查看更多>>摘要：Fringe projection profilometry (FPP) performs poorly when measuring non-Lambertian surfaces, since the measured points are missing in specular regions. The existing solutions need to make a trade-off between precision and efficiency, because no extra information about specular regions is available. To tackle the specular reflection problem of FPP, this paper proposes a multi-sensor measurement method by integrating FPP with nearfield photometric stereo (NFPS). Firstly, the point clouds in non-specular regions are measured by FPP. Then, a deep neural network is applied to estimate the normal map of the surface by NFPS. Finally, the intact point clouds are reconstructed by minimizing the depth gradient error calculated from the normal map. The proposed method can achieve high-precision measurement without any human intervention. In the experiment of measuring an aluminum alloy free-form surface, the deviation of the profile error between the proposed method and a coordinate measuring machine is only 6.9 mu m.
查看更多>>摘要：In this paper, the detections of targets' longitudinal and angular accelerations, including uniform and variable accelerations, have been investigated, based on vortex electromagnetic (EM) waves carrying orbital angular momentum (OAM), in which the time-frequency analysis approaches are used to process the echo signal. Compared with other methods, the Choi-Williams distribution (CWD) is more suitable for detecting, which has better energy concentration and less cross term. Meanwhile, the multi-OAM modes method has been proposed to decouple the longitudinal and angular accelerations and detect the concrete acceleration coefficients. And the detection errors have been analyzed by transmitting the OAM waves with different mode combinations of l= 1, 3, 5 at 3 GHz. The results indicate that increasing mode intervals and decreasing topological charges can relatively improve detection accuracy in an appropriate sampling frequency range. In addition, the proposed method is also applicable to the case that the transmission modes are impure in practical application. And the directions of the longitudinal and angular accelerations can be acquired by sending OAM with different amounts of power. This work paves the way of detecting 3-dimensional velocity of complex target.
查看更多>>摘要：Phase-sensitive optical time domain reflectometry (phi-OTDR) has been applied in security monitoring. However, phi-OTDR cannot directly measure strain and intensity of an applied disturbance, thereby limiting the choice of features for intrusion pattern recognition and hazard assessment. This paper proposes a quantitative method to measure disturbances using amplitude-based (phi-OTDR. The optical-fibre multiparameter optimization (FMPO) method is developed. The FMPO analyses the curve pattern of optical intensity signals to calculate strain. No extra module is needed, instead a specially designed bio-inspired algorithm is introduced. Quantification indices to gauge disturbance intensities are derived for practical use. A piezoelectric ceramic cylinder test demonstrated a linear correlation between the quantification indices and the vibration amplitude (R-2 = 0.8956). The calculated strains of 34 driven voltages agreed well with theoretical values within 1000 ne. In a pendulum-impact experiment, five intrusion intensities were successfully identified, which indicated that FMPO performed well in the field.
查看更多>>摘要：In this article, the longitudinal beam bunch behaviors of the Hefei Light source-II (HLS-II) are effectively investigated and analyzed based on the beam multi-parameter measurement system. Simultaneously, the temporal beam characteristic parameter extraction (T-BCPE) method is developed for measuring the longitudinal impedances of machine. In the case of 100.4 kV radio-frequency (RF) voltage, the inductance and resistance in the longitudinal coupling impedance of HLS-II are obtained as 115 +/- 13 nH and 1320 +/- 310 0 by extracting bunch lengthening factor and asymmetry factor, respectively. In addition, the longitudinal beam dynamical characteristics and potential-well distortion are also in-depth analyzed above the threshold current of the microwave instability. As a result, the longitudinal broadband impedance of HLS-II is measured to be 8.94 +/- 0.44 0 while 0.339 +/- 0.004 of the scaling factor in combination with the theoretical analysis.
查看更多>>摘要：An electrochemical biosensor for arsenite concentration determination is developed in this study using arsenite oxidase (ArOx). Gold nanoparticles (AuNP) were used in this study to improve the analytical characteristics of the biosensor by providing a suitable nano-environment for the enzyme activity. The enzyme and the nanoparticles were electrodeposited on the glassy carbon (GC) working electrode to prepare the GC-AuNP-ArOx electrode. The linear measurement range of the biosensor was between 10(1) and 10(4) nM, while its detection limit was obtained equal to 5 nM. The effects of enzyme concentration, pH, storage temperature, and storage time on the biosensor's performance were investigated. Results showed that an enzyme concentration of 7 mu M at the physiological pH exerted the highest biosensor response (7 mu A anodic current/10 nM arsenite). No undesirable interference of heavy metals was observed on the biosensor response, and the biosensor showed excellent reproducibility compared to a conventional chemosensor.
