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[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Measurement of Relative Position of Camera and Optical Beacon by Simultaneous Passive Method
摘要： The paper deals with a problem of a passive measurement of the relative position of an optical beacon and an optical camera by a simultaneous analytical method. The beacon is composed of nine light sources which are arranged in space in a defined way. The proposed beacon layout enables the measurement of the beacon range and one position angle of the camera. This paper presents the mathematical model of the measurement method and the results, which were gathered on the basis of the experimental measurements. The standard commercial camera and lenses with four different focal lengths were used.
关键词： simultaneous passive method,optical camera,optical beacon,measurement,lens focal length,relative position
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - A Device for Rapid Measurement of Nitrate Levels in Aqueous Solutions Based on Spectrophotometric Method
摘要： Method and device for rapid measurement of nitrate levels in aqueous solutions based on spectrophotometric method. The proposed method was realized with irradiation of test sample and measuring its optical density in the ultraviolet at three wavelengths.
关键词： UV-LEDs,nitrate-ions,water,measurement of nitrate,ultraviolet spectroscopy
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 8th International Conference on Consumer Electronics - Berlin - Berlin (2018.9.2-2018.9.5)] 2018 IEEE 8th International Conference on Consumer Electronics - Berlin (ICCE-Berlin) - Using the Hilbert-Huang transform to increase the robustness of video based remote heart-rate measurement from human faces
摘要： Measuring the heart rate(HR) in a conventional way, e.g. using an electrocardiogram, leads to several disadvantages for the patient, such as skin irritation or discomfort. For this reason, remote-based measurement techniques have become more and more popular in recent years. Most of the methods that have been presented use recordings of human faces. These methods recognize minimal changes, invisible to the human eye, in the color spectrum of a persons face to measure heart activity. As a by-product, it is also possible to determine the breath frequency by this method. However, measuring the HR based on a video of someones face is a challenge, as has been reported. One of the biggest problems is ambient light change during the process. To solve this problem and enhance the robustness of the measurement technique, a new approach is proposed in this paper. By using the empirical mode decomposition of the Hilbert Huang transform and independent component analysis (ICA), it is possible to reduce significantly the effects of changes in ambient light conditions. The proposed combination of these two techniques ensures a much greater robustness to changes in light conditions and therefore greater accuracy and can be used in a realistic application environment.
关键词： measurement,BSS,heart rate,ICA,photoplethysmography,Hilbert-Huang transform
更新于2025-09-23 15:22:29
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High Strain Sensitivity Temperature Sensor Based on a Secondary Modulated Tapered Long Period Fiber Grating
摘要： A novel sensor structure has been proposed and experimentally investigated for simultaneous strain and temperature measurement. The structure is fabricated by weak power modulation of CO2 laser exposure on tapered long period fiber grating (LPFG). Compared with the transmission spectrum of the tapered LPFG, two peaks appear in the transmission spectrum of the novel structure. These resonance peaks exhibit different sensitivity responses; thus, simultaneous measurement of strain and temperature is realized by monitoring the wavelength shift of the two peaks. Experiment results indicate that strain sensitivities of the two peaks are 1.82 pm/με and 8.17 pm/με, and temperature sensitivities are 47.9 pm/°C and 65 pm/°C, respectively.
关键词： strain,simultaneous measurement,temperature,Taper,CO2 Laser
更新于2025-09-23 15:22:29
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[IEEE 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Rome, Italy (2018.6.20-2018.6.22)] 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Shape Measurement of Large Structures in Space: Experiments
摘要： A method to reconstruct the shape of a large planar structure in space is introduced and demonstrated through a lab-scale experiment. Lightweight sun sensors are distributed on the structure to measure local angles relative to the sun. The methodology to integrate the measured angles into the shape of the structure, based on a decomposition of the shape into basis functions is introduced. This methodology has been implemented on a lab-scale experiment. The design of the sensors is based on a 4 pixel pinhole camera. The calibration method for these sensors is presented as well as the techniques to integrate and communicate with them. A 1.2 m by 20 cm structure was designed and populated with sensors to show the performance of an integrated system. Preliminary results show an accuracy of 1 mm RMS on the shape reconstruction of this structure.
关键词： reconstruction,shape,measurement,sensor,sun,solar,laboratory,experiment,structure,sail,antenna array
更新于2025-09-23 15:22:29
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Defects and Improvements of Pockels Transducer Voltage Segmentation
摘要： The sensing range and sensitivity of optical voltage transducer are badly limited by the inherent half-wave voltage of the electro-optic crystals and a nonlinear polarization demodulation based on Malus’ law. A multi-segmented structure can meet the requirement of the half-wave voltage but is only suitable for 500 kV and above voltage levels with incident wavelength of 632.8 nm, but it is not suitable for all voltage levels if the incident wavelength is greater than 1330 nm. By the way in the multi-segmented structure its optical path and devices are deviated easily by vibrations and thermal expansion and contraction. In this paper, the multi-segmented structure is improved to be suitable for various high-voltage levels with the wavelength of 632.8 nm or greater, and moreover, a new approach is presented to use MgTiO3 ceramics to enwrap around BGO (Bi4Ge3O12) crystal to reduce the integral voltage errors from 0.260% to 0.012%.
