Improving reconstructions of digital holograms

Digital holography is a two step process of recording a hologram on an electronic sensor and reconstructing it numerically. This thesis makes a number of contri- butions to the second step of this process. These can be split into two distinct parts: A) speckle reduction in reconstructions of digital holograms (DHs), and B) modeling and overcoming partial occlusion e®ects in reconstructions of DHs, and using occlusions to reduce the effects of the twin image in reconstructions of DHs. Part A represents the major part of this thesis. Speckle reduction forms an important step in many digital holographic applications and we have developed a number of techniques that can be used to reduce its corruptive effect in recon- structions of DHs. These techniques range from 3D filtering of DH reconstructions to a technique that filters in the Fourier domain of the reconstructed DH. We have also investigated the most commonly used industrial speckle reduction technique - wavelet filters. In Part B, we investigate the nature of opaque and non-opaque partial occlusions. We motivate this work by trying to ¯nd a subset of pixels that overcome the effects of a partial occlusion, thus revealing otherwise hidden features on an object captured using digital holography. Finally, we have used an occlusion at the twin image plane to completely remove the corrupting effect of the out-of-focus twin image on reconstructions of DHs

Critical factors that affect the functioning of a research and evaluation capacity building partnership: A causal loop diagram

Introduction: Public health policy and practice is strengthened by the application of quality evidence to decision making. However, there is limited understanding of how initiatives that support the generation and use of evidence in public health are operationalised. This study examines factors that support the internal functioning of a partnership, the Western Australian Sexual Health and Blood-borne Virus Applied Research and Evaluation Network (SiREN). SiREN aims to build research and evaluation capacity and increase evidence-informed decision making in a public health context. Methods: This study was informed by systems concepts. It developed a causal loop diagram, a type of qualitative system model that illustrated the factors that influence the internal operation of SiREN. The causal loop diagram was developed through an iterative and participatory process with SiREN staff and management (n = 9) via in-depth semi-structured interviews (n = 4), workshops (n = 2), and meetings (n = 6). Results: Findings identified critical factors that affected the functioning of SiREN. Central to SiREN’s ability to meet its aims was its capacity to adapt within a dynamic system. Adaptation was facilitated by the flow of knowledge between SiREN and system stakeholders and the expertise of the team. SiREN demonstrated credibility and capability, supporting development of new, and strengthening existing, partnerships. This improved SiREN’s ability to be awarded new funding and enhanced its sustainability and growth. SiREN actively balanced divergent stakeholder interests to increase sustainability. Conclusion: The collaborative development of the diagram facilitated a shared understanding of SiREN. Adaptability was central to SiREN achieving its aims. Monitoring the ability of public health programs to adapt to the needs of the systems in which they work is important to evaluate effectiveness. The detailed analysis of the structure of SiREN and how this affects its operation provide practical insights for those interested in establishing a similar project

'Excessive drinking - An inescapable part of university life?' A focus group study of Australian undergraduates

The university environment reinforces positive alcohol-related expectations and motivations for drinking among undergraduate students. High levels of hazardous consumption in this population lead to significant negative alcohol-related consequences, for individuals and those around them. This study sought to explore the contexts in which those who engage in hazardous drinking consume alcohol, their perceptions of safety and harm, and receptivity to health messages. Undergraduate university students (n = 69; aged 17 - 24 of both genders [57% female]) were purposively recruited into one of seven focus groups after screening with the Alcohol Use Disorders Identification Test (AUDIT) to select for hazardous drinking (score, >8) or moderate drinking. A focus group interview schedule was developed, which was informed by theory and tested for validity by a panel of experts.Qualitative analysis of the data revealed four thematic clusters: positive expectations; inescapable culture; defining situations; and permissible drunkenness. Drinking was associated with various personal and social advantages that reinforced participants’ intentions and/or willingness to drink. Alcohol played a meaningful role in the way in which participants identified with youth and university culture. Economical drinking was prominent, with students constantly negotiating pathways to intoxication within the confines of their budgets. Heavy drinking was viewed as permissible when in the home environment and/or in the company of trusted friends. Most students were unreceptive to health messages, and advice on restricting alcohol consumption seemed to have limited impact on drinking behaviour. Our findings clarify why some university students maintain or increase drinking behaviour despite known negative out- comes and offer useful insights to inform further research and the development of alcohol interventions specifically targeted at students

