检索结果-南通市图书馆

Science China(Technological Sciences) 2017年第10期60卷 1518-1536页

作者： YANG YongTao ZHENG Hong xu dongdong State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of Sciences Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of Technology Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Yangtze River Scientific Research Institute

A partition-of-unity （PU） based ＂FE-Meshfree＂ three-node triangular element （Trig3-RPIM） was recently developed for linear elastic problems. This Trig3-RPIM element employs hybrid shape functions that combine the shape functions of three-node triangular element （Trig3） and radial-polynomial basis functions for the purpose of synergizing the merits of both finite element method and meshfree method. Although Trig3-RPIM element is capable of obtaining higher accuracy and convergence rate than the Trig3 element and four-node iso-parametric quadrilateral element without adding extra nodes or degrees of freedom （DOFs）, the nodal stress field through Trig3-RP1M element is not continuous and extra stress smooth operations are still needed in the post processing stage. To further improve the property of Trig3-RPIM element, a new PU-based triangular element with continuous nodal stress, called Trig3-RPIMcns, is developed. Numerical examples including several linear, free vibration and forced vibration test problems, have confirmed the correctness and feasibility of the proposed Trig3-RPIMcns element.

关键词： partition of unity FE-Meshfree element Trig3-RPlMcns mesh distortion radial-polynomial basis functions

Engineering porous architectures in multicomponent PdCuBP mesoporous nanospheres for electrocatalytic ethanol oxidation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2021年第9期14卷 3274-3281页

作者： Hao Lv Yaru Wang dongdong xu Ben Liu Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Center of Biomedical Functional MaterialsSchool oj Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China College of Chemistry Sichuan UniversityChengdu 610064China

Porous features of mesoporous metal nanocrystals are critically important for their applications in catalysis,sorption,and biomedicine and ***,precisely engineering porous architectures of mesoporous metals is still highly ***,we report a facile soft-templating strategy to precisely engineer porous architectures of multicomponent PdCuBP mesoporous nanospheres(MSs)by using the surfactants with different amphiphilic *** kinds of MSs with distinct porous architectures,including three-dimensional(3D)opened/interconnected dendritic mesopores(dMSs),one-dimensional(1D)cylindered mesopores(cMSs),and zero-dimensional(0D)spherical mesopores(sMSs),are *** surfactant-templating method is generally extended to regulate elemental compositions of multicomponent *** resultant Pd-based MSs have been evaluated as the electrocatalysts for ethanol oxidation reaction(EOR).Our results show that quaternary PdCuBP dMSs display remarkably high catalytic activity and better stability for electrocatalytic EOR,compared to those of multicomponent MSs with other porous architectures and less elemental *** studies reveal that PdCuBP dMSs combine multiple structural and compositional advantages,which kinetically accelerate the electron/mass transfers and also improve the tolerances to poisoning *** believe that the porous architecture engineering in mesoporous metal electrocatalysts will present a new way to design highly efficient electrocatalysts with desired porous systems and explore their relations towards(electro)catalysis.

关键词： porous architectures multicomponent alloys mesoporous nanosphere surfactant electrocatalysis

A linearly-independent higher-order extended numerical manifold method and its application to multiple crack growth simulation

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

Journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1256-1263页

作者： dongdong xu Aiqing Wu Cong Li Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Changjiang River Scientific Research InstituteWuhanChina State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhanChina

The numerical manifold method(NMM)can be viewed as an inherent continuous-discontinuous numerical method,which is based on two cover systems including mathematical and physical ***-order NMM that adopts higher-order polynomials as its local approximations generally shows higher precision than zero-order NMM whose local approximations are ***,higherorder NMM will be an excellent choice for crack propagation problem which requires higher stress *** addition,it is crucial to improve the stress accuracy around the crack tip for determining the direction of crack growth according to the maximum circumferential stress criterion in fracture ***,some other enriched local approximations are introduced to model the stress singularity at the crack ***,higher-order NMM,especially first-order NMM wherein local approximations are first-order polynomials,has the linear dependence problems as other partition of unit(PUM)based numerical methods *** overcome this problem,an extended NMM is developed based on a new local approximation derived from the triangular plate element in the finite element method(FEM),which has no linear dependence ***,the stresses at the nodes of mathematical mesh(the nodal stresses in FEM)are continuous and the degrees of freedom defined on the physical patches are physically ***,the extended NMM is employed to solve multiple crack propagation *** shows that the fracture mechanics requirement and mechanical equilibrium can be satisfied by the trial-and-error method and the adjustment of the load multiplier in the process of crack *** numerical examples are illustrated to verify the feasibility of the proposed extended *** numerical examples indicate that the crack growths simulated by the extended NMM are in good accordance with the reference *** the effectiveness and correctness of the developed NMM have been validated.

