Kalman filtering for positioning and heading control of ships and offshore rigs

In this article, we have described the main components of a ship motion-control system and two particular motion-control problems that require wave filtering, namely, dynamic positioning and heading autopilot. Then, we discussed the models commonly used for vessel response and showed how these models are used for Kalman filter design. We also briefly discussed parameter and noise covariance estimation, which are used for filter tuning. To illustrate the performance, a case study based on numerical simulations for a ship autopilot was considered. The material discussed in this article conforms to modern commercially available ship motion-control systems. Most of the vessels operating in the offshore industry worldwide use Kalman filters for velocity estimation and wave filtering. Thus, the article provides an up-to-date tutorial and overview of Kalman-filter-based wave filtering.

Interactive effects from self-reported physical and psychosocial factors in the workplace on neck pain and disability in female office workers

This study explored the interaction between physical and psychosocial factors in the workplace on neck pain and disability in female computer users. A self-report survey was used to collect data on physical risk factors (monitor location, duration of time spent using the keyboard and mouse) and psychosocial domains (as assessed by the Job Content Questionnaire). The neck disability index was the outcome measure. Interactions among the physical and psychosocial factors were examined in analysis of covariance. High supervisor support, decision authority and skill discretion protect against the negative impact of (1) time spent on computer-based tasks, (2) non-optimal placement of the computer monitor, and; (3) long duration of mouse use. Office workers with greater neck pain experience a combination of high physical and low psychosocial stressors at work. Prevention and intervention strategies that target both sets of risk factors are likely to be more successful than single intervention programmes. Statement of Relevance The results of this study demonstrate that the interaction of physical and psychosocial factors in the workplace has a stronger association with neck pain and disability than the presence of either factor alone. This finding has important implications for strategies aimed at the prevention of musculoskeletal problems in office workers.

Synthesis and characterization of titanium sol–gels in varied gravity

Two unique test systems were designed and built to allow the effects of varied gravity (high, normal, reduced) during synthesis of titanium sol–gels to be studied. A centrifuge capable of providing high gravity environments of up to 70 g for extended periods while applying a 100 mbar vacuum and a temperature of 40–50 °C to the reaction chambers was developed. The second system was used in the QUT Microgravity Drop Tower Facility also provided the same thermal and vacuum conditions used in the centrifuge, but was required to operate autonomously during free fall. Through the use of post synthesis instrumental characterization, it was found that increased gravity levels during synthesis, had the greatest effect on the final products. Samples produced in reduced and normal gravity appeared to form amorphous gels containing very small particles with moderate surface areas. Whereas crystalline anatase (TiO2), was found to form in samples synthesized above 5 g with significant increases in crystallinity, particle size and surface area observed when samples were produced at gravity levels up to 70 g. It is proposed that for samples produced in higher gravity, an increased concentration gradient of water is forms at the bottom of the reacting film due to forced convection. The particles formed in higher gravity diffuse downward toward this excess of water, which favors the condensation reaction of remaining sol–gel precursors with the particles promoting increased particle growth. Due to the removal of downward convection in reduced gravity, particle growth due to condensation reaction processes are physically hindered hydrolysis reactions favored instead. Another significant finding from this work was that anatase could be produced at relatively low temperatures of 40–50 °C instead of the conventional method of calcination above 450 °C solely through sol–gel synthesis at higher gravity levels.

EDDY

This exhibiton bought together a selection of artists - Danielle Clej, Channon Goodwin, Christopher Handran, Majena Mafe, Erika Scott and Mark Webb - to explore the role conversations and incidental engagements play as part of making art.The premise of the show focused on how these artists might respond to the process of sharing ideas and responses to one other in the making of artwork.

Experience has no shadow : Bell tower III

I created Experience Has No Shadow (2010) following a successful Ausdance Qld choreographic grant in 2010, which comprised of two solos and a video-dance at the Performance Space at the Judith Wright Centre. The aim of the Bell Tower III residency was to research and construct a Stage One Development that explored choreographic approaches to oral histories. Like many first generation Australians, oral histories are the way memories and experiences of distant homelands often offer the only connection to cultural origins. Consequently, I drew on auto-ethnographic references in the form of family stories – specifically those of my mother’s family - told and retold by my mother and her family as East German refugees during World War II. While working on the video, I explored a way to make a direct connection to the past stories by using a recording of my mother’s voice. She is re-telling a favourite story about Salamo the circus horse that was sold to my great grandfather as a work horse. Rather than representing the text literally, I attempted to capture the intensity of the storytelling which accompanied abstract footage of Avril Huddy filmed through perspex glass producing animal-like shapes that continually blur and morph in and out of focus. Strangely, by tying the story in with the filmed images a whole new story seems to emerge. Two distinct solos were created in collaboration with the performers, Expressions Dance Company’s Elise May and QUT’s Avril Huddy. These were performed at the Judith Wright Centre for Contemporary Arts, Performance Space, 1st April, 2010. The simplicity of its design became a key concept behind the work in terms of sets, spacing requirements, and costumes – almost minimalist. The choreographic process was conceived as highly collaborative, with commissioned music (and eventually lighting features) to act as equal partners in the performance.

