Angular dependence of the response of the nanoDot OSLD system for measurements at depth in clinical megavoltage beams

Purpose The purpose of this investigation was to assess the angular dependence of a commercial optically stimulated luminescence dosimeter (OSLD) dosimetry system in MV x-ray beams at depths beyondd max and to find ways to mitigate this dependence for measurements in phantoms. Methods Two special holders were designed which allow a dosimeter to be rotated around the center of its sensitive volume. The dosimeter's sensitive volume is a disk, 5 mm in diameter and 0.2 mm thick. The first holder rotates the disk in the traditional way. It positions the disk perpendicular to the beam (gantry pointing to the floor) in the initial position (0°). When the holder is rotated the angle of the disk towards the beam increases until the disk is parallel with the beam (“edge on,” 90°). This is referred to as Setup 1. The second holder offers a new, alternative measurement position. It positions the disk parallel to the beam for all angles while rotating around its center (Setup 2). Measurements with five to ten dosimeters per point were carried out for 6 MV at 3 and 10 cm depth. Monte Carlo simulations using GEANT4 were performed to simulate the response of the active detector material for several angles. Detector and housing were simulated in detail based on microCT data and communications with the manufacturer. Various material compositions and an all-water geometry were considered. Results For the traditional Setup 1 the response of the OSLD dropped on average by 1.4% ± 0.7% (measurement) and 2.1% ± 0.3% (Monte Carlo simulation) for the 90° orientation compared to 0°. Monte Carlo simulations also showed a strong dependence of the effect on the composition of the sensitive layer. Assuming the layer to completely consist of the active material (Al2O3) results in a 7% drop in response for 90° compared to 0°. Assuming the layer to be completely water, results in a flat response within the simulation uncertainty of about 1%. For the new Setup 2, measurements and Monte Carlo simulations found the angular dependence of the dosimeter to be below 1% and within the measurement uncertainty. Conclusions The dosimeter system exhibits a small angular dependence of approximately 2% which needs to be considered for measurements involving other than normal incident beams angles. This applies in particular to clinicalin vivo measurements where the orientation of the dosimeter is dictated by clinical circumstances and cannot be optimized as otherwise suggested here. When measuring in a phantom, the proposed new setup should be considered. It changes the orientation of the dosimeter so that a coplanar beam arrangement always hits the disk shaped detector material from the thin side and thereby reduces the angular dependence of the response to within the measurement uncertainty of about 1%. This improvement makes the dosimeter more attractive for clinical measurements with multiple coplanar beams in phantoms, as the overall measurement uncertainty is reduced. Similarly, phantom based postal audits can transition from the traditional TLD to the more accurate and convenient OSLD.

Australia's disabling income support system: Tracing the history of the disability pension from 1908 to today

This article is based on a historical-comparative policy and discourse analysis of the principles underpinning the Australian disability income support system. It determines that these principles rely on a conception of disability that sustains a system of coercion and paternalism that perpetuates disability and referred to as disablism. The article examines the construction of disability in Australian income support across four major historical epochs spanning the period 1908-2007. Contextualisation of the policy trajectory and discourses of the contemporary disability pension regime for the time period 2008-now is also provided. Two major themes were found to have interacted with the ideology of disablism. This article argues that a non-disabling provision based on social citizenship, rather than responsible or productive citizenship, counters the tendency for authoritarian and paternal approaches. [Abridged]

Countering disablism: An alternative universal income support system based on egalitarianism

The long-term vision of economic security and social participation for people with a disability held by disability activists and policy-makers has not been realised on a global scale. This is despite the implementation of various poverty alleviation initiatives by international and national governments. Indeed within advanced Western liberal democracies, the inequalities and poverty gaps have widened rather than closed. This article is based on findings from a historical-comparative policy and discourse analysis of disability income support system in Australia and the Basic Income model. The findings suggest that a model such as Basic Income, grounded in principles of social citizenship, goes some way to maintaining an adequate level of subsistence for people with a disability. The article concludes by presenting some challenges and a commitment to transforming income support policy.

