Minimization of railhead edge stresses through shape optimization

The railhead is severely stressed under the localized wheel contact patch close to the gaps in insulated rail joints. A modified railhead profile in the vicinity of the gapped joint, through a shape optimization model based on a coupled genetic algorithm and finite element method, effectively alters the contact zone and reduces the railhead edge stress concentration significantly. Two optimization methods, a grid search method and a genetic algorithm, were employed for this optimization problem. The optimal results from these two methods are discussed and, in particular, their suitability for the rail end stress minimization problem is studied. Through several numerical examples, the optimal profile is shown to be unaffected by either the magnitude or the contact position of the loaded wheel. The numerical results are validated through a large-scale experimental study.

Multi-cursor multi-user mobile interaction with a large shared display

When using a mobile device to control a cursor on a large shared display, the interaction must be carefully planned to match the environment and purpose of the systems use. We describe a ‘democratic jukebox’ system that revealed five recommendations that should be considered when designing this type of interaction relating to providing feedback to the user; how to represent users in a multi-cursor based system; where people tend to look and their expectation of how to move their cursor; the orientation of screens and the social context; and, the use of simulated users to give the real users a sense that they are engaging with a greater audience.

Success factors for ICT shared services in the higher education sector

Shared services is a prominent organizational arrangement for organizations, in particular for support functions. The success (or failure) of shared services is a critical concern as the move to shared services can entail large scale investment and involve fundamental organizational change. The Higher Education (HE) sector is particularly well poised to benefit from shared services as there is a need to improve organizational performance and strong potential from sharing. Through a multiple case study of shared services experiences in HE, this study identifies ten important antecedents of shared services success: (1) Understanding of shared services; (2) Organizational environment; (3) Top management support; (4) IT environment; (5) Governance; (6) Process centric view; (7) Implementation strategy; (8) Project management; (9) Change management; and (10) Communication. The study then develops a preliminary model of shared services success that addresses the interdependencies between the success factors. As the first empirical success model for shared services, it provides valuable guidance to practice and future research.

Experimental investigation of wheel/rail rolling contact at railhead edge

Wheel-rail rolling contact at railhead edge, such as a gap in an insulated rail joint, is a complex problem; there are only limited analytical, numerical and experimental studies available on this problem in the academic literature. This paper describes experimental and numerical investigations of railhead strains in the vicinity of the edge under the contact of a loaded wheel. A full-scale test rig was developed to cyclically apply wheel/rail rolling contact load to the edge zone of the railhead. An image analysis technique was employed to determine the railhead vertical, lateral and shear strain components. The vertical strains determined using the image analysis method have been validated with the strain gauge measurements and used for the calibration of a 3D nonlinear Finite Element Model (FEM) that simulates the wheel/rail contact at the railhead edge and use suitable boundary conditions commensurate to the experimental setup. The FEM was then used to determine other states of strains.

Building shared situational awareness in surgery through distributed dialogue

Background Failure to convey time-critical information to team members during surgery diminishes members’ perception of the dynamic information relevant to their task, and compromises shared situational awareness. This research reports the dialog around clinical decisions made by team members in the time-pressured and high-risk context of surgery, and the impact of these communications on shared situational awareness. Methods Fieldwork methods were used to capture the dynamic integration of individual and situational elements in surgery that provided the backdrop for clinical decisions. Nineteen semi structured interviews were performed with 24 participants from anaesthesia, surgery, and nursing in the operating rooms of a large metropolitan hospital in Queensland, Australia. Thematic analysis was used. Results: The domain “coordinating decisions in surgery” was generated from textual data. Within this domain, three themes illustrated the dialog of clinical decisions, i.e., synchronizing and strategizing actions, sharing local knowledge, and planning contingency decisions based on priority. Conclusion Strategies used to convey decisions that enhanced shared situational awareness included the use of “self-talk”, closed-loop communications, and “overhearing” conversations that occurred at the operating table. Behaviours’ that compromised a team’s shared situational awareness included tunnelling and fixating on one aspect of the situation.

Towards a typology of structural arrangements for shared services : evidence from the higher education sector

Shared services are increasingly prevalent in practice, their introduction potentially entailing substantive and highly consequential organizational redesign. Yet, attention to the structural arrangements of shared services has been limited. This study explores types of structural arrangements for shared services that are observed in practice, and the salient dimensions along which those types can be usefully differentiated. Through inductive attention to the shared services literature, and content analysis of 36 secondary case studies of shared services in the higher education sector, three salient dimensions emerged: (1) the existence or not of a separate organizational entity, (2) an intra- or inter-organizational sharing boundary, and (3) involvement or not of a third party. Each dimension being dichotomous yields 23 combinations, or eight shared services structural arrangement types. Each of the eight structural arrangement types is defined and demonstrated through case examples. The typology offers clarity around shared services structural arrangements. It can serve as a useful analytical tool for researchers investigating the phenomenon further, and for practitioners considering the introduction or further development of shared services arrangements. Important follow on research is suggested too.

Vertical infrastructure inspection using a quadcopter and shared autonomy control

This paper presents a shared autonomy control scheme for a quadcopter that is suited for inspection of vertical infrastructure — tall man-made structures such as streetlights, electricity poles or the exterior surfaces of buildings. Current approaches to inspection of such structures is slow, expensive, and potentially hazardous. Low-cost aerial platforms with an ability to hover now have sufficient payload and endurance for this kind of task, but require significant human skill to fly. We develop a control architecture that enables synergy between the ground-based operator and the aerial inspection robot. An unskilled operator is assisted by onboard sensing and partial autonomy to safely fly the robot in close proximity to the structure. The operator uses their domain knowledge and problem solving skills to guide the robot in difficult to reach locations to inspect and assess the condition of the infrastructure. The operator commands the robot in a local task coordinate frame with limited degrees of freedom (DOF). For instance: up/down, left/right, toward/away with respect to the infrastructure. We therefore avoid problems of global mapping and navigation while providing an intuitive interface to the operator. We describe algorithms for pole detection, robot velocity estimation with respect to the pole, and position estimation in 3D space as well as the control algorithms and overall system architecture. We present initial results of shared autonomy of a quadrotor with respect to a vertical pole and robot performance is evaluated by comparing with motion capture data.

Molecular dynamics investigation on edge stress and shape transition in graphene nanoribbons

Graphene nanoribbon (GNR) with free edges demonstrates unique pre-existing edge energy and edge stress, leading to non-flat morphologies. Using molecular dynamics (MD) methods, we evaluated edge energies as well as edge stresses for four different edge types, including regular edges (armchair and zigzag), armchair edge terminated with hydrogen and reconstructed armchair. The results showed that compressive stress exists in the regular and hydrogen-terminated edges along the edge direction. In contrast, the reconstructed armchair edge is generally subject to tension. Furthermore, we also investigated shape transition between flat and rippled configurations of GNRs with different free edges. It was found that the pre-existing stress at free edges can greatly influence the initial energy state and the shape transition.

Libraries as co-working spaces : understanding user motivations and perceived barriers to social learning

This paper aims to inform design strategies for smart space technology to enhance libraries as environments for co-working and informal social learning. The focus is on understanding user motivations, behaviour, and activities in the library when there is no programmed agenda. The study analyses gathered data over five months of ethnographic research at ‘The Edge’ – a bookless library space at the State Library of Queensland in Brisbane, Australia, that is explicitly dedicated to co-working, social learning, peer collaboration, and creativity around digital culture and technology. The results present five personas that embody people’s main usage patterns as well as motivations, attitudes, and perceived barriers to social learning. It appears that most users work individually or within pre-organised groups, but usually do not make new connections with co-present, unacquainted users. Based on the personas, four hybrid design dimensions are suggested to improve the library as a social interface for shared learning encounters across physical and digital spaces. The findings in this paper offer actionable knowledge for managers, decision makers, and designers of technology-enhanced library spaces and similar collaboration and co-working spaces.

