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Based on past studies on the bank effect, the purpose of this paper is to use hydrodynamic principles to simulate the overtaking and the head-on encounter phenomenon of two ships.

The ship model used in this study was established through a computer aided design (CAD) tool. Computational fluid dynamics (CFD) package was used to simulate the hydrodynamic interaction effect of the overtaking and the head-on encounter situation between two ships of different speeds. The conditions for simulation include such parameters as the speed of the ship model, the distance between the ships, and the navigation time.

A chart is also used to demonstrate the two ships ' distribution of flow field and pressure, and to continually compare the changes in the sway force and the yaw speed. A relationship diagram of the overtaking and the head-on encounter process is also established to serve as a reference in maritime science in terms of research regarding the complex fluid dynamics that occurs when ships are merged with the sea.

The application of CFD simulation results presented in this study for the ship-ship interaction support the following major conclusions: first, it is evident from the two analysis charts of angular velocity, and sway force that the cycle gradually becomes shorter with the decrease of speed of the V1 vessel during the overtaking and the head-on process; this phenomenon is most significant when the ship width is at 0.5B. Second, the ship-ship interaction increase significantly for a S2S value of 0.5B. Thus, the results indicate that the ship-ship interaction effects must be taken into consideration when performing ship handling maneuvers involving passing and meeting.

This paper aims to discuss traffic patterns generated by swarms of robots while commuting to and from a base station.

The paper adopts a mathematical evaluation and robot swarm simulation. The swarm approach is bottom‐up: designing individual agents the authors are looking for emerging group behaviour patterns. Examples of group behaviour patterns are human‐driven motorized traffic which is rigidly structured in two lanes, while army ants develop a three‐lane pattern in their traffic. The authors copy army ant characteristics onto their robots and investigate whether the three lane traffic pattern may emerge. They follow a three‐step approach. The authors first investigate the mathematics and geometry of cases occurring when applying the artificial potential field method to three “perfect” robots. Any traffic pattern (two, three or more lanes) appears to be possible. Next, they use the mathematical cases to study the impact of limited visibility by defining models of sensor designs. In the final step the authors implement ant inspired sensor models and a trail following mechanism on the robots in the swarm and explore which traffic patterns do emerge in open space as well as in bounded roads.

The study finds that traffic lanes emerge in the swarm traffic; however the number of lanes is dependent on the initial situation and environmental conditions. Intrinsically the applied robot models do not determine a specific number of traffic lanes.

The paper presents a method for studying and simulating robot swarms.

This paper aims to describe the advancements of the activities that have been carried out, in the Cost-Optimized Avionics SysTem (COAST) project, to complete the design and in-flight demonstration of the Tactical Separation System (TSS), which is an automatic support system to the pilot’s decision-making, onboard on small air transport (SAT) vehicles under single pilot operations, in the separation management.

In the framework of the Clean Sky 2 funded project COAST, some enabling technologies for single pilot operations in the EASA CS-23 category vehicles are designed and demonstrated in flight. Among the relevant flight management technologies addressed in the project, the specific one devoted to the real-time support to pilot’s decision-making in maintaining the vehicle self-separation is the TSS, designed by the Italian Aerospace Research Centre.

The TSS design started in the year 2016 and has been completed in the year 2021 after successful in-flight demonstration in the dedicated flight test campaign. The system has been validated by means of several simulation campaigns and finally demonstrated its effectiveness in providing its intended functionalities (situational awareness, conflict detection, conflict resolution) to the pilot in real flight trials, involving the presence of real conflicting aircraft.

The TSS contributes enabling the implementation of single pilot operations in CS-23 category vehicles, thanks to the possibility to support the pilot with provision of consolidated traffic picture, detection of conflicting surrounding traffic and suggestion of suitable conflict resolution manoeuvre real-time during the flight, through dedicated human–machine interface designed on purpose. The TSS supports the new separation modes that are envisaged in the future SESAR ATM target concept, with particular reference to the possible delegation of the separation responsibility to the pilot.

The purpose of this paper is to solve the problem that mobile robots are still based on reactive collision avoidance in unknown dynamic environments leading to a lack of interaction with obstacles and limiting the comprehensive performance of mobile robots. A dynamic window approach with multiple interaction strategies (DWA-MIS) is proposed to solve this problem.

The algorithm firstly classifies the moving obstacle movement intention, based on which a rule function is designed to incorporate positive incentives to motivate the robot to make correct avoidance actions. Then, the evaluation mechanism is improved by considering the time cost and future information of the environment to increase the motion states. Finally, the optimal objective function is designed based on genetic algorithm to adapt to different environments with time-varying multiparameter optimization.

Faced with obstacles in different states, the mobile robot can choose a suitable interaction strategy, which solves the limitations of the original DWA evaluation function and avoids the defects of reactive collision avoidance. Simulation results show that the algorithm can efficiently adapt to unknown dynamic environments, has less path length and iterations and has a high comprehensive performance.

A DWA-MIS is proposed, which increases the interaction capability between mobile robots and obstacles by improving the evaluation function mechanism and broadens the navigation strategy of DWA at a lower computational cost. After real machine verification, the algorithm has a high comprehensive performance based on real environment and provides a new idea for local path planning methods.

THE airborne Eros II Collision Avoidance System (CAS) designed and produced by McDonnell Douglas Corporation is actuated when the computer calculates the aircraft is within 25 sec of or ½ mile of another aircraft whichever event occurs first. At the same time, the pilot of one of the aircraft gets a command to climb while the pilot of the other aircraft is instructed to descend, thus avoiding a potential mid‐air collision.

This paper aims to present a finite element formulation to approximate systems of reaction–diffusion–advection equations, focusing on cases with nonlinear reaction. The formulation is based on the orthogonal sub-grid scale approach, with some simplifications that allow one to stabilize only the convective term, which is the source of potential instabilities. The space approximation is combined with finite difference time integration and a Newton–Raphson linearization of the reactive term. Some numerical examples show the accuracy of the resulting formulation. Applications using classical nonlinear reaction models in population dynamics are also provided, showing the robustness of the approach proposed.

A stabilized finite element method for advection–diffusion–reaction equations to the problem on nonlinear reaction is adapted. The formulation designed has been implemented in a computer code. Numerical examples are run to show the accuracy and robustness of the formulation.

The stabilized finite element method from which the authors depart can be adapted to problems with nonlinear reaction. The resulting method is very robust and accurate. The framework developed is applicable to several problems of interest by themselves, such as the predator–prey model.

A stabilized finite element method to problems with nonlinear reaction has been extended. Original contributions are the design of the stabilization parameters and the linearization of the problem. The application examples, apart from demonstrating the validity of the numerical model, help to get insight in the system of nonlinear equations being solved.