Search

This paper proposes a smoothed DGWW global planning method based on the BAS algorithm to optimize the GWO algorithm to solve the problem of the poor local path and low convergence speed in a complex environment of unmanned ships route planning. This method integrates the method of using the two tentacles on the head of the beetle to perform the optimal search in the BAS algorithm into the GWO algorithm so local optimization can be avoided. Then, the Bezier curve is used in the acute angle removing in the path and realistic path matching. The simulation results show that: the DGWW algorithm has a smoother path, fewer turning points, and a larger search range compared with the GWO algorithm; it can produce a better path, and the local exploration is more detailed compared with the BAS algorithm.

In this paper, the design principles of sensor data flow in ship information system (SIS) structure are researched. In order to save communication resources to achieve the practicable maximum without sacrificing the expected performance of system, an observability analysis-based setting method is proposed to shorten the length of each sensor data flow. In addition, according to the determined data flow length, a scheduling algorithm is presented to set the content of data flow as well. This scheduling algorithm is based on a double-index evaluation method, which includes the variation of sensor data during assigned steps, meanwhile the deviation between estimated value and real value of observation is considered as well. Besides these, algorithm and hardware realization examples are provided at the end of this paper. 1. Introduction The past three decades have witnessed the rapid spreading of a ship information system (SIS) architecture in which sensors and actuators exchange information with a Command Control Interface (CCI) through a communication network. Based on such wide-scale networks, ship control/monitoring systems (such as Integrated Bridge System, Standard Machinery Control System) are able to be linked together. These technological advances make it possible to create a highly integrated real-time control architecture in a modern ship (Geer 2009). As a result, several SISs have been widely applied in different types of ships, e.g., RICE (Lister and Rosie 1995), Ship System 2000 (Källberg and Stråhle 2001), GEDMS (Meier and Manfredi 2006), FORCEnet (Waters et al. 2005), and Total Ship Computing Environment (Henry et al. 2009). For most designers, the SIS is more like a special application case of Supervisory Control and Data Acquisition (SCADA) system, the theory research of SIS is scattered and immethodical. However, there also exist several differences in normal SCADA system and SIS. For example, the connection principle between distributed controller units (DCUs) and remote terminal units in SIS is mere proximity instead of task relation, which has reduced the difficulty of planning and laying networks greatly, but increases the complexity of every control processes in SIS, most missions in SIS are designed to be completed by several DCUs cooperatively. Such structure has been summarized briefly by Liu et al. (2014a). Mostly, a SIS could be regarded as a wide-scale sensor/actuator network under a highly integrated structure in the ship environment, which increases the importance of sensor information obtaining ability. In recent years, the U.S. Naval Research Laboratory has developed a multisensory real-time detection system for situational awareness named "Volume Sensor" (Minor et al. 2007). This designed framework can serve as a template for a variety of real-time sensing and situational awareness applications.

After decades of research, X-band marine radars have been broadly used for wind measurement. For retrieving the wind direction based on the wind-induced streaks, a lot of effort has been expended on three celebrated approaches&mdash, the local gradient method (LGM), the adaptive reduced method (ARM), and the energy spectrum method (ESM). This paper presents a scientific study of these methods. The contrast of retrieving the real measured marine radar images and vane measured results is evaluated, in perspective of the error statistics and algorithm operation efficiency. Interference factors, such as the historical information of the measured area, reference wind speed, and sea condition showing in the monitoring equipment are also concerned. The tentative results showed that LGM is robust, which can be implemented in most radar images, because it allows for a lower selection of requirements compared with the other two methods. For ARM, the better retrieval performance is a tradeoff with extra computation, which is expensive. ESM is superior to the other two algorithms in terms of accuracy and computation load, however, this algorithm is sensitive in rain-contaminated radar images, meaning it is a good choice for data post-processing in the lab.

This paper proposes a risk evaluation method for ship micro grid with distributed generations. Firstly, a unit risk evaluation method is proposed, including the evaluation system establishment principle, calculation method of component risk parameters and index weight. Secondly, according to the risk evaluation method, the risk evaluation model of ship micro grid is established. After that, taking an actual ship micro grid as an example, the simulation is carried out under the conditions of strong illumination with wind and weak illumination with no wind. Finally, the simulation results show that PV and Wind power can improve the robustness of ship micro grid under power fluctuations, reduce the risk occurrence probability and expected demand not supplied of ship micro grid. This is consistent with the actual situation of ship micro grid, and verifies the correctness of the method.