检索结果-南通市图书馆

A Deblurring Procedure for Two-dimensional Small Angle X-ray Scattering Patterns

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 2016年第4期34卷 505-512页

作者： Ran Chen Zhi-yong Yi Jia-xue Liu 刘震宇门永锋 State Key laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

A general pre-processing procedure of the measured SAXS patterns for reducing the effect of beam stop and beam stop holder is described. A proper method for automatically choosing the regularization parameter is implemented. The method works out on the two-dimensional SAXS patterns. After deblurring, the corresponding two-dimensional patterns will be converted into one-dimensional integrated intensity distribution curves. We tested the program using both calculated artificial data and real experimental data such as polystyrene and poly（methyl methacrylate） latices. The deblurred results are satisfactory showing the effectiveness of the method. The deblurring process of a typical two-dimensional SAXS pattern using the Matlab based program can be completed in few seconds on normal personal computers.

关键词： Deblur PS latex PMMA colloidal dispersion SAXS.

Velocity plus displacement equivalent force control for real-time substructure testing

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2018年第1期17卷 87-102页

作者： Zhou Huimeng D.Wagg Wang Tao Key laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration Harbin 150080 China Institute of Engineering mechanics China Earthquake Administration PR China Dept. of Mechanical Engineering University of Sheffield United Kingdom

This paper employs a velocity plus displacement（V＋D）-based equivalent force control（EFC） method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological（MR） damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions.

关键词： real-time substructure test EFC velocity/displacement control newmark-β method stability

Two-dimensional equations for thin-films of ionic conductors

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and mechanics(English Edition) 2018年第8期39卷 1071-1088页

作者： Shuting LU Chunli ZHANG Weiqiu CHEN Jiashi YANG Department of Engineering mechanics Zhejiang University Soft Matter Research Center Zhejiang University Key laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Department of Mechanical and Materials Engineering University of Nebraska-Lincoln

A theoretical model is developed for predicting both conduction and diffusion in thin-film ionic conductors or cables. With the linearized Poisson-Nernst-Planck(PNP)theory, the two-dimensional(2D) equations for thin ionic conductor films are obtained from the three-dimensional(3D) equations by power series expansions in the film thickness coordinate, retaining the lower-order equations. The thin-film equations for ionic conductors are combined with similar equations for one thin dielectric film to derive the 2D equations of thin sandwich films composed of a dielectric layer and two ionic conductor layers. A sandwich film in the literature, as an ionic cable, is analyzed as an example of the equations obtained in this paper. The numerical results show the effect of diffusion in addition to the conduction treated in the literature. The obtained theoretical model including both conduction and diffusion phenomena can be used to investigate the performance of ionic-conductor devices with any frequency.

关键词： ionic conduction and diffusion linearized Poisson-Nernst-Planck(PNP) theory two-dimensional(2D) equation ionic conductor thin-film

Effect of TiO_2 and ZrO_2 reinforcements on properties of Al_2O_3 coatings fabricated by thermal flame spraying

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第5期26卷 1345-1352页

作者： Rassim YOUNES Mohand Amokrane BRADAI Abdelhamid SADEDDINE Youcef MOUADJI Ali BILEK Abderrahim BENABBAS laboratory of mechanics Materials and Energetic Faculty of Technology University of Bejaia laboratory of mechanics Faculty of Engineering Sciences Campus Chaabet-ErsasUniversity of Constantine Mechanical laboratory of Structure and Energetic Mechanical Engineering DepartmentUniversity of Tizi-Ouzou laboratory Processes for Materials Energy Water and Environment Faculty of Science and TechnologyUniversity of Bouira

The alumina composite coatings reinforced with 25% ZrO2 （denoted as AZ-25） and 3% TiO2 （denoted as AT-3） were deposited on low carbon steel using a thermal flame spraying. The microstructure, phase composition, microhardness and tribological properties of the coatings were investigated. The XRD results of the coatings reinforced by TiO2 （AT-3） revealed the presence of α-Al2O3 phase as matrix and new metastable phases of α-Al2O3 and α-Al2O3. However, the coatings reinforced by ZrO2 （AZ-25） consist of α-Al2O3 as matrix, q-ZrO2 and m-ZrO2. In most studied conditions, the AT-3 coating displays a better tribological performance, i.e., lower coefficient of frictions and wear rates, than the AZ-25 coating. It was also found that the microhardness of the coatings was decreased with the reinforcement of ZrO2 and increased with TiO2.

