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Achievements of Truss Models for Reinforced Concrete Structures 被引量:2
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作者 P. G. Papadopoulos H. Xenidis +3 位作者 P. Lazaridis A. Diamantopoulos P. Lambrou Y. Arethas 《Open Journal of Civil Engineering》 2012年第3期125-131,共7页
Achievements are presented for truss models of RC structures developed in previous years: 1. Two constitutive models, biaxial and triaxial, are based on regular trusses, with bars obeying nonlinear uniaxial σ-ε laws... Achievements are presented for truss models of RC structures developed in previous years: 1. Two constitutive models, biaxial and triaxial, are based on regular trusses, with bars obeying nonlinear uniaxial σ-ε laws of material under simulation;both models have been compared with test results and show a dependence of Poisson ratio on curvature of σ-ε law. 2. A truss finite element has been used in the nonlinear static and dynamic analysis of plane RC frames;it has been compared with test results and describes, in a simple way, the formation of plastic hinges. 3. Thanks to the very simple geometry of a truss, the equilibrium equations can be easily written and the stiffness matrix can be easily updated, both with respect to the deformed truss, within each step of a static incremental loading or within each time step of a dynamic analysis, so that to take into account geometric nonlinearities. So the confinement of a RC column is interpreted as a structural stability effect of concrete. And a significant role of the transverse reinforcement is revealed, that of preventing, by its close spacing and sufficient amount, the buckling of inner longitudinal concrete struts, which would lead to a global instability of the RC column. 4. The proposed truss model is statically indeterminate, so it exhibits some features, which are not met by the “strut-and-tie” model. 展开更多
关键词 Reinforced CONCRETE structure TRUSS Model CONSTITUTIVE Law Material and Geometric NONLINEARITIES CONCRETE Cracking Reinforcement Yield CONCRETE ULTIMATE Compressive Strength Plastic HINGE RC Column Confinement Buckling of Inner CONCRETE Struts Global Instability
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World-Universe Model—Alternative to Big Bang Model 被引量:1
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 2020年第1期133-158,共26页
This manuscript provides a comparison of the Hypersphere World-Universe Model (WUM) with the prevailing Big Bang Model (BBM) of the Standard Cosmology. The performed analysis of BBM shows that the Four Pillars of the ... This manuscript provides a comparison of the Hypersphere World-Universe Model (WUM) with the prevailing Big Bang Model (BBM) of the Standard Cosmology. The performed analysis of BBM shows that the Four Pillars of the Standard Cosmology are model-dependent and not strong enough to support the model. The angular momentum problem is one of the most critical problems in BBM. Standard Cosmology cannot explain how Galaxies and Extra Solar systems obtained their substantial orbital and rotational angular momenta, and why the orbital momentum of Jupiter is considerably larger than the rotational momentum of the Sun. WUM is the only cosmological model in existence that is consistent with the Law of Conservation of Angular Momentum. To be consistent with this Fundamental Law, WUM discusses in detail the Beginning of the World. The Model introduces Dark Epoch (spanning from the Beginning of the World for 0.4 billion years) when only Dark Matter Particles (DMPs) existed, and Luminous Epoch (ever since for 13.8 billion years). Big Bang discussed in Standard Cosmology is, in our view, transition from Dark Epoch to Luminous Epoch due to Rotational Fission of Overspinning Dark Matter (DM) Supercluster’s Cores. WUM envisions Matter carried from the Universe into the World from the fourth spatial dimension by DMPs. Ordinary Matter is a byproduct of DM annihilation. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: Angular Momentum problem in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;Fermi Bubbles—two large structures in gamma-rays and X-rays above and below Galactic center;Diversity of Gravitationally-Rounded Objects in Solar system;some problems in Solar and Geophysics [1]. WUM reveals Inter-Connectivity of Primary Cosmological Parameters and calculates their values, which are in good agreement with the latest results of their measurements. 展开更多
