Bioinspired Autonomous Visual Vertical Control of a Quadrotor Unmanned Aerial Vehicle

Near-ground maneuvers, such as hover, approach, and landing, are key elements of autonomy in unmanned aerial vehicles. Such maneuvers have been tackled conventionally by measuring or estimating the velocity and the height above the ground, often using ultrasonic or laser range finders. Near-ground maneuvers are naturally mastered by flying birds and insects because objects below may be of interest for food or shelter. These animals perform such maneuvers efficiently using only the available vision and vestibular sensory information. In this paper, the time-to-contact (tau) theory, which conceptualizes the visual strategy with which many species are believed to approach objects, is presented as a solution for relative ground distance control for unmanned aerial vehicles. The paper shows how such an approach can be visually guided without knowledge of height and velocity relative to the ground. A control scheme that implements the tau strategy is developed employing only visual information from a monocular camera and an inertial measurement unit. To achieve reliable visual information at a high rate, a novel filtering system is proposed to complement the control system. The proposed system is implemented onboard an experimental quadrotor unmanned aerial vehicle and is shown to not only successfully land and approach ground, but also to enable the user to choose the dynamic characteristics of the approach. The methods presented in this paper are applicable to both aerial and space autonomous vehicles

Materials have driven the historical development of the Tennis Racket

© 2019 by the authors. The tennis racket has developed since the origins of Lawn Tennis in the 1870s. This study investigated how the tennis racket developed from 1874 to 2017, using measurements and material classifications for 525 samples. Racket measurements covered geometric, inertial and dynamic properties, and the number of strings. Rackets predating 1970 were mainly wooden, and typically characterised by head areas below 0.05 m2, masses over 350 g and natural frequencies below 120 Hz. Rackets from the 1970s were made from wood, metal and fibre-polymer composites, with most postdating 1980 made from fibre-polymer composites with a larger head, lower mass and higher natural frequency than their predecessors. Principal component analysis was used to reduce the dimensionality of the number of variables. Principal component one (PCA1) accounted for 35% of the variance in the measured racket properties, and was found to be significantly affected by material. Head width was best correlated with principal component one (r = 0.897, p < 0.001), followed by head length (r = 0.841, p < 0.001) and natural frequency (r = 0.813, p < 0.001). Early rackets were constrained by the limitations of wood, and the move to composites, which began in the 1970s, allowed this observed increase in head size and natural frequency. As material development has been a major driver of racket design in the past, we propose that new materials and manufacturing techniques, like additively manufactured composites, could further improve the tennis racket. The measurement techniques described here can be used to monitor developments in racket design

Effects of the physical state of tropospheric ammonium-sulfate-nitrate particles on global aerosol direct radiative forcing

International audienceThe effect of aqueous versus crystalline sulfate-nitrate-ammonium tropospheric particles on global aerosol direct radiative forcing is assessed. A global three-dimensional chemical transport model predicts sulfate, nitrate, and ammonium aerosol mass. An aerosol thermodynamics model is called twice, once for the upper side (US) and once for lower side (LS) of the hysteresis loop of particle phase. On the LS, the sulfate mass budget is 40% solid ammonium sulfate, 12% letovicite, 11% ammonium bisulfate, and 37% aqueous. The LS nitrate mass budget is 26% solid ammonium nitrate, 7% aqueous, and 67% gas-phase nitric acid release due to increased volatility upon crystallization. The LS ammonium budget is 45% solid ammonium sulfate, 10% letovicite, 6% ammonium bisulfate, 4% ammonium nitrate, 7% ammonia release due to increased volatility, and 28% aqueous. LS aerosol water mass partitions as 22% effloresced to the gas-phase and 78% remaining as aerosol mass. The predicted US/LS global fields of aerosol mass are employed in a Mie scattering model to generate global US/LS aerosol optical properties, including scattering efficiency, single scattering albedo, and asymmetry parameter. Global annual average LS optical depth and mass scattering efficiency are, respectively, 0.023 and 10.7 m2 (g SO42?)?1, which compare to US values of 0.030 and 13.9 m2 (g SO42?)?1. Radiative transport is computed, first for a base case having no aerosol and then for the two global fields corresponding to the US and LS of the hysteresis loop. Regional, global, seasonal, and annual averages of top-of-the-atmosphere aerosol radiative forcing on the LS and US (FL and FU, respectively, in W m2?) are calculated. Including both anthropogenic and natural emissions, we obtain global annual averages of FL = ?0.750, FU = ?0.930, and ?FU,L = 24% for full sky calculations without clouds and FL = ?0.485, FU = ?0.605, and ?FU,L = 25% when clouds are included. Regionally, ?FU,L = 48% over the USA, 55% over Europe, and 34% over East Asia. Seasonally, ?FU,L varies from 18% in DJF to 75% in SON over the USA. The global annual average contribution from anthropogenic aerosol is FL = ?0.314 and FU = ?0.404, which yield normalized direct radiative forcings (G) of GL = ?205 W (g SO42?)?1 and GU = ?264 W (g SO42?)?1