关键词： thermal spraying coatings reinforcements friction coefficient wear rate

A More Accurate Reconstruction Method for Detecting Large-Depth Defects in Plates Using SH Guided Waves

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2021年第2期34卷 174-183页

作者： Yihui Da Qi Li Bin Wang Dianzi Liu Zhenghua Qian State Key laboratory of mechanics and Control of Mechanical Structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China School of Engineering University of East AngliaNorwich NR47TJUK

The inspection of thickness thinning defects and corrosion defects is greatly significant for the health prediction of plate *** main aim of this research is to propose a novel and effective approach to achieve the accurate and rapid detection of arbitrary defects using shear horizontal(SH)guided waves,particularly for large-depth and complex *** proposed approach combines the quantitative detection of Fourier transform with a reference model-based strategy to improve the accuracy of large-depth defect *** the shallow defect profile is theoretically constructed by inverse Fourier transform of the product of reflection coefficients and integral coefficients of reference models,the unknown large-depth defect can be initially assessed using the relevant information from a predefined reference *** iteratively updating the integral coefficients of reference models,the accuracy of reconstruction of large-depth defects is much *** achieve the converged defect profile,a termination criterion,the root mean square error,is applied to guarantee the construction of defects with a high level of ***,the hybrid finite element method is used to simulate the propagation of SH guided waves in plates for calculating the reflection coefficients of plates with ***,to demonstrate the capability of the developed reconstruction method for defect detection in terms of accuracy and efficiency,three types of large-depth defect profiles,i.e.,a rectangular flaw,a double-rectangular flaw and a complex flaw,are *** show that the discrepancy between the predicted defect profile and the real one is quite small,even in the largest-depth defect case where the defect depth is equal to 0.733 times the plate thickness,the minimal difference is *** is noted that the fast convergence of the proposed approach can be achieved by no more than ten updates for the worst case.

关键词： Large-depth defect SH guided wave Iterative strategy Reference model Hybrid FEM

Optical planar waveguides in Yb^(3+)-doped phosphate glasses produced by He^+ ion implantation

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 Physics B 2012年第7期21卷 347-351页

作者：刘春晓李玮楠韦玮彭波 State Key laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision MechanicsChinese Academy of Sciences School of Electronic and Information Engineering Hefei Normal University Key laboratory for Organic Electronics&Information Displays and Institute of Advanced Materials Nanjing University of Posts&Telecommunications

Optical planar waveguides in Yba＋-doped phosphate glasses are fabricated by implanting triple-energy helium ions. The guiding modes and the near-field intensity distribution are measured by using the prism-coupling method and the end-face coupling setup with a He Ne laser at 633 nm The intensity calculation method （ICM） is used to reconstruct the refractive index profile of the waveguide. The absorption and the fluorescence investigations reveal that the glass bulk features are well preserved in the active volumes of the waveguides, suggesting the fabricated structures for possible applications as waveguide lasers.

关键词： waveguide ion implantation laser materials photoluminescence

Temporal and Spatial Evolution of Laser-Induced Plasma from a Slag Sample

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2015年第8期17卷 649-655页

作者：王静鸽付洪波倪志波陈兴龙贺文干董凤忠 Anhui Provincial Key laboratory of Photonic Devices and Materials Anhui Institute of Optics and Fine MechanicsChinese Academy of Sciences Hefei University of Technology University of Science and Technology of China

Laser-Induced Breakdown Spectroscopy （LIBS） has been demonstrated to be an effective method for slag analysis. In order to better clarify the nature of the plasma generated from a slag sample, an Nd：YAG pulse laser at 1064 nm wavelength was used to ablate the slag sample in air. The temporal and spatial evolutions of plasma parameters, including emission intensity, electronic density and plasma temperature, have been studied. It is shown that the electron density and plasma temperature drop off rapidly with the delay time as a result of plasma expansion and cooling. It has been found that the electron density of the whole plasma is close to that of the center regions in the plasma. The results of the spatial distributions on the two-dimensional plane have shown that there is a big region with lower electron density values caused by the recombination process in the center of the plasma. The maximum of the plasma temperature takes place at the regions close to the target, and the border of the plasma front-head has higher plasma temperatures than that of the center part.

