Tailoring of the plasmonic and waveguide effect in bulk-heterojunction photovoltaic devices with ordered, nanopatterned structures

Wang, D.H.,Kyaw, A.K.K.,Du, Q.G.,Choi, D.G.,Park, J.H. Elsevier Science 2014 Organic Electronics Vol.15 No.11

Various nano-patterned bulk-heterojunction (BHJ) films with different diameters and pitches were fabricated by a stamping method to tailor the plasmonic effect. The nanopatterned BHJ active layers exhibit regular-ordered embossing structures, which were confirmed by the surface morphological analysis with SEM and AFM. The simulation results confirm that devices with nanopatterned BHJ film with a diameter/pitch of 265/400nm exhibit a strong improvement in E-field distribution intensity due to the combination of the plasmonic and waveguide modes compared to devices without a nanopattern, with 150/400nm, or with 265/800nm, which led to increased J<SUB>SC</SUB> and cell efficiency in J-V curves under solar light illumination. The optimized plasmonic effect plays an important role in the light harvesting of BHJ devices.

Enhanced energy storage properties in PbZrO3 thin films via the incorporation of NiO

Wang X.W.,Chen J.Y.,Hu S.Y.,Yu K.X.,Yang F.,Shi Y.J.,Li J.H.,Hou M.Z.,Liu A.D.,Zheng M.M.,Yin S.Q.,Hu Y.C.,Shang J. 한국물리학회 2023 Current Applied Physics Vol.52 No.-

In this study, NiO–PbZrO3 composite films were deposited on SiO2/Si substrates buffered with LaNiO3 films via the sol-gel coating technique. The effects of NiO addition in PZO thin films on the microstructure, dielectric properties, leakage mechanism, ferroelectric properties and energy storage properties have been discussed. The dielectric constant increased with the addition of NiO, while the leakage current density decreased. Compared with pure PZO films, the maximum polarization of the composite films was improved. For the composite films prepared using the NiO precursor solution with 0.05 mol/L, the recoverable energy storage density of the NiO-PZO composite film is up to 19.6 J/cm3 under the electric field of 1038 kV/cm, which is 30% higher than that of the pure PZO film under the same conditions. Also, the energy storage efficiency of the composite film reaches 48%. Accordingly, we demonstrate a simple and convenient method by adding NiO to fabricate thin films with high energy storage performance.

Tests and finite element analysis on the local buckling of 420 MPa steel equal angle columns under axial compression

G. Shi,Z. Liu,H.Y. Ban,Y. Zhang,Y.J. Shi,Y.Q. Wang 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.1

Local buckling can be ignored for hot-rolled ordinary strength steel equal angle compression members, because the width-to-thickness ratios of the leg don’t exceed the limit value. With the development of steel structures, Q420 high strength steel angles with the nominal yield strength of 420 MPa have begun to be widely used in China. Because of the high strength, the limit value of the width-to-thickness ratio becomes smaller than that of ordinary steel strength, which causes that the width-to-thickness ratios of some hot-rolled steel angle sections exceed the limit value. Consequently, local buckling must be considered for 420 MPa steel equal angles under axial compression. The existing research on the local buckling of high strength steel members under axial compression is briefly summarized, and it shows that there is lack of study on the local buckling of high strength steel equal angles under axial compression. Aiming at the local buckling of high strength steel angles, this paper conducts an axial compression experiment of 420MPa high strength steel equal angles, including 15 stub columns. The test results are compared with the corresponding design methods in ANSI/AISC 360-05 and Eurocode 3. Then a finite element model is developed to analyze the local buckling behavior of high strength steel equal angles under axial compression, and validated by the test results. Followingthe validation, a finite element parametric study is conducted to study the influences of a range of parameters, and the analysis results are compared with the design strengths by ANSI/AISC 360-05 and Eurocode 3.

