Fabrication and simulation studies on D-shaped optical fiber sensor via surface plasmon resonance

This paper describes simulation and experimental methods for designing a D-shaped surface plasmon resonance (SPR) fibre sensor. The sensor consists of two set-up approaches. Finite element method is used in simulation on the fibre sensor device. Two experimental methods for detecting relative intensity are used by varying the wavelength of the optical signal sources and the thickness of gold layer coated on the D-shaped fibre. In the first method, the sensor device works by detecting the relative intensity of two optical signal sources having different wavelengths. In the second set-up, the relative intensity between two D-shaped fibres coated with different thicknesses of gold is measured when a single signal source is launched at the input. The difference in intensities of the signal outputs is used to estimate the refractive index at the sensing region. A prototype SPR D-shaped fibre sensor has been fabricated and the experimental results show good agreement with simulation.     

Surface roughness in diamond abrasive finishing

Polished surface roughness is shown to depend on a ratio of natural vibration frequencies of molecular fragments on the tool and workpiece surface. The factors that have the greatest effect on the machined surface roughness are the following: (a) the number of molecular fragments the debris particles consist of, (b) the most probable size of the particles, (c) natural vibration frequencies of the fragments of the tool and workpiece materials, (d) workpiece material thermal conductivity, and (e) machining conditions.     

Temperature sensors based on multimode chalcogenide fibre Bragg gratings

In this work, a theoretical study was conducted on temperature sensing in Ge–Sb–Se multimode fibre Bragg grating (MM-FBG). The sensing characteristics of the designed MM-FBGs with different fibre parameters and operating wavelengths were calculated using a coupled model method. The temperature sensitivity of this MM-FBG was found to improve significantly by shifting the operating wavelength from telecom range to mid-infrared (MIR) and utilizing the wide transmission range of Ge–Sb–Se glasses. The temperature sensitivity of the proposed Ge–Sb–Se MM-FBG was calculated to be 0.0758 nm/°C at 1550 nm, which is 7.58 times higher than silica FBGs at 1550 nm, and the temperature sensitivity was calculated to be more than 0.16 nm/°C at 3390 nm, which is 2.2 times higher than that at 1550 nm. In addition, the proposed MM-FBGs provided multi-peak information, and the sensitivity of each peak was calculated to be comparable to the single-mode FBG. The proposed Ge–Sb–Se MM-FBG has great potential for temperature sensing in MIR because of its advantages of simple preparation, high coupling efficiency, multi-peak information and wide working window.     

二氧化硅对复合材料感应器灵敏度的影响

为了制备碳黑-二氧化硅-环氧树脂基复合材料弯曲角度感应器,采用K-控制仪将该材料涂层到透明薄膜上,通过研究感应器电阻率随弯曲角度的变化情况及扫描电镜分析,探讨二氧化硅对感应灵敏度的影响.结果表明,从0°弯曲角开始,随着弯曲角度的增加,感应器的电阻率先下降后增加.当感应器中二氧化硅含量低时,碳黑颗粒易于形成聚集,材料中形成的导电通路密度相对较低,容易受外加条件的影响,其对弯曲角度的感应灵敏度较高.碳黑与聚合物分子间存在着较好的物理化学作用,制备的感应器具有良好的感应重复性.     

TbDyFe-FeNi多层膜/光纤磁传感器特性研究

以TbDyFe-FeNi多层膜/光纤复合结构为研究对象,采用ANSYS软件对多层膜厚度及外加磁场对光纤中传输光波的磁致相位位移大小的影响规律进行了研究.ANSYS计算结果发现,磁致相位位移大小随着薄膜厚度增加而增大;由于TbDyFe-FeNi多层膜的磁致伸缩性能,磁致相位位移值随磁场强度变化关系出现良好的线性关系.搭建M-Z干涉仪,实验论证TbDyFe-FeNi多层膜/光纤复合结构的磁探测性能,进一步证实了ANSYS模拟计算结果.     