关键词 Big Bang MODEL Four Pillars of Standard Cosmology ANGULAR MOMENTUM Problem Black Holes Hypersphere World-Universe MODEL Multicomponent DARK MATTER Macroobjects structure Law of Conservation of ANGULAR MOMENTUM Medium of the World Inter-Connectivity of Primary Cosmological Parameters The Beginning of the World DARK EPOCH Rotational Fission Luminous EPOCH Macroobject Shell MODEL DARK MATTER Core Gravitational Burst Intergalactic Plasma Microwave Background Radiation Far-Infrared Background Radiation Emergent Phenomena CODATA
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Hierarchical microstructures with high spatial frequency laser induced periodic surface structures possessing different orientations created by femtosecond laser ablation of silicon in liquids 被引量:19
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作者 Dongshi Zhang Koji Sugioka 《Opto-Electronic Advances》 2019年第3期1-18,共18页
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro... High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles. 展开更多
关键词 HIGH spatial frequency LASER induced periodic SURFACE structures SILICON LASER ablation in liquids HIERARCHICAL MICROstructureS femtosecond LASER HIGH fluence formation mechanism SURFACE melting nanocapillary wave SURFACE plasmon polaritons second-harmonic generation
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Lipid-Protein Microinclusions in the Morphological Structures of Organelle Membranes Studied by Fluorescent Confocal Microscopy
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作者 Michael Yu. Chernyshov Vadim N. Nurminsky Natalia V. Ozolina 《Advances in Biological Chemistry》 2017年第1期42-59,共18页
Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles... Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles. During this study, identification of lipid microinclusions having the form of such lipid-protein structural microformations as lipid-protein microdomains, vesicles and membrane tubular structures (cytoplasmic transvacuolar strands and nanotubes) located in organelle membranes or bound up with them was conducted. Such membrane probes as laurdan, DPH, ANS and bis-ANS were used. Comparison of fluorescence intensity of these membrane probes was conducted. This investigation of the morphological properties of lipid-protein structural microformations was accompanied with analysis of 1) the phase state and 2) dynamics of microviscosity variations in the membrane elements of isolated plant cell organelles. Distributions of laurdan fluorescence generalized polarization (GP) values for the membrane on the whole and for the intensively fluorescing membrane segments were obtained. It was discovered that the microviscosity of intensively fluorescing membrane segments essentially differed from the microviscosity of the rest part of the membrane. In conclusion, some results of the study of peculiar properties of lipid-protein structural microformations related to the structure of organelle membranes and the discoveries made in this investigation are discussed. 展开更多
关键词 Identification of Lipids MORPHOLOGICAL structure of Cell Organelles MORPHOLOGICAL structure of Vacuolar MEMBRANE FLUORESCENT Confocal Microscopy FLUORESCENT Probes Lipid-Protein Structural MEMBRANE Microinclusions Types of Microformations Identified Lipid-Protein Microdomains Lipid-Protein MEMBRANE Nanotubes Vesicles Cytoplasmic Strands Microviscosity
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Using Neural Networks to Predict Secondary Structure for Protein Folding 被引量:1
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作者 Ali Abdulhafidh Ibrahim Ibrahim Sabah Yasseen 《Journal of Computer and Communications》 2017年第1期1-8,共8页