关键词： Numerical manifold method (NMM) Physical cover Multiple crack propagation Linear independence Nodal stress continuity

Modeling complex crack problems using the three-node triangular element fitted to numerical manifold method with continuous nodal stress

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2017年第10期60卷 1537-1547页

作者： YANG YongTao xu dongdong SUN GuanHua ZHENG Hong State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of Sciences Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Yangtze River Scientific Research Institute Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of Technology

A three-node triangular element fitted to numerical manifold method with continuous nodal stress, called Trig_3-CNS(NMM)element, was recently proposed for linear elastic continuous problems and linear elastic simple crack problems. The Trig_3-CNS(NMM) element can be considered as a development of both the Trig_3-CNS element and the numerical manifold method(NMM).Inheriting all the advantages of Trig_3-CNS element, calculations using Trig_3-CNS(NMM) element can obtain higher accuracy than Trig_3 element without extra degrees of freedom(DOFs) and yield continuous nodal stress without stress smoothing. Inheriting all the advantages of NMM, Trig_3-CNS(NMM) element can conveniently treat crack problems without deploying conforming mathematical mesh. In this paper,complex problems such as a crucifix crack and a star-shaped crack with many branches are studied to exhibit the advantageous features of the Trig_3-CNS(NMM) element. Numerical results show that the Trig_3-CNS(NMM) element is prominent in modeling complex crack problems.

关键词： numerical manifold method Trig3-CNS (NMM) element stress intensity factor complex crack problems

A universal strategy for fast,scalable,and aqueous synthesis of multicomponent palladium alloy ultrathin nanowires

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2021年第2期64卷 245-252页

作者： Hao Lv xuwen Guo Lizhi Sun dongdong xu Ben Liu College of Chemistry Sichuan UniversityChengdu 610064China Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Center of Biomedical Functional MaterialsSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China

Noble metal alloy nanowires(NWs)with ultrathin diameters(2–3 nm)and precisely controllable elemental compositions have attracted dramatically growing attention for(electro)*** numerous achievements in past two decades,noble metal alloy NWs are mostly synthesized with the traditional oil-phase methods that suffer from some undesirable ***,we report a general strategy for fast,scalable,and aqueous synthesis of multicomponent Pd-based alloy ultrathin NWs with an average diameter of 2.6 nm,ranging from bimetallic PdM(PdFe,PdCo,PdNi,PdCu,PdZn,PdRu,PdRh,PdAg,PdCd,PdIr,PdPt,PdAu)and binary PdS/PdP NWs,to trimetallic PdM1M2 NWs(PdAuCu,PdCoNi,PdCuZn,PdCuNi,PdAgCu,PdAuCu,PdRuAg,PdAuRu,and PdPtAu),and to tetrametallic PdM1M2M3 NWs(PdAuAgCu,PdCoCuNi,PdAuCuNi,PdPtAuCu,and PdIrPtAu).The key to the success of this aqueous synthesis is the utilization of N2H4 as the extremely strong reducing agent that directs the synchronous reduction and anisotropic nucleation growth of multicomponent Pd alloy NWs along nanoconfined columnar phase assembled with amphiphilic dioctadecyldimethylammonium ***-resultant Pd-based alloy ultrathin NWs exhibit multiple structural and compositional synergies,which remarkably optimize the removal of poisoning ethoxy intermediates and thus improve electrocatalytic performance towards ethanol oxidation reaction(EOR).Among them,tetrametallic PdAuCuNi alloy ultrathin NWs hold a high EOR activity of 5.14 A mg-1 Pd and a low activation energy of 13.1 kJ mol^-1,both of which are much better than its counterpart catalysts alloyed with less *** work represents an important advance in precise aqueous synthesis of multicomponent noble metal alloy ultrathin NWs as the high-performance electrocatalysts for various targeted applications.

