A study on eccentric behavior of discharge valve in refrigerant compressor using laser sensors

2020 ◽  
Vol 34 (3) ◽  
pp. 1149-1156
Author(s):  
Young Nam Jang ◽  
Young Lim Lee
2020 ◽  
Vol 67 (1) ◽  
pp. 133-141
Author(s):  
Dmitriy O. Khort ◽  
Aleksei I. Kutyrev ◽  
Igor G. Smirnov ◽  
Rostislav A. Filippov ◽  
Roman V. Vershinin

Technological capabilities of agricultural units cannot be optimally used without extensive automation of production processes and the use of advanced computer control systems. (Research purpose) To develop an algorithm for recognizing the coordinates of the location and ripeness of garden strawberries in different lighting conditions and describe the technological process of its harvesting in field conditions using a robotic actuator mounted on a self-propelled platform. (Materials and methods) The authors have developed a self-propelled platform with an automatic actuator for harvesting garden strawberry, which includes an actuator with six degrees of freedom, a co-axial gripper, mg966r servos, a PCA9685 controller, a Logitech HD C270 computer vision camera, a single-board Raspberry Pi 3 Model B+ computer, VL53L0X laser sensors, a SZBK07 300W voltage regulator, a Hubsan X4 Pro H109S Li-polymer battery. (Results and discussion) Using the Python programming language 3.7.2, the authors have developed a control algorithm for the automatic actuator, including operations to determine the X and Y coordinates of berries, their degree of maturity, as well as to calculate the distance to berries. It has been found that the effectiveness of detecting berries, their area and boundaries with a camera and the OpenCV library at the illumination of 300 Lux reaches 94.6 percent’s. With an increase in the robotic platform speed to 1.5 kilometre per hour and at the illumination of 300 Lux, the average area of the recognized berries decreased by 9 percent’s to 95.1 square centimeter, at the illumination of 200 Lux, the area of recognized berries decreased by 17.8 percent’s to 88 square centimeter, and at the illumination of 100 Lux, the area of recognized berries decreased by 36.4 percent’s to 76 square centimeter as compared to the real area of berries. (Conclusions) The authors have provided rationale for the technological process and developed an algorithm for harvesting garden strawberry using a robotic actuator mounted on a self-propelled platform. It has been proved that lighting conditions have a significant impact on the determination of the area, boundaries and ripeness of berries using a computer vision camera.


Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 895
Author(s):  
Adam Szeleziński ◽  
Adam Muc ◽  
Lech Murawski ◽  
Marcin Kluczyk ◽  
Tomasz Muchowski

The paper presents the measurement process and test results for six thin-walled plates with different dynamic characteristics caused by different defects of welded joints. The tests were carried out using non-destructive testing (NDT). The authors made an attempt to determine the validity of the use and degree of effectiveness of the tests based on laser vibrometry in detecting defects in welded joints. The tests of welded plates were carried out using displacement laser sensors and piezoelectric accelerometers, while the source of vibration extortion was a modal hammer. In the adopted measurement methodology, the application of accelerometers was to obtain the reference data, which allowed for comparison with the measurement data obtained from the laser vibrometer. The analysis of the obtained measurement data, in the fields of time and frequency, made it possible to verify the correctness of the data obtained by means of laser vibrometry and to determine the requirements which are necessary for the correct performance of NDT tests and in the future structural health monitoring (SHM) system of welded joints with the use of a laser vibrometer. The mathematical model developed in the MSC software Pastran-Nastran was also used in the work. The model was developed for the purpose of mutual verification of the measurement and calculation tests. At the present stage of work, it can be stated that the results obtained by laser vibrometry methods should be treated as a supplement to the research conducted with traditional piezoelectric accelerometers. In certain situations, they can be used as an alternative to accelerometers, due to the fact that laser sensors do not require direct contact with the examined object. Where the object under test may be in a strong electromagnetic field, optical sensors are better suited than contact sensors.


2004 ◽  
Author(s):  
Andreas Frank ◽  
Klaus Bohnert ◽  
Karim Haroud ◽  
Hubert Braendle

Author(s):  
Katarzyna Zdanowicz ◽  
Boso Schmidt ◽  
Hubert Naraniecki ◽  
Steffen Marx

<p>The bond behaviour of concrete specimens with carbon textile reinforcement was investigated in the presented research programme. Pull-out specimens were cast from self-compacting concrete with expansive admixtures and in this way chemical prestress was introduced. The aim of the research was to compare bond behaviour between prestressed specimens and non-prestressed control specimens. During pull-out tests, the pull-out force and notch opening were measured with a load cell and laser sensors. Further, bond - slip and pull-out force - crack width relationships were drawn and compared for prestressed and non-prestressed specimens. Chemically prestressed specimens reached 24% higher bond strength than non-prestressed ones. It can be therefore concluded, that chemical prestressing positively influences the bond behaviour of concrete with textile reinforcement and thus better utilisation of its properties can be provided.</p>


2017 ◽  
Author(s):  
L. Rodriguez-Cobo ◽  
M. A. Quintela ◽  
R. Ruiz-Lombera ◽  
R. A. Perez-Herrera ◽  
M. Lopez-Amo ◽  
...  

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