Optical monitoring of thin film properties using in-situ measurement of transmittance and reflectance

Having a good reproducibility and uniformity of the coating properties is a mutual challenge for all coating processes. To face this challenge adequately, it is not only necessary to have accurate control of the coating process but also to have the capability to monitor the optical properties of the coating layers during or directly after deposition. Especially in sensitive multi-layer products produced by large area coating technology, small uniformity variations may give rise to a variation in the visual appearance or other deviations from the product requirements. It becomes necessary to monitor the individual layer thicknesses, requiring sensitive and accurate optical measurement techniques that offer nanoscale precision over large areas. This demand for sensitivity and accuracy puts a strain on the limits of existing in-line measurement capability. The objective of this paper is to discuss some of the measurement problems and give practical solutions to improve accuracy and repeatability of in-situ transmittance and reflectance measurements for optical monitoring of thin film properties.     

Developing methods for effective monitoring of complicated systems

An approach is given to planning measurement monitoring methods for establishing how well complicated objects meet the requirements of standardization documents, which is based on computer simulation. An example is given of defining the accuracy specifications for measurements from calculations on customers’ and producers’ risks, and also monitoring errors of the first and second kinds. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 19–22, May, 2007.     

一种高效的网格监控数据收集方法

为提高在面向服务的网格环境下以简单对象访问协议（SOAP）通信方式收集网格资源监控事件的效率,基于对监控事件依次传输时的低效率和收集者SOAP通信处理负载过大的现象的分析,针对具有较长生命期的监控事件提出了一种高效的收集方法——资源本地和资源间分别采用缓存和协同机制;在监控事件生命期允许的范围内先行跨资源汇聚尽量多的监控事件,再将它们通过单个SOAP消息一并发送至收集者。实验结果表明,所提方法不仅能使网格资源个体监控事件的SOAP传输开销降低50％～85％,还可将收集者上的SOAP通信处理负载降低75％左右。     

Socio-economic effects monitoring: toward improvements informed by bio-physical effects monitoring

In this paper, using two case studies from the Hibernia offshore platform construction project, we argue that follow-up based on the hypothesistesting approach typically adopted in biophysical effects monitoring could be more widely adopted in socio-economic effects monitoring. While there are some significantly different issues associated with socio-economic and biophysical monitoring, we argue that such an approach in the socio-economic context would encourage more focused attention on monitoring objectives, more appropriate data collection and clearer identification of project-specific impacts, thereby offering more credible and useful information to decision-makers than is now often the case.     

Silicon photomultipliers for radioactive waste online monitoring

A prototype demonstrator for the online monitoring of short-medium term radioactive waste repositories is currently under development at INFN-LNS. Such a system is planned to be distributed, fine-grained, robust, reliable, and based on low-cost components. With the main purpose of counting gamma radiation, we implemented a new kind of mini-detector based on silicon photomultipliers and scintillating fibers that behaves like a cheap scintillating Geiger-Muller counter and is suitable to be deployed in the shape of a grid around waste drums.     

Automated system for monitoring atmospheric pollution

An automated system is described for monitoring atmospheric pollution gas composition and aerosol content. Technical characteristics and the principles of system functioning are provided. Translated from Izmeritel’naya Tekhnika, No. 12. pp. 52–55, December, 2008.     

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.     

Characterisation of SiC photo-detectors for solar UV radiation monitoring

Silicon carbide has a potential for solar UV radiation monitoring: extremely resistant to UV radiation damage, nearly-blind to visible and infrared radiation and less sensitive to temperature variations than standard radiometric systems. A radiometer composed by three SiC photodiodes has been designed, manufactured and tested under solar radiation. Two photodiodes are equipped with filters in the UVB (280-315 nm) and UVA (315-400 nm) ranges while a third is filtered to match the erythemal action spectrum. UVA, UVB components of the solar radiation as well as UV index (UVI) at the earth's surface have been determined in two site positions in Tuscany, Italy. Data as a function of day-light allowed us to evaluate total optical thickness for UVA and UVB: τ_UVA=0.46 and τ_UVB=1.8. UVI values measured during the year well compares with computed ones used for weather forecast procedures.     

