Hip and knee kinematics display complex and time-varying sagittal kinematics during repetitive stepping: Implications for design of a functional fatigue model of the knee extensors and flexors

The validity of fatigue protocols involving multi-joint movements, such as stepping, has yet to be clearly defined. Although surface electromyography can monitor the fatigue state of individual muscles, the effects of joint angle and velocity variation on signal parameters are well established. Therefore, the aims of this study were to i) describe sagittal hip and knee kinematics during repetitive stepping ii) identify periods of high inter-trial variability and iii) determine within-test reliability of hip and knee kinematic profiles. A group of healthy men (N = 15) ascended and descended from a knee-high platform wearing a weighted vest (10%BW) for 50 consecutive trials. The hip and knee underwent rapid flexion and extension during step ascent and descent. Variability of hip and knee velocity peaked between 20-40% of the ascent phase and 80-100% of the descent. Significant (p<0.05) reductions in joint range of motion and peak velocity during step ascent were observed, while peak flexion velocity increased during descent. Healthy individuals use complex hip and knee motion to negotiate a knee-high step with kinematic patterns varying across multiple repetitions. These findings have important implications for future studies intending to use repetitive stepping as a fatigue model for the knee extensors and flexors.

Simulation-based fully Bayesian experimental design for mixed effects models

In this paper, we present fully Bayesian experimental designs for nonlinear mixed effects models, in which we develop simulation-based optimal design methods to search over both continuous and discrete design spaces. Although Bayesian inference has commonly been performed on nonlinear mixed effects models, there is a lack of research into performing Bayesian optimal design for nonlinear mixed effects models that require searches to be performed over several design variables. This is likely due to the fact that it is much more computationally intensive to perform optimal experimental design for nonlinear mixed effects models than it is to perform inference in the Bayesian framework. In this paper, the design problem is to determine the optimal number of subjects and samples per subject, as well as the (near) optimal urine sampling times for a population pharmacokinetic study in horses, so that the population pharmacokinetic parameters can be precisely estimated, subject to cost constraints. The optimal sampling strategies, in terms of the number of subjects and the number of samples per subject, were found to be substantially different between the examples considered in this work, which highlights the fact that the designs are rather problem-dependent and require optimisation using the methods presented in this paper.

A design approach to the study of people's experiences with technologies in the context of public transport

Relevant to the study of people’s attitudes towards public transport use is the consideration to the role of technology as part of the travel experience. Technologies aim to enhance daily tasks but tend to change the way people interact with products and can be perceived as difficult to use. This is critical in the context of “public use” where products and services are to be used by the population at large: adults, children, elderly, people with disabilities, and tourists. From different perspectives, the topic of users and the use of technologies have been studied in the social sciences and human computer interaction fields; however, earlier approaches fail to address the ways in which experiential knowledge informs people’s interactions with products and technologies, and how such information could guide the design of future technologies. This paper describes a pilot study, part of a larger ongoing exploratory research that investigates people’s experiences with infrastructure, systems, and technologies in the context of public transport. The methodological approach included focus groups, field observations, and retrospective verbal reports. At this stage, the study found that four context led factors were the primary source of reference informing participants’ actions and interactions; they are: (i) context >> experience, (ii) context >> interface, (iii) context >> knowledge, (iv) context >> emotion.

An object-oriented design of a World Model for autonomous city vehicles

This paper presents an object-oriented world model for the road traffic environment of autonomous (driver-less) city vehicles. The developed World Model is a software component of the autonomous vehicle's control system, which represents the vehicle's view of its road environment. Regardless whether the information is a priori known, obtained through on-board sensors, or through communication, the World Model stores and updates information in real-time, notifies the decision making subsystem about relevant events, and provides access to its stored information. The design is based on software design patterns, and its application programming interface provides both asynchronous and synchronous access to its information. Experimental results of both a 3D simulation and real-world experiments show that the approach is applicable and real-time capable.

