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In this article, a novel normal-skew mixture (NSM) distribution is presented to model the normal and/or heavy-tailed and/or skew nonstationary distributed noises. The NSM distribution can be formulated as a hierarchically Gaussian presentation by leveraging a Bernoulli distributed random variable. Based on this, a novel robust Kalman filtering framework can be developed utilizing the variational Bayesian method, where the one-step prediction and measurement-likelihood densities are modeled as NSM distributions. For implementation, several exemplary robust Kalman filters (KFs) are derived based on some specific cases of NSM distribution. The relationships between some existing robust KFs and the presented framework are also revealed. The superiority of the proposed robust Kalman filtering framework is validated by a target tracking simulation example. [ABSTRACT FROM AUTHOR]

Since the Gaussian-inverse Wishart hierarchical form has similar properties to Student’s $t$ distribution, we name it generalized $t$ distribution in this article. Based on this, a robust generalized $t$ distribution-based Kalman filter (GTKF) is proposed for state-space models that are eroded by state and measurement outliers. Different from the existing algorithms, the state transition and measurement likelihood densities are directly modeled as generalized $t$ distributions by employing the one-step smoothing strategy.An analytical closed-form solution can be obtained through the variational inference approach. Moreover, two variants of the proposed GTKF are also presented to apply to different engineering scenarios. Simulation and experimental examples demonstrate that the proposed GTKFs yield improved robustness over the existing algorithms. [ABSTRACT FROM AUTHOR]

In cooperative localization for autonomous underwater vehicles (AUVs), the practical stochastic noise may be heavy-tailed, and nonstationary distributed because of acoustic speed variation, multipath effect of acoustic channel, and changeable underwater environment. To address such noise, a novel heavy-tailed mixture (HTM) distribution is first proposed in this article, and then expressed as a hierarchical Gaussian form by employing a categorical distributed auxiliary vector. Based on that, a novel HTM distribution based robust Kalman filter is proposed, where the one-step prediction, and measurement likelihood probability density functions are, respectively, modeled as an HTM distribution, and a Normal-Gamma-inverse Wishart distribution. The proposed filter is verified by a lake experiment about cooperative localization for AUVs. Compared with the cutting-edge filter, the proposed filter has been improved by 50.27% in localization error but no more than twice computational time is required. [ABSTRACT FROM AUTHOR]

In this paper, an improved variational adaptive Kalman filter for cooperative localization with inaccurate prior information is proposed, in which the prior scale matrix of the one-step prediction error covariance matrix is adaptively estimated by using the expectation-maximization algorithm. A novel alternate iteration strategy is proposed to reduce the computational complexity of the proposed method. Convergence analysis and theoretical comparisons with the existing advanced adaptive Kalman filtering methods are also provided. Based on this, a new master-slave cooperative localization method is proposed. Lake experiment results of cooperative localization for autonomous underwater vehicles demonstrate the advantages of the proposed method over existing methods. Compared with the cutting-edge adaptive master-slave cooperative localization method, the proposed method has been improved by 22.52% in average localization error but no more than twice computational time is needed. [ABSTRACT FROM AUTHOR]

In cooperative localization for autonomous underwater vehicles (AUVs), the practical state and measurement noises may be non-stationary non-Gaussian distributed because of sensor outliers, multi-path effect of acoustic channel, and changeable underwater environment. In this paper, a couple of novel mixture distributions, i.e., the Gaussian-Slash mixture distribution and the Gaussian-generalized hyperbolic skew Student’s t mixture distribution, are proposed to model such state and measurement noises, respectively. By introducing two Bernoulli distributed random variables, both the proposed mixture distributions can be expressed as hierarchically Gaussian forms. Based on this, a novel mixture distributions based robust Kalman filter (MDRKF) is derived by exploiting the variational Bayesian inference. A lake experiment about the cooperative localization for AUVs demonstrated that the proposed MDRKF has better localization accuracy but higher computational complexity than the existing state-of-the-art filtering algorithms. [ABSTRACT FROM AUTHOR]