Protein Secondary Structure Prediction (PSSP) is considered as one of the major challenging tasks in bioinformatics, so many solutions have been proposed to solve that problem via trying to achieve more accurate predi... Protein Secondary Structure Prediction (PSSP) is considered as one of the major challenging tasks in bioinformatics, so many solutions have been proposed to solve that problem via trying to achieve more accurate prediction results. The goal of this paper is to develop and implement an intelligent based system to predict secondary structure of a protein from its primary amino acid sequence by using five models of Neural Network (NN). These models are Feed Forward Neural Network (FNN), Learning Vector Quantization (LVQ), Probabilistic Neural Network (PNN), Convolutional Neural Network (CNN), and CNN Fine Tuning for PSSP. To evaluate our approaches two datasets have been used. The first one contains 114 protein samples, and the second one contains 1845 protein samples. 展开更多
关键词 Protein Secondary structure Prediction (PSSP) NEURAL NETWORK (NN) Α-HELIX (H) Β-SHEET (E) Coil (C) Feed Forward NEURAL NETWORK (FNN) Learning Vector Quantization (LVQ) Probabilistic NEURAL NETWORK (PNN) Convolutional NEURAL NETWORK (CNN)
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Mapping theme trends and knowledge structures for human neural stem cells:a quantitative and co-word biclustering analysis for the 2013-2018 period 被引量:5
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作者 Wen-Juan Wei Bei Shi +3 位作者 Xin Guan Jing-Yun Ma Ya-Chen Wang Jing Liu 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第10期1823-1832,共10页
Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends a... Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells. 展开更多
关键词 nerve REGENERATION human NEURAL stem cells PubMed bibliometric ANALYSIS biclustering ANALYSIS co-word ANALYSIS strategic diagram ANALYSIS social network ANALYSIS hot research topics mapping THEME TRENDS knowledge structures NEURAL REGENERATION
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Structure Sorting of Multiple Macromolecular States in Heterogeneous Cryo-EM Samples by 3D Multivariate Statistical Analysis
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作者 Bruno P. Klaholz 《Open Journal of Statistics》 2015年第7期820-836,共17页
Heterogeneity of biological samples is usually considered a major obstacle for three-dimensional (3D) structure determination of macromolecular complexes. Heterogeneity may occur at the level of composition or conform... Heterogeneity of biological samples is usually considered a major obstacle for three-dimensional (3D) structure determination of macromolecular complexes. Heterogeneity may occur at the level of composition or conformational variability of complexes and affects most 3D structure determination methods that rely on signal averaging. Here, an approach is described that allows sorting structural states based on a 3D statistical approach, the 3D sampling and classification (3D-SC) of 3D structures derived from single particles imaged by cryo electron microscopy (cryo-EM). The method is based on jackknifing & bootstrapping of 3D sub-ensembles and 3D multivariate statistical analysis followed by 3D classification. The robustness of the statistical sorting procedure is corroborated using model data from an RNA polymerase structure and experimental data from a ribosome complex. It allows resolving multiple states within heterogeneous complexes that thus become amendable for a structural analysis despite of their highly flexible nature. The method has important implications for high-resolution structural studies and allows describing structure ensembles to provide insights into the dynamics of multi-component macromolecular assemblies. 展开更多
关键词 Heterogeneity Structural Biology Cryo Electron Microscopy Particle SORTING MULTIPLE States Macromolecular Complexes RESAMPLING Jackknifing BOOTSTRAPPING Multivariate Statistical Analysis 3D MSA 3D-SC RIBOSOME RNA Polymerase
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可控多孔结构生物活性钛的制备及其体外细胞培养(英文) 被引量:13
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作者 李祥 王成焘 +2 位作者 王林 张文光 李元超 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2010年第10期1697-1701,共5页
采用电子束熔化(EBM)成形工艺,制造具有可控多孔结构的Ti6Al4V植入体,分析测试其微观孔隙结构特征、孔隙率以及力学性能。扫描电镜观测结果表明,所制备的钛合金植入体孔隙结构特征与设计结构相符合,证明EBM技术能够实现钛合金植入体孔... 采用电子束熔化(EBM)成形工艺,制造具有可控多孔结构的Ti6Al4V植入体,分析测试其微观孔隙结构特征、孔隙率以及力学性能。扫描电镜观测结果表明,所制备的钛合金植入体孔隙结构特征与设计结构相符合,证明EBM技术能够实现钛合金植入体孔隙结构的控制;测得多孔植入体的孔隙率为60.1%,相应的抗压强度为163MPa,弹性模量为14GPa,与人体骨组织弹性模量相近。利用改进的碱热处理方法进行表面改性,并浸泡在模拟体液中以诱导磷灰石的形成。体外细胞培养试验结果表明,培养7d后成骨细胞在改性的试件表面大量粘附、生长、增殖。 展开更多
