Design, implementation and characterisation of a contactless power transfer system for rotating applications

This paper describes the design, implementation and characterisation of a contactless power transfer system for rotating applications. The power transfer system is based upon a zero-voltage-switched, full-bridge, DC-DC converter, but utilises a non-standard transformer. This transformer allows power transfer between its primary and secondary windings while also allowing free rotation between these windings. The aim of this research is to develop a solution that could replace mechanical slip-rings in certain applications where a non-contacting system would be advantageous. Based upon the design method presented in this paper, a 2 kW prototype system is constructed. Results obtained from testing the 2 kW prototype are presented and discussed. This discussion considers how the performance of the transformer varies with rotation and also the overall efficiency of the system

Novel actuator design to overcome stiction and backlash for low-velocity applications

This paper presents a novel actuator design that ameliorates or eliminates the effects of non-linearities that are characteristically present in geared actuator systems and which are very problematic for low velocity applications. The design centres on the providing an internal rotational element within a single actuator to ensure operation of actuator away from the stiction region, whilst allowing zero velocity external output of the actuator. The construction has the added advantage of substantially reducing backlash. The prototype comprises two commercially available servo-actuators to test the principle of operation and results presented indicate that the concept is worth exploring further.

Clinical potential and design of programmable mechanical impedances for orthotic applications

A person with a moderate or severe motor disability will often use specialised or adapted tools to assist their interaction with a general environment. Such tools can assist with the movement of a person's arms so as to facilitate manipulation, can provide postural supports, or interface to computers, wheelchairs or similar assistive technologies. Designing such devices with programmable stiffness and damping may offer a better means for the person to have effective control of their surroundings. This paper addresses the possibility of designing some assistive technologies using impedance elements that can adapt to the user and the circumstances. Two impedance elements are proposed. The first, based on magnetic particle brakes, allows control of the damping coefficient in a passive element. The second, based on detuning the P-D controller in a servo-motor mechanism, allows control of both stiffness and damping. Such a mechanical impedance can be modulated to the conditions imposed by the task in hand. The limits of linear theory are explored and possible uses of programmable impedance elements are proposed.

The design of UV absorbing systems for horticultural applications

The synthesis and fluorescence behavior of a series of bis(trisilylalkyl)anthracene molecules is described. The photodegradation of these molecules under UV light has been monitored and compared to a commercially available fluorescent optical brightener. There is a relationship between the structure and the rate of photo decay. The materials with more bulky substituents exhibit the greater stability towards UV. For bis(triphenylsilyl)anthracene the photostability appears to be comparable with a commercially available optical brightener, but the molecule may be susceptible to thermal decay.

Approaches for multicopper oxidases in the design of electrochemical sensors for analytical applications

We report an effective approach for the construction of a biomimetic sensor of multicopper oxidases by immobilizing a cyclic-tetrameric copper(II) species, containing the ligand (4-imidazolyl)ethylene-2-amino-1-ethylpyridine (apyhist), in the Nafion (R) membrane on a vitreous carbon electrode surface. This complex provides a tetranuclear arrangement of copper ions that allows an effective reduction of oxygen to water, in a catalytic cycle involving four electrons. The electrochemical reduction of oxygen was studied at pH 9.0 buffer solution by using cyclic voltammetry, chronoamperometry, rotating disk electrode voltammetry and scanning electrochemical microscopy techniques. The mediator shows good electrocatalytic ability for the reduction of O(2) at pH 9.0, with reduction of overpotential (350 mV) and increased current response in comparison with results obtained with a bare glassy carbon electrode. The heterogeneous rate constant (k(ME)`) for the reduction of O(2) at the modified electrode was determined by using a Koutecky-Levich plot. In addition, the charge transport rate through the coating and the apparent diffusion coefficient of O(2) into the modifier film were also evaluated. The overall process was found to be governed by the charge transport through the coating, occurring at the interface or at a finite layer at the electrode/coating interface. The proposed study opens up the way for the development of bioelectronic devices based on molecular recognition and self-organization. (C) 2010 Elsevier Ltd. All rights reserved.

An investigation of the development of navigation design guidelines for online educational applications delivery to a primary school audience

Despite growing interest in educational websites for children, there has been surprisingly little research conducted into the design of websites intended for a younger audience. This research aims to determine how the design principles identified in the extant body of literature, might be fused with the development practices currently employed within a focus organisation (case study organisation), to synthesise and partially validate a set of website navigation design guidelines for use when developing website navigation for primary school students, between the ages of nine and twelve years.

