金属涂层SPR的单端面LPFG折射率传感器(英文)

提出了一种新型的单端面反射的镀有金属膜的长周期光纤光栅传感器.这种基于表面等离子体谐振的具有三层结构的传感器分为两个部分,光栅部分用连续CO2激光脉冲制作,金属膜是由真空镀膜制成.在光栅上镀上各种不同厚度的薄金属膜来激发表面等离子体波,用这种光纤光栅传感器来测量液体的折射率,并研究它的反射谐振谱的特性.在标准气压下,镀有80 nm银膜的光栅从水(ns=1.33)到酒精(ns=1.36)中光栅谐振波长改变了1.14nm,其敏感度达到折射率变化～5×10-4谐振波长改变20 pm.研究发现不同厚度的不同金属膜显示了不同的敏感度.通过比较光栅在空气,水,酒精,甘油,以及在它们的混合物溶液中的谐振波长,得到这种反射式的长周期光纤光栅传感器的敏感特性.为制作一种高性能的用来测量折射率的光纤光栅传感器提供了一个有益的参考.     

基于级联长周期光纤光栅的溶液折射率与浓度的测量研究

级联长周期光纤光栅的谐振峰对外界折射率较敏感,利用该特性制成的折射率传感器可以实现对溶液折射率和浓度的实时在线测量。通过对不同折射率的NaCl溶液和蔗糖溶液的实验研究,得出溶液折射率、浓度与谐振峰之间的关系。实验结果表明: LPGP较为灵敏的外界折射率范围为1~1.4513,在此范围内,随着外界折射率的增加,透射谱干涉峰的幅值逐渐减小而谐振波长逐渐向短波方向漂移。该传感器可应用于生物、化学、过程控制等高灵敏度传感领域的各种溶液进行监控,具有较高的实用价值。     

LP模型分析涂覆长周期光纤光栅复折射率传感器

对于涂覆长周期光纤光栅(LPG)传感元件,涂覆层折射率大于包层折射率时将具有很高的灵敏度.然而在涂覆层厚度为纳米量级时,涂覆层的折射率将具有一定的吸收,吸收将对LPG传感元件产生一定的影响.本文在线偏振(LP)模近似理论和耦合模理论(CMT)的理论模型基础上,通过数值计算对这一情况进行研究讨论.详细分析了模式转变点附近和远离模式转变点区域涂覆LPG的模式结构和透射谱情况.在无吸收的理想模型基础上,详细分析了消光系数对模式转变和重新组合的影响,以及模式结构的转变对LPG透射谱的影响,得出吸收将会导致LPG灵敏度、可测量的动态范围的变化.最后,文章给出了一种新型的LPG吸收传感元件的模型.     

利用光纤光栅测量加速度的方法研究

提出了一种基于长周期光纤光栅(LPFG)弯曲特性的加速度传感方法.传感系统采用悬臂梁结构,LPFG粘贴于悬臂梁的上表面,将悬臂梁的自由端受力产生的梁体弯曲转变成长周期曲率的变化,来监测光栅谐振谱的幅值和波长变化.并在系统中加入布拉格光栅(FBG),利用其反射特性记录固定波长处长周期光栅谐振谱的变化,然后将其转化为加速度...     

基于双模LPFG折射率不敏感双参量传感器

环境折射率和环境温度变化是影响光纤应变测量误差的主要因素。本文利用双模光纤纤芯双模式(LP01和LP11)支持特性设计了一款环境折射率不敏感的双模光纤(DMF)长周期光纤光栅(LPFG)应变传感器。设计了传感器模型结构,制作了最优化参数的传感器样品。实验测试了DMF-LPFG传感结构对外部环境中应变、温度和折射率的响应。通过在单模光纤上用紫外激光刻写的布拉格光栅(FBG)解决了环境温度的交叉影响。轴向应变实验结果表明,该新型结构传感器在0με~840με应变范围内其轴向应变灵敏度可以达到-5.4 pm/με,该灵敏度值相比较于普通LPFG有很大提高。温度在25℃~80℃范围内其灵敏度为58.86 pm/℃,表现出较好的线性度。同时,传感器对环境折射率变化表现出不敏感特性。通过采用双参数矩阵对少模LPFG和FBG的应变和温度灵敏度进行处理,可以实现双参数的同时解调。该新型复合光栅结构具有良好的传感性能和工程应用前景。     