A proposed benchmark problem for cargo nuclear threat monitoring

There is currently a great deal of technical and political effort focused on reducing the risk of potential attacks on the United States involving radiological dispersal devices or nuclear weapons. This paper proposes a benchmark problem for gamma-ray and X-ray cargo monitoring with results calculated using MCNP5, v1.51. The primary goal is to provide a benchmark problem that will allow researchers in this area to evaluate Monte Carlo models for both speed and accuracy in both forward and inverse calculational codes and approaches for nuclear security applications. A previous benchmark problem was developed by one of the authors (RPG) for two similar oil well logging problems (Gardner and Verghese, 1991, [1]). One of those benchmarks has recently been used by at least two researchers in the nuclear threat area to evaluate the speed and accuracy of Monte Carlo codes combined with variance reduction techniques. This apparent need has prompted us to design this benchmark problem specifically for the nuclear threat researcher.This benchmark consists of conceptual design and preliminary calculational results using gamma‐ray interactions on a system containing three thicknesses of three different shielding materials. A point source is placed inside the three materials lead, aluminum, and plywood. The first two materials are in right circular cylindrical form while the third is a cube. The entire system rests on a sufficiently thick lead base so as to reduce undesired scattering events. The configuration was arranged in such a manner that as gamma-ray moves from the source outward it first passes through the lead circular cylinder, then the aluminum circular cylinder, and finally the wooden cube before reaching the detector. A 2 in.×4 in.×16 in. box style NaI (Tl) detector was placed 1 m from the point source located in the center with the 4 in.×16 in. side facing the system. The two sources used in the benchmark are ¹³⁷Cs and ²³⁵U.     

Improved multivariate image analysis for product quality monitoring

Product quality monitoring by image texture analysis underwent a tremendous growth in the last few years in several industrial sectors, due to the availability of low-cost digital imaging sensors. Multivariate image analysis (MIA) can be used within an image texture analysis technique to provide a spatial statistical characterization of an image. However, in most cases this spatial characterization is possible only for very local texture neighborhoods, due to the high computational cost of MIA. In this paper, the iMIA (improved Multivariate Image Analysis) algorithm is proposed, that improves over previous implementations of MIA by extending its range of applicability due to its reduced computational complexity and memory requirements. The proposed algorithm uses the Fourier transform and the convolution theorem to efficiently compute the MIA model, in such a way that the image texture can be characterized by taking into account also large neighborhood sizes. The proposed approach is applied to two case studies concerning the estimation of the fiber diameter distribution in nanostructured membranes, and the classification of paper surfaces. The results suggest that the optimum range of spatial statistics used for characterizing the image is related to the size of the main textural features.     

CdTe photoconductors for LHC luminosity monitoring

Detectors made from CdTe photoconductors are being used with great success in LEP to monitor the vertical beam emittance. They can withstand tremendous irradiation of up to 10¹³ Gy from hard X-rays. For the LHC it is proposed to measure the relative luminosity with monitors located inside absorbers 142 m downstream of the interaction points. The detectors will receive an integrated dose of about 10⁸ Gy per year there, where the high neutron flux is of particular concern.

Thick polycrystalline-CdTe detectors were recently tested for speed, sensitivity before and after receiving up to 10¹⁵ neutrons/cm². The test results are presented here, along with a comparison of the calculated charge deposition in silicon, diamond and GaAs detectors.     

