Implementation of efficient terahertz (THz) wave control is essential for THz technology development for applications including sixth-generation communications and THz sensing. Therefore, realization of tunable THz devices with large-scale intensity modulation capabilities is highly desirable. By integrating perovskite and graphene with a metallic asymmetric metasurface, two ultrasensitive devices for dynamic THz wave manipulation through low-power optical excitation are demonstrated experimentally here.
View Article and Find Full Text PDFThe data collected from complex process industries are usually time series with considerable nonlinearities and dynamics, as well as excessive redundancy. Moreover, there are temporal and spatial correlations between input variables and key performance variables. These characteristics bring great difficulties to data-driven modeling of the key performance variables.
View Article and Find Full Text PDFHigh-precision logging equipment is critical for measuring the borehole diameter and drilling offset in coal mining and petroleum drilling. We propose a module composition and positioning principle for an ultrasonic transducer based on an ultrasonic logging instrument for shaft sinking by drilling (ULISSD) for calculating the reflection distance. The logging distance, which is the primary performance index of a logging system, is determined by using the self-reception sensitivity and error of the ultrasonic transducer in a downhole system.
View Article and Find Full Text PDFField crops are generally planted in rows to improve planting efficiency and facilitate field management. Therefore, automatic detection of crop planting rows is of great significance for achieving autonomous navigation and precise spraying in intelligent agricultural machinery and is an important part of smart agricultural management. To study the visual navigation line extraction technology of unmanned aerial vehicles (UAVs) in farmland environments and realize real-time precise farmland UAV operations, we propose an improved ENet semantic segmentation network model to perform row segmentation of farmland images.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
August 2020
In this study, a tunable bifunctional polarization-independent metamaterial device based on Dirac semimetal films (DSFs) and vanadium dioxide () is investigated. At the insulator state, a polarization-independent electromagnetically induced reflectance effect can be achieved via destructive interference between bright and dark modes. When transitions to a metallic state, the proposed device behaves as a dual-band polarization-independent absorber with 99.
View Article and Find Full Text PDFIn this paper, the tunable properties of metamaterial absorbers based on 3D Dirac semimetal films (DSFs) in the terahertz (THz) regime are discussed in theory. We consider the absorbers with square-shaped, circular-patch, and cross-shaped resonators. These resonances are theoretically polarization-insensitive at normal incidence because of their 90° rotational symmetry and can achieve perfect absorption in numerical simulation.
View Article and Find Full Text PDFAnalyzing geological drilling hole images acquired by Axial View Panoramic Borehole Televiewer (APBT) is a key step to explore the geological structure in a geological exploration. Conventionally, the borehole images are examined by technicians, which is inefficient and subjective. In this paper, three dominant types of borehole-wall images on coal-rock mass structure, namely, border images, fracture images and intact rock mass images are mainly studied.
View Article and Find Full Text PDFSteel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball's outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS.
View Article and Find Full Text PDFTo efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained.
View Article and Find Full Text PDFSheng Wu Yi Xue Gong Cheng Xue Za Zhi
December 2008
The rapid development in the fields of electroscience, computer science, and biomedical engineering are propelling the electrophysiologyical techniques. Recent technological advances have made it possible to simultaneously record the activity of large numbers of neurons in awake and behaving animals using implanted extracellular electrodes. Several laboratories use chronically implanted electrode arrays in freely moving animals because they allow stable recordings of discriminated single neurons and/or field potentials from up to hundreds of electrodes over long time periods.
View Article and Find Full Text PDFConf Proc IEEE Eng Med Biol Soc
October 2012
Correctly counting the live cells plays a great role in the ectogenetic anti-virus experiment. According to the irregular shape and arbitrary size of the wall pasted Hela cells overlapping each other, we propose a scheme to segment and count the cells using Gabor filter with different parameters and Morphological operation. Experiments reveal that filters with different parameters will lead to different results and a better segmentation will be achieved based on the characteristics of cells and optimal parameters.
View Article and Find Full Text PDFConf Proc IEEE Eng Med Biol Soc
September 2008
The recognition technology based on biological feature is a hot topic in recent years, and the recognition technology concerning the skull features was studied in this paper. The central projection transform about the two-dimension skull image was performed, the central projection function of the gray value was obtained, the average difference function of the central projection value and it's vectors were defined, and the research on the vector feature of the average difference function was carried out. This feature is robust in noisy backgrounds, less calculation consuming, and it can also be used to recognize other objects.
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