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Underwater images typically suffer from color deviations and low visibility due to the wavelength-dependent light absorption and scattering. To deal with these degradation issues, we propose an efficient and robust underwater image enhancement method, called MLLE. Specifically, we first locally adjust the color and details of an input image according to a minimum color loss principle and a maximum attenuation map-guided fusion strategy. Afterward, we employ the integral and squared integral maps to compute the mean and variance of local image blocks, which are used to adaptively adjust the contrast of the input image. Meanwhile, a color balance strategy is introduced to balance the color differences between channel a and channel b in the CIELAB color space. Our enhanced results are characterized by vivid color, improved contrast, and enhanced details. Extensive experiments on three underwater image enhancement datasets demonstrate that our method outperforms the state-of-the-art methods. Our method is also appealing in its fast processing speed within 1s for processing an image of size $1024\times 1024 \times 3$ on a single CPU. Experiments further suggest that our method can effectively improve the performance of underwater image segmentation, keypoint detection, and saliency detection. The project page is available at https://li-chongyi.github.io/proj [ABSTRACT FROM AUTHOR]

This paper presents an adaptive neural fault-tolerant control algorithm for the path-following activity of the underactuated surface vehicle (USV) using the novel output-based triggering approach. In the algorithm, the event-triggered mechanism is designed utilizing the attitude states from the kinematics aspect of USV. Both the control inputs and the related calculation thread are implemented only at the trigger instants. Furthermore, neural networks (NNs) are employed to remodel the model uncertainties, and the adaptive observer is developed to estimate and compensate for the effect of the unknown actuator faults. With the direct Lyapunov theorem, the semi-global uniformly ultimately bounded (SGUUB) stability can be guaranteed for the closed-loop system in aspects of both the trigger instant and the continuous interval. The comparison experiment has been illustrated to verify the effectiveness of the proposed algorithm, which can effectively improve the information transmission performance and the fault-tolerant capability. [ABSTRACT FROM AUTHOR]

The consensus control of second-order linear multi-agent systems with velocity constraint under directed graphs is investigated. In this brief, a new distributed sliding mode control scheme is proposed. The novelty of this scheme is that we integrate the logarithmic barrier function with the sliding surface, then the consensus is achieved by showing the convergence of the sliding variable to zero, meanwhile, the boundedness of the sliding variable indicates the velocity constraint is satisfied. With the proposed method, the semi-global consensus control of second-order linear multi-agent systems with velocity constraints can be easily achieved under directed graph. The effectiveness of the results is illustrated through a numerical example. [ABSTRACT FROM AUTHOR]

The finite-time formation control of second-order linear multi-agent systems subject to constraints on both relative positions and relative velocities is studied in this brief. A novel barrier function-based sliding mode control (BFSMC) method, in which the relative state constraints are embedded through the barrier function, is proposed. The boundedness of sliding variable guarantees the satisfaction of the relative state constraints, and the convergence of the sliding variable to zero ensures that the formation will be reached in finite time. The singularity in controller is avoided. The effectiveness of the results is illustrated through a numerical example. [ABSTRACT FROM AUTHOR]

In this article, an asynchronous output-feedback controller is proposed for a class of Markovian jump systems (MJSs) with generally bounded transition rates (TRs). Specifically, two cases have been considered, one of which assumes the TR being completely unknown, while the other specifies the TR range. In particular, the designed asynchronous output-feedback controller is independent of the system modes, implying a sustainable controlling behavior against unavailable system modes. It is worth noting that the mode-dependent controller can be treated as a special case of the independent one. Furthermore, the existing conditions of such a controller are acquired in terms of linear matrix inequalities. Finally a practical example, concerning a single-machine infinite-bus power system, is given to confirm the feasibility of the proposed controller. [ABSTRACT FROM AUTHOR]

This article presents a novel composite neural learning fault-tolerant algorithm to implement the path-following activity of underactuated vehicles with event-triggered input. With the input event-triggered mechanism, the dominant superiority is to reduce the communication burden in the channel from the controller to actuators. In the proposed scheme, the system uncertainties are dealt with in the fusion of the neural networks (NNs) and the dynamic surface control (DSC) method. The serial-parallel estimation model (SPEM) is constructed to estimate the error dynamics, where the derived prediction error could improve the compensation effect of the NNs. As for the gain uncertainties and the unknown actuator faults, four adaptive parameters are designed to stabilize the related perturbation and not be affected by the triggering instants. Based on the direct Lyapunov theorem, considerable efforts have been made to guarantee the semiglobal uniformly ultimately bounded (SGUUB) stability of the closed-loop system. Finally, comparison and practical experiments are illustrated to verify the superiority of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This article proposes a method on simultaneous estimation of the system fault and sensor fault for a kind of the Markovian jump system with generally uncertain transition rates. In order to estimate these system fault and sensor fault, we first design a novel reduced-order observer, in which the gain matrix can not only decouple the existed unknown input, but also compel the observer error dynamic system to be stable. Then, the existing conditions of the proposed observer are derived in terms of linear matrix inequalities, making the problem tractable. Finally, an example is provided to illustrate the effectiveness and validation of the proposed method. [ABSTRACT FROM AUTHOR]