Remote Sensing and Data Collection from Solar Powered Wireless Sensor Network using an Unmanned Aerial Vehicle System

Sensor networks for environmental monitoring present enormous benefits to the community and society as a whole. Currently there is a need for low cost, compact, solar powered sensors suitable for deployment in rural areas. The purpose of this research is to develop both a ground based wireless sensor network and data collection using unmanned aerial vehicles. The ground based sensor system is capable of measuring environmental data such as temperature or air quality using cost effective low power sensors. The sensor will be configured such that its data is stored on an ATMega16 microcontroller which will have the capability of communicating with a UAV flying overhead using UAV communication protocols. The data is then either sent to the ground in real time or stored on the UAV using a microcontroller until it lands or is close enough to enable the transmission of data to the ground station.

An automated emergency landing system for fixed-wing aircraft: Planning and control

A number of hurdles must be overcome in order to integrate unmanned aircraft into civilian airspace for routine operations. The ability of the aircraft to land safely in an emergency is essential to reduce the risk to people, infrastructure and aircraft. To date, few field-demonstrated systems have been presented that show online re-planning and repeatability from failure to touchdown. This paper presents the development of the Guidance, Navigation and Control (GNC) component of an Automated Emergency Landing System (AELS) intended to address this gap, suited to a variety of fixed-wing aircraft. Field-tested on both a fixed-wing UAV and Cessna 172R during repeated emergency landing experiments, a trochoid-based path planner computes feasible trajectories and a simplified control system executes the required manoeuvres to guide the aircraft towards touchdown on a predefined landing site. This is achieved in zero-thrust conditions with engine forced to idle to simulate failure. During an autonomous landing, the controller uses airspeed, inertial and GPS data to track motion and maintains essential flight parameters to guarantee flyability, while the planner monitors glide ratio and re-plans to ensure approach at correct altitude. Simulations show reliability of the system in a variety of wind conditions and its repeated ability to land within the boundary of a predefined landing site. Results from field-tests for the two aircraft demonstrate the effectiveness of the proposed GNC system in live operation. Results show that the system is capable of guiding the aircraft to close proximity of a predefined keyhole in nearly 100% of cases.

Organisational driving safety systems analysis: Fleet safety situational issues and system gaps

The identification of safety hazards and risks and their associated control measures provides the foundation for any safety program and essentially determines the scope, content and complexity of an effective occupational health and safety management system. In the case of work-related road safety (WRRS), there is a gap within current knowledge, research and practice regarding the holistic assessment of WRRS safety systems and practice. In order to mitigate this gap, a multi-level process tool for assessing WRRS safety systems was developed from extensive consultation, practice and informed by theoretical models and frameworks. Data collection for the Organisational Driving Safety Systems Analysis (ODSSA) tool utilised a case study methodology and included multiple information sources: such as documents, archival records, interviews, direct observations, participant observations, and physical artefacts. Previous trials and application of the ODSSA has indicated that the tool is applicable to a wide range of organisational fleet environments and settings. This paper reports on the research results and effectiveness of the ODSSA tool to assess WRRS systems across a large organisation that recently underwent considerable organisational change, including amalgamation of multiple organisations. The outcomes of this project identified considerable differences in the degree by which the organisation addressed WRRS across their vehicle fleet operations and provided guidelines for improving organisations’ WRRS systems. The ODSSA tool was pivotal in determining WRRS system deficiencies and provided a platform to inform mitigation and improvement strategies.

Understanding the use of a bug tracking system in a global software development setup

Bug fixing is a highly cooperative work activity where developers, testers, product managers and other stake-holders collaborate using a bug tracking system. In the context of Global Software Development (GSD), where software development is distributed across different geographical locations, we focus on understanding the role of bug trackers in supporting software bug fixing activities. We carried out a small-scale ethnographic fieldwork in a software product team distributed between Finland and India at a multinational engineering company. Using semi-structured interviews and in-situ observations of 16 bug cases, we show that the bug tracker 1) supported information needs of different stake holder, 2) established common-ground, and 3) reinforced issues related to ownership, performance and power. Consequently, we provide implications for design around these findings.

Active Adaptive Gyrostabiliser Control System

A gyrostabiliser control system and method for stabilising marine vessel motion based on precession information only. The control system employs an Automatic Gain Control (AGC) precession controller (60). This system operates with a gain factor that is always being gradually minimized so as to let the gyro flywheel (12) develop as much precession as possible - the higher the precession, the higher the roll stabilising moment. This continuous gain change provides adaptation to changes in sea state and sailing conditions. The system effectively predicts the likelihood of maximum precession being reached. Should this event be detected, then the gain is rapidly increased so as to provide a breaking precession torque. Once the event has passed, the system again attempts to gradually decrease the gain.

