检索结果-南通市图书馆

A Jacobi Spectral Collocation Method for Solving Fractional Integro-Differential Equations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications on Applied Mathematics and Computation 2021年第3期3卷 509-526页

作者： Qingqing Wu Zhongshu Wu xiaoyan zeng Department of Mathematics Shanghai UniversityShanghai 200444China

The aim of this paper is to obtain the numerical solutions of fractional Volterra integrodifferential equations by the Jacobi spectral collocation method using the Jacobi-Gauss collocation *** convert the fractional order integro-differential equation into integral equation by fractional order integral,and transfer the integro equations into a system of linear equations by the Gausssian *** furthermore perform the convergence analysis and prove the spectral accuracy of the proposed method in L∞*** numerical examples demonstrate the high accuracy and fast convergence of the method at last.

关键词： Fractional integro-differential equation Caputo fractional derivative Jacobi spectral collocation method Convergence analysis

Effect of rotation angle on surface morphology, microstructure, and mechanical properties of Inconel 718 alloy fabricated by high power laser powder bed fusion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第23期154卷 30-42页

作者： Qiao Zhong Kaiwen Wei Taoyuan Ouyang Xiangyou Li xiaoyan zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 China Beijing Research Institute of Telemetry Beijing 100076 China

Rotation angle of the laser scan direction between two adjacent layers is a key controlling parameter during the high-power (≥ 1 kW) laser powder bed fusion (HP-LPBF) process. This study investigates the influences of rotation angles (θ = 0°, 45°, 90°, 105°) on the surface morphology, microstructure, and mechanical properties of Inconel 718 (IN718) alloy produced by HP-LPBF. Results show that adopting low rotation angles (e.g., 0° and 45°) is prone to relatively poor surface finish and lack-of-fusion defects, whereas adopting high rotation angles (e.g., 90° and 105°) induces smaller surface roughness and better relative density. Each case reveals a noticeable edge effect but the maximal heights witness a downward trend with the increase of rotation angle. There are some minor differences in the primary dendrite arm spacing and grain morphology by varying the rotation angles. Moreover, the tensile property is slightly enhanced as the rotation angle increases. The present work suggests that high rotation angles like 90° and 105° would probably be more favorable for the 1 kW HP-LPBF process than rotation angles with relatively low values.

关键词： High-power laser powder bed fusion Rotation angle Surface morphology Microstructure Mechanical properties Inconel 718 alloy

Fabrication of polyetheretherketone(PEEK)-based 3D electronics with fine resolution by a hydrophobic treatment assisted hybrid additive manufacturing method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Extreme Manufacturing 2023年第3期5卷 519-532页

作者： Liexin Wu Li Meng Yueyue Wang Ming Lv Taoyuan Ouyang Yilin Wang xiaoyan zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China

Additive manufacturing(AM)is a free-form technology that shows great potential in the integrated creation of three-dimensional(3D)***,the fabrication of 3D conformal circuits that fulfill the requirements of high service temperature,high conductivity and high resolution remains a *** this paper,a hybrid AM method combining the fused deposition modeling(FDM)and hydrophobic treatment assisted laser activation metallization(LAM)was proposed for manufacturing the polyetheretherketone(PEEK)-based 3D electronics,by which the conformal copper patterns were deposited on the 3D-printed PEEK parts,and the adhesion between them reached the 5B high ***,the 3D components could support the thermal cycling test from-55℃ to 125℃ for more than 100 ***,the application of a hydrophobic coating on the FDM-printed PEEK before LAM can promote an ideal catalytic selectivity on its surface,not affected by the inevitable printing borders and pores in the FDM-printed parts,then making the resolution of the electroless plated copper lines improved *** consequence,Cu lines with width and spacing of only60μm and 100μm were obtained on both as-printed and after-polished PEEK ***,the potential of this technique to fabricate 3D conformal electronics was demonstrated.