Visual cognition of the indoor environment can benefit from the spatial layout estimation, which is to represent an indoor scene with a 2-D box on a monocular image. In this paper, we propose to fully exploit the edge and semantic information of a room image for layout estimation. More specifically, we present an encoder–decoder network with shared encoder and two separate decoders, which are composed of multiple deconvolution (transposed convolution) layers, to jointly learn the edge maps and semantic labels of a room image. We combine these two network predictions in a scoring function to evaluate the quality of the layouts, which are generated by ray sampling and from a predefined layout pool. Guided by the scoring function, we apply a novel refinement strategy to further optimize the layout hypotheses. Experimental results show that the proposed network can yield accurate estimates of edge maps and semantic labels. By fully utilizing the two different types of labels, the proposed method achieves the state-of-the-art layout estimation performance on the benchmark datasets. [ABSTRACT FROM AUTHOR]

For leader-following multiagent systems with input saturation, the existing protocols use a low gain feedback approach to achieve semi-global consensus. The main drawback of this approach is the ineffective utilization of the actuator potential, resulting in bad performance. To improve the transient performance of the consensus tracking, this paper proposes a gain scheduled approach for multiagent systems subject to the saturator saturations. A novel kind of scheduler-based protocols are proposed, which consists of state feedback controllers with time-varying gain and parameter schedulers. The role of the controllers is to achieve the consensus tracking, while the schedulers can accelerate this consensus progress by enlarging the gain parameter. To remove the dependence of the schedulers on global information, a minimum-value-based consensus algorithm is put forward, with idea of driving all values of agents throughout the network to their minimum value. Its implementation is guaranteed by the network-topology connectivity. Finally, our approach is further extended to the case where the leader’s control input is nonzero, time-varying, and bounded. The discontinuous protocol and its continuous approximation counterpart are designed, yielding the exact- and quasi-consensus tracking, respectively. Simulation results verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this brief, a sliding mode controller (SMC) established via a new adaptive reaching law is proposed for discrete-time systems. To guarantee a smaller width of the quasi-sliding mode domain (QSMD), disturbance of the system is estimated based on the second-order difference of historical observation information, and the reaching law is designed on the choice of a negative power term that adapts to the variations of the switching function. Dynamics of the controlled system both outside and within the QSMD are analyzed. [ABSTRACT FROM AUTHOR]

The setup for testing radiated disturbance induced by insulated gate bipolar transistor (IGBT) and auxiliary circuits was established. The radiated disturbance characteristics of auxiliary circuits and methods to suppress the radiated electromagnetic interference (EMI) were experimentally studied. The radiated EMI bandwidth of the auxiliary circuit was concentrated in the range 30–300 MHz. The mathematical model for an IGBT was proposed based on the setup, which includes all the structures of the IGBT in detail. The electric fields were calculated from the IGBT model using the method of moments. Moreover, the characteristics of the radiated disturbances due to the IGBT operation and the effects of metal on the radiated electric fields were experimentally and calculatingly studied in the frequency range 1–30 MHz. The metal shielded box of drive can increase the radiated electric fields by approximately 10–30 dB in the range 1–30 MHz. The electric fields for all the frequencies decreased rapidly with the increase of distance. Additionally, methods to shield the IGBT in order to suppress the radiated EMI were proposed. The effective radiated EMI reduction from a shielded net was approximately 20 dB, and that of a shielded box was around 30 dB. [ABSTRACT FROM AUTHOR]

This paper describes a distributed system for the partial discharge (PD) detection and location in the substation. The proposed system is composed of several ultrahigh-frequency (UHF) antennas located dispersedly that form an array. These antennas are connected to the central control room by the optical fiber using the radio over fiber (RoF) technique to decrease the propagation attenuation of the PD signal. The scattered layout increases the coverage of the PD signal sensing and the time difference of arrived PD signals propagating to the antennas. The signal processing part and PD location propose a virtual measurement method based on the statistical simulation. This method only uses a set of measured delay data to simulate and generate multiple sets of delay data by randomly adding the delay error, which follows a specific distribution within the limit range and uses these data to locate the PD source and statistically process the results of location. The actual positioning effect of this method is great, and the positioning accuracy and efficiency of the system are improved. The experimental results of an application case in a 220-kV substation show that this distributed UHF sensor array system can get the location accuracy of 1° when the system error of the time difference is less than 5 ns, which can meet the requirements of the PD detection and location in the entire substation. [ABSTRACT FROM AUTHOR]

This paper addresses the robust consensus reliable control problem against actuator faults for linear parameter-varying multiagent systems. First, the actuator faults are modeled via a polytopic uncertainty method. Second, a distributed observer is designed for the single agent by sharing the communication network sensors to estimate the state information. Then by these estimated information, a robust consensus reliable control protocol against actuator faults is obtained and desired disturbance rejection performance can be guaranteed by this proposed protocol. Third, the nonconvexity conditions of the consensus control protocol can be translated into an linear matrix inequality optimization problem via simple matrix calculation. Finally, the effectiveness of the proposed reliable controller scheme is illustrated by two examples. [ABSTRACT FROM AUTHOR]