A comparative analysis of Mitochondrial genomes in Coleoptera (Arthropoda: Insecta) and genome descriptions of six new beetles

Coleoptera is the most diverse group of insects with over 360,000 described species divided into four suborders: Adephaga, Archostemata, Myxophaga, and Polyphaga. In this study, we present six new complete mitochondrial genome (mtgenome) descriptions, including a representative of each suborder, and analyze the evolution of mtgenomes from a comparative framework using all available coleopteran mtgenomes. We propose a modification of atypical cox1 start codons based on sequence alignment to better reflect the conservation observed across species as well as findings of TTG start codons in other genes. We also analyze tRNA-Ser(AGN) anticodons, usually GCU in arthropods, and report a conserved UCU anticodon as a possible synapomorphy across Polyphaga. We further analyze the secondary structure of tRNA-Ser(AGN) and present a consensus structure and an updated covariance model that allows tRNAscan-SE (via the COVE software package) to locate and fold these atypical tRNAs with much greater consistency. We also report secondary structure predictions for both rRNA genes based on conserved stems. All six species of beetle have the same gene order as the ancestral insect. We report noncoding DNA regions, including a small gap region of about 20 bp between tRNA-Ser(UCN) and nad1 that is present in all six genomes, and present results of a base composition analysis.

Functional magnetic resonance brain imaging of executive cognitive performance in young first-episode schizophrenia patients and age-matched long-term cannabis users

Converging evidence from epidemiological, clinical and neuropsychological research suggests a link between cannabis use and increased risk of psychosis. Long-term cannabis use has also been related to deficit-like “negative” symptoms and cognitive impairment that resemble some of the clinical and cognitive features of schizophrenia. The current functional brain imaging study investigated the impact of a history of heavy cannabis use on impaired executive function in first-episode schizophrenia patients. Whilst performing the Tower of London task in a magnetic resonance imaging scanner, event-related blood oxygenation level-dependent (BOLD) brain activation was compared between four age and gender-matched groups: 12 first-episode schizophrenia patients; 17 long-term cannabis users; seven cannabis using first-episode schizophrenia patients; and 17 healthy control subjects. BOLD activation was assessed as a function of increasing task difficulty within and between groups as well as the main effects of cannabis use and the diagnosis of schizophrenia. Cannabis users and non-drug using first-episode schizophrenia patients exhibited equivalently reduced dorsolateral prefrontal activation in response to task difficulty. A trend towards additional prefrontal and left superior parietal cortical activation deficits was observed in cannabis-using first-episode schizophrenia patients while a history of cannabis use accounted for increased activation in the visual cortex. Cannabis users and schizophrenia patients fail to adequately activate the dorsolateral prefrontal cortex, thus pointing to a common working memory impairment which is particularly evident in cannabis-using first-episode schizophrenia patients. A history of heavy cannabis use, on the other hand, accounted for increased primary visual processing, suggesting compensatory imagery processing of the task.

Comparing the effectiveness of education and technology in reducing wood smoke pollution: A field experiment

This study describes a field experiment assessing the effectiveness of education and technological innovation in reducing air pollution generated by domestic wood heaters. Two-hundred and twenty four households from a small regional center in Australia were randomly assigned to one of four experimental conditions: (1) Education only – households received a wood smoke reduction education pack containing information about the negative health impacts of wood smoke pollution, and advice about wood heater operation and firewood management; (2) SmartBurn only – households received a SmartBurn canister designed to improve combustion and help wood fires burn more efficiently, (3) Education and SmartBurn, and (4) neither Education nor SmartBurn (control). Analysis of covariance, controlling for pre-intervention household wood smoke emissions, wood moisture content, and wood heater age, revealed that education and SmartBurn were both associated with significant reduction in wood smoke emissions during the post-intervention period. Follow-up mediation analyses indicated that education reduced emissions by improving wood heater operation practices, but not by increasing health risk perceptions. As predicted, SmartBurn exerted a direct effect on emission levels, unmediated by wood heater operation practices or health risk perceptions.