关键词： laser-induced breakdown spectroscopy slag temporal and spatial evolution

Local buckling analysis of biological nanocomposites based on a beam-spring model

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied mechanics Letters 2015年第4期5卷 146-150页

作者： Zhiling Bai Baohua Ji Biomechanics and Biomaterials laboratory Department of Applied Mechanics School of Aerospace Engineering Beijing Institute of Technology

Biological materials such as bone, tooth, and nacre are load-bearing nanocomposites composed of mineral and protein. Since the mineral crystals often have slender geometry, the nanocomposites are susceptible to buckle under the compressive load. In this paper, we analyze the local buckling behaviors of the nanocomposite structure of the biological materials using a beam-spring model by which we can consider plenty of mineral crystals and their interaction in our analysis compared with existing studies. We show that there is a transition of the buckling behaviors from a local buckling mode to a global one when we continuously increase the aspect ratio of mineral, leading to an increase of the buckling strength which levels off to the strength of the composites reinforced with continuous crystals. We find that the contact condition at the mineral tips has a striking effect on the local buckling mode at small aspect ratio, but the effect diminishes when the aspect ratio is large. Our analyses also show that the staggered arrangement of mineral plays a central role in the stability of the biological nanocomposites.

关键词： Biological materials Nanostructure Staggered arrangement Buckling behaviors Aspect ratio Composite materials

Leakage detection of oil tank using terahertz spectroscopy

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第9期64卷 1947-1952页

作者： QIN FanKai CHEN SiTong CHEN Ru ZHAN HongLei MIAO XinYang XIANG WenFeng ZHAO Kun College of New Energy and Materials China University of PetroleumBeijing 102249China Beijing Key laboratory of Optical Detection Technology for Oil and Gas China University of PetroleumBeijing 102249China Key laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection Petroleum and Chemical Industry FederationChina University of PetroleumBeijing 102249China Detection and Beijing Key laboratory of failure Corrosionand Protection of Oil/Gas FacilitiesChina University of PetroleumBeijing 102249China

The necessity for safety in oil-gas storage and transportation has led to increasing technical requirements for on-line monitoring of damaged pores and oil leakage from tanks. In this study, the severity of damage of the oil tank at the micron level was detected by terahertz time-domain spectroscopy(THz-TDS), which is of great significance for the early detection and prevention of oil leakage. The THz amplitude(EP) was related to the severity of damaged according to the THz-TDS measurement of oil tanks with various degrees of damage, including intact, partially damaged, completely damaged, and seriously damaged *** and scattering effects co-occurred when the THz wave penetrated the tanks, with the collective tendencies being used to expressly monitor oil leakage from tanks. When the oil tank was damaged to form micron-level pores and the crude oil had not overflowed, the pore size was close to THz wavelength and the Mie scattering effect was obvious. After further destruction of the pores, the crude oil gradually spilled over and the scattering effect was gradually transformed from Mie scattering to Rayleigh scattering. In addition, the polar molecules in crude oil have strong resonance under the irradiation of THz wave, and the THz wave has strong attenuation. Eventually, surface tension of the oil flattens the surface of the tank, the scattering effect is gradually suppressed and replaced by the absorption effect. Absorption and scattering caused by THz waves passing through tanks coexist and have competing relationships. The change rule of EPcan successfully prove the phenomenon and can be considered as an important alternative for application to predict the degree of tank damage. Therefore, in this study, the detection of pores as small as micrometers on the oil tank was expected to greatly prevent oil leakage accidents and improve the safety of oil and gas storage and transportation.

关键词： absorption scattering terahertz spectroscopy oil tank leakage