Robust backstepping controllers for linear motor drives

This work presents robust backstepping controllers to achieve position tracking control of a linear motor drive system with parameter uncertainties, discontinuous frictional force, and unknown external disturbance. First, a robust control scheme is developed to provide asymptotic stability under tracking control of the linear drive system. The assumption of a constant upper bound on the disturbance during the control design can lead to an overly conservative controller. To avoid this, an adaptation mechanism has been proposed to adapt the upper bound based on the current state measurement and the delayed state and input variables. The developed control scheme was shown to provide a global asymptotic stability of the closed-loop linear motor drive system. The control strategies are evaluated by numerical simulation of the linear motor drive. The simulation results show that the use of the adaptive disturbance upper bound adjustment technique results in significant performance improvement

International Financial Reporting Standards’ Adoption and Financial Statement Effects: Evidence from Listed Deposit Money Banks in Nigeria

The motivation of this study is derived from prior studies which relate to the investigation of IFRS impact on the financial statements of banks. It examines the effects of the adoption of the International Financial Reporting Standards on the financial statements of banks. A regression model is estimated using pooled data and fitted with dependent variables. The results show that IFRS adoption has positively impacted some variables in the financial statement of banks, for example, profitability and growth potential. The paper also reveals that given the fair value perspective of IFRS, the transition to IFRS brings instability in income statement figures. Future research may identify the specific provisions of IFRS that are responsible for the positive impact on financial performance measures. Such detailed knowledge is useful to standard setters who may wish to improve existing accounting standards. Further research should extend the sample size and the time horizon of the study in order to add to the findings reported here. Keywords: IFRS, financial statement, income statement, fair value, profitability, growth, financial performance measures

Offset-free model predictive control: a study of different formulations with further results

This paper presents discussions on offset-free model predictive control (MPC) methods for linear discrete-time systems in the presence of deterministic system disturbances. The general approach is based on the use of a disturbance model and an observer to estimate the disturbance states. The recent development in offset-free MPC has established the equivalence of the velocity form (without output delay) to a specific choice of the disturbance model and observer. In this note, it was shown that this particular disturbance model and observer is not necessarily equivalent to the velocity form with output delay. Nevertheless, it was shown that the velocity form with output delay is equivalent to a different choice of the disturbance model and observer. An import of this result is that the velocity forms (with and without delayed output) belong to the same general approach - disturbance model and observer. Furthermore, areas that may be considered in future researches are also highlighted

Financial System Broadening and Economic Performance

A considerable amount of scholarly works have examined the link between financial system broadening and economic performance using varieties of econometric models. Although, most of these studies have concentrated attention on the developed economies, very few have examined the impact on emerging economies. In Nigeria, some efforts have been made, though not comprehensive enough to model this nexus. This has created gap in the literature which needs to be filled. It is in view of this that this study examines the tie between financial system broadening and economic performance. The time series data was collected from the Central Bank of Nigeria Statistical Bulletins covering a period of 55 years (1960 – 2014) and analyzed using descriptive statistics, Pearson’s correlation using SPSS 22, and multiple regression analysis using Eviews 8.0. The findings reveal that financial system broadening via aggregate money supply has positive effect on the economic performance. However, financial system broadening via credit to private sector has a negative effect on the economic performance. The study also finds that money supply is positively correlated with economic performance. Private sector credit also shows a positive relationship with economic performance. The study was limited by including only fifty-five years in the selection of period covered, making this possibly biased selection and it may not be adequate to generalize the results for Nigeria. The study has contributed to the economic performance literature with a better understanding of the role of financial system deepening and its association with economic performance. This study provides valuable knowledge to policy makers and economic managers, to refine their current policies and subsequently improve financial system broadening and economic performance. Keywords: Economic performance, financial system broadening, Nigeria

Biomass Yield and Nutritive Quality of \u3cem\u3ePanicum maximum\u3c/em\u3e in the Natural Pastures during the Dry Season in Abeokuta, Nigeria