关键词： PEEK fused deposition modeling hydrophobic treatment laser activation metallization integrated manufacturing of 3D electronics resolution

Heptamethine cyanines in bioorthogonal chemistry

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 131-137页

作者： Yuanyuan Liao Yuting Liang Yurou Huang xiaoyan zeng Tian He Jun Yin National Key Laboratory of Green Pesticide International Joint Research Center for Intelligent Biosensor Technology and HealthCollege of ChemistryCentral China Normal UniversityWuhan 430079China

Due to their excellent fluorescence properties and biological function,cyanine dyes have been widely applied in biological *** cyanine(Cy7)dyes,as a type of classic near-infrared(NIR)fluorescent dyes,are considered as one of the effective fluorescent tools in the living organisms due to their good biocompatibility and very low background *** reactions performed in living cells and tissues have developed by leaps and bounds in recent *** NIR fluorescent labeling technique involving cyanine has attracted widespread *** review summarizes their recent application in the field of bioorthogonal imaging,mainly concluding Cy7-type dyes,labeling strategy,bioimaging application,*** expect this work can provide some helps for the studies of NIR bioorthogonal reaction in vivo.

关键词： Fluorescent probes Heptamethine cyanines Bioorthogonal reaction Imaging Cell

Laser micro-cladding electronic pastes for fabrication of MIM thick film capacitors

在线全文

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2009年第1期2卷 86-91页

作者： Yu CAO Xiangyou LI xiaoyan zeng School of Optoelectronics and Engineering Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology

Two direct-write processing methods – direct material deposition by microPen and Nd:YAG laser microcladding – are integrated with computer-aided design/computer-aided manufacturing(CAD/CAM) technology for the fabrication of passive electronic components. A basic two-step procedure of the laser micro-cladding electronic paste(LMCEP) process for thick film pattern preparation is presented. In particular, metal-insulatormetal(MIM) type thick film capacitors are fabricated on ceramic substrates by the LMCEP process. Multilayer structures of the MIM thick film capacitors are demonstrated and discussed. Results of the frequency characteristics test show that the MIM thick film capacitors fabricated by the LMCEP process have excellent direct current(DC) voltage stability( < 2.48%), excellent frequency stability( < 2.6%) and low dissipation factor( < 0.6%), which are sufficient for many megahertz applications.

关键词： 79\bc\9c\d9\hcm0000078679.html

Weldability, microstructure and mechanical properties of laser-welded selective laser melted 304 stainless steel joints

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第9期35卷 1817-1824页

作者： Jingjing Yang Yun Wang Fangzhi Li Wenpu Huang Guanyi Jing Zemin Wang xiaoyan zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Xi'an Space Engine Factory Xi'an710100China

Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhardness, tensile properties and corrosion resistance of the laser welded stress-relieved SLMed 304 stainless steel joints are investigated, as the different sections of stress-relieved SLMed 304 stainless steel are joined. Results show that the SLMed 304 stainless steel plates have a good laser weldability. The microstructure of laser-welded joints consists of the cellular dendrites in austenite matrix within columnar grains, exhibiting a coarser dendrite structure, lower microhardness (~220HV) and tensile properties (tensile strength of ~750 MPa, and area reduction of ~27.6%), but superior corrosion resistance to those of SLMed plates. The dendrite arm spacing of the joints varies from ~3.7μm in center zone, to ~5.0 (xm in fusion zone, to ~2.5 in epitaxial zone. The SLMed anisotropy shows a negligible effect on the microstructure and performance of the laser-welded joints. The laser welding along the building directions of the SLMed base plates can induce a slightly finer dendritic structure and higher tensile properties.

关键词： Selective laser melting Laser welding 304 stainless steel Anisotropy

Controllable in-situ aging during selective laser melting: Stepwise precipitation of multiple strengthening phases in Inconel 718 alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第9期35卷 1925-1930页

作者： Huihui Yang Jingjing Yang Wenpu Huang Guanyi Jing Zemin Wang xiaoyan zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology

A controllable in-situ aging treatment of Inconel 718 alloy was successfully developed by governing the types and times of the thermal cycles during selective laser melting(SLM).The sequential precipitation of γ’,composite phase of primary/secondary γ’ coated by a γ " shell,and γ" occurs as the times of vertical thermal cycles increase when laser peak temperature(Tp)is between the precipitation temperature of strengthening phase(Tpre)and liquid temperature(T_L),which causes an increase in microhardness by 40 ***,short-term aging mechanisms on three types of strengthening phases are proposed based on a great number of vacancies in the matrix.

