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)

Pemahaman pelajar tingkatan lima katering terhadap bab kaedah memasak dalam mata pelajaran teknologi katering

Bab Kaedah Memasak merupakan salah satu bab yang penting dalam mata pelajaran Teknologi Katering. Faktor terpenting adalah memastikan pelajar menguasai serta memahami konsepnya adalah melalui proses pengajaran dan pembelajaran yang betul. Tinjauan awal di Sekolah Menengah Teknik yang menawarkan Kursus Katering, menunjukkan bahawa kebanyakan pelajar sukar untuk menguasai dan memahami bab tersebut. Berdasarkan hasil tinjauan , pengkaji ingin mengenalpasti pemasalahan dalam memahami bab tersebut. Di samping itu juga, pengkaji ingin mengenalpasti adakah pencapaian pelajar dalam PMR, minat, motivasi dan gaya pembelajaran mempengaruhi pemahaman pelajar, Kajian rintis telah dilakukan terhadap 10 orang responden dengan nilai alpha 0.91. Ini menunjukkan kebolehpercayaan terhadap kajian di jalankan adalah tinggi. Responden adalah terdiri daripada 30 orang pelajar Tingkatan Lima (ERT) Sekolah Menengah Teknik Muar, Johor. Keputusan skor min keseluruhan menunjukkan pelajar berminat dan mempunyai motivasi ynag baik dalam bidang ini. Namun begitu, gaya pembelajaran yang diamalkan tidak sesuai dan antara pemyebab wujudnya pemasalahan dalam memahami bab Kaedah Memasak. Ujian kolerasi menunjukkan bahawa tidak terdapat sebarang hubungan signifikan antara pencapaian PMR pelajar dengan pemahaman bab tersebut. Sementara minat, motivasi dan gaya pembelajaran membuktikan ada hubungan signifikan dengan pemahaman pelajar dalam bab Kaedah Memasak

Nonlinear robust integral sliding super-twisting sliding mode control application in autonomous underwater glider

1016-1027The design of a robust controller is a challenging task due to nonlinear behaviour of the glider and surround environment. This paper presents design and simulation of nonlinear robust integral super-twisting sliding mode control for controlling the longitudinal plane of an autonomous underwater glider (AUG). The controller is designed for trajectory tracking problem in existence of external disturbance and parameter variations for pitching angle and net buoyancy of the longitudinal plane of an AUG. The algorithm is designed based on integral sliding mode control and super-twisting sliding mode control. The performance of the proposed controller is compared to original integral sliding mode and original super-twisting algorithm. The simulation results have shown that the proposed controller demonstrates satisfactory performance and also reduces the chattering effect and control effort

Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)

904-913This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases

Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)

This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases

A New Roll and Pitch Control Mechanism for an Underwater Glider

In this paper, a new roll and pitch control mechanism for an underwater glider is described. The mechanism controls the glider’s pitch and roll without the use of a conventional buoyancy engine or movable mass. It uses water as trim mass, with a high flow rate water pump to shift water from water bladders located at the front, rear, left, and right of the glider. By shifting water between the left and right water bladder, a roll moment is induced. Similarly, pitch is achieved by shifting water between the front and rear water bladders. The water bladders act not only as a means for roll and pitch control but as a buoyancy engine as well. This eliminates the use of a dedicated mechanism for pitch and roll, thereby improving gliding efficiency and energy consumption, as the glider's overall size is decreased since the hardware required is reduced. The dynamics of the system were derived and simulated, as well as validated experimentally. The glider is able to move in a sawtooth pattern with a maximum pitch angle of 43.5˚, as well as a maximum roll angle of 43.6˚ with pitch and roll rates increase with increasing pump rate

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

Autonomous Sailboat Navigation

The purpose of this study was to investigate novel methods on an unmanned sailing boat, which enables it to sail fully autonomously, navigate safely, and perform long-term missions. The author used robotic sailing boat prototypes for field experiments as his main research method. Two robotic sailing boats have been developed especially for this purpose. A compact software model of a sailing boat's behaviour allowed for further evaluation of routing and obstacle avoidance methods in a computer simulation. The results of real-world experiments and computer simulations are validated against each other. It has been demonstrated that autonomous boat sailing is possible by the effective combination of appropriate new and novel techniques that will allow autonomous sailing boats to create appropriate routes, to react properly on obstacles and to carry out sailing manoeuvres by controlling rudder and sails. Novel methods for weather routing, collision avoidance, and autonomous manoeuvre execution have been proposed and successfully demonstrated. The combination of these techniques in a layered hybrid subsumption architecture make robotic sailing boats a promising tool for many applications, especially in ocean observation

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 334)

This bibliography lists 254 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during February, 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance