Performance optimization of flexible a-Si:H solar cells with nanotextured plasmonic substrate by tuning the thickness of oxide spacer layer

Xiao, Huapeng,Wang, Jun,Huang, Hongtao,Lu, Linfeng,Lin, Qingfeng,Fan, Zhiyong,Chen, Xiaoyuan,Jeong, Chaehwan,Zhu, Xufei,Li, Dongdong Elsevier 2015 Nano energy Vol.11 No.-

<P><B>Abstract</B></P> <P>Plasmonic thin film solar cells deposited on periodically textured photonic crystal substrates have been extensively studied since the substantially enhanced light absorption. The reduction of parasitic absorption losses in the metal and spacer layers becomes one of the key issues to achieve high efficiency solar cells. Herein, plasmonic amorphous silicon (a-Si:H) flexible thin film solar cells with different thickness of oxide spacer layers are systematically investigated. An increase of the spacer layer thickness leads to an evolution in surface morphology of AZO and final devices. More intriguingly, the increase of spacer layer thickness reduces the absorption in Ag layer while induces more absorption in spacer layer. The highest light absorption in silicon layer is observed as applying 100nm spacer layer, which is further verified by electrical measurements. Our observations demonstrate a versatile and convenient route towards rational design of light harvesting nanostructure for high performance plasmonic solar cells based on a broad range of materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amorphous silicon thin film solar cells are constructed on patterned substrates. </LI> <LI> The devices properties are studied as a function of spacer layer thickness. </LI> <LI> An increase of spacer layer thickness reduces the absorption loss of Ag layer. </LI> <LI> The device with 100nm spacer layer confines more incident light in silicon layer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Asymmetric coaxial three‑coil wireless power transmission system optimization

Dongdong Zhang,Xuesong Li,Jie Yang,Xiang Li,Thomas Wu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.9

With the rapid development of wireless power transmission (WPT) technology and the demand for a wide range of applications, the common two-coil system is becoming increasingly mature. However, the monotonous structure of two-coil systems limits their development. By incorporating relay coils, the distance of power transmission, efficiency, and electromagnetic field (EMF) leakage can be effectively improved. In this paper, the three-coil system is analyzed, and the relay coil parameters are optimized by an evolutionary algorithm. After that, based on the coil optimization, the compensation capacitance of the relay coil is analyzed and an analytical formula of the compensation capacitance of the optimized relay coil is obtained. The results show that the parameter-optimized system reduces current by 86.9%, increases efficiency by 10%, and suppresses EMF leakage by 18 dB. Meanwhile, the capacitor optimization further improves the transmission efficiency of the system.

The Study of Maximum Power Point Tracking Control for DFIG based on PSCAD

Li, Dongdong,Wang, Lu,Wang, Yun,Wang, Kaikai,Ye, Chensheng The Korean Institute of Electrical Engineers 2012 The Journal of International Council on Electrical Vol.2 No.3

In recent years, wind power has been developed rapidly. Doubly fed induction generator becomes the main model of wind power become the mainstream due to its high wind energy utilization efficiency and reactive power controllability. On the basis of analyzing the principle and mathematical model of DFIG, dual-loop control system based on the stator flux oriented vector control of DFIG was established, and active and reactive power decoupling control is realized. This paper shows speed control model and power control model which are control modes of the maximum wind power point tracking (MPPT). Simulation results show the control system has good performance and power control mode is more practical and stable than speed control mode.

Finite Element Model Methodology for Asphalt-coated Anchor used in Underground Main Powerhouse Anchored-on-rock Crane Girder

Dongdong Li,Ming Xiao,Juntao Chen,Jian Zhao 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.6

Uncoated or grout-coated rock anchoring systems are used in underground engineering to increase the carrying capacity of surrounding rock. 3D modeling has been used to simulate grout-coated anchor characteristics, but for less common coatings, e.g., asphalt, existing Finite Element (FE) models contain too many nodes and elements to be computationally efficient. Using AutoCAD and OpenGL visual FE modeling, a methodology is proposed for asphalt element generation in FE models; FORTRAN is used to rewrite the model file information and reduce the number of model elements and nodes while boosting modeling and computational efficiency. Implicit lever and column elements are introduced to simulate anchors with and without asphalt coatings, respectively, and appropriate stiffness matrices and iterative FE calculation formulas are derived. The resulting FE model is used to simulate the anchoring system. Results show that the asphalt coating technique reduces the surrounding rock wall’s damage zone and increases anchor stresses inside deep rock masses. This can improve the rock mass mechanical characteristics near the anchors and increase the stabilities of the surrounding rock and the safety crane girder. The proposed calculation and grid re-meshing method shows good adaptability and practicality, and can serve as a reference for similar FE analysis processes.

Experimental and Theoretical Study of the Torsional Mechanism of a Hybrid FRP-aluminum Triangular Deck-truss Structure

Dongdong Zhang,Qilin Zhao,Fei Li,Feng Li 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.6

This paper investigates the torsional mechanism of a hybrid FRP-aluminum triangular deck-truss structure composed of modular structural units. A pure torsion test was conducted on a 6-m cantilever specimen to characterize the structural responses. Based on the experimental results and structural layout, a simplified analytical model is established to predict the torsional stiffness of the hybrid triangular deck-truss structure. The derivation procedures and formulae are experimentally calibrated, finding that the formulae can be conveniently used with satisfactory accuracy. It is ultimately confirmed that the torsional center of the entire triangular truss collocates with the center of the orthotropic deck. The external torsional moment is primarily resisted by the FRP lower chords and the aluminum longitudinal beams, particularly for the FRP lower chords which should be given a great consideration in the torsion design.

Dual NURBS Path Smoothing for 5-Axis Linear Path of Flank Milling

Dongdong Li,Weimin Zhang,Wei Zhou,Tengfei Shang,Jürgen Fleischer 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.12

Linear path is still widely used to describe the five-axis machining trajectory. Five-axis tool path consists of two parts, one trajectory describes the tool tip position, and the other one represents the second point on tool axis to define the tool orientation. The natural disadvantages of G01 path are tangential and curvature discontinuities at freeform surface, which will lead to feedrate fluctuation and accuracy decrease due to the drive constraints of machine tool. In this study, a path smoothing method is proposed to smooth and optimize the linear path by using dual NURBS curves. Firstly, according to the accuracy requirements, the tool tip spline can be fitted. Secondly, the tool orientation spline can also be obtained by a coordinate system mapping method. Then, the synchronization equation of the two spline parameters is established to achieve interpolation synchronization of cutter location points. Finally, the smoothing dual NURBS tool path can be obtained with continuous curvature to improve the surface quality, motion stability and machining efficiency. Simulations and experiments validate its practicability and reliability. This method is no need to upgrade the CAM, and also could be integrated into CAM system to perform the 5-axis path smoothing.

Sevoflurane induces neuronal apoptosis via enhancing DNMT3L expression and promoting methylation of PSD95 promoter in postoperative cognitive dysfunction

Ling Yunzhi,Li Xiaohong,Yu Li,Sun Yiyun,Yang Dongdong,Li Zhiyi 대한독성 유전단백체 학회 2021 Molecular & cellular toxicology Vol.17 No.3

Background Postoperative cognitive dysfunction (POCD) is a central nervous system (CNS) complication and occurs quite frequently after anesthesia, especially in elderly patients. DNA (cytosine-5)-methyltransferase 3-like (DNMT3L) is an enzymatically inactive regulatory factor that can modulate gene expression via methylation. Few studies specifically focused on the role of DNMT3L in sevoflurane-induced POCD. Objective The cognitive dysfunction was determined by Morris water maze assay. Hippocampal neuron apoptosis was measured by TdT-mediated dUTP nick-end labeling (TUNEL) assay. Neuron proliferation and apoptosis were measured by cell counting kit-8 (CCK-8) and flow cytometry assay. The expression levels of DNMT3L and postsynaptic density protein-95 (PSD95) were measured by qRT-PCR and western blot. Results The sevoflurane-induced POCD aging rat model was established for in vivo study. Suppression of DNA methylation by 5-Aza-2′-deoxycytidine (5-AZA; a widely used methylation inhibitor) reversed sevoflurane-induced cognitive dysfunction and hippocampal neuron apoptosis in rats. Moreover, sevoflurane enhanced DNMT3L expression and induced methylation of PSD95 promoter in vivo. In vitro, sevoflurane induced neuronal apoptosis and DNMT3L expression to promote PSD95 methylation. Finally, rescue experiments indicated that sevoflurane induced neuron apoptosis by increasing DNMT3L expression and promoting methylation of PDS95 in POCD. Conclusion Sevoflurane induced neuronal apoptosis by increasing DNMT3L expression and promoting methylation of PDS95 in vivo and in vitro, providing a novel therapeutic strategy for POCD.

Experimental Investigation of Flow Control Technology for Grouting and Blocking of Flowing Water in Karst Conduits

Dongdong Pan,Zehua Bu,Haiyan Li,Zhenhao Xu,Jie Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8

Aiming at the grouting treatment in karst conduits with large flow and high velocity, we developed a simulation experiment system for conduit-type grouting blocking and investigated the blocking mechanism of flowing water grouting under the condition of flow control. Firstly, we studied the effect of flow control in conduit by controlling the opening of outlet valve and analyzed the variation law of velocity and pressure in conduits under different water heads, conduit diameters and valve opening quantitatively. Secondly, we conducted experiments of flowing water grouting under different flow control conditions, and revealed the influence law of flow control for flowing water grouting. The results show that: 1) with the increase of the intensity of flow control, the pressure in conduit increased gradually, and the velocity of flowing water decreased gradually. 2) When the volume ratio of water and cement was 1.2:1, the volume ratio of cement and sodium silicate was 2:1, the grouting volume was 540 L/h, and the flowing water velocity was 0.15 m/s, flowing water blocking under the condition of flow control achieved the optimal effect. 3) With flow control, the slurry deposition thickness increased more than 50% compared with no flow control; besides, the slurry retention rate increased, and the blocking effect significantly improved. The technology has been successfully applied in the grouting treatment project of China Resources Cement (Pingnan) Limestone Mine. And main water inflow points in the mine were blocked with an total amount of ~210,200 m3/d water reduction. This study provided some theoretical guidance and reference experience for treatment engineering of water inflow in karst area.

Power Closed-loop Control of Switched Reluctance Generator for High Efficiency Operation

Li, Zhenguo,Gao, Dongdong,Ahn, Jin-Woo Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.3

This paper describes a control method of turn-on/off angles to improve the efficiency of the switched reluctance generator(SRG) with a power closed-loop control system, and the inner-loop of the system is current hysteresis control. The SRG control system is constituted by the PI power controller and the two-level current hysteresis controller. By measuring and analyzing the system losses of different reference powers, speeds and turn-on/off angles, selection strategy of optimal turn-on/off angles is discussed. The proposed method is simple, reliable, and easy to achieve.

Effect of gas composition on dispersion characteristics of blowout gas on offshore platform

Dongdong Yang,Guoming Chen,Jihao Shi,Xinhong Li 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

Gas composition has a significant impact on the dispersion behavior and accumulation characteristics of blowout gas. However, few public studies has investigated the corresponding effect of gas composition. Therefore, this study firstly builds the FLACS-based numerical model about an offshore drilling platform. Then several scenarios by varying the composition of blowout gas are simulated while the scenario with the composition of “Deepwater Horizon” accident is regarded as the benchmark. Furthermore, the effects of the gas composition on the flammable cloud volume, the influenced area of flammable cloud, the influenced area of hydrogen sulfide and the critical time of the hydrogen sulfide spreading to the living area are analyzed. The results demonstrate that gas composition is a driving factor for dispersion characteristics of blowout gas. All the results can give support to reduce the risk of the similar accidents incurred by real blowouts.