scholarly journals Characteristics of Local Modulation Beam Propagating through Spatial Filter System

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Kewei You ◽  
Yanli Zhang ◽  
Xuejie Zhang ◽  
Jianqiang Zhu
Keyword(s):  
Beam Quality ◽  
Spatial Filter ◽  
Defect Size ◽  
Local Defect ◽  
Safe Operation ◽  
Systematic Analysis ◽  
Filter System ◽  
Local Defects ◽  
Local Modulation ◽  
Modulation Degree

As local defects may significantly harm beam quality and affect safe operation, a systematic analysis of the ability of a spatial filter to alleviate these adverse effects is required. Thus, the evolutional characteristics of a beam modulated by a local defect propagating through a spatial filter system at an image reply plane and a downstream plane are analyzed in detail. Modulation stripes appear at the image reply plane; these are caused by the pinhole cutoff effect. The modulation degree increases with increasing defect size. The maximum intensification factor can reach 3.2 under certain conditions. Thus, the defect size should be restricted to a reasonable size for safe operation with a specified pinhole size. Moreover, a maximal value appears at the downstream plane, and the intensity enhances with increasing defect size. To ensure beam quality, the maximum allowable defect size and angle of the spatial filter should meet special constraints. The maximum allowable defect size is calculated based on practical configuration parameters.

Perception of contour from motion and contextual modulation signals in human visual cortical areas recorded by 3D magnetometer-spatial filter system

1998 ◽  
Vol 31 ◽  
pp. S271
Author(s):  
Kenji Yoshikawa ◽  
Keisuke Toyama ◽  
Yoshio Ohtani ◽  
Shu Wakoh ◽  
Yoshimichi Ejima ◽  
...  
Keyword(s):  
Spatial Filter ◽  
Contextual Modulation ◽  
Filter System ◽  
Cortical Areas ◽  
Visual Cortical

An Experimental Approach in Defect Detection of a Single Row Ball Bearing Using Noise Generation Signal

2019 ◽  
Author(s):  
Aref Afsharfard ◽  
Seyed Hamid Reza Sanei
Keyword(s):  
Ball Bearing ◽  
Experimental Testing ◽  
Local Defect ◽  
Noise Generation ◽  
Frequency Spectra ◽  
Single Row ◽  
Outer Race ◽  
Bearing Defects ◽  
Cost Efficient ◽  
Local Defects

Abstract Bearings are critical mechanical components that are used in rotary machinery. Timely detection of defects in such components can prevent catastrophic failure. Noise is generated during the rotation of bearings even without the presence of defects due to finite number of rotating elements to carry the load. Such noise is associated with the change in effective stiffness during rotation, however, a sharp spike is observed in the noise level with presence of local defects. This study uses the noise generation aspect of roller bearings to identify local defect in a single row ball bearing with outer race stationary under radial load. Experimental testing is conducted on two identical bearings. The defective bearing is selected from a diesel engine subjected to 20 years of service. Dissecting the defective bearing revealed pitting and spalling of the inner race and balls, the most two common bearing defects. Both time and frequency analysis of sound pressure generated by the bearings were performed. The results show that there is a clear distinction in the time and frequency spectra between healthy and defective bearings. Findings of this study revealed that using a simple cost efficient in-house experimental setup, local defects can be readily detected.

Reliability Analysis Based on Fault Tree of Failure of Boiler Drum

2012 ◽  
Vol 271-272 ◽  
pp. 1750-1754
Author(s):  
Qian Tian ◽  
Ping Chen ◽  
Cong Luo
Keyword(s):  
Natural Circulation ◽  
Fault Tree ◽  
Reference Value ◽  
Safe Operation ◽  
Power Station ◽  
Systematic Analysis ◽  
The Core ◽  
Boiler Drum ◽  
Influent Factors ◽  
Power Station Boiler

Drum is the core pressure equipment of Natural Circulation Boiler. The harsh working conditions lead drum to be prone to failure in power station boiler system. This article presents a systematic analysis of factors which may cause the failure of the drum and builds the fault tree with the drum failure as the top event. Through calculating each order of minimum cut sets and importance degree of each basic event probability to determine the major influent factors for the failure of drum, this article puts forward the corresponding solutions and brings reference value to safe operation and maintenance of boiler drum.

The Application of Infrared Image Technology in the Detection of Local Defects of Solar Cell Module

2011 ◽  
Vol 347-353 ◽  
pp. 1206-1209
Author(s):  
Yong Qing Wang ◽  
Peng Chao Zhang ◽  
Shi Yuan Wang ◽  
Jing Feng Xiong ◽  
Ai Ling Cai ◽  
...  
Keyword(s):  
Solar Cell ◽  
Infrared Image ◽  
Local Defect ◽  
Image Library ◽  
Output Efficiency ◽  
Local Defects ◽  
Cell Module ◽  
Basic Standard ◽  
Solar Cell Module

If there are local defects in the solar cell module, the output efficiency of the module will decrease. This article introduces the detection of local defect of solar cell module based on the infrared image technology. It finally establishes an image library which contains some infrared images of seven kinds of defects and a basic standard which can judge the quality of the module. The reasons of some defects are listed in the article. The unqualified rate will greatly decrease for the technique. The research is helpful to eliminate the module that contains recessive defects. The life of the modules also will be extended.

