In the field of signal processing such as system identification, the affine projection algorithm (APA) is extensively implemented. However, running such algorithms in a non-Gaussian scenario may degrade its performance, since the second-order moment cannot extract all information from the signal. To prevent performance degradation of the algorithm in system identification tasks, we propose a novel APA based on least mean fourth (LMF) algorithm. The new algorithm, namely affine projection least mean fourth algorithm (APLMFA) is based on the high-order error power (HOEP) criterion and as such, can achieve improved performance. We also provide a convergence analysis for APLMFA. Numerical simulation results verify the presented APLMFA achieves smaller steady-state error as compared with the state-of-the-art algorithms.

The adaptive algorithms have been widely studied in Gaussian environment. However, the impulsive noise and other non-Gaussian noise may largely deteriorate the performance of algorithm in practical applications. To address this problem, in this paper, we propose two novel adaptive algorithms for system identification problem with mixed noise scenarios. Both proposed algorithms are based on the framework of the affine projection (AP) algorithm. The first proposed algorithm, termed as VS-APMCCA, combines variable step-size (VS) strategy and maximum correntropy criterion (MCC) to obtain improved performance. For further performance improvement, the VC-VS-APMCCA is developed, which is based on the variable center (VC) scheme of MCC. The convergence analysis of the VC-VS-APMCCA is conduced. Finally, simulation results demonstrate the superior performance of the VS-APMCCA and VC-VS-APMCCA.

Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC) has recently been considered as a key enabling technique for 5G cellular networks to satisfy future users’ network needs, such as ultra-high transmission rate, ultra-high throughput, ultra-low latency and ultra-high density connections. A group of users is allowed to share the same spectrum and multiplex the power domain to transmit data. In this paper, we investigate the optimization of bandwidth allocation and user grouping under the conditions of transmission power limit, bandwidth allocation limit, and user traffic requirements, so that the total resource consumption is minimized. The key idea to solve the problem is to use the layer structure of the problem and divide the problem into the optimization grouping problem and the bandwidth allocation problem. We propose a simulated annealing algorithm to solve the optimization grouping problem.

In this letter, we investigate the joint channel bandwidth and rate allocations for downlink non-orthogonal multiple access with the objective of maximizing the resource utilization efficiency (RUE). In particular, we take into account the utility of base station (BS) in serving the mobile terminals' traffic and the cost in consuming channel bandwidth and measure the RUE as the ratio between the BS's utility and the total power consumption. Despite the non-convexity of the joint optimization problem, we propose a three-layered vertical decomposition and design an efficient algorithm to compute the optimal solution. Extensive numerical results are provided to validate the performance of our proposed algorithms.

In order to obtain the three-dimensional (3D) distribution of fish in a marine ranching, a method using imaging sonar to calculate the 3D coordinates of fish is proposed in this paper. The imaging sonar used in this re-search is a Dual-frequency Identification sonar (DIDSON). It is a multi-beam sonar that uses acoustic lens to form individual beams. It constructs a high-definition two-dimensional image for target detection by transmitting ultra-sonic beams underwater and receiving the echo signals. It sets a new standard for excellence in underwater vision in black and turbid waters due to obtaining near-video quality dynamic images for the identification of objects un-derwater. In addition, split-beam echo-sounders have also been used on some occasions to monitor the movements of fishes. Despite the improvements achieved in fish monitoring techniques, the interpretation and classification of the data collected by the traditional acoustic techniques are often challenging and require extensive experience and effort. The DIDSON bridges the gap between existing fisheries-assessment sonar and optical systems. In a DID-SON, 96 transducer elements constitute a linear array and each element both transmits and receives acoustic beams such that echo amplitude is determined by the intensity of the reflected signal. It can obtain the distance and azi-muth of the target from sonar images, but it is unable to acquire the elevation of the target from the images. To overcome this difficulty and obtain the fish distribution, a new method is proposed. Firstly, the sonar is fixed on the outside of the ship′s rail and submerged in the water to collect fish′s information through the investigation on navigation. At the same time, the beam emission direction is on the same plane with the sonar′s moving direction. After data collection, image processing is conducted, including image construction, background elimination and target extraction from horizontal field-of-view. Target association based on Interacting Multiple Model Joint Prob-abilistic Data Association Filtering (IMMJPDAF) is carried out to deal with the extracted targets, thus the rela-tions of one target in different frame images can be obtained. The 3D target coordinates are acquired according to the spatial geometric relationship between the positions in two consecutive frame images. Finally, multiple target trajectories in 3D space and the depth distribution of targets are obtained through the correlation algorithm. The ex-periment was carried out in Dishui Lake which is located in Shanghai. Experimental results showed that the pro-posed method can effectively acquire the fish movement tracks in 3D space underwater and the distributions in depth. It also showed that most fish swam in the depth 3-5 meters. It will help to analyze the fish behavior and provide technical support for fishery resource assessment in a marine ranching.

