Wear Behavior of Harmonic Structured 304L Stainless Steel

Wear behavior of a harmonic structured 304L austenitic stainless steel with periodically distributed fine and coarse grains was examined and compared with a sintered non-harmonic structured 304L stainless steel and a low carbon conventional 304 stainless steel using fretting wear tests at varying loads in ball-on-flat contact configuration. Characterization was accomplished using scanning electron microscope, energy-dispersive spectroscopy, optical profilometry and Raman spectroscopy. Coefficient of friction and wear volume were minimum at intermediate normal load of 5 N, whereas maximum at 10 N for the harmonic stainless steel compared to other two steels. Harmonically distributed fine- and coarse-grained structure attributes to the higher wear rate of the harmonic structured steel at higher load because of differential interaction of the ball with the harmonically distributed hard (fine) and relatively soft (coarse) regions.     

介质损耗带电检测数字化处理方法的研究

目前对介质损耗角进行带电检测通常采用快速ＦＦＴ算法,但这种方法在窗长不等于被测信号周期或其整数倍时,会出现“频谱泄漏”现象,从而使测量结果产生误差。文中介绍了一种采用数字滤波与相关技术相结合的新算法,较好地解决了这一问题。     

基于 TOPSIS 和灰色关联法的乡村振兴评价研究

乡村振兴战略是当前我国的一项重要战略,构建乡村振兴评价体系有利于评估乡村振兴战略实施的效果。在相关文献研究的基础上,选取了 5 个一级指标和 17 个二级指标构建了乡村振兴评价指标体系,运用TOPSIS 加灰色关联法,对我国 2014-2018 年的乡村振兴总体发展水平进行了实证研究,同时计算和分析了各个子系统的灰色关联相对贴近度和年动态趋势。数据表明,2014-2018 年间我国乡村振兴水平总体呈现增长趋势。各个子系统和总体水平趋势不完全一致,加大对乡村人才流失等现象的关注和政策扶持力度有利于提高乡村振兴水平。     

Dip Coating of Water-Resistant PEDOT:PSS Films Based on Physical Crosslinking

Water-resistant poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films are valuable in biomedical applications; however, they typically require crosslinkers to stabilize the films, which can introduce undesired aggregation or phase separation reactions. Herein, a dipping-based process to prepare PEDOT:PSS films on nonplanar surfaces without crosslinker is developed. Sequential soaking of a dip-coated PEDOT:PSS film in ethanol and water imparts water resistance to the film. Microscopic and spectroscopic techniques are used to monitor the process and confirm that the ethanol soaking elutes the excess PSS from the film bulk, which stabilizes the film prior to the water-soaking process. The obtained films act as conductors and semiconductors on curved surfaces, including 3D-printed objects. A film deposited on a curved surface is successfully applied as the channel layer in a neuromorphic organic electrochemical transistor. This approach can enable integrated bioelectronic and neuromorphic applications that can be readily deployed for facile prototyping.     

Composition Regulation by Flow Copolymerization of Methyl Methacrylate and Glycidyl Methacrylate with Free Radical Method

It is important to match the feeding ratio of comonomers to the composition ratio in the resulting copolymers as closely as possible in industrial production, where the goal is often to produce more a homogeneous composition in copolymers. In this study, a flow copolymerization system with a conventionally initiated free radical method, together with randomly selected polymerization conditions is investigated. It is succeeded in achieving a closer match between the composition ratio and feeding ratio than previously reported in the copolymerization of styrene with methyl methacrylate and of glycidyl methacrylate with methyl methacrylate, which will widen the range of applications, by precisely controlling the mixing and heating in a flow polymerization apparatus. This is confirmed by the fact that the estimated values of reactivity ratios, r₁ and r₂, which are used in the reaction kinetics of copolymerization, are close to 1.     

Control system for automatic search and transportation of an object by a mobile robot with obstacle avoidance function

Artificial Life and Robotics - In this paper, using image processing and distance measurement, we develop a control system for automatic grasping and obstacle avoidance by a mobile robot. First,...     

Impact of the O/P ratio on the optical properties and structures of fluoride–phosphate glass

Ca(PO₃)₂–AlF₃–CaF₂–BaF₂–BaO glasses were prepared by the melt quenching method, and the effects of the O/P ratio on the optical properties and glass structure were investigated. The bandgap energy showed no significant change at O/P = 3.0–3.4 but drastically decreased with the increase in the O/P from 3.6 to 4.0. In addition, the refractive index dispersion was analyzed based on the Lorentz model, and it was found that the decrease in the resonance frequency in the ultraviolet region with the increase in the O/P ratio resulted in an increase in the refractive index and dispersion. Analysis of the infrared absorption and Raman scattering spectra revealed that the phosphate chains were broken, and isolated Q⁰ units were generated with the increase in the O/P ratio from 3.6 to 4.0. Based on the structural change of the glass, the origin of the nonlinear dependence of the optical properties on the O/P ratio was discussed.     

Fluorophore-Decorated Mie Resonant Silicon Nanosphere for Scattering/Fluorescence Dual-Mode Imaging

Inorganic nanoparticles with multiple functions have been attracting attention as multimodal nanoprobes in bioimaging, biomolecule detection, and medical diagnosis and treatment. A drawback of conventional metallic nanoparticle-based nanoprobes is the Ohmic losses that lead to fluorescence quenching of attached molecules and local heating under light irradiation. Here, metal-free nanoprobes capable of scattering/fluorescence dual-mode imaging are developed. The nanoprobes are composed of a silicon nanosphere core having efficient Mie scattering in the visible to near infrared range and a fluorophore doped silica shell. The dark-field scattering and photoluminescence images/spectra for nanoprobes made from different size silicon nanospheres and different kinds of fluorophores are studied by single particle spectroscopy. The fluorescence spectra are strongly modified by the Mie modes of a silicon nanosphere core. By comparing scattering and fluorescence spectra and calculated Purcell factors, the fluorescence enhancement factor is quantitatively discussed. In vitro scattering/fluorescence imaging studies on human cancer cells demonstrate that the developed nanoparticles work as scattering/fluorescence dual-mode imaging nanoprobes.