An approach to bioassess pelagic ciliate biodiversity at different taxonomic resolutions in response to various habitats in the Amundsen Sea (Antarctica)

Jiang, Y.,Liu, Q.,Yang, E. J.,Wang, M.,Lee, Y.,Lee, S. Springer Science + Business Media 2016 Polar biology Vol.39 No.3

<P>The rapid melting of glaciers and loss of sea ice will result in changes in habitat conditions that may drive substantial changes in biodiversity. In order to bioassess the changing polar ecosystem and evaluate biological conservation, pelagic ciliate communities at different taxonomic resolutions were studied at five habitats in the Amundsen Sea during the austral summer from December 2010 to January 2011. Distinctive spatial patterns were observed in the communities among the five habitats (oceanic areas, transitional areas, polynyas, edges of glaciers, and edges of sea ice) in response to environmental variability (e.g., temperature, salinity, chlorophyll a, and nutrients). The distributions in the numbers of different taxonomic levels and of three biodiversity indices (Shannon-Wiener H', Pielou's J', and Margalef D) also revealed clear spatial variability with the maximum mean species number and indices in the polynya and maximum genus and family numbers in the transitional area. The presence/absence of data at taxonomic resolutions up to the family level provided sufficient information to evaluate the ecological patterns of pelagic ciliate communities and could accurately reflect habitat variations. The k-dominance curves illustrated clearly that maximum diversity was presented in the polynya at the species level and in the transitional area at the genus and family level. We suggest that the diversity at higher taxonomic resolutions should be considered more in future monitoring. Our findings provide basic data and an approach toward answering important questions about biological conservation, especially the biodiversity at various taxonomic resolutions in response to the increasing climate changes in polar ecosystems.</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.

Effects of loading history on seismic performance of SRC T-shaped column, Part I: Loading along web

Wang, J.,Liu, Z.Q.,Xue, J.Y.,Hu, C.M. 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.2

This paper describes an experimental study on the seismic performance of steel reinforced concrete (SRC) T-shaped columns. The lateral loads were applied along the web of the column with different loading histories, such as monotonic loading, mixed loading of variable amplitude cyclic loading and monotonic loading, constant amplitude cyclic loading and variable amplitude cyclic loading. The failure modes, load-displacement curves, characteristic loads and displacements, ductility, strength and stiffness degradations and energy dissipation capacity of the column were analyzed. The effects of loading history on the seismic performance were focused on. The test results show that the specimens behaved differently in the aspects of the failure mode subject to different loading history, although all the failure modes can be summarized as flexural failure. The hysteretic loops of specimens are plump, and minimum values of the failure drift angles and ductility coefficients are 1/24 and 4.64, respectively, which reflect good seismic performance of SRC T-shaped column. With the increasing numbers of loading cycles, the column reveals lower bearing capacity and ductility. The strength and stiffness of the column with variable amplitude cyclic loading degrades more rapidly than that with constant amplitude cyclic loading, and the total cumulative dissipated energy of the former is less.

Experimental Characterization and Computational Modelling for Fatigue Behavior of a Ni-Based Single Crystal Alloy Considering Surface Roughness

J. J. Wang,Z. X. Wen,Y. M. Zhang,Y. Q. Yang,H. Q. Pei,Z. F. Yue 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

Using a combination of tests and numerical simulations, the fatigue behaviors of a Ni-based single crystal (SC) alloy withdifferent surface roughnesses (SRs) are studied. The test results demonstrate that the fatigue life decreases with increasingSR, while the strain accumulation shown an opposite trend. Surface defects can give rise to the nucleation, aggregationand growth of surface cracks, which are the principal inducement of fatigue failure. Finite element models of the actualsurface topography were established, and the notched plate models whose modelling parameters were determined by theSR parameters ( Rz , Rsm , Ra ) were used to equivalently simplify, the equivalent errors are within 5%. In addition, a semiempiricalformula between the surface stress concentration factor ( Kt ) and the SR parameters was fitted. By introducing theKt expressed by the SR parameters into a fatigue damage model based on crystal plasticity theory, a fatigue life predictionmethod of a Ni-based SC alloy that considers SR was established, and it has been verified to exhibit excellent consistencywith the test results.

