检索结果-南通市图书馆

Elastic, Piezoelectric and Acoustic Properties of Wurtzite MnO from Density Functional Calculation

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2013年第6期59卷 751-755页

作者： han han Surface Physics Laboratory (National Key Laboratory) Key Laboratory of Computational Physical Sciencesand Department of Physics ~dan University Shanghai 200433 China

The wurtzite MnO has been obtained lately and is expected to have large potentiai in varies applications. Since elastic properties are the bases of various applications, we calculate these properties of wurtzite MnO based on the density-functionai theory and compare it with other two phases of MnO （rocksalt and zinc-blende MnO）. The Young＇s modulus of wurtzite and zinc-blende MnO are 65.6 GPa and 73.4 GPa, respectively, which are much lower than those of rocksaJt MnO （177.6 GPa）. More importantly, both the Poisson ratio and the bulk modulus to shear modulus ratio indicate that wurtzite MnO should have much better ductile properties than rocksalt MnO. The calculated piezoelectric constants of wurtzite MnO are comparable to those of ZnO, This suggests wurtzite MnO is a good piezoelectric material. Furthermore, the slowness surfaces of acoustic waves of them are given from Christoffel equation.

关键词： wurtzite MnO density functional calculation elastic properties piezoelectric properties acousticproperties

Failure modes of lattice sandwich plate by additive-manufacturing and its imperfection sensitivity

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第2期36卷 430-447页

作者： Bin Ji han han Renbang Lin Hao Li Shanghai Key Laboratory of Spacecraft Mechanism Shanghai 201109China Aerospace System Engineering Shanghai Shanghai 201109China

Additive-manufacturing process has substantially promoted the development of lattice structure and makes it possible to fabricate complex lattice sandwich ***-plane compression load always appears in engineering,such as in the primary structure of *** order to reveal potential engineering application in future,this paper focuses on the lattice sandwich plate that is fabricated by additive-manufacturing and subjected to in-plane ***,five failure modes are proposed for lattice sandwich plate under in-plane compression,including Euler buckling,shear buckling,face sheet dimpling,face sheet wrinkling and face sheet ***,an optimization method is proposed to obtain the optimum sizes,including the panel thickness,the length of rod,the size of rod cross-section,the inclined angle of rod and the wideness ratio of ***,the in-plane compression experiment is operated after measuring the geometrical imperfection of the specimen by the optical *** method is adopted to illustrate the effect on failure behaviors caused by the imperfections of struts,face sheets and global *** introducing these imperfection,numerical result can be well agreed with experimental result and explain the failure mechanisms mostly derived from the radius imperfection for the struts.

关键词： Additive-manufacturing Lattice structure In-plane compression Failure mode Imperfection sensitivity

Network Coding-Aware Routing Protocol in Wireless Mesh Networks

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2015年第1期20卷 40-49页

作者： Yan Gu han han Xujie Li Jie Guo College of Computer and Information Hohai University

Network coding mechanisms, such as COPE, can improve network throughput effectively in Wireless Mesh Networks（WMN）. While the Hybrid Wireless Mesh Protocol（HWMP） is suitable for WMN, its extension with COPE does not provide any added benefits; specifically, HWMP cannot establish paths with more coding opportunities. As a result, the advantages of network coding cannot be exploited sufficiently. This paper proposes improvements upon HWMP with a new, network Coding-Aware routing protocol（CAHWMP） for WMN. In the CAHWMP protocol, we propose a coding criterion based on data streams to devise an algorithm for actively detecting coding opportunities during path discovery. CAHWMP subsequently establishes paths using the codingaware routing metric, which can balance channel resource consumption and the gain due to sharing resources introduced by network coding. Simulation results show that CAHWMP can establish paths with more coding opportunities; as a result, it improves network performance such as network throughput.