Upward-looking ground-penetrating radar for monitoring snowpack stratigraphy

Operational remote monitoring of snowpack stratigraphy, melt water intrusions and their evolution with time for forecasting snowpack stability is not possible to date. Determination of the spatial variability of snowpack conditions on various scales requires a number of point measurements with various methods. These methods are either destructive or do not provide information about the internal structure of the snowpack. The application of a remotely controlled non-destructive sensor system would help to gain a higher spatio-temporal resolution about information of the snowpack. In this study we present results from upward-looking ground-penetrating radar (GPR) surveys from horizontal caves dug in the front wall of snow pits at the bottom of the snowpack. GPR data are compared with vertical profiles of snow hardness and density, obtained in the snow pit. Data were acquired in different areas with varying snow conditions with various GPR impulse systems, frequencies and polarizations. Radar experiments with high frequencies (> 1 GHz) detect internal layers in the snowpack in dry snow, but fail to provide clear reflections at the upper snow-air transition because of attenuation. In wet snow, the radar signals < 1 GHz are capable to penetrate a meter-thick snowpack and detect the snow surface, although the signal is strongly attenuated. Analysis of reflection phases and magnitudes allows interpretation of their physical origin in terms of changes in electrical permittivity. Varying antenna polarization causes a strongly different signal response, likely caused by the snow-pit wall present in our set-up. Forward calculation of density-based reflection coefficients between neighboring layers of varying hardness yields ambiguous results in terms of correspondence with observed radar reflections apart except for interferences of neighboring reflections. Moreover, we identify several pitfalls for future applications. The system set-up used here represents a basis for further developments towards a system, which is capable of improving information on the spatial and temporal snowpack characteristics.     

Properties of SnO2 films fabricated using a rectangular filtered vacuum arc plasma source

Transparent and conducting SnO₂ films of 57–200nm thickness were deposited on microscope glass slide substrates, using a rectangular filtered vacuum arc deposition system. The 40 glass slides were equally distributed on a 400 × 420mm substrate carriage, and were exposed to a Sn plasma beam, produced by a rectangular vacuum arc plasma gun with a Sn cathode, and passed through a rectangular magnetic macroparticle filter towards the substrates. The carriage with the substrates was transported past the 94 × 494mm filter outlet. The SnO₂ films were fabricated on the glass substrates at room temperature by maintaining the chamber oxygen background pressure at 0.52Pa. The film composition, and electrical and optical properties were studied as a function of the film thickness. The films were stored under ambient air conditions, and their electrical resistance was measured as a function of storage time over a period of several months.

The average resistivity of films was 10–17mΩ cm for films with thickness (t) less than 100nm, but that of t > 100nm it was 5–9mΩ cm. The resistivity of the films with t > 100nm did not change significantly after 8months of storage in ambient air. The optical transmittance of the films in the visible spectrum was in the range of 75–90%. The optical constants, i.e., the refractive index and the extinction coefficient of the films at wavelength λ = 550nm were in the range of 2.02–2.09 and 0.013–0.023, respectively, and the optical band gap energy was 4.15–4.21eV. Unlike the electrical resistivity, the optical parameters weakly depended on t.     

基于压电智能骨料的沥青混凝土路面车辆动态荷载监测

本文提出了一种基于压电智能骨料（Smart aggregate, SA）的沥青混凝土（Asphalt concrete, AC）路面车辆荷载监测方法。首先,考虑不同车速进行了埋入SA的AC块体动态加载试验研究,采用电液伺服试验机进行动态荷载加载,给出了SA在给定边界条件下的灵敏度,并分析了加载速率对其影响;其次,建立了嵌入SA的AC块体的有限元模型,模拟了试验中实际加载边界条件,分析了AC中的应力分布,进而得出了SA的灵敏度,并与试验结果进行了对比。最后,通过有限元模拟,研究了AC弹模变化对SA灵敏度的影响。研究表明,对于埋入SA的AC路面,车辆动态荷载下SA灵敏度为线性,常温下AC弹模变化对SA灵敏度影响可忽略不计。本文提出的基于SA的AC路面车辆荷载监测方法是可行的。     

A data acquisition system for machine tool condition monitoring

A flexible, generically applicable and inexpensive data acquisition system (DAS), for machine tool condition monitoring, has been designed, constructed and installed as part of a European Union sponsored project. The DAS is more than just a data logger and an array of sensors. It also consists of a methodology for analysing data logging requirements and a relational database that supports this methodology. The database is held on a central ‘maintenance management’ computer. The monitoring to be carried out by the DAS is specified through this database, which contains detailed information about the DAS's facilities. This feature makes it simple to reconfigure the DAS to implement new monitoring requirements and to customize its operation to meet the needs of different machines. The information in the database is transformed into a look-up table that is read by the software that sets up and controls the data logging processes.     

