LbCS navigation controllers of Twining Lagrangian swarm individuals

This paper presents stabilizing velocity controllers for the individuals of two Lagrangian swarms, which navigates from their initial configuration space to their final configuration space, ensuring intra and inter swarm individual collision avoidance. The motion of the individuals is based on Reynold's rules of separation, alignment, and cohesion. Using the three pillars (safety, shortest and smoothest path) of Lyapunov based control scheme (LbCS), the velocity controllers of the individuals of the two swarms are derived from multiple Lyapunov functions. The effectiveness of the controllers is validated through computer simulations

Navigation of an n - link revolute robotic arm via hierarchal landmarks

This paper presents a dynamic n-link revolute robotic arm that can perform a sequence of tasks and navigate via hierarchal landmarks to its target. The stability condition with multiple Lyapunov functions for switched systems is considered. The multiple Lyapunov functions are formulated from the Lyapunov-based Control Scheme (LbCS) as a tool for analyzing Lyapunov stability. A new set of switched nonlinear, time-invariant, continuous, and stabilizing velocity controllers of the proposed R n robotic arm are developed

Lyapunov - based controllers of an n - link Prismatic Robot Arm

This research provides a generalized stabilizing velocity controllers for planer robot arm with a base rotational joint and n∈N translation joint for navigation. The end-effector of the planer robot arm has to navigate from an initial to a final configuration space in an environment, which cluttered with obstacles. The velocity controllers are developed from a Lyapunov function, total potentials, designed via Lyapunov-based control scheme (LbCS) falling under the classical approach of artificial potential fields method. The effectiveness of the controllers is validated through computer simulations

A car - like mobile manipulator with an n - link Prismatic Arm

In this research, the Lyapunov based Control Scheme (LbCS) is used to solve the motion planning and control problem of a car-like mobile robot with a long extendible prismatic arm comprising n∈N links. The prismatic arm consists of a base revolute joint and n∈N translational joints, and is mounted on the wheeled car-like mobile platform. The kinematic model of the manipulator is developed, and velocity based algorithms are utilized to firstly, move the car-like base from an initial position to its pseudo-target and secondly, maneuver the end-effector to its designated target, taking into account the restrictions and limitations of the prismatic links and the steering control laws of the system. Computer simulations are presented to illustrate the effectiveness of the proposed control laws

An overview of sea cucumber fishery management in the Fiji Islands

The Fijian sea cucumber fishery began in the early 1800's in response to demand from Asian markets for bêche-de-mer. The fishery has shown classic 'boom and bust' production cycles for much of its life. From 1984-2012 a total of 8,620 t of bêche-de-mer were exported from Fiji. Particularly large volumes were exported in 1987 (>600 t), 1988 (>700 t) and 1996 (>600 t) and declines in export volumes are notable following these peaks. Subsequent export peaks of around 400 t in 2005 and 2011, are considerably lower than those in the 1980s and 1990s and after 2005, annual exports averaged 243 t. Between 2003 and 2012 export volumes of high value species declined from 14-8%, while that of medium value species increased from 50-59%. Sandfish (Holothuria scabra) appeared on export manifests in 2003 and 2004 despite an export moratorium for this species. Despite numerous recommendations to improved sustainability of the Fijian sea cucumber fishery, management measures consist primarily of an export size limit of 7.62 cm for bêche-de-mer. Over-exploitation of the resource and declining sea cucumber stocks have resulted. A historic overview of the Fijian sea cucumber fishery was provided within the context of the various fishery management approached adopted by other South Pacific Island nations. It includes data gathered by interviews with sea cucumber fishermen, bêche-de-mer processors and other stakeholders and makes recommendations for an effective management plan for a fishery that is an important livelihood activity for coastal communities in Fiji

Switch controllers of an n - link revolute manipulator with a prismatic end effector for landmark navigation

Robotic arms play an indispensable role in multiple sectors such as manufacturing, transportation and healthcare to improve human livelihoods and make possible their endeavors and innovations, which further enhance the quality of our lives. This paper considers such a robotic arm comprised of n revolute links and a prismatic end-effector, where the articulated arm is anchored in a restricted workspace. A new set of stabilizing switched velocity-based continuous controllers was derived using the Lyapunov-based Control Scheme (LbCS) from the category of classical approaches where switching of these nonlinear controllers is invoked by a new rule. The switched controllers enable the end-effector of the robotic arm to navigate autonomously via a series of landmarks, known as hierarchal landmarks, and finally converge to its equilibrium state. The interaction of the inherent attributes of LbCS that are the safeness, shortness and smoothness of paths for motion planning bring about cost and time efficiency of the controllers. The stability of the switched system was proven using Branicky’s stability criteria for switched systems based on multiple Lyapunov functions and was numerically validated using the RK4 method (Runge–Kutta method). Finally, computer simulation results are presented to show the effectiveness of the continuous time-invariant velocity-based controllers