Tourism destination modelling: building a sustainable planning tool for Australian tourism destinations

The Ningaloo Destination Model is a tourism planning tool for the Ningaloo Coast region of Western Australia that assesses the economic, social and environmental impacts of different planning decisions and events. This report describes the features of the tourism destination model, and analyses its application in the region and to other parts of Australia. Destination modelling integrates a number of research methodologies developed through past STCRC projects (on visitor spending and characteristics, social impacts and economic impacts), secondary data and ecological research. The key to this process is a model development technique that uses scenario planning methodologies to facilitate stakeholder engagement and conceptual modelling techniques to facilitate research integration. The report describes the methodologies used for model development and for data collection, provides two case studies demonstrating outputs, and explores applications of the Ningaloo Destination Model to the region, to other locations and to other sectors. The Ningaloo Destination Model provides estimates of the impacts of plans and events related to tourism in four dimensions: tourism specific; economy; social; and environmental (both resource use and ecological). These outputs are explored through two case studies: a nodal coastal development; and a large resort development. The model can be used for four broad (oftentimes overlapping) categories of assessment: operational planning and decision making for specific organisations and groups (such as local government or agencies that manage land or sea use), regional planning, participatory planning and collaborations and to assist monitoring and evaluation.The Ningaloo Destination Model will be available to the general public (in a limited format) through websites; to agencies through a desktop version; and through integration into a larger model of the region being developed by the CSIRO. Destination modelling is relevant for other tourism destinations and a process for the rapid and cost-effective application of destination modelling is feasible. While much of the data is available, a broader roll-out would require benchmarking of water, electricity and waste data, and developing a wireframe for all tourism destinations. Making destination modelling tools broadly available would significantly broaden the impacts considered in tourism planning and lead to enhancement of desirable effects of tourism development, and early mitigation of negative impacts across Australia. The techniques developed for destination modelling were also found to be applicable to other sectors

Effects of the physical state of tropospheric ammonium-sulfate-nitrate particles on global aerosol direct radiative forcing

The effect of aqueous versus crystalline sulfate-nitrate-ammonium tropospheric particles on global aerosol direct radiative forcing is assessed. A global three-dimensional chemical transport model predicts sulfate, nitrate, and ammonium aerosol mass. An aerosol thermodynamics model is called twice, once for the upper side (US) and once for lower side (LS) of the hysteresis loop of particle phase. On the LS, the sulfate mass budget is 40% solid ammonium sulfate, 12% letovicite, 11% ammonium bisulfate, and 37% aqueous. The LS nitrate mass budget is 26% solid ammonium nitrate, 7% aqueous, and 67% gas-phase nitric acid release due to increased volatility upon crystallization. The LS ammonium budget is 45% solid ammonium sulfate, 10% letovicite, 6% ammonium bisulfate, 4% ammonium nitrate, 7% ammonia release due to increased volatility, and 28% aqueous. LS aerosol water mass partitions as 22% effloresced to the gas-phase and 78% remaining as aerosol mass. The predicted US/LS global fields of aerosol mass are employed in a Mie scattering model to generate global US/LS aerosol optical properties, including scattering efficiency, single scattering albedo, and asymmetry parameter. Global annual average LS optical depth and mass scattering efficiency are, respectively, 0.023 and 10.7 m² (g SO₄^-2)^-1, which compare to US values of 0.030 and 13.9 m² (g SO₄^-2)^-1. Radiative transport is computed, first for a base case having no aerosol and then for the two global fields corresponding to the US and LS of the hysteresis loop. Regional, global, seasonal, and annual averages of top-of-the-atmosphere aerosol radiative forcing on the LS and US (<i>F_L </i> and <i>F_U</i>, respectively, in W m^-2) are calculated. Including both anthropogenic and natural emissions, we obtain global annual averages of <i>F_L</i>=-0.750, <i>F_U</i>=-0.930, and <font face='Symbol'>D</font><i>F_U,L</i>=24% for full sky calculations without clouds and <i>F_L</i>=-0.485, <i>F_U</i>=-0.605, and <font face='Symbol'>D</font><i>F_U,L</i>=25% when clouds are included. Regionally, <font face='Symbol'>D</font><i>F_U,L</i>=48% over the USA, 55% over Europe, and 34% over East Asia. Seasonally, <font face='Symbol'>D</font><i>F_U,L</i>varies from 18% in DJF to 75% in SON over the USA. The global annual average contribution from anthropogenic aerosol is <i>F_L</i>=-0.314 and <i>F_U</i>=-0.404, which yield normalized direct radiative forcings (<i>G</i>) of <i>G_L</i>=-205 W (g SO₄^-2)^-1 and <i>G_U</i>=-264 W (g SO₄^-2)^-1

