曲面形貌轮廓仪传感器的机构设计

介绍一种适于曲面形貌测量的新型触针式轮廓仪的传感机构。它采用顶尖支承作为测杆的支承形式，并以测杆自重为传感器的测力源，无导头。本文分析了其动态特性和动态测力问题。     

Method for Measuring a Surface Profile Using a Mechatronic Profiler with Parallel Control of Sensor Drives

Measurement Techniques - Issues associated with improving the maneuverability and operating speed of a mechatronic profiler, as well as extending the profile measurement range for various surfaces,...     

基于PSO-ESPRIT算法的SAW温度传感器解调方法

目的 为了提高声表面波(Surface acoustic wave,SAW)温度传感器的测量精度,设计一种基于PSO-ESPRIT算法的高精度SAW温度传感器解调方法。方法 以ESPRIT谱估计方法为基础,把Hankel矩阵的时间窗长度与计算噪声方差时的K值作为粒子群优化(Particle swarm optimization, PSO)算法的输入变量,并以频率估计标准差作为粒子的适应度函数,利用PSO对ESPRIT算法中的参数进行优化,以改善频率估计精度,从而提高SAW回波信号频率估计的分辨率,实现SAW温度传感器的高精度解调。结果 仿真和实验结果表明,所设计的方法与其他谱估计算法相比,其对SAW回波信号估计的频率误差最小,标准差小于0.66kHz。把设计的算法用于SAW温度传感器的温度解调,得到的温度值与实际温度的误差小于0.4℃。结论 测试结果说明,设计的温度解调方法提高了SAW回波信号频率解调精度,可用于SAW温度传感器的解调,实现了对食品包装储运过程中温度的实时监测。     

PVDF薄膜传感器用于测试块状岩石表面爆炸应力的研究

采用PVDF（聚偏二氟乙烯）薄膜传感器对岩石表面爆炸应力进行测量,并分析炮孔内不同填塞介质对爆炸应力波在岩石介质中传播的影响。在直径为28 mm、孔深为25 cm的炮孔内填塞不同的介质（空气、水或沙子）,采用不同的装药结构分别进行爆破试验,通过PVDF薄膜传感器得到了不同工况下岩石表面应力波时程曲线。分析炮孔内不同填塞介质对爆炸应力波透射的影响发现,水作为炮孔填塞介质时,爆炸应力波透射能力强,炸药爆炸产生的能量用于岩石破碎的比例高。水作为炮孔填塞介质时,为达到岩石开裂效果,装药结构设计为1发8^#雷管加2 g传爆药（聚黑-14）;当沙子作为炮孔填塞介质时,为达到岩石的开裂效果,装药结构设计为1发8^#雷管、2 g传爆药（聚黑-14）和20 g炸药（聚黑-2）;前者炸药用量仅为后者的15.3%。炸药使用量减少,也降低了爆破次生危害的影响程度。用PVDF薄膜传感器在岩石表面直接测量爆炸应力的方法是可行的。     

低温等离子体接枝改性PVDF膜

采用低温等离子体接枝技术改性聚偏氟乙烯膜(PVDF),在PVDF膜表面引入疏水性单体苯乙烯,达到改变膜表面孔径的大小和孔径分布的目的.通过傅立叶红外光谱仪(FTIR-ATR)对改性前后的PVDF膜表面进行了结构分析,考察了PVDF膜接枝前后官能团的变化.采用示差扫描量热仪(DSC)分析了PVDF改性前后膜的孔径分布,考察了改性条件对膜孔径大小和分布的影响.通过扫描电子显微镜(SEM)和原子力显微镜(AFM)观测了PVDF膜改性前后表面形貌的变化.研究了接枝温度、接枝时间等接枝条件对PVDF改性膜纯水通量的影响.结果表明,随着照射时间和接枝时间的延长,PVDF改性膜的孔径分布变窄,纯水通量下降,接枝率提高.     

Polydimethylsiloxane (PDMS) Composite Membrane Fabricated on the Inner Surface of a Ceramic Hollow Fiber: From Single-Channel to Multi-Channel

The fabrication of a separation layer on the inner surface of a hollow fiber (HF) substrate to form an HF composite membrane offers exciting opportunities for industrial applications, although challenges remain. This work reports on the fabrication of a polydimethylsiloxane (PDMS) composite membrane on the inner surface of a single-channel or multi-channel ceramic HF via a proposed coating/cross-flow approach. The nanostructures and transport properties of the PDMS HF composite membranes were optimized by controlling the polymer concentration and coating time. The morphology, surface chemistry, interfacial adhesion, and separation performance of the membranes were characterized by field-emission scanning electron microscope (FE-SEM), attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, the nano-indentation/scratch technique, and pervaporation (PV) recovery of bio-butanol, respectively. The formation mechanism for the deposition of the PDMS layer onto the inner surface of the ceramic HF was studied in detail. The optimized inner surface of the PDMS/ceramic HF composite membranes with a thin and defect-free separation layer exhibited a high flux of ~1800 g·m⁻²·h⁻¹ and an excellent separation factor of 35–38 for 1 wt% n-butanol/water mixtures at 60 °C. The facile coating/cross-flow methodology proposed here shows great potential for fabricating inner-surface polymer-coated HFs that have broad applications including membranes, adsorbents, composite materials, and more.     