Managing social and intellectual capital to inform design and development of learning objects : issues, applications and technologies

The purpose of this paper is to present and analyse a case example of the development and implementation of a digital learnmg object in context with academic literature in the field. The paper's content describes the creation of a multimedia learning object from conception in 2004 to completion m 2006. Provided is the rationale and outcome of a strategically funded University project aimed at illuminating an industrial case study of good management and communication practices for use in classrooms throughout the entire university. This paper is intended to act as a guide for others. Our experience as academics in successful dialogue With educational technologists will inspire and inform those embarking on similar projects, and aspects of it will generalise to development and implementation Issues for other kinds of learning objects.

Design and analysis of hull configurations for a low-cost, autonomous underwater robot as an enabling technology for system of system applications

The objective of this research is to model and analyze candidate hull configurations for a low-cost, modular, autonomous underwater robot. As the computational power and speed of microprocessors continue to progress, we are seeing a growth in the research, development, and the utilization of underwater robots. The number of applications is broadening in the R&D and science communities, especially in the area of multiple, collaborative robots. These underwater collaborative robots represent an instantiation of a System of Systems (SoS). While each new researcher explores a unique application, control method, etc. a new underwater robot vehicle is designed, developed, and deployed. This sometimes leads to one-off designs that are costly. One limit to the wide-scale utilization of underwater robotics is the cost of development. Another limit is the ability to modify the configuration for new applications and evolving requirements. Consequently, we are exploring autonomous underwater vehicle (AUV) hull designs towards the goal of modularity, vehicle dexterity, and minimizing the cost. In our analysis, we have employed 3D solid modeling tools and finite element methods. In this paper we present our initial results and discuss ongoing work.

Design and simulation of an interdigital-chaotic advection micromixer for lab-on-a-chip applications

This paper presents the design and simulation of a novel passive micromixer. The micromixer consists of two inlet tanks, one mixing channel and two outlet channels. In order to maximise the mixing efficiency, the following considerations are made: (i) The inlet tanks are followed by a series of microchannels, in which the flow is split. The microchannels are arranged in an interdigital manner to maximise the contact area between the two flows. (ii) The microchannels attached to the lower inlet tank have an upward slope while those attached to the upper tank have a downward slope. The higher-density flow is fed to the lower inlet tank and gets an upward velocity before entering the mixing channel. (iii) Two triangular barriers are placed within the mixing channel to impose chaotic advection and perturb the less-mixed flow along the top and bottom surfaces of the channel. (iv) Finally, two outlet channels are incorporated to discard the less-mixed flow. Three-dimensional simulations are carried out to evaluate the performance of the micromixer. Simulations are performed in the absence and presence of the gravitational force to analyse the influence of gravity on the micromixer. Mixing efficiencies of greater than 92% are achieved using water and a 1011'density biological solvent as the mixing fluids.

Design and simulation of an interdigital-chaotic advection micromixer for lab-on-a-chip applications

The paper presents the design and simulation of a novel passive micromixer. The micromixer consists of two inlet tanks, one mixing channel and two outlet channels. In order to maximise the mixing efficiency, the following considerations are made : (i) The inlet tanks are followed by a series of microchannels, in which the flow is split. The microchannels are arranged in an interdigital manner to  maximise the contact area between the two flows. (ii) The microchannels attached to the lower inlet tank have an upward slope while those attached to the upper tank have a downward slope. The higher-density flow is fed to the lower inlet tank and gets an upward velocity before entering the mixing channel. (iii) Two triangular barriers are placed within the mixing channel to impose chaotic advection and perturb the less-mixed flow along the top and bottom surfaces of the channel. (iv) Finally, two outlet channels are incorporated to discard the less-mixed flow. Three-dimensional simulations are carried out to evaluate the performance of the micromixer. Simulations are performed in the absence and presence of the gravitational force to analyse the influence of gravity on the micromixer. Mixing efficiencies of greater than 92 % are achieved using water and a low-density biological solvent as the mixing fluids.

Design and construction of a micropump for drug delivery applications

This paper presents design, construction, and evaluation of a micropump for drug delivery applications. The proposed micropump consists of three components: fluidics, electronics, and software. The fluidics component includes a silicone elastic diaphragm, a microservo, housing and two check valves. The diaphragm is modeled and simulated to establish its geometrical specifications. The housing is built using a rapid prototype machine. The electronics component consists of a microcontroller, a microswitch array, a simple display and a power unit. The software component is written in C and receives inputs from user, controls the microservo speed and displays the programmed speed. A number of experiments are conducted to evaluate the performance and capabilities of the micropump. The experiments focus on measurement of flow rate, dosage and duration of operation. A discussion of the performance and capabilities of the developed micropump is also given.