Formyl Peptide Receptor as a Novel Therapeutic Target for Anxiety-Related Disorders

Formyl peptide receptors (FPR) belong to a family of sensors of the immune system that detect microbe-associated molecules and inform various cellular and sensorial mechanisms to the presence of pathogens in the host. Here we demonstrate that Fpr2/3-deficient mice show a distinct profile of behaviour characterised by reduced anxiety in the marble burying and light-dark box paradigms, increased exploratory behaviour in an open-field, together with superior performance on a novel object recognition test. Pharmacological blockade with a formyl peptide receptor antagonist, Boc2, in wild type mice reproduced most of the behavioural changes observed in the Fpr2/3(-/-) mice, including a significant improvement in novel object discrimination and reduced anxiety in a light/dark shuttle test. These effects were associated with reduced FPR signalling in the gut as shown by the significant reduction in the levels of p-p38. Collectively, these findings suggest that homeostatic FPR signalling exerts a modulatory effect on anxiety-like behaviours. These findings thus suggest that therapies targeting FPRs may be a novel approach to ameliorate behavioural abnormalities present in neuropsychiatric disorders at the cognitive-emotional interface

Induction of Biogenic Magnetization and Redox Control by a Component of the Target of Rapamycin Complex 1 Signaling Pathway

Most organisms are simply diamagnetic, while magnetotactic bacteria and migratory animals are among organisms that exploit magnetism. Biogenic magnetization not only is of fundamental interest, but also has industrial potential. However, the key factor(s) that enable biogenic magnetization in coordination with other cellular functions and metabolism remain unknown. To address the requirements for induction and the application of synthetic bio-magnetism, we explored the creation of magnetism in a simple model organism. Cell magnetization was first observed by attraction towards a magnet when normally diamagnetic yeast Saccharomyces cerevisiae were grown with ferric citrate. The magnetization was further enhanced by genetic modification of iron homeostasis and introduction of ferritin. The acquired magnetizable properties enabled the cells to be attracted to a magnet, and be trapped by a magnetic column. Superconducting quantum interference device (SQUID) magnetometry confirmed and quantitatively characterized the acquired paramagnetism. Electron microscopy and energy-dispersive X-ray spectroscopy showed electron-dense iron-containing aggregates within the magnetized cells. Magnetization-based screening of gene knockouts identified Tco89p, a component of TORC1 (Target of rapamycin complex 1), as important for magnetization; loss of TCO89 and treatment with rapamycin reduced magnetization in a TCO89-dependent manner. The TCO89 expression level positively correlated with magnetization, enabling inducible magnetization. Several carbon metabolism genes were also shown to affect magnetization. Redox mediators indicated that TCO89 alters the intracellular redox to an oxidized state in a dose-dependent manner. Taken together, we demonstrated that synthetic induction of magnetization is possible and that the key factors are local redox control through carbon metabolism and iron supply