Robust data assimilation in river flow and stage estimation based on multiple imputation particle filter

In this paper, new method is proposed for a more robust Data Assimilation (DA) design of the river flow and stage estimation. By using the new sets of data that are derived from the incorporated Multi Imputation Particle Filter (MIPF) in the DA structure, the proposed method is found to have overcome the issue of missing observation data and contributed to a better estimation process. The convergence analysis of the MIPF is discussed and shows that the number of the particles and imputation influence the ability of this method to perform estimation. The simulation results of the MIPF demonstrated the superiority of the proposed approach when being compared to the Extended Kalman Filter (EKF) and Particle Filter (PF)

A GAIN-SCHEDULED CONTROL SCHEME FOR IMPROVED MANEUVERABILITY AND POWER EFFICIENCY OF UNDERWATER GLIDERS

Underwater gliders are a relatively new type of low-power, long duration underwater vehicle that use changes in buoyancy to propel themselves forward. They are widely used today for oceanographic research, and a number of theoretical control schemes have been derived over the years. However, despite their nonlinear dynamics that evolve as a function of their environment and operating conditions, most fielded gliders use linear control methods, such as static-gain proportional-integral (PI) or proportional-integral-derivative (PID) compensators for motion control, which can significantly limit vehicle performance. This thesis develops an alternative approach to underwater glider control that employs control system gain-scheduling to improve vehicle performance and efficiency over a wider range of operating conditions as compared to static or fixed-gain approaches. The primary contribution of this thesis is the development of a practical gain-scheduling procedure using linearized models of the decoupled pitch and yaw dynamics of the vehicle. This methodology improves on the current fixed-gain topologies used on fielded gliders today, while being straightforward and cost-effective to implement. In this thesis, the development of a nonlinear dynamical model of a Slocum glider using computer-aided design (CAD) and computational fluid dynamics (CFD) simulations was also carried out to support the high-fidelity characterization of the controller topologies. A nonlinear numerical simulation of the Slocum glider was developed in Matlab and was used to assess the performance improvements and the increased robustness of the gain-scheduled PID method to a standard fixed-gain PID approach

Selected Papers from the 2018 IEEE International Workshop on Metrology for the Sea

This Special Issue is devoted to recent developments in instrumentation and measurement techniques applied to the marine field. ¶The sea is the medium that has allowed people to travel from one continent to another using vessels, even today despite the use of aircraft. It has also been acting as a great reservoir and source of food for all living beings. However, for many generations, it served as a landfill for depositing conventional and nuclear wastes, especially in its deep seabeds, and we are assisting in a race to exploit minerals and resources, different from foods, encompassed in it. Its health is a great challenge for the survival of all humanity since it is one of the most important environmental components targeted by global warming. ¶ As everyone may know, measuring is a step that generates substantial knowledge about a phenomenon or an asset, which is the basis for proposing correct solutions and making proper decisions. However, measurements in the sea environment pose unique difficulties and opportunities, which is made clear from the research results presented in this Special Issue