Functional MRI BOLD response to Tower of London performance of first-episode schizophrenia patients using cortical pattern matching

Due to its three-dimensional folding pattern, the human neocortex; poses a challenge for accurate co-registration of grouped functional; brain imaging data. The present study addressed this problem by; employing three-dimensional continuum-mechanical image-warping; techniques to derive average anatomical representations for coregistration; of functional magnetic resonance brain imaging data; obtained from 10 male first-episode schizophrenia patients and 10 age-matched; male healthy volunteers while they performed a version of the; Tower of London task. This novel technique produced an equivalent; representation of blood oxygenation level dependent (BOLD) response; across hemispheres, cortical regions, and groups, respectively, when; compared to intensity average co-registration, using a deformable; Brodmann area atlas as anatomical reference. Somewhat closer; association of Brodmann area boundaries with primary visual and; auditory areas was evident using the gyral pattern average model.; Statistically-thresholded BOLD cluster data confirmed predominantly; bilateral prefrontal and parietal, right frontal and dorsolateral; prefrontal, and left occipital activation in healthy subjects, while; patients’ hemispheric dominance pattern was diminished or reversed,; particularly decreasing cortical BOLD response with increasing task; difficulty in the right superior temporal gyrus. Reduced regional gray; matter thickness correlated with reduced left-hemispheric prefrontal/; frontal and bilateral parietal BOLD activation in patients. This is the; first study demonstrating that reduction of regional gray matter in; first-episode schizophrenia patients is associated with impaired brain; function when performing the Tower of London task, and supports; previous findings of impaired executive attention and working memory; in schizophrenia.

The effect of a meteorological tower on its top-mounted anemometer

The wind-speed at a site can be measured by installing anemometers on top of meteorological (met) towers. In addition to other sources of error, accelerated airflow, or speed-up, around the top of met towers can cause incorrect anemometer measurements. We consider a particular example where an anemometer was located only 2 tower diameters above the met tower. Using a standard computational fluid-dynamics package, we found the maximum error for this configuration to be 2% of the wind-speed. We conclude that a top-mounted anemometer should be located at the windward side of its met tower, raised 5 diameters above the top. This will reduce speed-up error to less than 1%.

Dataset-invariant covariance normalization for out-domain PLDA speaker verification

In this paper we introduce a novel domain-invariant covariance normalization (DICN) technique to relocate both in-domain and out-domain i-vectors into a third dataset-invariant space, providing an improvement for out-domain PLDA speaker verification with a very small number of unlabelled in-domain adaptation i-vectors. By capturing the dataset variance from a global mean using both development out-domain i-vectors and limited unlabelled in-domain i-vectors, we could obtain domain- invariant representations of PLDA training data. The DICN- compensated out-domain PLDA system is shown to perform as well as in-domain PLDA training with as few as 500 unlabelled in-domain i-vectors for NIST-2010 SRE and 2000 unlabelled in-domain i-vectors for NIST-2008 SRE, and considerable relative improvement over both out-domain and in-domain PLDA development if more are available.

The multivariate A/C/E model and the genetics of fiber architecture

We present a new algorithm to compute the voxel-wise genetic contribution to brain fiber microstructure using diffusion tensor imaging (DTI) in a dataset of 25 monozygotic (MZ) twins and 25 dizygotic (DZ) twin pairs (100 subjects total). First, the structural and DT scans were linearly co-registered. Structural MR scans were nonlinearly mapped via a 3D fluid transformation to a geometrically centered mean template, and the deformation fields were applied to the DTI volumes. After tensor re-orientation to realign them to the anatomy, we computed several scalar and multivariate DT-derived measures including the geodesic anisotropy (GA), the tensor eigenvalues and the full diffusion tensors. A covariance-weighted distance was measured between twins in the Log-Euclidean framework [2], and used as input to a maximum-likelihood based algorithm to compute the contributions from genetics (A), common environmental factors (C) and unique environmental ones (E) to fiber architecture. Quanititative genetic studies can take advantage of the full information in the diffusion tensor, using covariance weighted distances and statistics on the tensor manifold.

Speed-based diagnostics of aerodynamic and mass imbalance in large wind turbines

Any kind of imbalance in the operation of a wind turbine has adverse effect on the downstream torsional components as well as tower structure. It is crucial to detect imbalance at its very inception. The identification of the type of imbalance is also required so that appropriate measures of fault accommodation can be performed in the control system. In particular, it is important to distinguish between mass and aerodynamic imbalance. While the former is gradually caused by a structural anomaly (e.g. ice deposition, moisture accumulation inside blade), the latter is generally associated to a fault in the pitch control system. This paper proposes a technique for the detection and identification of imbalance fault in large scale wind turbines. Unlike most other existing method it requires only the rotor speed signal which is readily available in existing turbines. Signature frequencies have been proposed in this work to identify imbalance type based on their physical phenomenology. The performance of this technique has been evaluated by simulations using an existing benchmark model. The effectiveness of the proposed method has been confirmed by the simulation results.