Recovery rates for eight commercial sea cucumber species from the Fiji Islands

Determination of the original weight and length of sea cucumbers processed and dried to become bêche-de-mer (BDM), is an important tool in sea cucumber fishery management. The only management mechanism for the sea cucumber fishery in the Fiji Islands is a minimum length prescribed for BDM for export. However, different commercial species have different shrinkage rates during processing and previous studies have suggested modification of fisheries management for sea cucumbers to include species-specific minimum harvest size limits This study determined weight-based and length-based recovery rates (i.e. the length/weight of BDM recovered after processing from the initial length/weight of fresh sea cucumber), for eight commercial sea cucumber species following processing to BDM; White Teatfish (Holothuria fuscogilva), Black Teatfish (Holothuria whitmaei), Tigerfish (Bohadschia argus), Surf Redfish (Actinopyga mauritiana), Hairy Blackfish (Actinopyga miliaris), Stonefish (Actinopyga lecanora), Prickly Redfish (Thelenota ananas) and Sandfish (Holothuria scabra). Length and weight recovery rates varied between species and ranged from the highest recovery values of 54.9% for length and 11% for weight in Black Teatfish, to the lowest recovery values of 32.6% for length and 3.0% for weight in Sandfish and Tigerfish, respectively. Length-based and weight-based relationships were generated for each species through the various stages of processing from fresh to dried (BDM) allowing estimation of initial fresh weight/length from partially or fully processed BDM and vice versa. Information generated in this study provides a basis for developing more species-specific harvest size restrictions for sea cucumbers in the Fiji Islands, and has application in stock assessment studies, estimation of harvest data, monitoring of harvest size limits and standardizing catch data

Computational intelligence approaches for energy load forecasting in smart energy management grids: state of the art, future challenges, and research directions and Research Directions

Energy management systems are designed to monitor, optimize, and control the smart grid energy market. Demand-side management, considered as an essential part of the energy management system, can enable utility market operators to make better management decisions for energy trading between consumers and the operator. In this system, a priori knowledge about the energy load pattern can help reshape the load and cut the energy demand curve, thus allowing a better management and distribution of the energy in smart grid energy systems. Designing a computationally intelligent load forecasting (ILF) system is often a primary goal of energy demand management. This study explores the state of the art of computationally intelligent (i.e., machine learning) methods that are applied in load forecasting in terms of their classification and evaluation for sustainable operation of the overall energy management system. More than 50 research papers related to the subject identified in existing literature are classified into two categories: namely the single and the hybrid computational intelligence (CI)-based load forecasting technique. The advantages and disadvantages of each individual techniques also discussed to encapsulate them into the perspective into the energy management research. The identified methods have been further investigated by a qualitative analysis based on the accuracy of the prediction, which confirms the dominance of hybrid forecasting methods, which are often applied as metaheurstic algorithms considering the different optimization techniques over single model approaches. Based on extensive surveys, the review paper predicts a continuous future expansion of such literature on different CI approaches and their optimizations with both heuristic and metaheuristic methods used for energy load forecasting and their potential utilization in real-time smart energy management grids to address future challenges in energy demand managemen

Evaluating teacher-developed test and student achievement in an undergraduate statistics course: An action research

In this study, we used an action research approach to ascertain the degree to which first year undergraduate students had achieved the course learning outcomes of a 100-level course in statistics. In order to achieve a valid interpretation of student achievement, the researchers first had to ensure that the examination items were of reasonable quality and the examination was reliable. We analysed student papers to arrive at specific item statistics such as discrimination index and item-rest correlations. We also checked the Cronbach’s alpha reliability for the overall test. Findings related to student achievement for each learning outcome suggest that three out of the six course learning outcomes were achieved to our satisfaction. The study provided useful points for reflection for us in terms of improving our own teaching using action research. For example, university teachers can reflect on ways of improving in content areas where students’ course learning outcomes were not met. In this particular study, we found that topics such as “confidence interval” and “probability” are areas in which students’ face greater difficulty and thus would require more attention from the teaching staff. These findings provide useful insights on how university teachers can evaluate their own pedagogical practices

A Stable Nonlinear Switched System for Landmark-aided Motion Planning

To guarantee navigation accuracy, the robotic applications utilize landmarks. This paper proposes a novel nonlinear switched system for the fundamental motion planning problem in autonomous mobile robot navigation: the generation of continuous collision free paths to a goal configuration via numerous land marks (waypoints) in a cluttered environment. The proposed system leverages the Lyapunov based control scheme (LbCS) and constructs Lyapunov like functions for the system’s subsystems. These functions guide a planar point mass object, representing an autonomous robotic agent, towards its goal by utilizing artificial landmarks. Extracting a set of nonlinear, time invariant, continuous, and stabilizing switched velocity controllers from these Lyapunov like functions, the system invokes the controllers based on a switching rule, enabling hierarchical landmark navigation in complex environments. Using the well known stability criteria by Branicky for switched systems based on multiple Lyapunov functions, the stability of the proposed system is provided. A new method to extract action landmarks from multiple landmarks is also introduced. The control laws are then used to control the motion of a nonholonomic car like vehicle governed by its kinematic equations. Numerical examples with simulations illustrate the effectiveness of the Lyapunov based control laws. The proposed control laws can automate various processes where the transportation of goods or workers between different sections is required