Fluctuation of acoustic load significantly weakens the performance of ultrasonic system. To address this problem in a simple way, we consider the main input and output variables related to the ultrasonic transducer's performance and propose a detailed mathematical model based on the simplest LC matching network containing only one capacitor and one inductor. In this model, a new resonance frequency brought by matching components was found and defined. The optimum analysis method is used to solve the model, and a high-tolerance matching method against load fluctuation is obtained. Analysis indicates that when activated at the mechanical resonance frequency, the impedance and apparent power of the PT matched by the proposed method are constant no matter how the load changes, and thereby can significantly increase the stability and robustness of ultrasonic systems. For its simple structure and high performance, the proposed matching method can be widely applied in most ultrasonic systems. The tolerance of the proposed method against other environmental factors and high-order LC matching networks were also discussed. In addition, the feasibility and advantage of the proposed matching method are also verified by experiments.
Two closely related, aerobic, Gram-stain-negative, motile, oval-shaped, non-endospore-forming, moderately thermophilic bacteria, designated strains SYSU G05006T and SYSU G05005, were isolated from a bioreactor enrichment and the original sample was collected from Rehai National Park, Tengchong, Yunnan Province, PR China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that these two strains were closely related to Caldovatus sediminis YIM 72346T (96.75 and 96.89 % sequence similarity, respectively). The whole genome size of strain SYSU G05006T was 3.87 Mbp with a DNA G+C content of 75.33 mol%. The average nucleotide identity (ANI based on the MUMmer algorithm≤90.31 % and ANI based on blast≤89.36 %) and digital DNA–DNA hybridization (≤35.10 %) values between strain SYSU G05006T and other members of the family Acetobacteraceae were all lower than the threshold values recommended for distinguishing novel prokaryotic species. Optimal growth of the strain was observed at 55 °C and pH 6.0. Ubiquinone-10 was the predominant respiratory lipoquinone. The major cellular fatty acids included iso-C14 : 0, C16 : 1 ω5c, summed feature 5 and summed feature 7. The major polar lipids consisted of diphosphatidylglycerol, one unidentified aminolipid, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified phospholipids and two unidentified lipids. Based on results of phylogenetic analyses, comparative genomics and phenotypic characteristics, we describe a new species of the genus Caldovatus represented by strain SYSU G05006T (=KCTC 82831T=MCCC 1K06125T), for which we propose the name Caldovatus aquaticus sp. nov.
A certain model should be used to predict and track the space objects that may affect the operation of satellites. In this paper, the Two-Line Elements (TLE) and the Simplified General Perturbations 4 (SGP4) models are used to calculate the position and velocity vectors of satellite A/B in the True Equator Mean Equinox (TEME) coordinate system and the Earth-Centered Inertial (ECI) system. Satellite A is selected as the observation platform to carry the camera, and the imaging positions of target satellite B on the camera of satellite A in the TEME and ECI coordinate systems are calculated respectively. The imaging trajectories are superimposed to generate several turns. The difference between the imaging positions in TEME and ECI coordinate systems is calculated, and the influence of the Earth's precession and nutation on the imaging trajectory is analyzed.
The piezoelectric polymer PVDF and its copolymers have a long history as transducer materials for medical and biological applications. An efficient use of these polymers can potentially both lower the production cost and offer an environment-friendly alternative for medical transducers which today is dominated by piezoelectric ceramics containing lead. The main goal of the current work has been to compare the image quality of a low-cost in-house transducers made from the copolymer P(VDF-TrFE) to a commercial PVDF transducer. Several test objects were explored with the transducers used in a scanning acoustic microscope, including a human articular cartilage sample, a coin surface, and an etched metal film with fine line structures. To evaluate the image quality, C- and B-scan images were obtained from the recorded time series, and compared in terms of resolution, SNR, point-spread function, and depth imaging capability. The investigation is believed to provide useful information about both the strengths and limitations of low-cost polymer transducers.
With the development of the next generation of intelligent battlefield situation awareness technology, infrared multi-target tracking plays an increasingly important role in complex background. However, the commonly used infrared target tracking algorithm, weak small target enhanced motion information ignores the apparent feature, large target enhanced apparent feature ignores the motion information. To solve the above problems, this paper proposes a target tracking method based on the fusion of location, detection and feature matching, constructs the target motion information predictor information and target detection response, so as to achieve fast target tracking. Firstly, the Bayesian multi-target filter is used, and the weight factor of the corresponding Gaussian component is added to the Kalman filter to obtain the number and state set of the targets in the scene at a certain time, and the target position predictor is established to complete the primary correlation based on the fast position prediction. Then, according to the feature distribution of the detection response, the secondary correlation based on the effective features of the targets is completed, Form the final complete track of the target. In this paper, the multi-target complex scene multi-target motion environment simulation experiments, the experimental results show that the algorithm can better track the target in complex motion environment.
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