动态流量计及其应用

文中介绍了动态流量计的基本原理 ，提高稳定精度和动态频度的设计关键、智能优化设计方案。作者研制的动态流量计是国内流量控制系统中所缺乏和急需的器件，已成功地应用在国产液压电梯流量反馈控制样机上。     

氧化铝颗粒的表面改性及其在C平面(0001)蓝宝石衬底上的化学机械抛光(CMP)性质

为了提高氧化铝颗粒的CMP性能, 本工作探索了一种合适的改性方法。同时, 为了改善其化学机械性能, 通过与其表面羟基的硅烷化化学反应和与Al和仲胺的络合两种作用, 用N-(2-氨基乙基)-3-氨基丙基三甲氧基硅烷表面改性氧化铝颗粒。本工作给出了化学反应机理, 即N-(2-氨基乙基)-3-氨基丙基三甲氧基硅烷接枝到氧化铝表面。通过傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)表征了改性氧化铝颗粒的组成和结构。结果表明: N-(2-氨基乙基)-3-氨基丙基三甲氧基硅烷已被成功地接枝到氧化铝颗粒的表面, 导致改性比未改性的氧化铝颗粒具有更好的化学和机械性能。测试了未改性和改性的氧化铝颗粒在蓝宝石基底上的CMP性能。结果显示: 改性氧化铝颗粒比未改性氧化铝颗粒有更高的材料去除速率和更好的表面质量。即, 改性氧化铝颗粒在pH=10时比未改性氧化铝颗粒在pH=13.00时表现出更高的材料去除率, 这将为减少设备腐蚀提供新思路。     

检测表面粗糙度的光纤传感器研究

论述了测量表面粗糙度的反射散射比光纤传感器的结构、工作原理。介绍了它具有的抗干扰能力强、测量精度高、重复性好、可测微小面积和孔洞底面等异型表面等特点。给出了实测结果 ,并对影响测量的各种因素进行了分析讨论     

Modification on crystallization of poly(vinylidene fluoride) (PVDF) by solvent extraction of poly(methyl methacrylate) (PMMA) in PVDF/PMMA blends

The crystallization modification of poly(vinylidene fluoride) (PVDF) was investigated for the blend films of PVDF and poly(methyl methacrylate) (PMMA). The mass crystallinity (χ_c) and further, the β-phase content (F_(β)) of PVDF, were studied for the as-prepared blend films with different mass ratios. In addition, the variations of χ_c and F_(β) were systematically probed once the PMMA component was removed from the related blend systems. DSC, FTIR and XRD measurements all indicated that 1) χ_c, F_(β) and even the content of α-phase (F_(α)) decreased with the addition of PMMA; 2) with the extraction of PMMA, both χ_c and F_(β) increased while F_(α) decreased. It is worth noting that the increase of χ_c and F_(β) depended on the relative amount of extracted PMMA (E_PMMA), i.e., the more PMMA was removed, the more χ_c and F_(β) increased. These results reveal the hindrance effect from the PMMA constituent to the crystallization of PVDF, and consequently, this restriction would be released when the PMMA was extracted.     

Studying the Surface Conductivity of a Thallium Bilayer on Si(111) Substrate after Adsorption of Lithium and Rubidium

Changes in the state of a thallium bilayer on Si(111) substrate, Si(111)6 × 6–Tl, after adsorption of lithium and rubidium were studied using low-energy electron-diffraction and four-point probe-conductivity measurements. New surface reconstructions 5 × 1 and \(5\sqrt 3 \times 5\sqrt 3 \) were observed after the adsorption of lithium, and 2 × 2 and \(\sqrt 3 \times \sqrt 3 \) reconstructions appeared after the adsorption of rubidium. The surface conductivity of silicon substrates was studied as a function of the dose of deposited adsorbate. It is established that the formation of both 5 × 1 and 2 × 2 reconstructions retains the conducting properties of a two-dimensional channel constituted by the thallium bilayer.     

Parametric Analysis of Acoustic Emission Signals for Evaluating Damage in Composites Using a PVDF Film Sensor

With the increased utilization of advanced composites in strategic industries, the concept of Structural Health Monitoring (SHM) with its inherent advantages is gaining ground over the conventional methods of NDE and NDI. The most attractive feature of this concept is on-line evaluation using embedded sensors. Consequently, development of methodologies with identification of appropriate sensors such as PVDF films becomes the key for exploiting the new concept. And, of the methods used for on-line evaluation acoustic emission has been most effective. Thus, Acoustic Emission (AE) generated during static tensile loading of glass fiber reinforced plastic composites was monitored using a Polyvinylidene fluoride (PVDF) film sensor. The frequency response of the film sensor was obtained with pencil lead breakage tests to choose the appropriate band of operation. The specimen considered for the experiments were chosen to characterize the differences in the operation of the failure mechanisms through AE parametric analysis. The results of the investigations can be characterized using AE parameter indicating that a PVDF film sensor was effective as an AE sensor used in structural health monitoring on-line.     