关键词： ultrathin nanowires multicomponent alloys palladium synthetic chemistry ethanol oxidation reaction

A multispectral image compression and encryption algorithm based on tensor decomposition and chaos

在线全文

学校读者我要写书评

暂无评论

High Technology Letters 2022年第2期28卷 134-141页

作者： xu dongdong DU Limin Electronin Information Engineering College Changchun UniversityChangchun 130022P.R.China

A multi spectral image compression and encryption algorithm that combines Karhunen-Loeve(KL) transform,tensor decomposition and chaos is proposed for solving the security problem of multi-spectral image compression and ***,in order to eliminate residual spatial redundancy and most of the spectral redundancy,the image is performed by KL ***,to further eliminate spatial redundancy and reduce block effects in the compression process,two-dimensional discrete 9/7 wavelet transform is performed,and then Arnold transform and encryption processing on the transformed coefficients are ***,the tensor is decomposed to keep its intrinsic structure intact and eliminate residual space ***,differential pulse filters are used to encode the coefficients,and Tent mapping is used to implement confusion diffusion encryption on the code *** experimental results show that the method has high signal-to-noise ratio,fast calculation speed,and large key space,and it is sensitive to keys and plaintexts with a positive effect in spectrum assurance at the same time.

关键词： Karhunen-Loeve(KL)transform tensor decomposition differential pulse filter Tent map

Identification and functional characterization of the AGO1 ortholog in maize

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2016年第8期58卷 749-758页

作者： dongdong xu Hailong Yang Cheng Zou Wen-xue Li Yunbi xu Chuanxiao Xie Institute of Crop Science Chinese Academy of Agricultural Sciences

Eukaryotic Argonaute proteins play primary roles in mi RNA and si RNA pathways that are essential for numerous developmental and biological processes. However, the functional roles of the four Zm AGO1 genes have not yet been characterized in maize（Zea mays L.）. In the present study, Zm AGO1 a was identified from four putative Zm AGO1 genes for further characterization. Complementation of the Arabidopsis ago1-27 mutant with Zm AGO1 a indicated that constitutive overexpression of Zm AGO1 a could restore the smaller rosette, serrated leaves, later flowering and maturation, lower seed set, and darker green leaves at late stages of the mutant to the wild-type phenotype. The expression profiles of Zm AGO1 a under five different abiotic stresses indicated that Zm AGO1 a shares expression patterns similar to those of Argonaute genes in rice, Arabidopsis, and ***, variation in Zm AGO1 a alleles among diverse maize germplasm that resulted in several amino acid changes revealed genetic diversity at this locus. The present data suggest that Zm AGO1 a might be an important AGO1 ortholog in maize. The results presented provide further insight into the function of ZmAGO1a.

关键词： AGO1 functional complementation maize ZmAGO1a

Ultrathin curved PdNiRu nanosheets as bifunctional catalysts for oxygen reduction and ethylene glycol oxidation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第5期17卷 3777-3784页

作者： Xianzeng Li Tingyu Lu Huan Pang Mingyi Zhang dongdong xu Lin xu Min Han Jun Yang Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Center of Biomedical Functional MaterialsSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Fujian Cross Strait Institute of Flexible Electronics(Future Technology) Fujian Normal UniversityFuzhou 350117China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China State Key Laboratory of Coordination Chemistry Nanjing UniversityNanjing 210023China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225009China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China

Pd-based metallic nanosheets with advanced physicochemical properties have been widely prepared and employed in various electrocatalytic ***,few concerns were focused on their multiple performances in different ***,highly curved and ultrathin PdNiRu nanosheets(NSs)are developed by facile wet-chemistry strategy and exhibit excellent electrocatalytic performance toward both oxygen reduction reaction(ORR)and ethylene glycol oxidation reaction(EGOR).Owing to the synergistically structural(e.g.,ultrathin,curved,defects/steps-rich)and compositional(ternary alloy)advantages,PdNiRu NSs exhibited enhanced ORR and EGOR specific/mass activities and better stability/durability than control *** specific activity(5.52 mA·cm^(−2))and mass activity(1.13 A·mg_(Pd)^(−1))of the PdNiRu NSs in ORR are 4.8 and 3.4 times as the ones of commercial Pt/C,*** mass activity of PdNiRu NSs(3.86 A·mg_(Pd)^(−1))in EGOR is 2.6 times as commercial Pd/C(1.51 A·mg_(Pd)^(−1)).This study is helpful for the development of desired electrocatalysts with multi-functional application in practical fuel cells.