关键词： high voltage measurement,Optical voltage transducer,multi-segmented structure,integral voltage error
更新于2025-09-23 15:22:29
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A Novel Design of Through-Hole Depth On-Machine Optical Measuring Equipment for Automatic Drilling and Riveting
摘要： In the aerospace manufacturing industry, it is impossible to achieve precise and efficient automatic drilling and riveting for largescale composite board parts. The bottleneck is that the depth detection of rivet holes still relies on manual operation, which seriously affects the assembly efficiency and stability of composite board parts. In order to realize accurate and efficient on-machine automatic measurement for through holes in the automatic drilling and riveting process of largescale composite board parts, this paper presents a novel hole depth measuring device. Its mechanical structure is developed based on our newly designed measurement scheme and optical path, the purpose of which is to convert the hole depth data into displacement data of the probe motion. Its electrical hardware consists of three units: a laser transceiver unit to pick up laser spots; a displacement measuring unit to capture the probe movement in real time; and a driving unit to achieve motion control of the probe. Finally, the experimental results indicated that the proposed method and device are capable of performing automatic measurements for through-hole depth. In addition, factors affecting the measuring accuracy and stability of the device are initially analyzed and discussed, which lay a foundation for subsequent research on error compensation and probe calibration.
关键词： image processing,depth detection,automatic drilling and riveting,through-hole depth,large-scale composite board,on-machine measurement
更新于2025-09-23 15:22:29
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Fast four-dimensional tensile test monitored via X-ray computed tomography: Elastoplastic identification from radiographs
摘要： A projection-based digital volume correlation method (presented in a companion paper) is extended to an integrated approach for the calibration of an elastoplastic law based on a single radiograph per loading step. Instead of following a two-step sequential procedure (i.e. first, measurement of the displacement field; second, identification), the integrated method aims at identifying few model parameters directly from the gray-level projections. The analysis of an in situ tensile test composed of 127 loading steps performed in 6 min is presented. An isotropic elastoplastic constitutive law with free-form hardening behavior (i.e. controlled by only eight parameters) is identified and shows a ductile behavior (up to 6.3% strain before failure). A large improvement on the residual quality is shown and validates the proposed model and procedure. The obtained displacement fields are similar to those measured with no mechanical integration. A different parameterization of the constitutive law provides a very close result, thereby assessing the robustness of the procedure.
关键词： inverse methods,in situ tests,Tomography,projection-based digital volume correlation,integrated digital volume correlation,four-dimensional measurement
更新于2025-09-23 15:22:29
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Ambient Tracer-LIF for 2-D quantitative measurement of fuel concentration in gas jets
摘要： A novel ambient tracer LIF technique with addition of tracer into ambient gas is proposed in this study to quantitatively measure the two dimensional (2-D) fuel concentration distribution in high-pressure gas jets. Firstly, the fundamental principle of the ambient tracer-LIF technique is described, and the equation of fuel concentration in a jet is deduced from the ambient fluorescence intensity. In the ambient tracer-LIF technique, the on-site calibration can be performed, and much more degrees of freedom in selection of tracers or target fuels can be achieved in principle. Then, the experiments are carried out with the high pressure gas injected into the environment doped with acetone in an optical accessible constant volume vessel. The fluorescence in the ambient is induced by using the 266 nm laser, and is recorded by the ICCD camera. The dedicated image processing is implemented to reduce the uncertainty and obtain the quantitative fuel concentration distribution in the jet. The uncertainties of the measurement results are evaluated, including both the systematic and random errors. The uncertainty propagation analysis shows that the measurement uncertainty increases with the local fuel concentration decreasing, and at the boundary regions of the jet, where the mixture is over lean, the relative uncertainty goes up to 26%. Finally, the temporal variations of the fuel concentration distribution in the gas jet are presented, and the effects of injection pressure are discussed. These results are believed to be valuable for development of numerical models and combustion system designs.
关键词： 2-D quantitative concentration measurement,On-site calibration,Ambient tracer-LIF,Natural gas direct injection
更新于2025-09-23 15:22:29
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Changes in anterior chamber eye during accommodation as assessed using a Dual Scheimpflug system
摘要： Purpose: To study the changes in anterior chamber depth (ACD), anterior chamber angle (ACA), and pupil diameter (PD) during accommodation. Methods: Eighty eyes of 80 subjects, aged 22 to 40 years, were included. The rotating Dual Scheimpflug and a Placido disc system (Galilei G4, Ziemer Ophthalmic Systems AG, Switzerland) was used to measure the changes in ACD, ACA, and PD during accommodation. ACD measurement was taken for the central zone and for 4 more positions, each in different orientation (nasal, superior, temporal and inferior), 4 mm away from the centre. ACA was measured for the whole eye as well for the nasal, superior, temporal, and inferior quadrants. These metrics were obtained for various accommodation stimuli, ranging from +1 D to -4 D in 1-D steps. Results: For a given position, the ACD did not vary significantly with accommodation. For the central ACD, the percentage of relative change between far and near vision was -4.11%. The ACA was significantly lower at the inferior, temporal, and superior positions. There was no change in the ACA of the whole eye and that of the nasal orientation. These two eye metrics were significantly lower in the superior-nasal than in the inferior-temporal region. At each vergence studied, the PD decreased significantly with accommodation. The relative change after the -4 D stimulus was -8.13%. Conclusion: ACA and PD varied significantly with accommodation, whereas no such variation of ACD was observed. Further, the anterior chamber was found to be asymmetrical, with the nasal-superior area becoming significantly shallower than the inferior temporal region.
关键词： Anterior chamber,Techniques, measures, measurement equipment,Pupil,Accommodation, ocular
更新于2025-09-23 15:22:29