The present study evaluated the potential protective effects of puerarin and its associated mechanism on burn-induced myocardial damage. A total of 40 healthy adult Wistar rats were randomly divided into four groups: i) Sham; ii) burn; iii) burn + puerarin; and iv) puerarin. Serum levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 were measured using ELISA. Myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were determined in myocardial homogenates using a commercial assay kit. TUNEL staining and western blot analysis of cleaved and pro-caspase-3 were also performed to assess apoptosis. Activation of p38-MAPK, ERK, JNK and AKT were measured using western blot analysis. Left ventricular systolic pressure, maximum rates of increase/decrease in left ventricular pressure, creatine kinase MB activity and cardiac troponin T levels were found to be altered in the burn group 12 h after burn, which were reversed by puerarin treatment. Injection of puerarin following burn injury also reduced heart water content. Serum levels of IL-1β, TNF-α and IL-6 were significantly higher in the burn group compared with those in the sham group. Puerarin treatment reduced serum levels of IL-1β, TNF-α and IL-6, in addition to reducing MPO activity and MDA levels in myocardial tissues. Puerarin inhibited the activation of caspase-3, p38, ERK and JNK following severe burn, but elevated Akt activation following severe burn. In conclusion, puerarin improved cardiac function in rats following severe burn injury, which may be due to reduced myocardial injury, inhibition of cardiomyocyte apoptosis and reduced oxidative inflammatory stress; the MAPK and AKT signaling pathways are proposed to the underlying mechanism of these findings. [ABSTRACT FROM AUTHOR]

In this article, we focus on addressing the nonlinear filtering problem with large prior uncertainty but high measurement accuracy, which may be encountered in the application of tightly coupled global navigation satellite system (GNSS)/inertial navigation system (INS) integration. Although the existing methods, such as progressive Gaussian approximate filter (PGAF), can address this problem, it has poor estimation accuracy. To improve the estimation accuracy of PGAF, the step sizes as well as the measurement noise covariance matrix (MNCM) are jointly estimated based on the variational Bayesian approach, from which a novel PGAF with variable step size is developed. Tightly coupled GNSS/INS integration simulations illustrate that the proposed filter outperforms the existing methods both in estimation accuracy and rate of convergence. [ABSTRACT FROM AUTHOR]

Owing to its relatively low absorption loss and high data transmission rate, wireless blue light communication is becoming an increasingly attractive technology for underwater applications. Here, we demonstrate an underwater optical wireless communication (UOWC) system that communicates using blue light-emitting diodes (LEDs) with a dominant wavelength of 455 nm. Under the on-off keying modulation scheme, the waterproof UOWC system achieves a bidirectional communication rate of 4 Mbps based on the transmission control protocol (TCP) and exhibits real-time full-duplex video communication with a transmission distance of 12 m in a swimming pool, offering great potential for practical use in real-world scenarios, such as carried around or attached to an autonomous vehicle.

With recent advancements in deep ultraviolet (DUV) light-emitting diodes (LEDs) and solar-blind photodetectors, wireless DUV light communication is emerging as a novel technique, which can extend transmission ranges and avoid solar interference. Herein, a full-duplex, real-time wireless light communication system using 275 nm DUV LEDs is proposed. We adopted high-power DUV LEDs and designed a high-speed transmitter, a high-sensitivity receiver, and a main processing unit for the system. Furthermore, the DUV communication system, using a Reed-Solomon (RS) encoder and an on-off keying (OOK) modem with frequency control, achieves a 10 Mbit/s bidirectional data transmission rate within 5 m in free space, while a full-duplex video communication link is formed. The encapsulated DUV communication system described in this Letter provides a feasible scheme for confidential and anti-electromagnetic interference communication in Internet of Things (IoT) applications.

Celastrol (CEL) was shown to display anti-inflammatory properties, and played an important role in anti-apoptosis. There were inflammation mediated by cytokines and apoptosis distinctly in the progression of acute lung injury (ALI) burn-induced. This study was conducted to explore the role of CEL in ALI induced by burns. In order to induce burn injury, rats were exposed to a 92°C water bath for 18 seconds. After burn experiment, the Burn + Celastrol group received CEL, and vehicle (DMSO) was used to treat the rats from Burn + Vehicle group. And the Sham + Burn group received no treatment. Vascular protein leakage was detected by Evans blue (EB) concentration to evaluate the lung microvascular permeability. Then wet-to-dry lung weight ratio (W/D), and hematoxylin and eosin staining (H&E) were measured respectively to investigate interstitial edema, neutrophil recruitment, and histopathological changes in lung tissues burn-induced ALI. To explore the mechanism of action of CEL, we assessed levels of inflammatory cytokines by ELISA assay, TUNEL staining and western blotting. Then we detected apoptosis-related factors, including the amount of apoptotic cells, caspase-3 activity, and Bax or Bcl-xl, respectively. The pulmonary microvascular hyperpermeability, histopathological characteristics, and a high W/D were attenuated by CEL for burn-injury rats. The concentration of cytokines burn-induced ALI from tissues and serum were decreased by CEL. Furthermore, after CEL treatment, TUNEL-positive cells, the protein level of Bax and caspase-3 activity reduced, and the level of Bcl-xl in protein increased. In conclusion, in lung injury burn-induced, CEL has a positive effect on anti-inflammation and anti-apoptosis. Thus, CEL could be as a latent for the cure of ALI burn-induced., Competing Interests: None., (IJCEP Copyright © 2019.)