关键词 CELL CULTURE in VITRO porous structure Scanning electron microscope mechanical properties surface modification simulated body fluid APATITE formation characterization metal forming CULTURE time CELL CULTURE strength of
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Predictions of Electronic, Transport, and Structural Properties of Magnesium Sulfide (MgS) in the Rocksalt Structure
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作者 Uttam Bhandari Cheick Oumar Bamba +2 位作者 Yuriy Malozovsky La Shounda Franklin Diola Bagayoko 《Journal of Modern Physics》 2018年第9期1773-1784,共12页
We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport and bulk properties of rock salt magnesium sulfide (MgS). In the absence of experimental data on ... We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport and bulk properties of rock salt magnesium sulfide (MgS). In the absence of experimental data on these properties, except for the bulk modulus, these results are predictions. Our calculations utilized the Ceperley and Alder local density approximation (LDA) potential and the linear combination of Gaussian orbitals (LCGO). The key difference between our computations and other previous ab-initio DFT ones stems from our use of successively larger basis sets, in consecutive, self-consistent calculations, to attain the ground state of the material. We predicted an indirect (&Gamma;-X) band gap of 3.278 eV for a room temperature lattice constant of 5.200&Aring;. We obtained a predicted low temperature indirect (&Gamma;-X) band gap of 3.512 eV, using the equilibrium lattice constant of 5.183&Aring;. We found a theoretical value of 79.76 GPa for the bulk modulus;it agrees very well with the experimental finding of 78 &plusmn;3.7 GPa. 展开更多
关键词 DENSITY Functional Theory (DFT) Local DENSITY Approximation (LDA) Linear Combination of Atomic ORBITALS (LCAO) BAND Gap BAND structure The Bagayoko ZHAO and WILLIAMS (BZW) Method
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Geologic-Geophysical Indicators of the Deep Structure of Zones of Geothermal Anomalies for Allocation of Channels of the Deep Heat and Mass Transfer 被引量:5
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作者 R. A. Umurzakov H. A. Abidov G. Yu. Yuldashev 《Open Journal of Geology》 2017年第9期1452-1463,共12页
On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to... On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to obtain important data on a deep structure of sites. Data of gas-chemical and geothermal observations show about confinedness of abnormal concentration of methane to zones of the increased values of the temperature field the measured values of temperatures (Tegermen Square and others). On geoelectric section mines 2-D of inversion of the MT-field depth of 4000 m are lower, among very high-resistance the chemogenic and carbonate deposits of the Paleozoic is traced the subvertical carrying-out abnormal zone. This zone is identified as the channel of a deep heat and mass transfer with which hydrocarbon (HC) deposits are connected. It is shown that electro-investigation when using a geophysical complex can and has to become “advancing” at exploration by oil and gas. 展开更多
关键词 Anomaly of the Thermal Field Thermogeochemical Data JUVENILE Gases Channel Heat and Mass Transfer DEEP structure GEOELECTRIC Section Deposits of Oil and Gas
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DEFINITING AND ITS GEOLOGIC MEANING OF SOUTH-NORTH TREND FAULTED STRUCTURE BELT IN QIANGTANG BASIN, NORTH PART OF TIBET 被引量:7
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作者 Liu Chiyang,Yang Xingke,Ren Zhangli,Wang Dingyi,Cheng Gang,Zheng Menlin 《地学前缘》 EI CAS CSCD 2000年第S1期223-224,共2页