关键词： wireless mesh network network coding-aware Hybrid Wireless Mesh Protocol(HWMP) COPE mechanism coding criterion

All-Polymer Solar Cells with Perylenediimide Polymer Acceptors

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2017年第2期35卷 293-301页

作者： Yi-kun Guo Yun-ke Li han han 颜河赵达慧 Beijing National Laboratory for Molecular Sciences Center for the Soft Matter Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China Department of Chemistry Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

Four polymers based on perylenediimide co-polymerized with thiophene, bithiophene, selenophone and thieno[3,2-b]thiophene were investigated as the acceptor materials in all-polymer solar cells. Two different donor polymers, poly[4,8-bis（5-（2-ethylhexyl）thiophen-2-yl）benzo[ 1,2-b;4,5-b＇]dithiophene-2,6-diyl-alt-（4-（2-ethylhexyl）-3-fluorothieno[3,4- b]thiophene）-2-carboxylate-2,6-diyl] （PTB7-Th） and poly[（5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl）-alt-（3,3＇-di（2- dodecyltetradecyl）-2,2＇;5＇,2＂;5＂,2＇-quaterthiophen-5,5＇＂-diyl）] （PffBT4T-2DT）, with suitably complementary absorption spectra and energy levels were applied and examined. Among all different donor-acceptor pairs studied here, the combination of PTB7-Th：poly[NN-bis（1-hexylheptyl）-3,4,9,10-pery,enediimide-1,6/1,7-diyl-alt-2,5-thiophene] （PDI-Th） exhibited the best power conversion efficiency （PCE） of 5.13%, with open-circuit voltage （Vo：） = 0.79 lV, short-circuit current density （Jsc） = 12.35 ***-2 and fill-factor （FF） = 0.52. The polymer of PDI-Th acceptor used here had a regio-irregular backbone, conveniently prepared from a mixture of 1,6- and 1,7-dibromo-PDI. It is also noteworthy that neither additive nor post- treatment is required for obtaining such a cell performance.

关键词： All-polymer solar cells Polymer acceptor Perylenediimides Donor-acceptor pair

Numerical investigation of the influence of vortex generator on propeller cavitation and hull pressure fluctuation by DDES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第3期34卷 444-450页

作者： Yun Long han-qiao han Bin Ji Xin-ping Long Wuhan Second Ship Design and Research Institute Wuhan430064China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China

In this study,the delayed detached eddy simulation(DDES)is coupled with a homogenous cavitation model to simulate the cavitating turbulent flow around a propeller behind a full body ship with special emphasis on the influence of the vortex generator(VG)on the propeller cavitation and the hull pressure *** small calculation uncertainty as evaluated by the DDES verification and validation(V&V)method indicates that the present simulation can accurately reproduce the propeller performance and cavitation,and the predicted hull pressure fluctuation is in a fairly good agreement with the available experimental *** mechanism is explored through the current numerical results how the VG affects the local velocity distribution,along with the influences of the VG on the propeller cavitation and the hull pressure *** is shown that the streamwise vortex is induced by the VG near the hull boundary *** very low velocity region in the hull wake is reduced due to the effect of the streamwise ***,the propeller cavitation develops more mildly and the hull pressure fluctuation decreases due to the influence of the VG.

关键词： Propeller cavitation delayed detached eddy simulation(DDES) vortex generator(VG) streamwise vortex

High Open-circuit Voltage and Low Voltage Loss in All-polymer Solar Cell with a Poly(coronenediimide-vinylene)Acceptor

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第11期38卷 1157-1163,I0005页

作者： han han Fu-Jin Bai Rong Wei han Yu Yi-Kun Guo He Yan Da-Hui Zhao Beijing National Laboratory for Molecular Sciences Centre for the Soft Matter Science and EngineeringThe Key Laboratory of Polymer Chemistry and Physics of the Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Centre for Tissue Restoration&Reconstruction Hong Kong University of Science and Technology(HKUST)Clear Water BayKowloonHong Kong 999077China

Reducing the voltage loss(Vloss)is a critical factor in optimizing the open-circuit voltage(Voc)and overall power-c on version efficie ncy(PCE)of polymer solar *** the current work,by designing a novel electron-accepting unit of coronenediimide(CDI)and using it as the main functional building block,a new polymer acceptor CDI-V is developed and applied to fabricate all-polymer solar *** with the perylenediimide-based polymer acceptors we previously reported,the current CDI-V polymer possesses a noticeably elevated lowest unoccupied molecular orbital(LUMO).Thereby,by virtue of the enlarged energy gap between the donor HOMO and acceptor LUMO,a high Voc value of 1.05 V is achieved by the all-polymer photovolatic device,along with an impressively low Vloss of 0.55 *** remarkably,in spite of an extremely small LUMO level offset of 0.01 eV exhibited by the donor and acceptor polymers,effective charge separation still takes place in the allpolymer device,as evidenced by a proper short-circuit current(Jsc)of 9.5 mA·cm^-2 and a decent PCE of 4.63%.