Panicum maximum Jacq. is among the prominent grass species in the grazing lands of the South-western part of Nigeria. An understanding of cutting management to find out the best agronomic practices that will improve the yield and nutritive value of these grass species, especially in the dry season formed the focus of this research work. The objective of the research is therefore to evaluate the effects of cutting height and interval on the dry matter yield (DMY), digestibility and chemical composition of P. maximum in the natural pasture during the dry season

StrathVoyager Student Team Technical Report to NJORD Challenge 2023

Starting from basic design and operational concepts on paper, as modular ASV was designed and built within approximately 12 months on a budget of around £5000. The boat participating in the Njord competition features a catamaran design comprised of two custom designed NPL hulls. The catamaran platform was designed to be fully modular and is constructed with 3D-printed hulls and carbon fibre decks. The platform is propelled using a static dual-thruster configuration. Computation is facilitated by an Nvidia Jetson, a Raspberry Pi 4B, and an Arduino MEGA. The system is powered by two custom-made 5S BMS 21V Li-Ion battery packs. The navigation sensor system consists of an Ouster OS32 3D Lidar with a built-in IMU, a Stereovision Zed Mini depth camera, an Adafruit Ultimate GPS Module PA1616D, and an Adafruit BNO055 Absolute Orientation Sensor. Further internal sensors, including voltage, current sensors, as well as a temperature sensor, are integrated. The ASV connects wirelessly to a remote control via an nRF2401 module, and to a laptop for operation monitoring via Holybro Telemetry Sik radio. Autonomous operation is enabled through sensor fusion of camera and Lidar information to identify environmental features, such as waypoints, and to generate virtual waypoints for the autonomous control system. The autonomous control system consists of an in-house developed deep reinforcement learning (DRL) algorithm that enables Line of Sight operation, as well as obstacle avoidance. As a backup, a general PID LOS waypoint tracking controller is also implemented in parallel. Extensive lab and pond testing has been carried out to develop and refine the system. Key features and innovations of the StrathVoyager ASV include: • Fully modular 3D printed and carbon fibre ASV. • Depth camera and 3D lidar sensor fusion for autonomous control. • DRL-based autonomous control

Autonomous underwater vehicle positioning control - a velocity form LPV-MPC approach

In this work, the positioning control of an autonomous underwater vehicle (AUV) is considered for docking operations in the presence of varying tidal currents. The AUV model is described by a dynamic model and a kinetic model, both are linear parameter varying (LPV). A velocity form LPV model predictive control (LPV-MPC) scheme is proposed, in which the AUV dynamic model is used for the states and the kinetic model is used for the output. The interdependence of AUV kinematic model and dynamic model is exploited to avoid increased state dimension. The complete velocity form controller design enables the cancellation of disturbance effects through the use of the AUV's velocity vector increment for predicting the future evolution of the system. Compared to the original predictive control for the Naminow-D AUV that uses a time-varying Kalman filter for state estimation to approximate disturbances, the proposed algorithm does not require an estimator to eliminate unknown current disturbance, therefore simplifies design and implementation. Simulation studies show the merit of the proposed controller over the original Naminow-D predictive controller especially in terms of improved transient response and reduced sensitivity to time-varying external disturbances

Fin control for ship roll motion stabilisation based on observer enhanced MPC with disturbance rate compensation

In this paper, a disturbance observer enhanced model predictive controller (MPC) which compensates for the wave-induced disturbance magnitude and rate is proposed for the ship roll motion stabilisation problem. The velocity model of the ship roll motion is used in the controller design to handle slowly varying modelling uncertainties and external disturbances. The rate of change of the disturbances induced by waves is then attenuated by formulating a control input that incorporates the estimated disturbance rate such that it is always in opposition to the rate of the environmental disturbances. The disturbance estimation was achieved by designing an observer based on convex optimisation formulated as an H2 minimisation problem. Numerical simulation studies, under various conditions of the sea, showed the effectiveness of the proposed MPC scheme in reducing the undesired ship roll motion induced by sea waves