There were more expounding to north—west (west) trend fault and north\|east trend fault within Qiangtang Basin, North Part of Tibet, in the past literature. With increasing of geophysical exploration data, nearly eas... There were more expounding to north—west (west) trend fault and north\|east trend fault within Qiangtang Basin, North Part of Tibet, in the past literature. With increasing of geophysical exploration data, nearly east\|west trend structure began to be taken note to. Since the year of 1995, by a synthetic study to geophysical and geological data, that south\|north trend faulted structures are well developed. These structures should be paid much more attention to, because they have important theoretical meaning and practical significance.1 Spreading of south\|north faulted structure belt According to different geological and geophysical data, the six larger scale nearly south\|north faulted structure belt could be distinguished within the scope of east longitude 84°~96° and near Qiangtang Basin. The actual location of the six belts are nearly located in the west of the six meridian of east longitude 85°,87°,89°,91°,93°,95° or located near these meridian. The six south\|north faulted structure belts spread in the same interval with near 2° longitude interval. The more clear and much more significance of south\|north trend faulted structure belts are the two S—N trend faulted structure belts of east longitude 87° and 89°. There are S—N trend faulted structure belts in the west of east longitude 83°,81°, or near the longitudes. The structure belts spreading features,manifestation,geological function and its importance, and inter texture and structure are not exactly so same. The structure belts all different degree caused different region of geological structure or gravity field and magnetic field. There is different scale near S—N trend faulted structure belt between the belts. 展开更多
关键词 QinghaiTibet plateau QIANGTANG Basin southnorth TREND structure BELT transverse transform structure strike\|slip adjustment division of eastwest region oil & gas prospecting
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谣言实现的社会机制及对信息的治理 被引量:31
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作者 李国武 《社会》 北大核心 2005年第4期143-155,共13页
Rumors are a type of false information, a consequence of an asymmetrical informational structure. This paper focuses on the social mechanisms of rumor fulfilling. Rumors with important contents related to people’s pe... Rumors are a type of false information, a consequence of an asymmetrical informational structure. This paper focuses on the social mechanisms of rumor fulfilling. Rumors with important contents related to people’s personal interests win acceptance through changing people’s expected payoffs, misleading people to the belief that acceptance of the rumor would beneficially outperform rejection of it. Nevertheless, it is risky to believe rumors; therefore, people make their decision whether to believe a rumor or not by referring to other people’s choices. An analysis was performed first within a game model that incorporated the variables of an individual’s expectancy and other people’s impact to predict whether the individual would accept or reject a rumor. Another analysis followed to further examine the functions of some dynamic mechanisms in rumor fulfilling when group pressure and network effects were introduced. Finally, an exploratory discussion on how to prevent rumors and erase their effects via information management strategies was presented. 展开更多
关键词 WHETHER structure people ANOTHER further network WOULD impact that first model group and type This with make game some when to of are WIN how via on
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Microstructure and mechanical properties of Ti-6Al-4V-5% hydroxyapatite composite fabricated using electron beam powder bed fusion 被引量:6
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作者 César A.Terrazas Lawrence E.Murr +3 位作者 Diego Bermudez Edel Arrieta David A.Roberson Ryan B.Wicker 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2019年第2期309-321,共13页