This paper proposes an underwater visual simultaneous localization and mapping system using a stereo camera. In front-end, the image data is used to execute feature detection and matching. And the vehicle motion is estimated by the feature matching result. In back-end, a global optimization method represented by a graph, is used to eliminate the errors. The mapping result is in the from 3-D point cloud, which is established by the information from color image and depth image.

In this paper, a new method based on the dual-frequency identification sonar imaging is presented to estimate the abundance of fish. The proposed method can detect, track and count fish individually. Fish targets can be acquired with a depth-first search algorithm once its edge is detected based on the Sobel Operator from a complicated image. Multiple fish targets can be tracked using the nearest neighbor algorithm combined with the Extended Kalman Filtering. In order to validate the effectiveness of the proposed method, an experiment was conducted in Qingcaosha reservoir in Shanghai. The manual detection method based on sonar images was used as a reference method. The results showed that the fish were identified with less than 5% error compared with the manual detection results. The statistical error of fish numbers between the automated method and the reference method was approximately 10%.

This paper used DIDSON to get information of underwater fish and carried out the real-time multiple-target tracking, particularly the targets were dense. Analysis of fishery resources was also done through the data post-processing. Real-time data processing mainly included DIDSON image building/enhancement/filter, target detection and multiple-target tracking. Nearest neighbor clustering algorithm combined with Extended Kalman Filter was applied to the multiple-target tracking. Data post-processing mainly implemented the statistics of fish duration, swimming speed, swimming direction, trajectory length, which will provide strong technical support for the fishery resources assessment.

Along with the development of ocean technology, the development of ocean detection, monitoring and exploitation has been made. Ocean observation network is a mature, all-weather fixed observation platform, which can achieve real-time and long term monitoring of its observation range. With the forming of mobile observation network, the underwater helicopter as an important part of mobile observation network, is responsible for the transportation of energy and information. The contactless power transmission (CPT) system for underwater helicopter has special requirements, such as long gap, high efficiency and low voltage. According to the characteristics of CPT system for the underwater helicopter, this paper establishes and analyzes the theoretical model of the CPT system. An experimental CPT system for the underwater helicopter was designed. Based on the theoretical model, a computer simulation was conducted. The transmission efficiency model was established and analyzed. The primary line loss was the key factor affecting transmission efficiency. A method of improving transmission efficiency of the CPT system was proposed, that is by reducing the internal resistance of the primary and secondary coils could effectively reduce the loss of the whole system. The experiment showed that the trial result is consistent with the theoretical model calculations..

Autonomous Underwater Vehicle docking technology is now extensively used in the field of underwater. Vision guidance, as one of its core components, shows a great development prospect. In this paper, a brief description of the vision guidance models and the previous algorithm were described. Both the advantages and disadvantages of that algorithm would be analyzed. By using grey-scale feature analysis, edge detection and morphology methods, we attempted to improve the algorithm of calculating the centers of target lights, getting both robustness and accuracy of vision guidance system improved, which would make further mechanical control easier.

A mechanical model of undersea tunnel shotcrete positioning system is presented, by which the positioning error of the spray nozzle at each working point can be calculated. The entire process was divided into four phases, for each stage, the separate calculation and analysis were carried out, and the error distributions were obtained. Compared with the calculating results, the experimental data showed that the error distribution of the positioning system was consistent with the theoretical model predictions.

In the process of resolving financing difficulties of small and medium enterprises (SMEs) in China, the measurement of credit risk of SMEs is a very challenging problem. In this paper we develop a novel model based on the original KMV model with tunable parameters to measure the credit risk of Chinese listed SMEs. By setting two credit warning lines to monitor the credit crisis of listed SMEs, we find that the predictive accuracy of adjusted KMV model is stable to the change of default points in Chinese listed SMEs, which is different from KMV Company's existing result. Our study shows that the credit risk of listed SMEs in China is relatively high and tends to increase during the chosen period from the year 2004 to 2006. We also find that the asset size has significant impact on credit risk and there are few credit risk fluctuations before and after the split share structure reform.

The credit risk measurement of the Small and Medium Enterprises (SMEs) is a big problem in resolving their financing difficulties. In this paper, by improving the precision of parameters, we use the improved KMV model to identify the credit risk of listed SMEs in China. The model effectiveness test indicates that the KMV model after adjusting parameters is sensitive to the changes of credit risk, and it can accurately diagnose the ST companies in high credit risk. We monitor the credit crisis of listed SMEs by setting two credit warning lines. The results show that the credit of 50% listed SMEs below the second grade warning line should be noticed. And the credit of 90% listed SMEs below the first grade warning line should be on alert, and some remedy measures should be taken as soon as possible. Our study shows that the probability of default in listed SMEs is very large in China. The situation of credit is not optimistic, which have not changed much in latest three years, but the default risk trend to increase in 2006.