Wear mechanisms and scale effects in two-body abrasion

The ‘particle size effect’ and its manifestation in abrasion still attracts considerable debate as to its origins and the ranking of its likely causes. Experiments have been conducted to study the important contribution that the formation of wear debris can have on the progression of wear. The experiments consist of unlubricated (dry) pin-on-disk tests with silicon carbide coated paper of varying particle size, with different pin material, diameter and loads. It has been observed that the influence of debris formation on wear rate is more pronounced for fine abrasives and soft-wearing materials. Consequently, it is proposed that the particle size effect can be explained in terms of geometrical scaling and the evolution of third-body effects with diminishing particle diameter.

A novel system for the measurement of body shape and construction of seating supports for patients

Patients with severe back deformities can greatly benefit from customized medical seating. Customized medical seating is made by taking measurements of each individual patient and making the seat as per these measurements. The current measuring systems employed by the industry are limited to use in clinics which are generally located only in major population centres. Patients living in remote areas are severely affected by this as the clinics could be far away and inaccessible for these patients. To provide service of customized medical seating requires a new measurement system which is portable so that the system could be transported to the patients in remote areas. The requirements for a new measurement system are analysed to suite the needs of Equipment Technology Services of the Cerebral Palsy League of Queensland. Design for a new measurement system was conceptualised by reviewing systems and technologies in various scientific disciplines. Design for a new system was finalised by optimizing each individual component. The final approach was validated by measuring difficult models and repeating the process to check for process variances. This system has now been adopted for clinical evaluation by ETS Suggestions have been made for further improvements in this new measurement approach.

Automated symbolic and numeric procedure for manipulator rigid-body dynamic significance analysis and simplification

This paper describes an automated procedure for analysing the significance of each of the many terms in the equations of motion for a serial-link robot manipulator. Significance analysis provides insight into the rigid-body dynamic effects that are significant locally or globally in the manipulator's state space. Deleting those terms that do not contribute significantly to the total joint torque can greatly reduce the computational burden for online control, and a Monte-Carlo style simulation is used to investigate the errors thus introduced. The procedures described are a hybrid of symbolic and numeric techniques, and can be readily implemented using standard computer algebra packages.

Development of a multi-scale finite element model of the osteoporotic lumbar vertebral body for the investigation of apparent level vertebra mechanics and micro-level trabecular mechanics.

Osteoporotic spinal fractures are a major concern in ageing Western societies. This study develops a multi-scale finite element (FE) model of the osteoporotic lumbar vertebral body to study the mechanics of vertebral compression fracture at both the apparent (whole vertebral body) and micro-structural (internal trabecular bone core)levels. Model predictions were verified against experimental data, and found to provide a reasonably good representation of the mechanics of the osteoporotic vertebral body. This novel modelling methodology will allow detailed investigation of how trabecular bone loss in osteoporosis affects vertebral stiffness and strength in the lumbar spine.

Three primary school students’ cognition about 3D rotation in a virtual reality learning environment

This paper reports on three primary school students’ explorations of 3D rotation in a virtual reality learning environment (VRLE) named VRMath. When asked to investigate if you would face the same direction when you turn right 45 degrees first then roll up 45 degrees, or when you roll up 45 degrees first then turn right 45 degrees, the students found that the different order of the two turns ended up with different directions in the VRLE. This was contrary to the students’ prior predictions based on using pen, paper and body movements. The findings of this study showed the difficulty young children have in perceiving and understanding the non-commutative nature of 3D rotation and the power of the computational VRLE in giving students experiences that they rarely have in real life with 3D manipulations and 3D mental movements.

Engineering an Ecosystem : Taking Cues from Nature’s Paradigm to Build Tissue in the Lab and the Body