Applying and testing design for intuitive interaction

Various tools have been developed to assist designers in making interfaces easier to use although none yet offer a complete solution. Through previous work we have established that intuitive interaction is based on past experience. From this we have developed theory around intuitive interaction, a continuum and a conceptual tool for intuitive use. We then trialled our tool. Firstly, one designer used the tool to design a camera. Secondly, seven groups of postgraduate students re-designed various products using our tool. We then chose one of these - a microwave – and prototyped the new and original microwave interfaces on a touchscreen. We tested them on three different age groups. We found that the new design was more intuitive and rated by participants as more familiar. Therefore, design interventions based on our intuitive interaction theory can work. Work is ongoing to develop the tool further.

Caring for emergency service personnel : does what we do work?

Most emergency service organisations have some form of staff support program that share general aims of promoting and maintaining the mental health of their workforce. Yet few of these services have been subject to evaluation and fewer still have commissioned external professional researchers to scrutinise their programs. The Queensland Ambulance (QAS) Service provides a comprehensive and multifaceted program that is both proactive and reactive in design and with the support of the Commissioner, was the subject of a rigorous evaluation throughout 2013. In this paper the program services are briefly outlined and the considered approach to the evaluation is presented within the context of existing scientific literature. Using focus groups, information regarding the uptake of the program’s various ‘arms’, and survey data, results suggest the program is widely used and that staff are very satisfied with the services provided. Further, analysis of established psychometric measures demonstrated organisational and interpersonal factors that are important in the promotion of mental health and in warding off the deleterious impacts that frontline emergency service staff can endure. Data presented in this paper indicate how best to ensure a professional quality of life for ambulance personnel, how to promote resilience to the sometimes extremely challenging aspects of the work role, and ways in which difficulties such as depression may be minimised.

Organizational work-related road safety situational analysis: More than just an audit tool

Although safety statistics indicate that road crashes are the most common form of work-related fatalities, many organizations fail to treat company vehicles in the same manner as other physical safety hazards within the workplace. Traditionally, work-related road safety has targeted primarily driver-related issues and not adequately addressed organizational processes, such as the organizations’ safety system and risk management processes and practice. This inadequacy generally stems from a lack of specific contextual knowledge and basic requirements to improve work-related road safety, including the supporting systems to ensure any intervention strategy or initiative’s ongoing effectiveness. Therefore, informed by previous research and based on a case study methodology, the Organizational Work-Related Road Safety Situational Analysis was developed to assess organizations’ current work-related road safety system, including policy, procedures, processes and practice. The situational analysis tool is similar to a safety audit however is more comprehensive in detail, application and provides sufficient evidence to enable organizations to mitigate and manage their work-related road safety risks. In addition, data collected from this process assists organizations in making informed decisions regarding intervention strategy design, development, implementation and ongoing effectiveness. This paper reports on the effectiveness of the situational analysis tool to assess WRRS systems across five differing and diverse organizations; including gas exploration and mining, state government, local government, and not for profit/philanthropy. The outcomes of this project identified considerable differences in the degree by which the organizations’ addressed work-related road safety across their vehicle fleet operations and provides guidelines for improving organizations’ work-related road safety systems.

Optimisation methods for coupled thermodynamic and 1D design of radial-inflow turbines

Optimisation is a fundamental step in the turbine design process, especially in the development of non-classical designs of radial-inflow turbines working with high-density fluids in low-temperature Organic Rankine Cycles (ORCs). The present work discusses the simultaneous optimisation of the thermodynamic cycle and the one-dimensional design of radial-inflow turbines. In particular, the work describes the integration between a 1D meanline preliminary design code adapted to real gases and the performance estimation approach for radial-inflow turbines in an established ORC cycle analysis procedure. The optimisation approach is split in two distinct loops; the inner operates on the 1D design based on the parameters received from the outer loop, which optimises the thermodynamic cycle. The method uses parameters including brine flow rate, temperature and working fluid, shifting assumptions such as head and flow coefficients into the optimisation routine. The discussed design and optimisation method is then validated against published benchmark cases. Finally, using the same conditions, the coupled optimisation procedure is extended to the preliminary design of a radial-inflow turbine with R143a as working fluid in realistic geothermal conditions and compared against results from commercially-available software RITAL from Concepts-NREC.

High mobility organic thin film transistor and efficient photovoltaic devices using versatile donor-acceptor polymer semiconductor by molecular design

In this work, we report a novel donor-acceptor based solution processable low band gap polymer semiconductor, PDPP-TNT, synthesized via Suzuki coupling using condensed diketopyrrolopyrrole (DPP) as an acceptor moiety with a fused naphthalene donor building block in the polymer backbone. This polymer exhibits p-channel charge transport characteristics when used as the active semiconductor in organic thin-film transistor (OTFT) devices. The hole mobilities of 0.65 cm2 V-1 s-1 and 0.98 cm2 V -1 s-1 are achieved respectively in bottom gate and dual gate OTFT devices with on/off ratios in the range of 105 to 10 7. Additionally, due to its appropriate HOMO (5.29 eV) energy level and optimum optical band gap (1.50 eV), PDPP-TNT is a promising candidate for organic photovoltaic (OPV) applications. When this polymer semiconductor is used as a donor and PC71BM as an acceptor in OPV devices, high power conversion efficiencies (PCE) of 4.7% are obtained. Such high mobility values in OTFTs and high PCE in OPV make PDPP-TNT a very promising polymer semiconductor for a wide range of applications in organic electronics.

The dynamics of expertise acquisition in sport : the role of affective learning design

Objectives The aim of this position paper is to discuss the role of affect in designing learning experiences to enhance expertise acquisition in sport. The design of learning environments and athlete development programmes are predicated on the successful sampling and simulation of competitive performance conditions during practice. This premise is captured by the concept of representative learning design, founded on an ecological dynamics approach to developing skill in sport, and based on the individual-environment relationship. In this paper we discuss how the effective development of expertise in sport could be enhanced by the consideration of affective constraints in the representative design of learning experiences. Conclusions Based on previous theoretical modelling and practical examples we delineate two key principles of Affective Learning Design: (i) the design of emotion-laden learning experiences that effectively simulate the constraints of performance environments in sport; (ii) recognising individualised emotional and coordination tendencies that are associated with different periods of learning. Considering the role of affect in learning environments has clear implications for how sport psychologists, athletes and coaches might collaborate to enhance the acquisition of expertise in sport.

Young people, citizenship and public space : a work in progress on issues and consequences

Tensions frequently occur when children and young people seek to make use of a multitude of public spaces (Loader 1996; White 1999).In Australia over a number of years, various strategies have been adopted by local councils, police and other stakeholders such as business groups, to respond to such tensions and disputes. However, rarely are children and young people involved in meaningful ways in the design and control of public space that reflects their needs and aspirations (White 1999; Freeman and Riordan 2002). This paper argues for a broader conceptualisation of the rights of citizenhip to include rights to use public space by children and young people.

Three-dimensional off-design numerical analysis of an organic Rankine cycle radial-inflow turbine

Optimisation of organic Rankine cycles(ORCs for binary cycle applications could play a major role in determining the competitiveness of low to moderate renewable sources. An important aspect of the optimisation is to maximise the turbine output power for a given resource. This requires careful attention to the turbine design notably through numerical simulations. Challenges in the numerical modelling of radial-inflow turbines using high-density working fluids still need to be addressed in order to improve the turbine design and better optimise ORCs. Thispaper presents preliminary 3D numerical simulations of a high-density radial-inflow ORC turbine in sensible geothermal conditions. Following extensive investigation of the operating conditions and thermodynamic cycle analysis, therefrigerant R143a is chosen as the high-density working fluid. The 1D design of the candidate radial-inflow turbine is presented in details. Furthermore, commercially-available software Ansys-CFX is used to perform preliminary steady-state 3D CFD simulations of the candidate R143a radial-inflow turbine for a number of operating conditions including off-design conditions. The real-gas properties are obtained using the Peng–Robinson equations of state.The thermodynamic ORC cycle is presented. The preliminary design created using dedicated radial-inflow turbine software Concepts-Rital is discussed and the 3D CFD results are presented and compared against the meanline analysis.