A novel, Ti-6 Al-4 V(Ti64)/Hydroxyapatite(HA at 5% by weight concentration) metal/ceramic composite has been fabricated using electron beam powder bed fusion(EPBF) additive manufacturing(AM): specifically, the commerc... A novel, Ti-6 Al-4 V(Ti64)/Hydroxyapatite(HA at 5% by weight concentration) metal/ceramic composite has been fabricated using electron beam powder bed fusion(EPBF) additive manufacturing(AM): specifically, the commercial electron beam melting(EBM?) process. In addition to solid Ti64 and Ti64/5% HA samples, four different unit cell(model) open-cellular mesh structures for the Ti64/5% HA composite were fabricated having densities ranging from 0.68 to 1.12 g/cm^3, and corresponding Young's moduli ranging from 2.9 to 8.0 GPa, and compressive strengths ranging from ~3 to 11 MPa. The solid Ti64/5%HA composite exhibited an optimal tensile strength of 123 MPa, and elongation of 5.5% in contrast to a maximum compressive strength of 875 MPa. Both the solid composite and mesh samples deformed primarily by brittle deformation, with the mesh samples exhibiting erratic, brittle crushing. Solid, EPBF-fabricated Ti64 samples had a Vickers microindentation hardness of 4.1 GPa while the Ti64/5%HA solid composite exhibited a Vickers microindentation hardness of 6.8 GPa. The lowest density Ti64/5%HA composite mesh strut sections had a Vickers microindentation hardness of 7.1 GPa. Optical metallography(OM) and scanning electron microscopy(SEM) analysis showed the HA dispersoids to be highly segregated along domain or grain boundaries, but homogeneously distributed along alpha(hcp) platelet boundaries within these domains in the Ti64 matrix for both the solid and mesh composites. The alpha platelet width varied from ~5 μm in the EPBF-fabricated Ti64 to ~1.1 m for the Ti64/5%HA mesh strut. The precursor HA powder diameter averaged 5 μm, in contrast to the dispersed HA particle diameters in the Ti64/5%HA composite which averaged 0.5 m. This work highlights the use of EPBF AM as a novel process for fabrication of a true composite structure, consisting of a Ti64 matrix and interspersed and exposed HA domains, which to the authors' knowledge has not been reported before. The results also illustrate the prospects not only for fabricating specialized, novel composite bone replacement scaffolds and implants, through the combination of Ti64 and HA, but also prospects for producing a variety of related metal/ceramic composites using EPBF AM. 展开更多
关键词 Hydroxyapatite (HA) Metal-matrix ceramic composites Open-cellular (mesh) structures ELECTRON-BEAM powder bed FUSION (EPBF) Additive manufacturing (AM) Mechanical properties Microstructure characterization
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Dynamic Analysis of Soil Structure Interaction Effect on Multi Story RC Frame
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作者 Hailu Getachew Kabtamu Gang Peng Denghong Chen 《Open Journal of Civil Engineering》 2018年第4期426-446,共21页
In this study dynamic analysis of Soil Structure Interaction (SSI) effect on multi story reinforced concrete (RC) frame founded on soft soil (flexible base) is made and compared with fixed base. Two model 2D RC frames... In this study dynamic analysis of Soil Structure Interaction (SSI) effect on multi story reinforced concrete (RC) frame founded on soft soil (flexible base) is made and compared with fixed base. Two model 2D RC frames with 7 and 12 story are selected for analysis. Winkler Spring and half space direct method models are used for flexible base for the frames founded on two types of soft soils with shear velocity Vs < 150 m/s Asper Seismic Codes of Chinese GB50011-2010 Soil IV and Ethiopian ES8-2015 soil D. The frames are subjected to strong ground motion matched to response spectrums of soft soil of Chinese GB50011-2010 and Ethiopian ES8-2015 for linear time history analysis. The dynamic analysis result shows Spring and Fixed base mass participation 90% reaches in 2 or 3 modes but in direct method 11 to 30 modes for story 12 and 7 respectively. However, both flexible base models have bigger fundamental period of vibration and inter story drift but smaller base shear than fixed base. In addition, within the flexible base models the inter-story drift, second order effect (P-Δ) and Story shear distribution are different along the height of frames. The spring model shows larger Story drift and second order effect (P-Δ) at the bottom of Story for both soft soils types. On the other hand, half space direct method model indicates value reverse to spring model;it gives bigger Story drift and P-Δ effect in the top stories than fixed base. Finally, this study concludes that base shear reduction due to SSI may not be always beneficial. Because the gravity load is constant in both fixed and flexible bases that cause bigger P-Δ effect at the bottom stories due to increase, inter story drift and decrease story shear in flexible base. 展开更多
