Path algebra for mobile robots

In this paper, we introduce a path algebra well suited for navigation in environments that can be abstracted as topological graphs. From this path algebra, we derive algorithms to reduce routes in such environments. The routes are reduced in the sense that they are shorter (contain fewer edges), but still connect the endpoints of the initial routes. Contrary to planning methods descended from Disjktra’s Shortest Path Algorithm like D , the navigation methods derived from our path algebra do not require any graph representation. We prove that the reduced routes are optimal when the graphs are without cycles. In the case of graphs with cycles, we prove that whatever the length of the initial route, the length of the reduced route is bounded by a constant that only depends on the structure of the environment.

Agent-based modelling of worker interactions and related impacts on workplace dynamics

This study uses agent based modelling to simulate the worker interactions within a workplace and to investigate how the interactions can have impact on the workplace dynamics. Two new models (Bounded Confidence with Bias model and Relative Agreement with Bias model) are built based on the theoretical foundation of two existing models. A new factor, namely bias, is added into the new models which raises several issues to be studied.

The impact of home loan key facts sheets on borrowers' comparisons of loan costs

This thesis evaluates the effectiveness of the prescribed design and distribution requirements of the Australian Government's home loan key facts sheets (KFS) aimed at helping borrowers compare loan costs. The findings show that despite effectively improving borrower decision-making, few borrowers were aware of their existence and function. It was also demonstrated that KFS have had limited market impact over the four year window since introduction, likely due to the requirement that KFS provision is not required unless formally requested by a borrower. Recommendations include transferring the burden of disclosure to lenders in the first instance to address this information gap.

A novel approach to 6-DOF adaptive trajectory tracking control of an AUV in the presence of parameter uncertainties

In this paper, the trajectory tracking control of an autonomous underwater vehicle (AUVs) in six-degrees-of-freedom (6-DOFs) is addressed. It is assumed that the system parameters are unknown and the vehicle is underactuated. An adaptive controller is proposed, based on Lyapunov׳s direct method and the back-stepping technique, which interestingly guarantees robustness against parameter uncertainties. The desired trajectory can be any sufficiently smooth bounded curve parameterized by time even if consist of straight line. In contrast with the majority of research in this field, the likelihood of actuators׳ saturation is considered and another adaptive controller is designed to overcome this problem, in which control signals are bounded using saturation functions. The nonlinear adaptive control scheme yields asymptotic convergence of the vehicle to the reference trajectory, in the presence of parametric uncertainties. The stability of the presented control laws is proved in the sense of Lyapunov theory and Barbalat׳s lemma. Efficiency of presented controller using saturation functions is verified through comparing numerical simulations of both controllers.

PMU measurement based dynamic load modeling using SVC devices in online environment

Online dynamic load modeling has become possible with the availability of Static Voltage Compensator (SVC) and Phasor Measurement Unit (PMU) devices. The power of the load response to the small random bounded voltage fluctuations caused from SVC can be measured by PMU for modelling purposes. The aim of this paper is to illustrate the capability of identifying an aggregated load model from high voltage substation level in the online environment. The induction motor is used as the main test subject since it contributes the majority of the dynamic loads. A test system representing simple electromechanical generator model serving dynamic loads through the transmission network is used to verify the proposed method. Also, dynamic load with multiple induction motors are modeled to achieve a better realistic load representation.

From workplace to profession: New focus for the information literacy discourse

The present paper suggests articulating the general context of workplace in information literacy research. The paper considers distinguishing between information literacy research in workplaces and professions. Referring to the results of a phenomenographic enquiry into web professionals’ information literacy as an example, it is indicated that work-related information literacy in particular contexts and depending on the nature of the context, is experienced beyond physical workspaces and at professional level. This involves people interacting with each other and with information at a broader level in comparison to a physically bounded workspace. Regarding the example case discussed in the paper, virtuality is identified as the dominant feature of the profession that causes information literacy to be experienced at a professional level. It is anticipated that pursuing the direction proposed in the paper will result in a more segmented image of work-related information literacy.

Switching period randomisation for multilevel converter modulation

The spectral energy associated with the carrier and sidebands of naturally sampled carrier based PWM can be spread by randomising the carrier (switch) half-period Tc = 1/2fc. So long as the switch duty cycle each period still correctly reflects the value of the modulating fundamental waveform as sampled during that switch period, then the fundamental component will remain undistorted. Natural sampling will ensure this occurs. Carrier based PWM can be extended to (m+1) level multilevel converter waveform generation by creating m triangular carriers, each with an equal 2*pi/m phase displacement. Alternatively the carrier disposition strategy calls for m amplitude displaced triangular carriers, each of amplitude 1/m and frequency mfc. Randomising these carrier sub-periods T0> = 1/2mfc is shown to generate (m+ 1) level PWM waveforms where the first (m-1) carrier groups are cancelled, while the remaining carrier and sidebands at multiples of mfc are spectrally spread. Numerous five level simulation and experimentally gathered randomised PWM waveforms are presented, showing the effects of the variation of the degree of randomisation, modulation depth and pulse number.

The problem with teamwork: A discursive investigation

- Background Teamwork sits comfortably within the vocabularies of most physical education teachers. It is used to both describe and prescribe student behaviour in a variety of physical and sport-related activities. Yet while supporters of sport and PE have readily employed the term, remarkably few pedagogues have taken the time to consider what teamwork refers to, let alone what it means to teach it. - Focus of study In this paper, we examine practitioners' constructions of teamwork. - Participants and setting Data were generated with seven physical education teachers (four male and three female) at a state-funded secondary school near Brisbane, Australia. The teachers ranged in experience from three months to more than 30 years. - Research design The investigation was a case study of one physical education department at a secondary school. - Data collection Three interviews were conducted with each of the teachers. The first was biographical in nature and covered themes such as education and sporting experiences. During the second interviews, teachers produced examples and statements on the topic of teamwork as it occurs within their lessons. The material from the second set of interviews was explored in the final set where the teachers were invited to elaborate on and explain comments from their previous interviews. - Analysis Data were considered from a discursive-constructionist perspective and attention was given to linguistic and grammatical features of the teachers' commentary as well as the cultural relevance of the utterances. The notion of ‘interpretive repertoires’ – essentially cultural explanations bounded by particular socio-linguistic features – provided the central unit of analysis. - Findings The teachers in the project made use of an array of discursive resources to make sense of teamwork. These constructions often bore little resemblance to one another or to existing theories of teamwork. In some cases, the teachers offered vague descriptions or drew on alternative concepts to make sense of teamwork. - Conclusions Without a certain level of agreement in their everyday usage, teachers' constructions of teamwork fail to be convincing or useful. We maintain that a more substantive conceptualisation of teamwork is needed in the field of sport pedagogy and offer suggestions on how this might be accomplished.