This manuscript took a 'top down' approach to understanding survival of inhabitant cells in the ecosystem bone, working from higher to lower length and time scales through the hierarchical ecosystem of bone. Our working hypothesis is that nature “engineered” the skeleton using a 'bottom up' approach,where mechanical properties of cells emerge from their adaptation to their local me-chanical milieu. Cell aggregation and formation of higher order anisotropic struc- ture results in emergent architectures through cell differentiation and extracellular matrix secretion. These emergent properties, including mechanical properties and architecture, result in mechanical adaptation at length scales and longer time scales which are most relevant for the survival of the vertebrate organism [Knothe Tate and von Recum 2009]. We are currently using insights from this approach to har-ness nature’s regeneration potential and to engineer novel mechanoactive materials [Knothe Tate et al. 2007, Knothe Tate et al. 2009]. In addition to potential applications of these exciting insights, these studies may provide important clues to evolution and development of vertebrate animals. For instance, one might ask why mesenchymal stem cells condense at all? There is a putative advantage to self-assembly and cooperation, but this advantage is somewhat outweighed by the need for infrastructural complexity (e.g., circulatory systems comprised of specific differentiated cell types which in turn form conduits and pumps to overcome limitations of mass transport via diffusion, for example; dif-fusion is untenable for multicellular organisms larger than 250 microns in diameter. A better question might be: Why do cells build skeletal tissue? Once cooperatingcells in tissues begin to deplete local sources of food in their aquatic environment, those that have evolved a means to locomote likely have an evolutionary advantage. Once the environment becomes less aquarian and more terrestrial, self-assembled organisms with the ability to move on land might have conferred evolutionary ad-vantages as well. So did the cytoskeleton evolve several length scales, enabling the emergence of skeletal architecture for vertebrate animals? Did the evolutionary advantage of motility over noncompliant terrestrial substrates (walking on land) favor adaptations including emergence of intracellular architecture (changes in the cytoskeleton and upregulation of structural protein manufacture), inter-cellular con- densation, mineralization of tissues, and emergence of higher order architectures?How far does evolutionary Darwinism extend and how can we exploit this knowl- edge to engineer smart materials and architectures on Earth and new, exploratory environments?[Knothe Tate et al. 2008]. We are limited only by our ability to imagine. Ultimately, we aim to understand nature, mimic nature, guide nature and/or exploit nature’s engineering paradigms without engineer-ing ourselves out of existence.

A geometrical approach to the motion planning problem for a submerged rigid body

The main focus of this paper is the motion planning problem for a deeply submerged rigid body. The equations of motion are formulated and presented by use of the framework of differential geometry and these equations incorporate external dissipative and restoring forces. We consider a kinematic reduction of the affine connection control system for the rigid body submerged in an ideal fluid, and present an extension of this reduction to the forced affine connection control system for the rigid body submerged in a viscous fluid. The motion planning strategy is based on kinematic motions; the integral curves of rank one kinematic reductions. This method is of particular interest to autonomous underwater vehicles which can not directly control all six degrees of freedom (such as torpedo shaped AUVs) or in case of actuator failure (i.e., under-actuated scenario). A practical example is included to illustrate our technique.

Decoupled trajectory planning for a submerged rigid body subject to dissipative and potential forces

This paper studies the practical but challenging problem of motion planning for a deeply submerged rigid body. Here, we formulate the dynamic equations of motion of a submerged rigid body under the architecture of differential geometric mechanics and include external dissipative and potential forces. The mechanical system is represented as a forced affine-connection control system on the configuration space SE(3). Solutions to the motion planning problem are computed by concatenating and reparameterizing the integral curves of decoupling vector fields. We provide an extension to this inverse kinematic method to compensate for external potential forces caused by buoyancy and gravity. We present a mission scenario and implement the theoretically computed control strategy onto a test-bed autonomous underwater vehicle. This scenario emphasizes the use of this motion planning technique in the under-actuated situation; the vehicle loses direct control on one or more degrees of freedom. We include experimental results to illustrate our technique and validate our method.

Controlling a submerged rigid body : a geometric analysis

In this paper we analyze the equations of motion of a submerged rigid body. Our motivation is based on recent developments done in trajectory design for this problem. Our goal is to relate some properties of singular extremals to the existence of decoupling vector fields. The ideas displayed in this paper can be viewed as a starting point to a geometric formulation of the trajectory design problem for mechanical systems with potential and external forces.

Human-body shadowing effects on indoor MIMO-OFDM channels at 5.2 GHz

Pedestrian movement is known to cause significant effects on indoor MIMO channels. In this paper, a statistical characterization of the indoor MIMO-OFDM channel subject ot pedestrian movement is reported. The experiment used 4 sending and 4 receiving antennas and 114 sub-carriers at 5.2 GHz. Measurement scenarios varied from zero to ten pedestrians walking randomly between transmitter (tx) and receiver (Rx) arrays. The empirical cumulative distribution function (CDF) of the received fading envelope fits the Ricean distribution with K factors ranging from 7dB to 15 dB, for the 10 pedestrians and vacant scenarios respectively. In general, as the number of pedestrians increase, the CDF slope tends to decrease proportionally. Furthermore, as the number of pedestrians increase, increasing multipath contribution, the dynamic range of channel capacity increases proportionally. These results are consistent with measurement results obtained in controlled scenarios for a fixed narrowband Single-Input Single-Output (SISO) link at 5.2 GHz in previous work. The described empirical characterization provides an insight into the prediction of human-body shadowing effects for indoor MIMO-OFDM channels at 5.2 GHz.

