3-D Image Measurement System for Small Machine Parts With Glossy Metal Surfaces

2012 ◽  
Author(s):  
Motoyoshi Sato ◽  
Ryo Shimamoto ◽  
Masanobu Mizoguchi
Keyword(s):  
Measurement System ◽  
High Frequency ◽  
Low Frequency ◽  
Objective Lens ◽  
Prototype System ◽  
Frequency Method ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Frequency Components ◽  
Shape From Focus

Keeping core parts of machines in proper condition is essential to improving productivity and quality of products. Metallic wear of knitting needles for circular knitting machines should be controlled within specific conditions. Currently, inspections of them are visually performed by skilled examiners, and automated inspection systems, which can measure 3-D shapes, are demanded. Because the needles have mirror glossed, complexly shaped surfaces, conventional lighting method, such as dome lights and diffuse on-axis lights, cannot irradiate the light evenly throughout the object and causes brightness unevenness, and that leads to 3-D measurement errors in image processors. To increase accuracy, we propose a new 3-D measurement system which equips omnidirectional EL (electroluminescence) lightings and DEHF (Dynamic Enhancement of High Frequency) method. Here, the system applies the shape from focus method, which moves the optical system vertically with respect to the fixed object and obtains a sequence of images that correspond to different levels of object focus. In the formation process of shallow depth of field microscopic images, a defocused imaging system plays the role of a low-pass filter. For this reason, the regions with high frequency components can be regarded as a focused area. The high frequency components are finally regarded as the contour of the object by the method. It recovers the 3-D shape of the object by estimation of height of the contours each image and arranging in the original order of the sequence of the height of the contours. The followings are novelties of our proposed system. Firstly, omnidirectional EL lightings irradiate an object with uniform lights from all directions. They are composed of the following lights: coaxial through objective lens, object lens perimeter, side and bottom lights, and each of which can adjust brightness; therefore they can reduce unevenness of brightness on the object. We adopted inorganic EL sheet as the lighting device. EL sheet is capable of plane emission and prevent the occurrence of the unevenness of the irradiated light by the point source of light. Secondly, algorithm for shape from focus can be improved by our DEHF method. Even if the above lightings are applied, there still remains low frequency non-uniformity of brightness. DEFH method removes the low frequency by subtracting mean filtered image from original one, and remaining high frequency content can be emphasized. We built a microscope based prototype system and conducted experiments. Through them, the validity of our proposed method was confirmed.

Design of the Broadband Standard Signal Generator for Laser Locating System of the Mine Hoisting Container

2013 ◽  
Vol 427-429 ◽  
pp. 2033-2036
Author(s):  
Di Fan ◽  
Yan Gao ◽  
Yue Zhao
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Standard ◽  
Analog Filters ◽  
Laser Ranging ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Noise Disturbance ◽  
Standard Signal ◽  
Low Pass

As the key junction between the ground and underground, hoisting systems as well as mines themselves are of vital importance to coalmine production. Laser ranging method is studied as a new solution of getting the real-time position directly. Furthermore, multi-scale phase based laser ranging principles are utilized in the system. The paper is aimed to conduct research into the problems existing in standard signal generating while using laser to locating the hoisting container, and to design standard sine generator circuits with DDS technology and DDS devices AD9850 to generate multiple frequency standard signals. In view of the serious noise disturbance in high frequency output, 4-order Chebyshev low-pass filter is designed, by using the integrated analog filters LT 6600-15, to filter the sine signals from AD9850 and to effectively weaken the noise disturbance. The established practical circuits are tested, obtaining trillion level high frequency and low frequency sine signals and fulfilling the requirements for the location system of hoisting containers.

The influence of the planted geophone on seismic land data

Geophysics ◽  
1980 ◽  
Vol 45 (8) ◽  
pp. 1239-1253 ◽  
Author(s):  
G. M. Hoover ◽  
J. T. O’Brien
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Mineral Exploration ◽  
Low Frequency ◽  
Soil Consolidation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Strong Damping ◽  
Local Soil ◽  
Oscillatory Coupling