关键词： Selective laser melting In-situ aging Inconel 718 Strengthening phases Stepwise precipitation

Cracking behavior and control of β-solidifying Ti-40Al-9V-0.5Y alloy produced by selective laser melting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第4期39卷 144-154页

作者： Piao Gao Wenpu Huang Huihui Yang Guanyi Jing Qi Liu Guoqing Wang Zemin Wang xiaoyan zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China China Academy of Launch Vehicle Technology Beijing 100076China

Aβ-solidifying Ti-40 Al-9 V-0.5 Y(at.%)alloy with a high cracking sensitivity has been successfully fabricated by selective laser melting(SLM)in this *** influence factors for cracking sensitivity,cracking behavior and crack inhibition mechanism were *** results show that the effects of process parameters on cracking sensitivity strongly depend on the cooling rate in molten pool with different heat transfer *** conduction mode with higher cooling rates exhibits a higher cracking sensitivity in comparison to the keyhole *** characteristics and phase transformations controlled by cooling rate determine the inherent ductility ofβ-solidifyingγ-Ti Al alloys during *** this basis,the formation and inhibition mechanism of solidification and cold cracking are ***,the crackfree Ti-40 Al-9 V-0.5 Y sample with fine equiaxed microstructures and favorable mechanical properties(microhardness of 542±19 HV,yield strength of 1871±12 MPa,ultimate strength of 2106±13 MPa and ultimate compressive strain of 10.89±0.57%)can be produced by *** strengthening mechanism can be attributed to grain refinement and precipitation strengthening.

关键词： Selective laser melting β-solidifyingγ-TiAl alloy Cracking behavior Cracking control Microstructure Phase transformation

Effects of Different Vermicompost Rates on Growth,2-Acetyl-1-Pyrroline,Photosynthesis and Antioxidant Responses of Fragrant Rice(Oryza sativa L.)Seedling

在线全文

学校读者我要写书评

暂无评论

Phyton-International Journal of Experimental Botany 2021年第4期90卷 1273-1283页

作者： Shaoyi Ruan Haowen Luo xiaoyan zeng Runhao Wen Feida Wu Xiangru Tang State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources College of AgricultureSouth China Agricultural UniversityGuangzhou510642China Scientific Observing and Experimental Station of Crop Cultivation in South China Ministry of Agriculture and Rural AffairsGuangzhou510642China Guangzhou Key Laboratory for Science and Technology of Fragrant Rice Guangzhou510642China

Vermicompost is an organic fertilizer contains multiple nutrient ***,the application of vermicompost in fragrant rice production is rarely *** order to study the effects of vermicompost application on fragrant rice(Oryza sativa L.)seedling performances,present study was conducted with two fragrant rice cultivars and four vermicompost rate treatments(0(CK),2.5(Wo1),5.0(Wo2)and 10.0(Wo3)g kg−1).The results showed that vermicompost treatments significantly increased dry weight of fragrant rice seedling by 8.31–32.56%compared with CK.21.10–59.13%higher net photosynthetic rates and 10.66–59.16%higher chlorophyll contents(chlorophyll a,chlorophyll b and total chlorophyll)were recorded in vermicompost treatments than *** of vermicompost also significantly increased 2-acetyl-1-pyrroline(2-AP,the key compound of fragrant rice aroma)content and reduced the transcript level of gene BADH2 which related to 2-AP biosynthesis in fragrant rice ***,compared with CK,vermicompost treatments enhanced activities of superoxide dismutase,peroxidase,catalase by 24.42–28.66%,24.98–25.73%and 22.45–23.57%,respectively.11.54–40.53%lower malonaldehyde contents were recorded in vermicompost treatments in related to *** conclusion,vermicompost improved growth,increased 2-AP content and might enhance stress resistant of fragrant rice seedling.

关键词： 2-acetyl-1-pyrroline fragrant rice gene expression photosynthesis vermicompost