关键词： All-polymer solar cell Coronenediimide Voltage loss Acceptors

Electrodeposited porous Pb electrode with improved electrocatalytic performance for the electroreduction of CO2 to formic acid

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2015年第1期9卷 57-63页

作者： Jing WANG Hua WANG Zhenzhen han Jinyu han Tianjin Co-innovation Center on Chemical Science & Engineering Key Laboratory for Green Chemical Technology of State Education Ministry School of Chemical Engineering & Technology Tianjin University Tianjin 300072 China

A porous Pb foam was fabricated electroche- mically at a copper substrate and then used as the cathode for the electroreduction of COE. The surface morphology and composition of the porous Pb electrode was characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The honeycomb-like porous structure was composed of needle-like Pb deposits. Cyclic voltammetry studies demonstrated that the porous Pb electrode had better electrocatalytic performance for the formation of formic acid from CO2 compared with a Pb plate electrode. The increase in current density was due to the large surface area of the porous Pb electrode, which provides more active sites on the electrode surface. The improved formic acid selectivity was due to the morphol- ogy of the roughened surface, which contains significantly more low-coordination sites which are more active for CO2 reduction. The highest current efficiency for formic acid was 96.8% at - 1.7 V versus saturated calomel electrode at 5℃. This porous Pb electrode with good catalytic abilities represents a new 3D porous material with applications for the electroreduction of CO2.

关键词： electrodeposited porous Pb carbon dioxide,electroreduction formic acid

Design and simulation of an innovative cylinder fabricated by selective laser melting

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第1期32卷 133-142页

作者： Guang MENG Bin JI han han Chengzhang GU Renbang LIN Fujun PENG Shanghai Academy of Spacelight Technology Shanghai Key Laboratory of Spacecraft Mechanism Aerospace System Engineering Shanghai

Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM processing, especially Selective Laser Melting(SLM), into primary structures that always occupy most of the whole mass of aircraft or spacecraft. In this paper, an innovative lattice sandwich structure that is suitable to be manufactured with SLM is adopted to design the typical cylinder under axial compression. Firstly, the mechanical properties of pyramidal lattice are investigated, and the bearing capacity of the lattice sandwich cylinder is given analytically for each failure mode. Secondly, a composite cylinder is re-designed in the form of lattice sandwich structure, which sizes are ultimately obtained through optimization. Finally, finite element model of the innovative cylinder is established and several kinds of imperfection are introduced to simulate the defects caused by SLM. Numerical result shows that the lattice sandwich design can obviously enhance the bearing capacity of cylindrical shell even though the original one is designed with composite material. In other words, SLM has great potential in improving the primary structure of spacecraft in the future.

关键词： Axial compression Cylinder Failure Imperfection Lattice sandwich structure Selective laser melting

Interfacial and Electrical Properties of GaAs Metal-Oxide-Semiconductor Capacitor with ZrAlON as the Interfacial Passivation Layer

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2017年第4期34卷 83-86页

作者： han-han Lu Jing-Ping Xu Lu Liu School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan 430074

The ZrTiON gate-dielectric GaAs metal-oxide-semiconductor （MOS） capacitors with or without ZrAION as the interfacial passivation layer （IPL） are fabricated and their properties are investigated. The experimental results show that the GaAs MOS capacitor with the ZrAION IPL exhibits better interracial and electrical properties, including lower interface-state density （1.14 × 10^12 cm^-2eV^-1）, smaller gate leakage current （6.82 × 10^-5 A//cm^2 at Vfb ＋1V）, smaller capacitance equivalent thickness （1.5 nm）, and larger k value （26）. The involved mechanisms lie in the fact that the ZrAION IPL can effectively block the diffusion of Ti and O towards the GaAs surface, thus suppressing the formation of interracial Ga-/As-oxides and As-As dimers, which leads to improved interracial and electrical properties for the devices.

关键词： MOS Zr Interfacial and Electrical Properties of GaAs Metal-Oxide-Semiconductor Capacitor with ZrAlON as the Interfacial Passivation Lay