Development of a Precision Surface Polishing System for Parts Fabricated by Fused Deposition Modeling

Additive manufacturing (AM) is the process of fabricating 3D physical models by layered manufacturing without the need of molds or dies. The surface finish of AM physical models is not satisfactory for most general engineering purposes. The aim of this study is to develop an acetone-vapor polishing system to smooth acrylonitrile butadiene styrene (ABS) parts fabricated by fused deposition modeling (FDM). Acetone vapor dissolved the outer surface of ABS parts, and the surface roughness of ABS parts with complex geometries can be significantly reduced. The advantages of this system include the flexibility to maintain dimensional accuracy, high polishing efficiency, low equipment costs, and no waste chemicals compared with conventional approaches.     

Picosecond Laser Surface Texturing of a Stavax Steel Substrate for Wettability Control

In this investigation, a picosecond laser was employed to fabricate surface textures on a Stavax steel substrate, which is a key material for mold fabrication in the manufacturing of various polymer products. Three main types of surface textures were fabricated on a Stavax steel substrate: periodic ripples, a two-scale hierarchical two-dimensional array of micro-bumps, and a micro-pits array with nano-ripples. The wettability of the laser-textured Stavax steel surface was converted from its original hydrophilicity into hydrophobicity and even super-hydrophobicity after exposure to air. The results clearly show that this super-hydrophobicity is mainly due to the surface textures. The ultrafast laser-induced catalytic effect may play a secondary role in modifying the surface chemistry so as to lower the surface energy. The laser-induced surface textures on the metal mold substrates were then replicated onto polypropylene substrates via the polymer injection molding process. The surface wettability of the molded polypropylene was found to be changed from the original hydrophilicity to super-hydrophobicity. This developed process holds the potential to improve the performance of fabricated plastic products in terms of wettability control and easy cleaning.     

SAW focusing by circular-arc interdigital transducers on YZ-LiNbO(3)

Using the angular spectrum theory and experimental velocity data of surface acoustic waves (SAW) on YZ-LiNbO(3), the focusing characteristics of a circular-arc interdigital transducer have been demonstrated. The calculated results show that the depth of focus is long and the compressed acoustic beam width is very narrow. The concept of a caustic is shown to be an excellent way of characterizing SAW focusing by a circular-arc interdigital transducer on YZ-LiNbO(3). Comparison between theoretical and experimental results shows good agreement.     

基于FLANN算法的速度传感器动态补偿

磁电式速度传感器由于自身工作原理,其固有频率下限值受到结构和体积的限制.应用于振动测试时常需对其工作频带进行补偿扩展,以使其能检测固有频率以下的速度信号.本文针对磁电式速度传感器,建立了其动态数学模型,给出了一种基于函数链人工神经网络(FLANN)算法的动态补偿策略.分析对比了采用传感器输入输出设计的FLANN算法补偿器与采用零极点配置法进行动态补偿的效果.结果表明,采用FLANN算法设计的补偿器具有更小的补偿误差,且有效扩展了速度传感器的使用频带,很好地满足了工程上超低频振动测量的要求.     

Estimating Surface Temperature of a Calibration Apparatus for Contact Surface Thermometers from Its Internal Temperature Profile

A calibration apparatus for contact surface thermometers was developed. Temperature of the upper surface of a copper cube of the calibration apparatus was used as reference surface temperature, which was estimated at around \(50\,{^{\circ }}\hbox {C}\), \(100\,{^{\circ }}\hbox {C}\), and \(150\,{^{\circ }}\hbox {C}\) by not only two conventional industrial platinum resistance thermometers (IPRTs) but also five small-sized platinum resistance thermometers (SSPRTs) calibrated based on the International Temperature Scale of 1990 (ITS-90). These thermometers were inserted horizontally into the copper cube and aligned along the center axis of the copper cube. In the case of a no-load state without anything on the upper surface, the temperature profile inside the copper cube linearly decreased from the lower part to the upper surface, which suggests that the heat conduction inside the copper cube can be regarded as a one-dimensional steady state. On the other hand, in the case of a transient state just after the contact surface thermometer was applied to the upper surface, the temperature profile became a round shape. We obtained good agreement between the curvature of the temperature profiles and the results estimated by using an error function used for a one-dimensional transient heat conduction problem. The temperature difference between the estimated temperature by linear extrapolation using two IPRTs and that by extrapolation using the error function was within \(0.2\,{^{\circ }}\hbox {C}\) in the transient state at around \(150\,{^{\circ }}\hbox {C}\). Over 10 min after the contact surface thermometer was applied, the temperature profile showed a linear shape again, which indicated that linear extrapolation using two IPRTs was well for the estimation of the reference surface temperature because the heat conduction state inside the copper cube came back to the one-dimensional steady state. Difference between the surface temperature and temperature detected by the contact surface thermometer was also observed after the contact surface thermometer touched on the upper surface. The difference was over \(0.1\,{^{\circ }}\hbox {C}\) at several minutes after the contact surface thermometer touching on the reference surface and was suppressed with passing time in the transient state and became negligible over 10 min.