关键词 Soil structure Interaction Dynamic Analysis Fixed BASE Flexible BASE Direct Method WINKLER Spring PERIOD of Vibration STORY SHEAR STORY DRIFT and P-Δ Effect
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Gunn器件中畴的静止-渡越-静止模式的实验观察和计算机模拟
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作者 王守武 郑一阳 +1 位作者 郗小林 张进昌 《Journal of Semiconductors》 EI CAS 1983年第4期321-333,共13页
本文讨论在GaAs n^+-n-n^+夹层结构的Cunn器件中畴的静止-渡越-静止模式,进行了实验观察和计算机模拟,指出在超过阈值的偏置电压下,当畴的耗尽层进入阳极附近的高掺杂区后,会逐渐停止下来形成准静态畴,这时畴外电场达到最大值.如果这时... 本文讨论在GaAs n^+-n-n^+夹层结构的Cunn器件中畴的静止-渡越-静止模式,进行了实验观察和计算机模拟,指出在超过阈值的偏置电压下,当畴的耗尽层进入阳极附近的高掺杂区后,会逐渐停止下来形成准静态畴,这时畴外电场达到最大值.如果这时阴极凹口仍不能形成新畴,则准静态畴将进一步调整成为真正的静止畴,而畴外电场也将由最大值下降到一个与偏压无关的固定值.经过理论分析,得到了静止畴所固有的与外加偏压无关的畴外电场与有源区掺杂浓度的关系式,并和计算机模拟的结果相比较,得到很好的符合.如果偏压的增加使准静态畴所对应的畴外电场最大值已经足够使阴极凹口形成新的畴,则静止畴将转变为渡越畴.如果偏压继续增加,使积累层尾部覆盖了阴极凹口,则畴会再次静止下来,直到偏压增加到畴发生雪崩为止.计算和实验表明,后一个静止区的电压变化范围要比前一个大得多.本文还讨论了两个转变电压和温度的关系及扩散系数对静止畴的影响. 展开更多
关键词 <Abstract>The TRANSFORMATIONS between stationary and TRANSIT DOMAINS in a GUNN device which has n^%PLUS%-n-n^%PLUS% SANDWICH structure with doping gradient near the anode are investigated.Experimental observation computer simulation carried out.When th
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Crustal density structure of the southern segment of the Liaocheng-Lankao fault, China 被引量:1
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作者 Lei Jiang Lanbo Liu +4 位作者 Zhiping Xu Xiaoguo Deng Lipu Yang Wei Xiong Shunqiang Xu 《Geodesy and Geodynamics》 2019年第5期347-355,共9页
The 1:200,000 middle-large scale Bouguer gravity anomaly data covering the southern segment of the Liaocheng-Lankao fault(SLLF)and its vicinity are analyzed with two methods.First,the Bouguer gravity anomaly data are ... The 1:200,000 middle-large scale Bouguer gravity anomaly data covering the southern segment of the Liaocheng-Lankao fault(SLLF)and its vicinity are analyzed with two methods.First,the Bouguer gravity anomaly data are decomposed by two-dimensional(2 D)wavelet to make the family of multi-scale modes correspond with density structure at different depths.Second,a two and half dimension(2.5 D)human-computer interaction inversion of the Bouguer gravity anomaly data are conducted with the constraints provided by two deep seismic sounding profiles(DSS1 and DSS2)crossing the study area to get the crustal density profiles.Based on the integrated study,we can draw the following conclusions:1)SLLF appears to be a deep fault with almost vertical dipping and rooted into the uppermost mantle;2)In the middle to upper crust SLLF shows an clear turning patterns and segmentation features;3)In the study area the epicentral distributions of the precisely re-located small earthquakes and the historical large earthquakes have a good correspondence with the turning patterns and segmentation features of SLLF;and 4)The results of the horizontal slices from 2 D wavelet decomposition show that there are significant differences in the density structure on the two sides of the fault.A well-defined concave structure with low density exists in the upper crust of the Dongming Depression on the west side of the fault,with the concave center being estimated at a depth of about 8 km.In contrast,the upper crust on the east side presents a relative thinner pattern in depth with a bit higher density.Meanwhile,the low-density structure in the middle crust underneath the fault is presumably caused by the uplift of the upper mantle materials and their intrusion along the deep rupture system.This paper clarified the inconsistency of fault system and epicenters of small earthquakes from upper to lower crust.The results indicated that the fault system plays an important governing role to the seismicity in this area. 展开更多
关键词 SOUTHERN SEGMENT of the Liaocheng-Lankao fault(SLLF) Bouguer gravity ANOMALIES Density structure Dongming depression Multi-scale wavelet decomposition Epicenters of small EARTHQUAKES
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华北克拉通晚中生代壳-幔拆离作用:岩石流变学约束 被引量:21
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作者 刘俊来 纪沫 +5 位作者 夏浩然 刘正宏 周永胜 余心起 张宏远 程素华 《岩石学报》 SCIE EI CAS CSCD 北大核心 2009年第8期1819-1829,共11页
