization (SFO), and stochastic fractal search (SFS) are integrated with a multilayer perceptron neural network to create the VSA-MLPNN, SFO-MLPNN, and SFS-MLPNN hybrids. The climate data of Arcata-Eureka station (operated by the US environmental protection agency) belonging to the years 1986-1989 and the year 1990 are used for training and testing the models, respectively. Trying different configurations revealed that the best performance of the VSA, SFO, and SFS is obtained for the population size of 400, 300, and 100, respectively. The results were compared with a conventionally trained MLPNN to examine the effect of the metaheuristic algorithms. Overall, all four models presented a very reliable simulation. However, the SFS-MLPNN (mean absolute error, MAE = 0.0997 and Pearson correlation coefficient, R_P = 0.9957) was the most accurate model, followed by the VSA-MLPNN (MAE = 0.1058 and R_P = 0.9945), conventional MLPNN (MAE = 0.1062 and R_P = 0.9944), and SFO-MLPNN (MAE = 0.1305 and RP = 0.9914). The findings indicated that employing the VSA and SFS results in improving the accuracy of the neural network in the prediction of pan evaporation. Hence, the suggested models are recommended for future practical applications.

Enhanced catalyst activity by decorating of Au on Ag@Cu₂O nanoshell

Chen, Lei,Liu, Maomao,Zhao, Yue,Kou, Qiangwei,Wang, Yaxin,Liu, Yang,Zhang, Yongjun,Yang, Jinghai,Jung, Young Mee Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.435 No.-

<P><B>Abstract</B></P> <P>We successfully synthesized Au-decorated Ag@Cu<SUB>2</SUB>O heterostructures via a simple galvanic replacement method. As the Au precursor concentration increased, the density of the Au nanoparticles (NPs) on the Ag@Cu<SUB>2</SUB>O surface increased, which changed the catalytic activity of the Ag@Cu<SUB>2</SUB>O-Au structure. The combination of Au, Ag, and Cu<SUB>2</SUB>O exhibited excellent catalytic properties, which can further effect on the catalyst activity of the Ag@Cu<SUB>2</SUB>O-Au structure. In addition, the proposed Ag@Cu<SUB>2</SUB>O-Au nanocomposite was used to transform the organic, toxic pollutant, 4-nitrophenol (4-NP), into its nontoxic and medicinally important amino derivative via a catalytic reduction to optimize the material performance. The proposed Au-decorated Ag@Cu<SUB>2</SUB>O exhibited excellent catalytic activity, and the catalytic reduction time greatly decreased (5 min). Thus, three novel properties of Ag@Cu<SUB>2</SUB>O-Au, i.e., charge redistribution and transfer, adsorption, and catalytic reduction of organic pollutants, were ascertained for water remediation. The proposed catalytic properties have potential applications for photocatalysis and localized surface plasmon resonance (LSPR)- and peroxidase-like catalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Au-decorated Ag@Cu<SUB>2</SUB>O heterostructures via a simple galvanic replacement method were designed. </LI> <LI> We can easily control the density of the Au NPs on Ag@Cu<SUB>2</SUB>O by changing the concentration of the Au precursor. </LI> <LI> Ag@Cu<SUB>2</SUB>O-Au nanomaterials with high absorption exhibited significantly enhanced catalytic activity for 4-NP. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Study on Blasting Characteristics of Shallow and Deep Soft-hard Rock Strata Based on Energy Field

Jianbin Cui,Liangfu Xie,Yongjun Qin,Xuejun Liu,Jiangu Qian 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

The expected blasting effect of rock mass is always affected by the soft-hard rock strata with anisotropic mechanical properties, especially under the influence of in-situ stress. Based on discrete element method (PFC2D), single-hole blasting experiments are carried out considering effect of soft-hard rock strata and in-situ stress. The result is analyzed from the perspectives of cracks state, cracks number, cracks extension range and energy fields. The results show that: 1) Under different in-situ stress fields, damage degree of rock mass increases first, then decreases rapidly and ultimately keeps stable with growth of soft rock thickness. Through fitting, better change laws are obtained. 2) When detonation in hard rock, if distance between blasthole and structural plane is larger than about 4 times the radius of crushing area, cracks development is restrained with the growth of in-situ stress. 3) Rock damage degree of rock firstly ascends and then descends with growth of Uniaxial Compressive Strength (UCS). Rock damage degree reaches maximum at about 40 MPa and descends with growth of in-situ stress, when it is greater than about 80 MPa. 4) When detonation in hard rock and lower in-situ stress, if structural plane is outside crushing area, peak kinetic energy will decrease with the growth of in-situ stress as well as peak friction energy, which is contrary to the peak strain energy.