This paper deals with the optimum dynamic positioning control problem for marine ships in the presence of actuator gain uncertainties and unknown environmental disturbances. The proposed approach is formulated as two modules, i.e., the guidance part and the control part. By utilizing the improved extremum seeking algorithm, the optimum-seeking guidance is developed in this note to generate the reasonable heading guidance for dynamic positioning ships. The main purpose of this design is to ensure the closed-loop system running efficiently and environment-friendly in practice. Combined with the proposed guidance principle, a robust neural control algorithm is developed based on the dynamic surface control, neural networks, and the robust neural damping technique. In this algorithm, the strong couplings of state variables and the gain uncertainty of actuators are tackled, and the system uncertainties are compensated requiring less (or no) information of the hydrodynamic structure, the actuator model and the external disturbances. Considerable effort is made to guarantee the semiglobal uniform ultimate bounded stability by employing the Lyapunov theory. The advantages of the proposed control scheme could be summarized as two points. First, the control approach is with the properties of optimization and energy-saving, which is meaningful for applying the theoretical algorithm. Second, the pitch ratio of thrusters is selected as the control inputs of interest, which is measurable in the practical plant. These characteristics would facilitate the implementation of the algorithm in engineering. Two examples are provided to verify the performance of the proposed scheme. [ABSTRACT FROM AUTHOR]

As reliability requirements become increasingly demanding for many engineering systems, conventional system reliability demonstration testing (SRDT) based on the number of failures depends on a large sample of system units. However, for many safety critical systems, such as missiles, it is prohibitive to perform such testing with large samples. To reduce the sample size, existing SRDT methods utilize test data from either system level or component level. In this paper, an aggregation-based SRDT methodology is proposed for hierarchical systems by utilizing multilevel reliability information of components, subsystems, and the overall system. Analytical conditions are identified for the proposed method to achieve lower consumer risk. The performances of different SRDT design strategies are evaluated and compared according to their consumer risks. A numerical case study is presented to illustrate the proposed methodology and demonstrate its validity and effectiveness. [ABSTRACT FROM AUTHOR]

The corridor of the high-voltage direct current transmission lines in China is very complex and there may be buildings near the lines. The conductivity of the building material may influence the electric field in the building. In this paper, based on the upstream FEM, a method is proposed to solve the coupled problem of the ion flow field in the air and the current field in the building model. The numerical results coincide with the analytic results and measurement results. The electric field in and on the building model is analyzed considering different conductivities. [ABSTRACT FROM PUBLISHER]

Poly-Si (p-Si) channel used in 3-D Flash memory devices is the main source of degraded performance, such as the high interface state density. Charge pumping (CP) signals in the 3-D nanoscale vertical device with p-Si channel are analyzed in this paper using the variable amplitude CP technique. For the first time, it has been demonstrated experimentally that the broad CP edge is due to the threshold voltage variation in the p-Si channel caused by both the trapping in interface states and the source/drain p-n junction diffusion, and their impacts can be separately evaluated. Hot carrier stress in the tunneling FET operation modes and statistical analysis are used to provide supporting evidence. [ABSTRACT FROM PUBLISHER]

Due to its importance and possible applications in visualization, tumor detection and preoperative planning, automatic small bowel segmentation is essential for computer-aided diagnosis of small bowel pathology. However, segmenting the small bowel directly on computed tomography (CT) scans is very difficult because of the low image contrast on CT scans and high tortuosity of the small bowel and its close proximity to other abdominal organs. Motivated by the intensity characteristics of abdominal CT images, the anatomic relationship between the mesenteric vasculature and the small bowel, and potential usefulness of the mesenteric vasculature for establishing the path of the small bowel, we propose a novel mesenteric vasculature map-guided method for small bowel segmentation on high-resolution CT angiography scans. The major mesenteric arteries are first segmented using a vessel tracing method based on multi-linear subspace vessel model and Bayesian inference. Second, multi-view, multi-scale vesselness enhancement filters are used to segment small vessels, and vessels directly or indirectly connecting to the superior mesenteric artery are classified as mesenteric vessels. Third, a mesenteric vasculature map is built by linking vessel bifurcation points, and the small bowel is segmented by employing the mesenteric vessel map and fuzzy connectness. The method was evaluated on 11 abdominal CT scans of patients suspected of having carcinoid tumors with manually labeled reference standard. The result, 82.5% volume overlap accuracy compared with the reference standard, shows it is feasible to segment the small bowel on CT scans using the mesenteric vasculature as a roadmap. [ABSTRACT FROM AUTHOR]

The ionized field under HVDC transmission lines is actually a 3-D field with considering the influence of wires sag, towers, up-and-downs on the ground, surrounding buildings and other situations and little of its calculation method has been reported. In this paper, a method to calculate the 3-D ionized field under HVDC transmission lines is proposed based on Deutsch's assumption which is simple, fast, and easy to use and the computation cost of which is low. After the validity of the method is testified, some examples are analyzed and some conclusion are given. [ABSTRACT FROM PUBLISHER]