A novel experimental set-up for turbidity sensing based on plastic optical fibre

A novel set-up for remote sensing the turbidity of a solution using plastic optical fibres together with a mirror is proposed. The authors have estimated turbidity of a liquid in terms of the nephelometric turbidity unit – NTU, a standard unit that relates the solution appearance with its turbidity for two proposed set-ups. Its performance was also investigated using clay sample measurements over a concentration range of 0–10 g/L. The proposed set-ups are useful for detection of suspended particles in a solution even in small quantities due to its high sensitivity, simplicity and robustness.     

The effect of fibre surface roughness on the mechanical behaviour of ceramic matrix composites

The interface between the matrix and the fibre plays an important role in controlling the strength and toughness of ceramic matrix composites. It has been found experimentally that depending on manufacturing process, the interface may show substantial surface roughness, which has been modelled analytically with certain degree of success. The analytical models, however, do not take into account the interface geometry. Instead, only the magnitude of the surface undulation is included. In this paper, a direct simulation of fibre–matrix interface roughness by the finite element method is performed on an axisymmetric unit cell with a fully debonded interface. The simulation is employed to account for the three dimensional stress state, surface roughness and interface friction, which are normally simplified or idealised in theoretical studies. The model gives the highly non-uniform interface shear and pressure, which have direct implications on the interface damage and composite behaviour. Under the approximation made in the model, the positive transverse strains does not show up in the simulation despite the fact that two different surface roughness are used.     

Correlation of roughness parameters Ra and Rq with an optical method of measuring them

A theoretically derived correlation between the roughness parameters R _a and R _q is given. An optical reflection method is proposed for measuring these parameters. An instrument is described that can implement this method. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 16–19, April, 2009.     

Modeling and analysis for surface roughness in machining glass fibre reinforced plastics using response surface methodology

Now a days glass fiber reinforced plastic (GFRP) composite materials are a feasible alternative to engineering materials. They have excellent properties and are being extensively used in variety of engineering applications. However, the users of FRP are facing difficulties to machine it, because of its anistropic properties. In this paper, an attempt has been made to model the surface roughness through response surface method (RSM) in machining GFRP composites. Four factors five level central composite, rotatable design matrix is employed to carryout the experimental investigation. Analysis of variance (ANOVA) is used to check the validity of the model. For finding the significant parameters student’s t-test is used. Also, an analysis of the influences of the entire individual input machining parameters on the response has been carried out and presented in this study.     

On the sensitivity of generic porous optical sensors

A porous material was considered as a platform for optical sensing. It was envisaged that the porous material was infiltrated by a fluid that contains an agent to be sensed. Changes in the optical properties of the infiltrated porous material provide the basis for detection of the agent to be sensed. Using a homogenization approach based on the Bruggeman formalism, wherein the infiltrated porous material was regarded as a homogenized composite material, the sensitivity of such a sensor was investigated. For the case of an isotropic dielectric porous material of relative permittivity ε(a) and an isotropic dielectric fluid of relative permittivity ε(b), it was found that the sensitivity was maximized when there was a large contrast between ε(a) and ε(b); the maximum sensitivity was achieved at midrange values of porosity. Especially high sensitivities may be achieved for ε(b) close to unity when ε(a)>1, for example. Furthermore, higher sensitivities may be achieved by incorporating pores that have elongated spheroidal shapes.     

Instruments for contactless monitoring of internal surface roughness

Instruments Dozor-V and Dozor-VK are described whose operation is based on a reflexometric method. Test results are presented for cylindrical surfaces with a diameter of 30–100 mm with various forms of machining and materials. The instruments replace visual monitoring for roughness specimens and they are intended for application directly under industrial conditions. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 29–32, March 2006.     

An optical fibre tip with double tapers etched by the interfacial layer

We fabricate double-tapered optical fibre tips by the interfacial layer etching method. The optical fibre is first etched by means of meniscus-based etching to obtain one-tapered fibre tip, which is etched again by the interfacial layer between the etchant and the overlay to obtain a double-tapered tip. The formation mechanism of the second taper is analysed. The impacts of the interfacial layer etching time, HF concentration and the overlay on the second cone angle are discussed. The second cone angle can be controlled by the interfacial layer etching time and the overlay. But the HF concentration has few impacts on the second cone angle. The double-tapered fibre tips can be applied for the contactless trapping of particles.     