Exploring shared services from an IS perspective : a literature review and research agenda

Shared services have gained significance as an organizational arrangement, in particular for support functions, to reduce costs, increase quality and create new capabilities. The Information Systems (IS) function is amenable to sharing arrangements and information systems can enable sharing in other functional areas. However, despite being a promising area for IS research, literature on shared services in the IS discipline is scarce and scattered. There is still little consensus on what shared services is. Moreover, a thorough understanding of why shared services are adopted, who are involved, and how things are shared is lacking. In this article, we set out to progress IS research on shared services by establishing a common ground for future research and proposing a research agenda to shape the field based on an analysis of the IS literature. We present a holistic and inclusive definition, discuss the primacy of economic-strategic objectives so far, and introduce conceptual frameworks for stakeholders and the notion of sharing. We also provide an overview of the theories and research methods applied. We propose a research agenda that addresses fundamental issues related to objectives, stakeholders, and the notion of sharing to lay the foundation for taking IS research on shared services forward.

Complexity of increasing the secure connectivity in wireless ad hoc networks

We consider the problem of maximizing the secure connectivity in wireless ad hoc networks, and analyze complexity of the post-deployment key establishment process constrained by physical layer properties such as connectivity, energy consumption and interference. Two approaches, based on graph augmentation problems with nonlinear edge costs, are formulated. The first one is based on establishing a secret key using only the links that are already secured by shared keys. This problem is in NP-hard and does not accept polynomial time approximation scheme PTAS since minimum cutsets to be augmented do not admit constant costs. The second one extends the first problem by increasing the power level between a pair of nodes that has a secret key to enable them physically connect. This problem can be formulated as the optimal key establishment problem with interference constraints with bi-objectives: (i) maximizing the concurrent key establishment flow, (ii) minimizing the cost. We prove that both problems are NP-hard and MAX-SNP with a reduction to MAX3SAT problem.

Sensitivity of edge detection methods for quantifying cell migration assays

Quantitative imaging methods to analyze cell migration assays are not standardized. Here we present a suite of two–dimensional barrier assays describing the collective spreading of an initially–confined population of 3T3 fibroblast cells. To quantify the motility rate we apply two different automatic image detection methods to locate the position of the leading edge of the spreading population after 24, 48 and 72 hours. These results are compared with a manual edge detection method where we systematically vary the detection threshold. Our results indicate that the observed spreading rates are very sensitive to the choice of image analysis tools and we show that a standard measure of cell migration can vary by as much as 25% for the same experimental images depending on the details of the image analysis tools. Our results imply that it is very difficult, if not impossible, to meaningfully compare previously published measures of cell migration since previous results have been obtained using different image analysis techniques and the details of these techniques are not always reported. Using a mathematical model, we provide a physical interpretation of our edge detection results. The physical interpretation is important since edge detection algorithms alone do not specify any physical measure, or physical definition, of the leading edge of the spreading population. Our modeling indicates that variations in the image threshold parameter correspond to a consistent variation in the local cell density. This means that varying the threshold parameter is equivalent to varying the location of the leading edge in the range of approximately 1–5% of the maximum cell density.

College, shared house, or home? The impact of living situation on university students’ drinking

University students are recognised as a heavy drinking group who are at risk of both short and long term harms from their alcohol consumption. This paper explores the social dynamics of drinking and the key differences between three core groups of university students – those who live at home, those living in college and those who live independently. We draw on a large scale survey of Australian university students on alcohol consumption and harm minimisation and extensive qualitative individual and focus group interviews with university students in Victoria, New South Wales and Queensland. Our data suggests that living at home supports safer drinking in comparison to the less regulated college context or living independently in shared households.

Life on the edge : the effects of building facade three dimensionality on public social behaviour

Links between the built environment and human behaviour have long been of interest to those involved in the fields of urban planning and architecture, but direct assessments of the links between the three-dimensional building façade form and human behaviour are rare. Much work has been completed on subjects’ responses to the aesthetic of architectural frontages but this has generally been conducted using two-dimensional images of structures and in no way assesses human responses when in the presence of these structures. This research has set about observing the behaviour of individuals and groups in the public realm and recording their reactions to architecture which has a distinct three-dimensional character, with particular reference to the street level façade. The behaviour was recorded and quantified and indicated that there is significant differences in human behaviour around these various types of architecture.

Chemically modified ribbon edge stimulated H2 dissociation: A first-principles computational study

First-principles computational studies indicate that (B, N, or O)-doped graphene ribbon edges can substantially reduce the energy barrier for H2 dissociative adsorption. The low barrier is competitive with many widely used metal or metal oxide catalysts. This suggests that suitably functionalized graphene architectures are promising metal-free alternatives for low-cost catalytic processes.