This study gives an analytical solution for wave interaction with a partially reflecting vertical wall protected by a submerged porous bar based on linear potential theory. The whole study domain is divided into multi...This study gives an analytical solution for wave interaction with a partially reflecting vertical wall protected by a submerged porous bar based on linear potential theory. The whole study domain is divided into multiple sub-regions in relation to the structures. The velocity potential in each sub-region is written as a series solution by the separation of variables. A partially reflecting boundary condition is used to describe the partial reflection of a vertical wall. Unknown expansion coefficients in the series solutions are determined by matching velocity potentials among different sub-regions. The analytical solution is verified by an independently developed multi-domain boundary element method(BEM) solution and experimental data. The wave run-up and wave force on the partially reflecting vertical wall are estimated and examined, which can be effectively reduced by the submerged porous bar. The horizontal space between the vertical wall and the submerged porous bar is a key factor, which affects the sheltering function of the porous bar. The wave resonance between the porous bar and the vertical wall may disappear when the vertical wall has a low reflection coefficient. The present analytical solution may be used to determine the optimum parameters of structures at a preliminary engineering design stage.展开更多
A compact multiband patch antenna is designed by using HFSS in this work, which is filled with composite right/left-handed transmission line （CRLH-TL） structures. The simulated results reveal that the operating freq...A compact multiband patch antenna is designed by using HFSS in this work, which is filled with composite right/left-handed transmission line （CRLH-TL） structures. The simulated results reveal that the operating frequency becomes lower with left-handed （LH） characteristics of the CRLH-TL structures enhanced, which enable antenna physical size reduction to a large extent. The proposed antenna is fabricated on the substrate Rogers R03201 （relative permittivity of 10.2）, which has a compact size of 12 mm×12 mm × 4 mm. Moreover, this antenna exhibits monopole-like radiation pattern at one resonance frequency and patch-like radiation at the other four resonant frequencies. Therefore, the designed antenna is useful for communication systems.展开更多
A five-band metamaterial absorber(MMA) based on a simple planar structure is proposed.It utilizes different areas of a single unit cell to match impedance,and produces different absorptive frequencies.Numerical calcul...A five-band metamaterial absorber(MMA) based on a simple planar structure is proposed.It utilizes different areas of a single unit cell to match impedance,and produces different absorptive frequencies.Numerical calculation shows that the MMA has five different absorption peaks at 3.78 GHz,7.66 GHz,10.9 GHz,14.5 GHz and 16.7 GHz,and their absorption rates reach 95.5%,98.6%,95.7%,96.6%and 99.8%,respectively.The proposed structure is polarization insensitive for transverse electric(TE) and transverse magnetic(TM) incident waves.Also,the absorptive characteristics over large incident angles are examined.In addition,we analyze the absorption mechanism by the surface current density and power flow density distributions.This simple structure provides a way to design multi-band MMA,and also saves the cost of fabrication.展开更多
Block copolymers can yield a diverse array of nanostructures.Their assembly structures are influenced by their inherent structures,and the wide variety of structures that can be prepared especially becomes apparent wh...Block copolymers can yield a diverse array of nanostructures.Their assembly structures are influenced by their inherent structures,and the wide variety of structures that can be prepared especially becomes apparent when one considers the number of routes available to prepare block copolymer assemblies.Some examples include self-assembly,directed assembly,coupling,as well as hierarchical assembly,which can yield assemblies having even higher structural order.These assembly routes can also be complemented by processing techniques such as selective crosslinking and etching,the former technique leading to permanent structures,the latter towards sculpted and the combination of the two towards permanent sculpted structures.The combination of these pathways provides extremely versatile routes towards an exciting variety of architectures.This review will attempt to highlight destinations reached by LIU Guojun and coworkers following these pathways.展开更多
基金supported by the National Natural Science Foundation of China (Project Nos.51322903 and 51279224)the Program for New Century Excellent University Talents in University (NCET-13-0528)
文摘This study gives an analytical solution for wave interaction with a partially reflecting vertical wall protected by a submerged porous bar based on linear potential theory. The whole study domain is divided into multiple sub-regions in relation to the structures. The velocity potential in each sub-region is written as a series solution by the separation of variables. A partially reflecting boundary condition is used to describe the partial reflection of a vertical wall. Unknown expansion coefficients in the series solutions are determined by matching velocity potentials among different sub-regions. The analytical solution is verified by an independently developed multi-domain boundary element method(BEM) solution and experimental data. The wave run-up and wave force on the partially reflecting vertical wall are estimated and examined, which can be effectively reduced by the submerged porous bar. The horizontal space between the vertical wall and the submerged porous bar is a key factor, which affects the sheltering function of the porous bar. The wave resonance between the porous bar and the vertical wall may disappear when the vertical wall has a low reflection coefficient. The present analytical solution may be used to determine the optimum parameters of structures at a preliminary engineering design stage.
文摘A compact multiband patch antenna is designed by using HFSS in this work, which is filled with composite right/left-handed transmission line （CRLH-TL） structures. The simulated results reveal that the operating frequency becomes lower with left-handed （LH） characteristics of the CRLH-TL structures enhanced, which enable antenna physical size reduction to a large extent. The proposed antenna is fabricated on the substrate Rogers R03201 （relative permittivity of 10.2）, which has a compact size of 12 mm×12 mm × 4 mm. Moreover, this antenna exhibits monopole-like radiation pattern at one resonance frequency and patch-like radiation at the other four resonant frequencies. Therefore, the designed antenna is useful for communication systems.
基金supported by the National Natural Science Foundation of China(No.61475079)the Ningbo Optoelectronic Materials and Devices Creative Team(No.2009B21007)+3 种基金the Educational Committee of Zhejiang Province(No.Y201430863)the Ningbo Natural Science Foundation(No.2014A610144)the Scientific Research Foundation of Graduate School of Ningbo University(No.G15056)the K.C.Wong Magna Fund in Ningbo University
文摘A five-band metamaterial absorber(MMA) based on a simple planar structure is proposed.It utilizes different areas of a single unit cell to match impedance,and produces different absorptive frequencies.Numerical calculation shows that the MMA has five different absorption peaks at 3.78 GHz,7.66 GHz,10.9 GHz,14.5 GHz and 16.7 GHz,and their absorption rates reach 95.5%,98.6%,95.7%,96.6%and 99.8%,respectively.The proposed structure is polarization insensitive for transverse electric(TE) and transverse magnetic(TM) incident waves.Also,the absorptive characteristics over large incident angles are examined.In addition,we analyze the absorption mechanism by the surface current density and power flow density distributions.This simple structure provides a way to design multi-band MMA,and also saves the cost of fabrication.
基金Guojun Liu wishes to thank NSERC of Canada for a Tier 1 Canada Research Chair and for funding
文摘Block copolymers can yield a diverse array of nanostructures.Their assembly structures are influenced by their inherent structures,and the wide variety of structures that can be prepared especially becomes apparent when one considers the number of routes available to prepare block copolymer assemblies.Some examples include self-assembly,directed assembly,coupling,as well as hierarchical assembly,which can yield assemblies having even higher structural order.These assembly routes can also be complemented by processing techniques such as selective crosslinking and etching,the former technique leading to permanent structures,the latter towards sculpted and the combination of the two towards permanent sculpted structures.The combination of these pathways provides extremely versatile routes towards an exciting variety of architectures.This review will attempt to highlight destinations reached by LIU Guojun and coworkers following these pathways.