Effects of loading history on seismic performance of SRC T-shaped column, Part I: Loading along web

J. Wang,Z.Q. Liu,J.Y. Xue,C.M. Hu 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.2

This paper describes an experimental study on the seismic performance of steel reinforced concrete (SRC) T-shaped columns. The lateral loads were applied along the web of the column with different loading histories, such as monotonic loading, mixed loading of variable amplitude cyclic loading and monotonic loading, constant amplitude cyclic loading and variable amplitude cyclic loading. The failure modes, load-displacement curves, characteristic loads and displacements, ductility, strength and stiffness degradations and energy dissipation capacity of the column were analyzed. The effects of loading history on the seismic performance were focused on. The test results show that the specimens behaved differently in the aspects of the failure mode subject to different loading history, although all the failure modes can be summarized as flexural failure. The hysteretic loops of specimens are plump, and minimum values of the failure drift angles and ductility coefficients are 1/24 and 4.64, respectively, which reflect good seismic performance of SRC T-shaped column. With the increasing numbers of loading cycles, the column reveals lower bearing capacity and ductility. The strength and stiffness of the column with variable amplitude cyclic loading degrades more rapidly than that with constant amplitude cyclic loading, and the total cumulative dissipated energy of the former is less.

Preparation and catalytic activity of K₄Zr₅O₁₂ for the oxidation of soot from vehicle engine emissions

Wang, Q.,Sohn, J.H.,Park, S.Y.,Choi, J.S.,Lee, J.Y.,Chung, J.S. Korean Society of Industrial and Engineering Chemi 2010 Journal of industrial and engineering chemistry Vol.16 No.1

Pure phase K<SUB>4</SUB>Zr<SUB>5</SUB>O<SUB>12</SUB> is synthesized via solid state method in the present work. Various K/Zr ratios and temperatures are applied, and the synthesis process is investigated in detail by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Its catalytic activity for soot oxidation is studied by temperature programmed oxidation with different types of soot/catalyst contacts. It is revealed that K<SUB>4</SUB>Zr<SUB>5</SUB>O<SUB>12</SUB> is very active in the presence of 2-10% O<SUB>2</SUB> for both tight and loose contacts (T<SUB>p(tight)</SUB>=335<SUP>o</SUP>C, T<SUB>p(ethanol)</SUB>=355<SUP>o</SUP>C and T<SUB>p(shaking)</SUB>=370<SUP>o</SUP>C). Thermal stability study shows that K<SUB>4</SUB>Zr<SUB>5</SUB>O<SUB>12</SUB> is highly stable up to at least 900<SUP>o</SUP>C.

The use of Taguchi optimization in determining optimum electrophoretic conditions for the deposition of carbon nanofiber on carbon fibers for use in carbon/epoxy composites

Wang, Y.Q.,Byun, J.H.,Kim, B.S.,Song, J.I.,Chou, T.W. Pergamon Press ; Elsevier Science Ltd 2012 Carbon Vol.50 No.8

Vapor grown carbon nanofibers (VGCNFs) were deposited on carbon fibers (CFs) using electrophoretic deposition (EPD). Composites of the resulting hybrid material (CF-VGCNF) in an epoxy matrix were fabricated by the vacuum-assisted resin transfer molding process. The electrical conductivities of the composites were significantly improved compared to those without the VGCNF reinforcement. The Taguchi method was used to optimize the EPD process conditions through the analysis of means and the analysis of variance for achieving a highly uniform deposition of carbon nanofibers. The parameters considered for optimization are: deposition time, applied voltage, concentration of VGCNF in a distilled water suspension, and the distance between anode (a carbon fabric) and cathode (a copper plate). An orthogonal array of L<SUB>9</SUB> (3<SUP>4</SUP>) was created in the statistical design of experiments. The through-thickness electrical conductivity of the composites produced using the optimum deposition conditions was more than 90 times that of carbon fiber/epoxy composites. When compared with the average electrical conductivity of the nine design experiments, the electrical conductivity of the CF-VGCNF/epoxy composite using a filler prepared under the optimum deposition conditions showed a 51% improvement.