关键词： ultrathin nanosheets noble metal electrocatalysts bifunctional

Multispectral image compression and encryption method based on tensor decomposition in wavelet domain

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

High Technology Letters 2024年第3期30卷 244-251页

作者： xu dongdong DU Limin DU Yunlong Electronic Information Engineering College Changchun UniversityChangchun 130022P.R.China

Multispectral image compression and encryption algorithms commonly suffer from issues such as low compression efficiency,lack of synchronization between the compression and encryption proces-ses,and degradation of intrinsic image structure.A novel approach is proposed to address these ***,a chaotic sequence is generated using the Lorenz three-dimensional chaotic mapping to initiate the encryption process,which is XORed with each spectral band of the multispectral image to complete the initial encryption of the ***,a two-dimensional lifting 9/7 wavelet transform is applied to the processed ***,a key-sensitive Arnold scrambling technique is employed on the resulting low-frequency *** effectively eliminates spatial redundancy in the multispectral image while enhancing the encryption *** optimize the compression and encryption processes further,fast Tucker decomposition is applied to the wavelet sub-band *** effectively removes both spectral redundancy and residual spatial redundancy in the multispectral ***,the core tensor and pattern matrix obtained from the decomposition are subjected to entropy encoding,and real-time chaotic encryption is implemented during the encoding process,effectively integrating compression and *** results show that the proposed algorithm is suitable for occasions with high requirements for compression and encryption,and it provides valuable insights for the de-velopment of compression and encryption in multispectral field.

关键词： multi-spectral image compression encryption Lorenz three-dimensional chaotic mapping Arnold scrambling transform fast Tucker decomposition

Material removal mechanisms in ultrasonic vibration-assisted high-efficiency deep grindingγ-TiAl alloy

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第11期37卷 462-476页

作者： Tao CHEN Xiaowei WANG Biao ZHAO Wenfeng DING Mingyue XIONG Jiuhua xu Qi LIU dongdong xu Yanjun ZHAO Jianhui ZHU National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China Centre for Precision Manufacturing University of StrathclydeGlasgow G11XJUK School of Mechanical Engineering Tongji UniversityShanghai 201804China State Key Laboratory for High Performance Tools Zhengzhou Research Institute for Abrasives and Grinding Co.LTDZhengzhou 450001China

Gamma titanium-aluminum intermetallic compounds(γ-TiAl)have gained considerable attentions in the aerospace industry due to their exceptional thermal resilience and comprehensive attributes,making them a prime example of lightweight and advanced *** address the frequent occurrence of burns and severe tool deterioration during the process of high-efficiency deep grinding(HEDG)onγ-TiAl alloys,ultrasonic vibration-assisted high-efficiency deep grinding(UVHEDG)has been *** indicate that in UVHEDG,the grinding temperature is on average 15.4%lower than HEDG due to the employment of ultrasonic vibrations,enhancing coolant penetration into the grinding area and thus reducing heat ***,UVHEDG possesses superior performance in terms of grinding forces compared to *** the material removal volume(MRV)increases,the tangential grinding force(F_(t))and normal grinding force(F_(n))of UVHEDG increase but to a lesser extent than in HEDG,with an average reduction of16.25%and 14.7%,*** primarily experiences microfracture of grains,whereas HEDG undergoes large-scale wear later in the process due to increased grinding *** surface roughness(R_(a))characteristics of UVHEDG are superior,with the average value of R_(a)decreasing by 46.5%compared to HEDG as MRV *** surface morphology in UVHEDG exhibits enhanced smoothness and a shallower layer of plastic *** chips generated by UVHEDG show a more shear-like shape,with the applied influence of ultrasonic vibration on chip morphology,thereby impacting material removal *** aforementioned findings contribute to enhanced machining efficiency and product quality ofγ-TiAl alloys after employing ultrasonic vibrations into HEDG.

关键词： Ultrasonic vibration-assisted high-efficiency deep grinding Grinding temperature Grinding forces Surface roughness Chip formation