光栅尺解调的分布式光纤光栅传感系统

提出了一种新的利用光栅尺解调一组光纤光栅布喇格波长移动的系统。当光纤光栅所受的应力或温度发生变化时,光纤光栅的布喇格波长会变化(移动)。本系统利用一组光纤光栅作为敏感元件置于被测场中;利用另一组光纤光栅作为跟踪元件,跟踪从作为敏感元件的光纤光栅反射回来的布喇格波长的移动。当作为跟踪元件的光纤光栅的布喇格波长与作为测量元件的光纤光栅的布喇格波长对准时,探测器探测到最大的光强,此时,记下光栅尺的输出作为系统的测量结果。采用数字化的方法确定反射回来的布喇格波长的峰值点,从而提高系统的测量精度,使系统的测量线性大于0.999。并利用一个测量分辨率为0.01μm的光栅尺读出系统的测量结果,使本系统对光纤光栅布喇格波长移动的测量分辨率小于1μ应变量。     

基于应变测量中光纤Bragg光栅温度补偿方案设计

设计两种温度分离和温度补偿方案来解决光纤Bragg光栅对温度、应变交叉敏感的问题,两种方案都采用Bragg光栅与长周期光栅相结合的方式,利用长周期光栅对温度具有高灵敏度的特性,且都避免在同一光纤、同一位置处写入两种光栅技术难,要求高的问题,并对两种方案的优点及不足之处进行分析说明。     

基于光纤光栅的扭矩测量系统设计

提出一种新的基于光纤光栅(FBG)技术的扭矩测量方法.分析了光纤光栅的传感机理,推导了扭矩与中心波长之间的数学关系,建立了双光纤光栅扭矩测量的理论模型.搭建实验平台,采用曲线拟合算法,对实测数据进行分析和处理,该扭矩测量系统的灵敏度达到22.89 pm/(N·m),最大非线性误差为0.23% FS,符合测量系统的误差要求,验证了此种扭矩测量方法的可行性.对温度补偿实验数据的分析表明:半桥式光纤光栅测量方案具有良好的温度补偿特性,能够补偿温度变化引入的测量误差,从而提高测量精度.     

基于结构性改变的光子晶体光纤光栅研究

利用多极法结合耦合模理论对一种基于结构性改变的光子晶体光纤光栅进行了研究,建立了其结构模型,理论分析了此种成栅工艺原理.计算了七层三角形对称排布空气孔包层有效折射率随波长变化情况,比较了不同光子晶体光纤结构成栅效果的差异.研究结果表明,光子晶体光纤包层中空气孔周期性塌缩可以形成光栅,空气孔排布层数,空气孔占空比、空气孔塌缩层数和塌缩程度等参数对光子晶体光纤光栅的传输特性有重要影响,得出了谐振波长和谐振带宽与上述参数之间的变化关系,并给出这种变化关系的解释.     

基于LPFG微弯特性的高精度位移检测系统

在研究长周期光纤光栅(LPFG)温度及微弯特性的基础上,通过引入聚合物温度增敏封装后的光纤布拉格光栅(FBG)作为解调滤波器,搭建了温度自补偿微位移检测系统.将LPFG粘贴于试件上进行微弯测试,在固定波长处.其插入损耗的变化与弯曲度变化呈线性关系.为解决LPFG带宽宽、谐振波长难以精确测量的问题,选择特定波长的FBG作为滤波器,实现了位移检测系统的功率化解调.同时,对FBG利用聚合物进行了温度增敏封装,使其温度灵敏度与LPFG尽量相同,消除了温度对系统的影响.试验结果表明,传感系统输出的光功率与微位移呈良好的线性关系,位移灵敏度为2μW/mm,分辨力为0.5×10-2 mm.所设计的系统结构简单、灵敏度高、线性度好,不受外界温度干扰.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.