Single-mode D-shaped optical fiber sensor for the refractive index monitoring of liquid

A new fabrication method is introduced for the production of D-shaped optical fiber. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of single-mode optical fiber in order to obtain a D-shaped cross section. Adjusting specific mechanical parameters allows for control of the volume of the D-shaped zone, while the fiber surface smoothness is governed by selection of polishing film grit size. To meet the accuracy and repeatability requirements, optical power loss is monitored during the entire polishing process in situ and in real time. This proposed technique possesses advantages of rapidity, safety, simplicity, repeatability and stability with high precision in comparison with contemporary methods for production. Sensor performance tests on the fiber reveal a linear response with linearity up to R² = 0.984 for surrounding refractive index in the range of 1.320–1.342 refractive index, which corresponds to different concentrations of the glucose solution test environment. The produced D-shaped optical fiber has potential sensing and monitoring applications in chemical, environmental, biological and biochemical fields.     

Measurement of the Spectral Characteristics of a Road Surface

The intensity of the emission of the noise from tires depends largely on the structure of the road surface, which in the range of acoustic frequencies is characterized by roughness. The design and principles governing the basic modules of a device for measuring the roughness of a surface are considered. The operating indicators of the device and a technique for processing the measured signal are given. __________ Translated from Izmeritel'naya Tekhnika, No. 10, pp. 45–47, October, 2005.     

Influence of steel roughness on internal and external corrosion of tinplate cans

Reductions in tin coatings and thickness of tinplate affect the properties of the tinplate surfaces. Computer-aided electrochemical test methods, impedance spectroscopy and X-ray microanalytical studies show that corrosion behaviour is influenced by the base material properties. This paper will give some information about surface properties of tinplate and aspects of internal and external corrosion resistance. Special attention is given to the formation of micropores in lacquered tinplate during stamping and beading.     

基于HHT变换的超光滑加工表面谱分析

Hilbert-Huang变换是最新发展起来的处理非线性非平稳信号的时频分析方法。其基本的实现分为两步,多分辨经验模态分解和瞬时频率的求解,随后可以获得信号的时—频谱。这种方法的关键部分是多分辨经验模态分解,任何复杂的信号都可以分解为有限数目并且具有一定物理意义的固有模态函数。本文针对表面粗糙度用HHT进行了分析,得出相应结论,对加工有一定的指导意义。     

Spectroscopic signature of phosphate crystallization in erbium-doped optical fibre preforms

In rare-earth-doped silica optical fibres, the homogeneous distribution of amplifying ions and part of their spectroscopic properties are usually improved by adding selected elements, such as phosphorus or aluminum, as structural modifier. In erbium ion (Er³⁺) doped fibres, phosphorus preferentially coordinates to Er³⁺ ions to form regular solvation shells around it. However, the crystalline structures described in literature never gave particular spectroscopic signature. In this article, we report emission and excitation spectra of Er³⁺ in a transparent phosphorus-doped silica fibre preform. The observed line features observed at room and low temperature are attributed to ErPO₄ crystallites.     

尺寸界线上表面粗糙度自动标注工具开发

提出在 Auto CAD中尺寸界线上的表面粗糙度自动标注算法 ,开发了标注工具 .通过自动获取机械零件图中尺寸界线的方位 ,确定粗糙度标注的旋转角 ,从而实现了表面粗糙度自动连续标注     

The influence of surface roughness on the starved lubrication of ball bearings

Abstract

A theoretical analysis is made for starved lubrication of a rigid point contact under the influence of surface roughness. The results show that both the directional property and the standard deviation of the combined surface roughness can affect the load carrying capacity of the lubricant film as well as the friction on the solid surfaces. The combined effects of speed ratio of the contiguous surfaces and the roughness on starved lubrication are also obtained. The results show that the effects of surface roughness may improve the starvation a little, but that they are not remarkable. A regression equation is found for determining the critically starved lubricant inlet level. Such an inlet level can indicate the minimum limit of lubricant supplied quantity, and, beyond this limit, the load carrying capacity of the lubricant film will decrease sharply. In addition, experiments have been carried out to observe the starved lubrication of a ball rolling on a flat glass disc. It is shown that higher surface speeds may make the starved condition much worse.