Laser beam wavefront diagnostics by a three-plate ring interferometer and a grating spatial filter system

1981 ◽  
Vol 17 (9) ◽  
pp. 1768-1771 ◽  
Author(s):  
Wang Zi-jiang ◽  
Cai Xi-jie ◽  
Wang Gui-ying ◽  
Bai Jian-rong
Keyword(s):  
Laser Beam ◽  
Spatial Filter ◽  
Filter System ◽  
Ring Interferometer

scholarly journals A Novel Spatial Filter System Compensates the Measurement Error Caused by Object's Pattern.

1992 ◽  
Vol 112 (11) ◽  
pp. 1056-1063 ◽  
Author(s):  
Masayuki Terashima ◽  
Masakatu Nomura ◽  
Michitaka Hori ◽  
Jyunichi Shimomura
Keyword(s):  
Measurement Error ◽  
Spatial Filter ◽  
Filter System

scholarly journals INVESTIGATION OF THE NEED TO ADJUST THE ROADS DESIGN STANDARDS OF IN QUARRIES

2020 ◽  
Vol 36 (1) ◽  
pp. 22-28
Author(s):  
I. Loginova ◽  
O. Kruzhilko ◽  
D. Vinivitin
Keyword(s):  
Practical Experience ◽  
Heavy Duty ◽  
Safe Operation ◽  
Design Standards ◽  
Systematic Analysis ◽  
Heavy Trucks ◽  
Dump Trucks ◽  
Opencast Mines ◽  
Constant Slope ◽  
Mining Vehicles

The purpose of this work is to justify the need to adjust the standards for designing roads in quarries, taking into account the Rules of labour protection in the development of minerals in an open way. The study is based on domestic (experience in Poltava GOK, Yeristovsky GOK) and foreign (mining enterprises in Australia, USA, Canada) practical experience in operating heavy-duty mining vehicles, as well as on a systematic analysis of current norms for technological design of roads in quarries. An analysis of the regulatory and legal issues related to the safety of operation of heavy-duty mining vehicles showed that the Ukrainian standards for designing roads in opencast mines have not changed 25 years. At the same time, the fleet of technological dump trucks used in quarries, technical characteristics, capabilities and prospects for their use, have significantly changed. The study and identification of the advantages of using roads with a constant slope without the installation of horizontal platforms provides the basis for developing recommendations for updating the design standards for roads in open pits, as the current standards do not meet the requirements for the safe operation of modern heavy-duty mining vehicles. It is proposed to update regulatory legal acts by reviewing them with corrective amendments, taking into account the appropriate level of safety when using heavy trucks. Implementation of the proposed standards to improve the transport scheme of the quarry will contribute to the safe operation of heavy mining vehicles.

scholarly journals Online Bearing Clearance Monitoring Based on an Accurate Vibration Analysis

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 389 ◽  
Author(s):  
Jianguo Wang ◽  
Minmin Xu ◽  
Chao Zhang ◽  
Baoshan Huang ◽  
Fengshou Gu
Keyword(s):  
Load Distribution ◽  
Lead Time ◽  
Cost Effective ◽  
Local Defect ◽  
Geometric Errors ◽  
Distribution Method ◽  
Outer Race ◽  
Bearing Clearance ◽  
Optimal Maintenance ◽  
Local Defects

Accurate diagnosis of incipient faults in wind turbine (WT) assets will provide sufficient lead time to apply an optimal maintenance for the expensive WT assets which often are located in a remote and harsh environment and their maintenance usually needs heavy equipment and highly skilled engineers. This paper presents an online bearing clearance monitoring approach to diagnose the change of bearing clearance, providing an early and interpretable indication of bearing health conditions. A novel dynamic load distribution method is developed to efficiently gain the general characteristics of vibration response of bearings without local defects but with small geometric errors. It shows that the ball pass frequency of outer race (BPFO) is the primary exciting source due to biased load distribution relating to bearing clearance. The geometric errors, including various orders of runouts on different bearing parts, can be the secondary excitation source. Both sources lead to compound modulation responses with very low amplitudes, being more than 20 dB lower than that of a small local defect on raceways and often buried by background noise. Then, Modulation Signal Bispectrum (MSB) is identified to purify the noisy signal and Gini index is introduced to represent the peakness of MSB results, thereby an interpretable indicator bounded between 0 and 1 is established to show bearing clearance status. Datasets from both a dedicated bearing test and a run-to-failure gearbox test are employed to verify the performance and reliability of the proposed approach. Results show that the proposed method is capable to indicate a change of about 20 µm in bearing clearance online, which provides a significantly long lead time compared to the diagnosis method that focuses only on local defects. Therefore, this method provides a big opportunity to implement more cost-effective maintenance works or carry out timely remedial actions to prolong the lifespan of bearings. Obviously, it is applicable to not only WT assets, but also most rotating machines.

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