查看更多>>摘要：This article highlights a hybrid methodology of Grey theory and the Ant Lion Optimizer algorithm (Grey-ALO). The proposed module aggregated the multiple responses such as Cutting force (Fc) and Surface roughness (SRa) into a single objective function. The effect of varying constraints, namely, nano-filler content (CNO Wt.%), cutting speed (S), feed (F) and depth of Cut (D), is examined using Taguchi experimental design. The optimal condition from the Grey-ALO hybrid module are found as W3-S3-F1-D1, i.e., 1.5 wt.% CNO, Spindle Speed at 1500 rpm, Feed at 50 mm/min, and 1 mm of cutting depth. The validation test reveals that the overall assessment values significantly improved from 0.9136 to 0.9156, which indicates the improved prediction performance of ALO with 0.2189% error. The finding confirms that the feed rate and weight% of CNOs are the highly influencing factor for Milling performances. It can be recommended to the manufacturing sector for quality and production control.
查看更多>>摘要：The indoor localization problem is considered for the transceiver separation radio frequency identification (RFID) system suffering from random noises and multipath interference. An RSS difference method is presented to preprocess the measured RSS to reduce the complexity of system modeling. Then, an improved three-point localization algorithm is designed to estimate the target location. Specifically, two solutions based on 2-norm and non-convex optimization are respectively proposed to weaken the influence of the noises and multipath on positioning performance. The simulation results show that the proposed method can significantly improve the localization accuracy and provide satisfactory robustness in different indoor environments.
查看更多>>摘要：A Various fiber-optics displacement sensor methods are presented yearly, and a high-resolution displacement sensor with cost-effective and straightforward operation is an essential demand. Here, we present a novel sensor structure for displacement measurement. The design is based on a hole in the one fiber's core, whereas a second fiber is utilized to move inside the hole made on the first fiber. The optical power coupling varies with the distance between the first and second fiber. The drilling length is investigated, and the four sensors are fabricated with different displacement ranges. The results show drilling length influences sensor's range, and the sensor has a nanometer resolution of about 8.647 nm with a sensitivity of 11.56 nW/mu m in between 0 mu m and 2500 mu m. Moreover, a maximum range of 4 mm is achieved. The designed structure could be used not only for displacement, but also for vibration, angle, and pressure sensor.
查看更多>>摘要：The design of a network of observation locations is addressed in the setting of estimating unknown parameters of a spatiotemporal system modelled by a partial differential equation. Interest is in estimating only a subset of these parameters as accurately as possible. The other parameters, called nuisance parameters, must also be estimated although we are interested in neither their values, nor accuracies. The maximal eigenvalue of the covariance matrix of the maximum-likelihood estimator of the parameters of interest is used as the measure of the identification accuracy. In order to make selection of a best subset of gauged sites from a possibly very large set of candidate sites computationally tractable, its convex relaxation is introduced. Two major problems to be tackled are the potential singularity of the optimal information matrix associated with all unknown parameters and the nondifferentiability of the optimality criterion. The former is settled by imposing a constraint on the minimal allowable value of the determinant of the information matrix. The latter is resolved by reformulating the problem as a convex semi-infinite programming problem whose solution is sought by solving a sequence of finite low-dimensional min-max problems using extremely efficient generalized simplicial decomposition. The excellent performance of the proposed technique is illustrated by an example involving optimal sensor node activation in a large sensor network collecting measurements to identify a moving contaminating source.
Omar, Nur Alia ShehIrmawati, RamliFen, Yap WingMuhamad, Ernee Noryana...
9页
查看更多>>摘要：In this work, a refractive index sensor using TiO2 extracted from moringa leaves-based nanocomposite thin film was developed to detect cadmium ions in an aqueous solution. The experimental results showed a good sensitivity response of 0.4825 degrees ppm 1, a strong binding affinity of 1.4362 ppm 1, and a low signal-to-noise ratio of 0.0755. The proposed sensor also showed good selectivity towards cadmium ions compared to zinc and mercury ions. The changes in the optical properties of titanium dioxide-based nanocomposite thin film towards different concentrations of cadmium ions solution were further demonstrated theoretically. Also, the observed increase in the surface roughness using atomic force microscopy proved the binding of Cd ions to the sensor film. This study is proposing a new potential of titanium dioxide extracted from moringa leaves-based nanocomposite thin film as a surface refractive index sensor for the detection of cadmium ions.
NSTL
Elsevier