Characteristics of the seismic data acquisition system that previously have been ignored become important as more sophisticated interpretive methods based on broader frequency bandwidths are developed to extract stratigraphic information from land data in hydrocarbon and mineral exploration. Theoretical and experimental results indicate that the geophone plant can be approximated by a damped oscillatory coupling, properties dependent upon the geophone mass, dimension of earth contact, and local soil consolidation. A massive geophone with minimal earth contact exhibits a low‐frequency plant resonance with weak damping and acts as a low‐pass filter to eliminate the high‐frequency components of a recorded signal. A lightweight geophone with large earth contact exhibits a high‐frequency plant resonance with strong damping and, consequently, filtering effects are minimal if the plant resonance is well above the signal bandwidth. Although signal filtering influences are weak for strong damping, phase delays can introduce errors of several milliseconds which resemble static errors. Additional complications arise since these time shifts are frequency dependent and, consequently, not identical for all reflection events in a seismic trace. The resonant frequency of the geophone plant increases with increased soil consolidation; however, damping demonstrates only a weak dependence upon consolidation. All of these factors can limit the effectiveness of common‐depth‐point (CDP) stacking methods if the proper technique is not practiced in the acquisition of broad‐bandwidth seismic data.

A modified Bessel filter for amplitude demodulation of respiratory electromyograms

1998 ◽  
Vol 84 (1) ◽  
pp. 378-388 ◽  
Author(s):  
Ronald S. Platt ◽  
Eric A. Hajduk ◽  
Manuel Hulliger ◽  
Paul A. Easton
Keyword(s):  
High Frequency ◽  
Stop Band ◽  
Pass Band ◽  
Third Order ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Transient Characteristics ◽  
Low Pass ◽  
Seventh Order ◽  
Frequency Components

Platt, Ronald S., Eric A. Hajduk, Manuel Hulliger, and Paul A. Easton. A modified Bessel filter for amplitude demodulation of respiratory electromyograms. J. Appl. Physiol. 84(1): 378–388, 1998.—We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.

Error Analyzing Method for Rotation Inertial Navigation System Based on Fourier Transform

2013 ◽  
Vol 336-338 ◽  
pp. 982-987 ◽  
Author(s):  
Jian Hua Cheng ◽  
Bing Yu Wang ◽  
Dai Dai Chen
Keyword(s):  
Fourier Transform ◽  
Navigation System ◽  
Inertial Navigation System ◽  
Inertial Navigation ◽  
Low Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Navigation Errors

According with the problem that the error propagative characteristics of rotation inertial navigation system can not be quantitatively analyzed, a new error analyzing method is proposed. As the inertial navigation system can be equivalent to a low pass filter, the method converted the complex gyro drifts into signal which can be quantitatively analyzed after modulating through Fourier transform, thus the low frequency components of the error can be extracted. The relationship between navigation errors and gyro drifts is built by using the conventional error equations of strapdown inertial navigation system. The comparative analyses and computer simulation of conventional, uniaxial unidirectional and uniaxial reciprocating system prove the correctness and feasibility of this method. This method provides an effective reference for other same types of control system error analyses.

Weaknesses of the Baxter-King Filter: Is a Pattern-Based Filter an Alternative? / Schwächen des Baxter-King Filters: Ist ein musterbasierter Filter eine Alternative?

2005 ◽  
Vol 225 (4) ◽  
Author(s):  
Georg Goldrian
Keyword(s):  
Time Series ◽  
High Frequency ◽  
Degree Of Approximation ◽  
Trigonometric Function ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Slow Moving ◽  
Ideal Filter

SummaryThe Baxter-King filter shows some weaknesses, particularly with regard to monthly time series. This procedure involves not only a loss of data for the border areas of time series, but suppresses inadequately high frequency components and shows as a low-pass filter only the performance of ordinary moving averages. Another important finding is that the maximal lag Κ not only determines the degree of approximation to an ideal filter, as Baxter and King argue, but also the ability to extract a slow moving component. A pattern-based filter, whose weights are generated by a trigonometric function as well, does not possess such weaknesses, and is thus a real alternative to the Baxter-King filter.

scholarly journals Enhancing SNR and generating contrast for cryo-EM images with convolutional neural networks

2020 ◽  
Author(s):  
Eugene Palovcak ◽  
Daniel Asarnow ◽  
Melody G. Campbell ◽  
Zanlin Yu ◽  
Yifan Cheng
Keyword(s):  
Image Processing ◽  
High Frequency ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Low Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Processing Pipeline ◽  
Visual Contrast ◽  
Low Pass