油品含水率多点实时监测系统的研制

提出了润滑系统油品含水率多点在线实时监测系统的实现方法,设计了基于变介电常数式电容传感器的润滑油品含水率变送器,根据高速线材厂液压循环润滑系统的特点,利用组态王软件,实现对液压系统的润滑油含水率进行多点实时监测.通过在高速线材厂液压循环系统的使用证明,该系统能够准确、快速地测出润滑油品的含水率并及时报警,从而避免了润滑失效所带来的潜在危害.     

LCM工艺实时监测技术的影响因素

为了提高复合材料液体成型(LCM) 工艺构件的质量稳定性和降低成本, 建立了直流电实时监测系统。实验表明, 该监测系统能够准确地反映监测点处树脂流动前锋的到达及其固化过程。研究了主要工艺因素对监测信号的影响规律, 发现系统对不同的树脂体系的响应差别较大, 监测饱满值随工艺温度的升高而增大, 随监测铜丝裸露长度的增加而增大, 纤维体积含量和纤维铺放角度对监测信号的影响不大。      

Modeling and monitoring methods for spatial and image data

ABSTRACT

Intelligent sensing and computerized data analysis are inducing a paradigm shift in industrial statistics applied to discrete part manufacturing. Emerging technologies (e.g., additive manufacturing, micro-manufacturing) combined with new inspection solutions (e.g., non-contact systems, X-ray computer tomography) and fast multi-stream high-speed sensors (e.g., videos and images; acoustic, thermic, power and pressure signals) are paving the way for a new generation of industrial big-data requiring novel modeling and monitoring approaches for zero-defect manufacturing. Starting from real industrial problems, some of the main challenges to be faced in relevant industrial sectors are discussed. Viable solutions and future open issues are specifically outlined.     

A new structural health monitoring system for composite laminates

The increasing use of composite laminates in safety critical structures has prompted the development of a robust structural health monitoring system for laminates, which uses metastable ferrous alloy inserts embedded within the laminate during component construction to provide an indication of the peak tensile strain encountered by the laminate. The metastable ferrous alloy insert has an austenitic crystal structure at room temperature, but upon application of strain, this transforms to a thermodynamically stable martensite, resulting in a change in magnetic susceptibility, which can be correlated with the peak strain experienced by the material (strain memory effect). This paper presents the test results that show that it is possible to manufacture a smart laminate in this fashion, and that sufficient strain is experienced by the insert to provide a significant change in magnetic susceptibility, thereby warning of a high strain level in the laminate. Various insert geometries and laminate thicknesses are also tested for their effect on the susceptibility measurements.     

A design condition for incorporating human judgement into monitoring systems

In safety monitoring, there exists an uncertainty situation in which the sensor cannot detect whether or not the monitored object is in danger. For the uncertainty zone identified by a non-homogeneous safety monitoring system that utilizes two types of sensors with different thresholds, operators or experts are expected to judge whether the real state is safe or dangerous on the basis of additional information from a detailed inspection or other related sensors output. However, the activities for inspection performed by relevant humans may require additional cost and introduce inspection errors. The present article proposes two types of an automatic monitoring system not involving any human inspection or a human–machine (H–M) cooperative monitoring system with inspection. In order to compare the systems, an approach based on the Dempster–Shafer theory is proposed as uncertainty analysis by this theory (it is simpler than by the traditional Bayesian approach). By comparing their expected losses as a result of failed dangerous failures or failed safe failures as well as the inspection errors, the condition is determined under which H–M cooperative systems incorporating human judgements are more effective than automatic monitoring systems.