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1

Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

Zhang W., Dong B., Zhang W., He Z., Xie S., Zhou Y.

Optica Applicata

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2018

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Vol. 48, nr 2

311--323

EN

Compression is one of the typical parameters measured in material mechanics. In this research, the compression displacement fields on the front and rear surfaces of an epoxy sample are measured by using a tilt depth-resolved wavenumber-scanning Michelson interferometer. The light source is a distributed feedback laser diode, the wavenumber of which can be modulated to about 1.017 × 104 m–1 by the temperature without mode hopping. A random-sampling Fourier transform is designed to evaluate the phase differences before and after the applied loads. Experimental results show that the depth-resolved measurement of the compression displacement field is of high accuracy. It can be used to analyze force propagation inside resin-based composites.

2

Digital volume correlation in an environment with intensive salt-and-pepper noise and strong monotonic nonlinear distortion of light intensity

Tu P., Bai Y., Xu W., Dong B., Ye S., Yang Q., Zhou Y.

Optica Applicata

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2017

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Vol. 47, nr 2

209--223

EN

Digital volume correlation is an image-based technique for internal 3D displacement and strain fields measurement or analysis widely used in the field of experimental mechanics. A widely used correlation function (criterion) of digital volume correlation is Pearson correlation function, which suffers from the problem of the acquired data being contaminated by salt-and-pepper noise and monotonic nonlinear distortion of the light intensity. In this work, a 3D correlation function called the Spearman correlation function is used to deal with those interferences. A numerical experiment shows that the performance of Spearman correlation function using integer-pixel registration in an environment with 10% salt-and-pepper noise is better than that of Spearman and Pearson correlation functions using sub-pixel registration in an environment with 1% salt-and-pepper noise. As the light intensity distortion is significant, the error of Pearson correlation function is considerable; meanwhile, the error of Spearman correlation function is small. In conclusion, Spearman correlation function is, in particular, practical and useful in digital volume correlation.

3

A Method to Estimate Leakage Current of Polluted Insulators

Xia Y., Jiang X., Sun C., Dong B.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 3b

161-164

EN

The effects of the applied voltage(U), equivalent salt deposit density (�PESDD) and relative humidity density(RH) on the leakage current (LC) are studied based on the least squares algorithm (LSA) in this study. Experiments' results show that, the maximal amplitude of LC Ih increases with the increase of �PESDD by an power function with a positive index 0.451, while increases with the increase of both U and RH by an exponential function with a positive index 0.017 for U and 9.751 for RH. The result can be used to evaluate the pollution condition of insulators based on LC.

PL

Zbadano prąd upływu zabrudzonych izolatorów uwzględniając przyłożone napięcie, względne zasolenia i względna wilgotność. Stwierdzono, że prąd upływu rośnie wraz z zasoleniem ze współczynnikiem potęgowym 0.45.

4

A novel flexible micro assembly system: implementation and performance analysis

Um D., Ryu D., Dong B., Foor D., Hawkins K.

Journal of Automation Mobile Robotics and Intelligent Systems

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2010

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Vol. 4, No. 3

10-15

EN

Demands for micro/nano products and assembly systems have been raised significantly to meet the ever complex technical needs for modern society. In this paper, we share the experiences and results of the study on the flexible micro assembly workcell focused primarily on a novel system implementation and system performance analysis. For flexible and autonomous assembly operations, we investigated a novel model based 3D depth measurement technology for faster and cost effective means to promote autonomous micro assembly systems in various industries. Micro parts, by its nature, are known of their shapes in advance for the majority of micro applications. We take advantage of the previously known shape of micro parts and hence apply a model based approach for a faster and cost effective localization and 3D depth measure of randomly loaded micro-parts on the workcell. The proposed 3D depth measuring method is based on the pattern recognition and multi-focus technique enabling it to extract only information useful for micro parts assembly for faster recognition. For demonstration purpose, silicon based oxide gears are fabricated by bulk micromachining and are used to study performance indices and to prove the usefulness of the proposed micro 3D depth measurement technology.