Flexural–torsional buckling behaviour and design of cold-formed steel compression members at elevated temperatures

Current design rules for the member capacities of cold-formed steel columns are based on the same non-dimensional strength curve for both fixed and pinned-ended columns at ambient temperature. This research has investigated the accuracy of using current ambient temperature design rules in Australia/New Zealand (AS/NZS 4600), American (AISI S100) and European (Eurocode 3 Part 1.3) standards in determining the flexural–torsional buckling capacities of cold-formed steel columns at uniform elevated temperatures using appropriately reduced mechanical properties. It was found that these design rules accurately predicted the member capacities of pin ended lipped channel columns undergoing flexural torsional buckling at elevated temperatures. However, for fixed ended columns with warping fixity undergoing flexural–torsional buckling, the current design rules significantly underestimated the column capacities as they disregard the beneficial effect of warping fixity. This paper has therefore recommended the use of improved design rules developed for ambient temperature conditions to predict the axial compression capacities of fixed ended columns subject to flexural–torsional buckling at elevated temperatures within AS/NZS 4600 and AISI S100 design provisions. The accuracy of the proposed fire design rules was verified using finite element analysis and test results of cold-formed lipped channel columns at elevated temperatures except for low strength steel columns with intermediate slenderness whose behaviour was influenced by the increased nonlinearity in the stress–strain curves at elevated temperatures. Further research is required to include these effects within AS/NZS 4600 and AISI S100 design rules. However, Eurocode 3 Part 1.3 design rules can be used for this purpose by using suitable buckling curves as recommended in this paper.

Experimental investigation and design of lipped channel beams in shear

Cold-formed high strength steel members are increasingly used as primary load bearing components in low rise buildings. Lipped channel beam (LCB) is one of the most commonly used flexural members in these applications. In this research an experimental study was undertaken to investigate the shear behaviour and strengths of LCB sections. Simply supported test specimens of back to back LCBs with aspect ratios of 1.0 and 1.5 were loaded at mid-span until failure. Test specimens were chosen such that all three types of shear failure (shear yielding, inelastic and elastic shear buckling) occurred in the tests. The ultimate shear capacity results obtained from the tests were compared with the predictions from the current design rules in Australian/NewZealand and American cold-formed steel design standards. This comparison showed that these shear design rules are very conservative as they did not include the post-buckling strength observed in the shear tests and the higher shear buckling coefficient due to the additional fixity along the web-flange juncture. Improved shear design equations are proposed in this paper by including the above beneficial effects. Suitable lower bound design rules were also developed under the direct strength method format. This paper presents the details of this experimental study and the results including the improved design rules for the shear capacity of LCBs. It also includes the details of tests of LCBs subject to combined shear and flange distortion, and combined bending and shear actions, and proposes suitable design rules to predict the capacities in these cases.

Exploring the internal dimensions of work stress : evidence from construction cost estimators in China

A recurring feature of modern practice is the stress placed on project professionals, with both debilitating effects on the people concerned and indirectly affecting project success. Cost estimation, for example, is an essential task for successful project management involving a high level of uncertainty. It is not surprising, therefore, that young cost estimators especially can become stressful at work due to a lack of experience and the heavy responsibilities involved. However, the concept of work stress and the associated underlying dimensions has not been clearly defined in extant studies in the construction management field. To redress this situation, an updated psychology perceived stress questionnaire (PSQ) , first developed by Levenstein et al (1993) and revised by Fliege et al (2005), is used to explore the dimensions of work stress with empirical evidence from the construction industry in China. With 145 reliable responses from young (less than 5 years’ experience) Chinese cost estimators, this study explores the internal dimensions of work stress, identifying four dimensions of tension, demands, lack of joy and worries. It is suggested that this four-dimensional structure may also be applicable in a more general context.