Fault tolerant vessel stabiliser control system

A vessel stabilizer control system includes a sensor fault detection means which senses the availability of sensing signals from a gyrostabilizer precession motion sensor and a vessel roll motion sensor. The control system controls the action of a gyro-actuator which is mechanically coupled to a gyrostabilizer. The benefit of employing fault sensing of the sensors providing the process control variables is that the sensed number of available process control variables (or sensors) can be used to activate a tiered system of control modes. Each tiered control mode is designed to utilize the available process control variables to ensure safe and effective operation of the gyrostabilizer that is tolerant of sensor faults and loss of power supply. A control mode selector is provided for selecting the appropriate control mode based on the number of available process control variables.

Boarding Control System - for Improved Accessibility to Offshore Wind Turbines

This paper considers the dynamic modelling and motion control of a Surface Effect Ship (SES) for safer transfer of personnel and equipment from vessel to-and-from an offshore wind-turbine. Such a vessel is a key enabling factor for operation and maintenance (O&M) of offshore wind-energy infrastructure. The control system designed is referred to as Boarding Control System (BCS). We investigate the performance of this system for a specific wind-farm service vessel–The Wave Craft. A two-modality vessel model is presented to account for the vessel free motion and motion whilst in contact with a wind-turbine. On a SES, the pressurized air cushion carries the majority of the vessel mass. The control problem considered relates to the actuation of the pressure such that wave-induced vessel motions are minimized. This leads to a safer personnel transfer in developed sea-states than what is possible today. Results for the BCS is presented through simulation and model-scale craft testing.

An evaluation of the indicators of threat to auditor independence in an Islamic legal system: The case of Iran

This study aimed to assist in developing a more effective framework for regulating auditor independence practice in Iran, a non-IFRS country with an Islamic legal system. It investigated the following general research question: In order to increase auditor independence in a non-IFRS country with an Islamic legal system, what are the potential indicators of threats to auditor independence, and how should a regulator prioritise addressing these threats?

Microgrid frequency control using multiple battery energy storage system (BESSs)

The work is a report of research on using multiple inverters of Battery Energy Storage Systems with angle droop controllers to share real power in an isolated micro grid system consisting of inertia based Distributed Generation units and variable load. The proposed angle droop control method helps to balance the supply and demand in the micro grid autonomous mode through charging and discharging of the Battery Energy Storage Systems while ensuring that the state of charge of the storage devices is within safe operating conditions. The proposed method is also studied for its effectiveness for frequency control. The proposed control system is verified and its performance validated with simulation software MATLAB/SIMULINK.

“We have to work within the system!”: Staff perceptions of organizational barriers to decision making for older adults with dementia in Australian aged care facilities

The current study explored the perceptions of direct care staff working in Australian residential aged care facilities (RACFs) regarding the organizational barriers that they believe prevent them from facilitating decision making for individuals with dementia. Normalization process theory (NPT) was used to interpret the findings to understand these barriers in a broader context. The qualitative study involved semi-structured interviews (N = 41) and focus groups (N = 8) with 80 direct care staff members of all levels working in Australian RACFs. Data collection and analysis were conducted in parallel and followed a systematic, inductive approach in line with grounded theory. The perceptions of participants regarding the organizational barriers to facilitating decision making for individuals with dementia can be described by the core category, Working Within the System, and three sub-themes: (a) finding time, (b) competing rights, and (c)not knowing. Examining the views of direct care staff through the lens of NPT allows possible areas for improvement to be identified at an organizational level and the perceived barriers to be understood in the context of promoting normalization of decision making for individuals with dementia.

Development and Simulation of a Variable Rate Controller for an Air search and Air Sampling Unmanned Aerial System

This report describes the development and simulation of a variable rate controller for a 6-degree of freedom nonlinear model. The variable rate simulation model represents an off the shelf autopilot. Flight experiment involves risks and can be expensive. Therefore a dynamic model to understand the performance characteristics of the UAS in mission simulation before actual flight test or to obtain parameters needed for the flight is important. The control and guidance is implemented in Simulink. The report tests the use of the model for air search and air sampling path planning. A GUI in which a set of mission scenarios, in which two experts (mission expert, i.e. air sampling or air search and an UAV expert) interact, is presented showing the benefits of the method.