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Computerized ionospheric tomography is a highly ill-posed inverse problem, and regularization tends to stabilize the problem to provide a unique solution. When a regularization method is used, the choice of an optimal parameter is a key issue. In this article, we propose an adaptive regularization method for 3-D ionospheric tomography based on the U-curve. The proposed approach uses a U-curve method to determine the optimal regularization parameter from Global Navigation Satellite Systems (GNSS) observation data. Comparative case studies are investigated based on GNSS simulated observations and real measurements. The simulation results indicate that the proposed method is superior to the adaptive regularization method based on the L-curve. In addition, we further validate the tomographic results with actual ionosonde station data. The results demonstrate the reliability and superiority of the proposed method compared to traditional methods. [ABSTRACT FROM AUTHOR]

To improve the seamless navigation ability of an integrated Global Positioning System (GPS)/inertial navigation system in GPS-denied environments, a hybrid navigation strategy called the self-learning square-root- cubature Kalman filter (SL-SRCKF) is proposed in this article. The SL-SRCKF process contains two innovative steps: 1) it provides the traditional SRCKF with a self-learning ability, which means that navigation system observations can be provided continuously, even during long-term GPS outages; and 2) the relationship between the current Kalman filter gains and the optimal estimation error is established, which means that the optimal estimation accuracy can be improved by error compensation. The superiority of the proposed SL-SRCKF strategy is verified via experimental results and prominent advantages of this approach include: 1) the SL-SRCKF comprises two cycle filtering systems that work in a tightly coupled mode, and this allows more accurate error correction results to be obtained during GPS outages; 2) the system's error prediction ability is effectively improved by introducing a long short-term memory, which provides much better performance than other neural networks, such as random forest regression or the recursive neural network; and 3) under different (30, 60, and 100 s) GPS outage conditions, the long-term stability of SL-SRCKF is much better than that of other error correction approaches. [ABSTRACT FROM AUTHOR]

A 2 T magnetic field system (second long) based on storage supercapacitor was designed and developed to fulfill the guiding magnetic field requirement of the high-power microwave devices. First, the basic principle of the supercapacitor magnetic field system was briefly introduced. Then the main parameters of the power supply and solenoid were discussed and calculated in detail. In the end, through the simulation and experiment, we verified that the magnetic field system based on supercapacitor could well meet guiding magnetic need. Finally, the roadblock and outlook of this magnetic system were analyzed generally. The method in this research would have certain reference value for the design of similar magnetic systems. [ABSTRACT FROM AUTHOR]

This brief presents a low-power fast-transient capacitor-less low-dropout regulator (CL-LDO) for system-on-a-chip applications. A low-quiescent-current class-AB amplifier with embedded slew-rate enhancement (SRE) circuit is proposed to improve both current efficiency and load transient performance. As the SRE circuit is directly controlled by the amplifier, only a minimum hardware overhead is required. The proposed CL-LDO is fabricated in a 0.18- ${\mu }\text{m}$ standard CMOS process. It occupies an active area of 0.031 mm2 and consumes a quiescent current of $10.2~\mu \text{A}$. It is capable of delivering a maximum load current of 100 mA at 1.0-V output from a 1.2-V power supply. The measured results show that a settling time of $0.22~\mu \text{s}$ is achieved for load steps from 1 mA to 100 mA (and vice versa) with an edge time of $0.1~\mu \text{s}$. [ABSTRACT FROM AUTHOR]

This paper considers the joint design of transmit waveforms and receive filters for airborne multiple-input-multiple-output (MIMO) radar systems. The aim is to maximize the output signal-to-interference-plus-noise ratio (SINR) such that we can achieve enhanced detection performance for a slow-moving target that might be obscured by clutter and jamming. We devise a cyclic algorithm to tackle the non-convex joint design problem. Considering practical implementation issues, we extend the algorithm to deal with constrained designs (i.e., the design of waveforms under a constant-envelope constraint and a similarity constraint, respectively). The convergence of all the devised algorithms is guaranteed. We provide several numerical examples to demonstrate the effectiveness of the proposed algorithms. [ABSTRACT FROM PUBLISHER]

This paper investigates graph spectral approaches to the problem of point pattern matching. Specifically, we concentrate on the issue of how to effectively use graph spectral properties to characterize point patterns in the presence of positional jitter and outliers. A novel local spectral descriptor is proposed to represent the attribute domain of feature points. For a point in a given point-set, weight graphs are constructed on its neighboring points and then their normalized Laplacian matrices are computed. According to the known spectral radius of the normalized Laplacian matrix, the distribution of the eigenvalues of these normalized Laplacian matrices is summarized as a histogram to form a descriptor. The proposed spectral descriptor is finally combined with the approximate distance order for recovering correspondences between point-sets. Extensive experiments demonstrate the effectiveness of the proposed approach and its superiority to the existing methods. [ABSTRACT FROM PUBLISHER]

This paper investigated the bacterial inactivation/sterilization effects of a gas-liquid gliding arc discharge reactor, which created plasma at atmospheric pressure and ambient temperature. Bacteria Escherichia coli were subjected to plasma treatment and the survivability was examined. With the bacteria suspension circulated at defined flow rate, the E. coli cells were almost killed in <3 min. The inactivation efficiency with circulation was much higher than that with no circulation, and it could even reach a reduction of 7 logarithm units in the number of viable bacteria within 30 s after 1-min treatment. Flow rates of the suspension caused slightly impact on the bacteria inactivation to a certain extent. Observations of scanning electron microscopy images helped to draw a conclusion that gas-liquid gliding arc discharge plasma acts under various mechanisms driven essentially by oxidation and electric effect. The results demonstrate that gas-liquid gliding arc discharge allows a rapid and complete inactivation of E. coli bacteria in the water, which shows the great industrial interest of gliding arc discharge technique for decontamination. [ABSTRACT FROM PUBLISHER]