Flexural and torsional rigidity of colonoscope at room and body temperatures

A series of experiments have been conducted to determine the flexural, EI, and torsional, GJ, rigidity of an Olympus colonoscope CF‐140S and torsional rigidity of a Pentax colonoscope EC‐3870 and the dependency of these properties on temperature and on the presence of loops. Along the length of the colonoscope, the Olympus colonoscope flexural rigidity varied between 260 and 400 Ncm2 and torsional rigidity varied between 68 and 88 Ncm2/deg, with an average of 76 Ncm2/deg for tests involving 0.86 Nm of anti‐clockwise torque. Results show a significant decrease of 10% in torsional rigidity between clockwise and anti‐clockwise torque. For the Pentax colonoscope flexural rigidity was not tested; its torsional rigidity varied between 34 and 76 Ncm2/deg, with an average of 46 Ncm2/deg for tests involving 0.43 Nm of anti‐clockwise torque. An increase in temperature of the Olympus colonoscope from 24°C to 37°C reduces EI by an average of 17% and GJ by an average of 7%. A right‐handed loop caused a significant increase in flexural rigidity, but other looping configurations had no significant influence.

Enhancing employment services for people with severe mental illness: the challenge of the Australian service environment

Objectives:  Comparatively few people with severe mental illness are employed despite evidence that many people within this group wish to obtain, can obtain and sustain employment, and that employment can contribute to recovery. This investigation aimed to: (i) describe the current policy and service environment within which people with severe mental illness receive employment services; (ii) identify evidence-based practices that improve employment outcomes for people with severe mental illness; (iii) determine the extent to which the current Australian policy environment is consistent with the implementation of evidence-based employment services for people with severe mental illness; and (iv) identify methods and priorities for enhancing employment services for Australians with severe mental illness through implementation of evidence-based practices. Method:  Current Australian practices were identified, having reference to policy and legal documents, funding body requirements and anecdotal reports. Evidence-based employment services for people with severe mental illness were identified through examination of published reviews and the results of recent controlled trials. Results:  Current policy settings support the provision of employment services for people with severe mental illness separate from clinical services. Recent studies have identified integration of clinical and employment services as a major factor in the effectiveness of employment services. This is usually achieved through co-location of employment and mental health services. Conclusions:  Optimal evidence-based employment services are needed by Australians with severe mental illness. Providing optimal services is a challenge in the current policy environment. Service integration may be achieved through enhanced intersectoral links between employment and mental health service providers as well as by co-locating employment specialists within a mental health care setting.

Multi-body modelling of wagon trains for crashworthiness analysis

Three-dimensional wagon train models have been developed for the crashworthiness analysis using multi-body dynamics approach. The contributions of the train size (number of wagon) to the frontal crash forces can be identified through the simulations. The effects of crash energy management (CEM) design and crash speed on train crashworthiness are examined. The CEM design can significantly improve the train crashworthiness and the consequential vehicle stability performance - reducing derailment risks.

Fashion, the body and technology : tracing early 20th century techno-utopian ideas, aesthetics and impulses in 21st century wearable technology

‘Wearable technology’, or the use of specialist technology in garments, is promoted by the electronics industry as the next frontier of fashion. However the story of wearable technology’s relationship with fashion begins neither with the development of miniaturised computers in the 1970s nor with sophisticated ‘smart textiles’ of the twenty-first century, despite what much of the rhetoric suggests. This study examines wearable technology against a longer history of fashion, highlighted by the influential techno-sartorial experiments of a group of early twentieth century avant-gardes including Italian Futurists Giacomo Balla and F.T. Marinetti, Russian Constructivists Varvara Stepanova and Liubov Popova, and Paris-based Cubist, Sonia Delaunay. Through the interdisciplinary framework of fashion studies, the thesis provides a fuller picture of wearable technology framed by the idea of utopia. Using comparative analysis, and applying the theoretical formulations of Fredric Jameson, Louis Marin and Michael Carter, the thesis traces the appearance of three techno-utopian themes from their origins in the machine age experiments of Balla, Marinetti, Stepanova, Popova and Delaunay to their twenty-first century reappearance in a dozen wearable technology projects. By exploring the central thesis that contemporary wearable technology resurrects the techno-utopian ideas and expressions of the early twentieth century, the study concludes that the abiding utopian impetus to embed technology in the aesthetics (prints, silhouettes, and fabrication) and functionality of fashion is to unify subject, society and environment under a totalising technological order.

Turbulence and suspended sediment measurements in an urban environment during the Brisbane River flood of January 2011

In urbanised areas, the flood flows constitute a hazard to populations and infrastructure as illustrated during major floods in 2011. During the 2011 Brisbane River flood, some turbulent velocity data were collected using acoustic Doppler velocimetry in an inundated street. The field deployment showed some unusual features of flood flow in the urban environment. That is, the water elevations and velocities fluctuated with distinctive periods between 50 and 100 s linked with some local topographic effects. The instantaneous velocity data were analysed using a triple decomposition. The velocity fluctuations included a large energy component in the slow fluctuation range, while the turbulent motion components were much smaller. The suspended sediment data showed some significant longitudinal flux. Altogether the results highlighted that the triple decomposition approach originally developed for period flows is well suited to complicated flows in an inundated urban environment.