AbstractIn cryogenic electron microscopy (cryo-EM) of radiation-sensitive biological samples, both the signal-to-noise ratio (SNR) and the contrast of images are critically important in the image processing pipeline. Classic methods improve low-frequency image contrast experimentally, by imaging with high defocus, or computationally, by applying various types of low-pass filter. These contrast improvements typically come at the expense of high-frequency SNR, which is suppressed by high-defocus imaging and removed by low pass filtration. Here, we demonstrate that a convolutional neural network (CNN) denoising algorithm can be used to significantly enhance SNR and generate contrast in cryo-EM images. We provide a quantitative evaluation of bias introduced by the denoising procedure and its influences on image processing and three-dimensional reconstructions. Our study suggests that besides enhancing the visual contrast of cryo-EM images, the enhanced SNR of denoised images may facilitate better outcomes in the other parts of the image processing pipeline, such as classification and 3D alignment. Overall, our results provide a ground of using denoising CNNs in the cryo-EM image processing pipeline.

scholarly journals Organ of Corti vibration within the intact gerbil cochlea measured by volumetric optical coherence tomography and vibrometry

2018 ◽  
Vol 120 (6) ◽  
pp. 2847-2857 ◽  
Author(s):  
Wei Dong ◽  
Anping Xia ◽  
Patrick D. Raphael ◽  
Sunil Puria ◽  
Brian Applegate ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
High Frequency ◽  
Mechanical Response ◽  
Low Frequency ◽  
Organ Of Corti ◽  
Corner Frequency ◽  
Gradual Transition ◽  
Optical Coherence ◽  
Pass Filter ◽  
Low Pass Filter

There is indirect evidence that the mammalian cochlea in the low-frequency apical and the more commonly studied high-frequency basal regions function in fundamentally different ways. Here, we directly tested this hypothesis by measuring sound-induced vibrations of the organ of Corti (OoC) at three turns of the gerbil cochlea using volumetric optical coherence tomography vibrometry (VOCTV), an approach that permits noninvasive imaging through the bone. In the apical turn, there was little frequency selectivity, and the displacement-vs.-frequency curves had low-pass filter characteristics with a corner frequency of ~0.5–0.9 kHz. The vibratory magnitudes increased compressively with increasing stimulus intensity at all frequencies. In the middle turn, responses were similar except for a slight peak in the response at ~2.5 kHz. The gain was ~50 dB at the peak and 30–40 dB at lower frequencies. In the basal turn, responses were sharply tuned and compressively nonlinear, consistent with observations in the literature. These data demonstrated that there is a transition of the mechanical response of the OoC along the length of the cochlea such that frequency tuning is sharper in the base than in the apex. Because the responses are fundamentally different, it is not appropriate to simply frequency shift vibratory data measured at one cochlear location to predict the cochlear responses at other locations. Furthermore, this means that the number of hair cells stimulated by sound is larger for low-frequency stimuli and smaller for high-frequency stimuli for the same intensity level. Thus the mechanisms of central processing of sounds must vary with frequency. NEW & NOTEWORTHY A volumetric optical coherence tomography and vibrometry system was used to probe cochlear mechanics within the intact gerbil cochlea. We found a gradual transition of the mechanical response of the organ of Corti along the length of the cochlea such that tuning at the base is dramatically sharper than that at the apex. These data help to explain discrepancies in the literature regarding how the cochlea processes low-frequency sounds.

Aliasing Effects on Nodal Acceleration Output From Nonlinear Finite Element Simulations

2000 ◽  
Author(s):  
Mark O. Neal ◽  
Chin-Hsu Lin ◽  
J. T. Wang
Keyword(s):  
Finite Element ◽  
High Frequency ◽  
Nonlinear Finite Element ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Averaging Filter ◽  
Very High ◽  
Acceleration Output

Abstract Nodal acceleration output from nonlinear finite element crash simulations often contains high frequency components. If this output is not sampled frequently enough the high frequency components will be aliased and the resulting acceleration output will be inaccurate. It is recommended in this paper that a low-pass filter be installed in the crashworthiness finite element codes which would remove the high frequency components of the nodal accelerations before they are sampled for output. This would completely eliminate aliasing error in acceleration output. Prior to this installation, there are several options for reducing the effects of aliasing on acceleration output. One option is to request very high sampling rates for acceleration output; however this will result in very large output files. Another option is to calculate the accelerations by differentiating the output velocities. This option, which effectively is an averaging filter acting on the accelerations, is available in the finite element code DYNA3D. The properties of this filter are examined in this paper and it is shown that this filter is very effective in reducing the effects of aliasing on acceleration output, although it should not be expected to completely eliminate potential aliasing problems. Finally, guidelines are presented for selecting nodes and sampling rates based on local natural frequencies that will reduce the effect of aliasing of the acceleration output.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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