What Does a Hand-Over Tell?—Individuality of Short Motion Sequences

Bekemeier H, Maycock J, Ritter H. What Does a Hand-Over Tell?—Individuality of Short Motion Sequences. Biomimetics. 2019;4(3): 55.How much information with regard to identity and further individual participant characteristics are revealed by relatively short spatio-temporal motion trajectories of a person? We study this question by selecting a set of individual participant characteristics and analysing motion captured trajectories of an exemplary class of familiar movements, namely handover of anobject to another person. The experiment is performed with different participants under different, predefined conditions. A selection of participant characteristics, such as the Big Five personality traits, gender, weight, or sportiness, are assessed and we analyse the impact of the three factor groups “participant identity”, “participant characteristics”, and “experimental conditions” on the observed hand trajectories. The participants’ movements are recorded via optical marker-based hand motion capture. One participant, the giver, hands over an object to the receiver. The resulting time courses of three-dimensional positions of markers are analysed. Multidimensional scaling is used to project trajectories to points in a dimension-reduced feature space. Supervised learning is also applied. We find that “participant identity” seems to have the highest correlation with the trajectories, with factor group “experimental conditions” ranking second. On the other hand, it is not possible to find a correlation between the “participant characteristics” and the hand trajectory features

Single-shot speckle reduction in numerical reconstruction of digitally recorded holograms: comment

Maycock J, Hennelly B, McDonald J. Single-shot speckle reduction in numerical reconstruction of digitally recorded holograms: comment. Optics Letters. 2015;40(17): 3953.We comment on a recent Letter by Hincapie et al. [Opt. Lett. 40, 1623 (2015)], in which the authors proposed a method to reduce the speckle noise in digital holograms. This method was previously published by us in Maycock [“Improving reconstructions of digital holograms,” Ph.D. thesis (National University of Ireland, 2012)] and Maycock and Hennelly [Improving Reconstructions of Digital Holograms: Speckle Reduction and Occlusions in Digital Holography (Lambert Academic, 2014)]. We also wish to highlight an important limitation of the method resulting from the superposition of different perspectives of the object/scene, which was not addressed in their Letter

Discriminating Liquids Using a Robotic Kitchen Assistant

Elbrechter C, Maycock J, Haschke R, Ritter H. Discriminating Liquids Using a Robotic Kitchen Assistant. Presented at the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2015), Hamburg, Germany.A necessary skill when using liquids in the preparation of food is to be able to estimate viscosity, e.g. in order to control the pouring velocity or to determine the thickness of a sauce. We introduce a method to allow a robotic kitchen assistant discriminate between different but visually similar liquids. Using a Kinect depth camera, surface changes, induced by a simple pushing motion, are recorded and used as input to nearest neighbour and polynomial regression classification models. Results reveal that even when the classifier is trained on a relatively small dataset it generalises well to unknown containers and liquid fill rates. Furthermore, the regression model allows us to determine the approximate viscosity of unknown liquids

Recognition of manual actions using vector quantization and dynamic time warping

Abstract. The recognition of manual actions, i.e., hand movements, hand postures and gestures, plays an important role in human-computer interaction, while belonging to a category of particularly difficult tasks. Using a Vicon system to capture 3D spatial data, we investigate the recognition of manual actions in tasks such as pouring a cup of milk and writing into a book. We propose recognizing sequences in multidimensional time-series by first learning a smooth quantization of the data, and then using a variant of dynamic time warping to recognize short sequences of prototypical motions in a long unknown sequence. An experimental analysis validates our approach. Short manual actions are successfully recognized and the approach is shown to be spatially invariant. We also show that the approach speeds up processing while not decreasing recognition performance

Approaching Manual Intelligence

Maycock J, Dornbusch D, Elbrechter C, Haschke R, Schack T, Ritter H. Approaching Manual Intelligence. KI - Künstliche Intelligenz. 2010;24(4):287-294.Grasping and manual interaction for robots so far has largely been approached with an emphasis on physics and control aspects. Given the richness of human manual interaction, we argue for the consideration of the wider field of ”manual intelligence” as a perspective for manual action research that brings the cognitive nature of human manual skills to the foreground. We briefly sketch part of a research agenda along these lines, argue for the creation of a manual interaction database as an important cornerstone of such an agenda, and describe the manual interaction lab recently set up at CITEC to realize this goal and to connect the efforts of robotics and cognitive science researchers towards making progress for a more integrated understanding of manual intelligence

Leisure craft sacrificial anodes as a source of zinc and cadmium to saline waters

12 months embarg