大陆岩石圈的流变学结构对于岩石圈深部过程(壳/幔过程)有着深刻的影响,直接表现在岩石圈壳-幔结构与浅部构造上。本文注意到华北克拉通晚中生代岩石圈减薄期间地壳的伸展、拆离与减薄在不同地区的宏观、微观构造及地壳岩石流变学等方... 大陆岩石圈的流变学结构对于岩石圈深部过程(壳/幔过程)有着深刻的影响,直接表现在岩石圈壳-幔结构与浅部构造上。本文注意到华北克拉通晚中生代岩石圈减薄期间地壳的伸展、拆离与减薄在不同地区的宏观、微观构造及地壳岩石流变学等方面的差异表现与区域变化,以及现今和晚中生代时期岩石圈厚度的不均匀性。讨论了以水为主体的地质流体的存在对于岩石圈流变性的影响。综合克拉通东部与西部地壳/地幔厚度变化特点以及下地壳和上地幔含水性特点,阐述了晚中生代时期华北克拉通岩石圈内部壳幔耦合与解耦的规律,提出了华北岩石圈壳-幔拆离作用模型以解释华北克拉通晚中生代岩石圈减薄的基本现象与深部过程。提出区域性伸展作用是岩石圈减薄的主要动力学因素,东部地区在晚中生代伸展作用过程中壳-幔具有典型的解耦性,上部地壳、下部地壳和岩石圈地幔的变形具有显著差异性。而西部区壳幔总体具有耦合性,下地壳与岩石圈地幔共同构成流变学强度很高且难以变形的岩石圈根。 展开更多
关键词 Late Mesozoic North China CRATON LITHOSPHERE thinning upper mantle during lower crust LITHOSPHERE structure continental LITHOSPHERE rheological strength processes Crustal extension
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A STUDY ON THE INFLUENCE OF CITRATE SODIUM, NaCl, KCl ON THE PE LIQUID CRYSTALLINE STRUCTURE BY MEANS OF THE SMALL ANGLE X-RAY SCATTERING
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作者 孙润广 王子浩 +1 位作者 王德华 张静 《Chinese Science Bulletin》 SCIE EI CAS 1992年第8期651-656,共6页
关键词 PHOSPHATIDYLETHANOLAMINE abbreviated as PE belongs to phospholipids. It is one of the important materials which forms BIOLOGICAL membranes and plays a very important role in maintaining the structure and FUNCTION of BIOLOGICAL membrane system. Therefore people HAVE been trying to explore the relations between its structure and FUNCTION in various ways. Since 1970s the phospholipid-water system HAVE been widely and profoundly studied by
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In situ atomic-scale observation of size-dependent (de) potassiation and reversible phase transformation in tetragonal FeSe anodes 被引量:1
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作者 Ran Cai Lixia Bao +12 位作者 Wenqi Zhang Weiwei Xia Chunhao Sun Weikang Dong Xiaoxue Chang Ze Hua Ruiwen Shao Toshio Fukuda Zhefei Sun Haodong Liu Qiaobao Zhang Feng Xu Lixin Dong 《InfoMat》 SCIE CAS CSCD 2023年第1期161-171,共11页
Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the explo... Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs. 展开更多
关键词 elucidated by geometric phase analysis and finite-element analysis. Despite the different intercalation behaviors the formed products of Fe and K 2 Se after full potassiation can be converted back into the original FESE phase upon depotassiation. In particular small-sized nanoflakes exhibit better cycling perfor- mance with well-maintained structural integrity. This article presents the first successful demonstration of ATOMIC-SCALE visualization that can reveal size- dependent potassiation dynamics. Moreover it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs. KEYWOR DS in situ transmission electron microscopy potassium-ion batteries potassium-ion storage mechanism SIZE-DEPENDENT effects TETRAGONAL FESE
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再论中产阶级:理论、历史与类型学 兼及一种全球化的视野 被引量:27
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作者 周晓虹 《社会》 北大核心 2005年第4期1-24,共24页
The emergence of the middle class was closely related to the appearance of industrial society and its consequential constant changes in the social structure. Karl Marx and other theorists in the same camp were among t... The emergence of the middle class was closely related to the appearance of industrial society and its consequential constant changes in the social structure. Karl Marx and other theorists in the same camp were among the earliest scholars who discussed that topic. For a quite long period of time, the debate was mainly focused on the characteristics of the “new middle class.” The middle class, however, has undergone a categorical transformation from the old to the new middle-class, and furthermore, this transformation itself has signified the transition in social patterns from industrial to post-industrial society as well as economic globalization, both of which have contributed to the growth and global expansion of the middle class, having thus fundamentally renovated the middle class. 展开更多
关键词 structure global from other among QUITE which and CAMP that time this well both have The new HAS of to its in who For
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