Real-Time Collision Avoidance for Programmable Machines from 3D Model Analysis

Collision avoidance in programmable machines can reduce programming and setup time, and reduce the likelihood of needing to replace or repair parts during commissioning. While collision avoidance can be accomplished manually by a thorough analysis of the 3D model of the machine, and additional PLC code, this may protect the machine, but costs additional time, and is susceptible to human error. The proposed system includes a computer program to export the 3D model of the machine, and a custom computer that is attached to the machine which manipulates the 3D model in real-time to detect approaching collisions. This computer signals the machine to stop when a collision is predicted. By performing interference detection on the 3D model of the machine, it effectively eliminates the possibility of human error, and saves the additional time that would otherwise be dedicated to the structural analysis and protection code mentioned above. This project used a Raspberry Pi 3 Model B+ connected to the machine via a fieldbus link, to read axis positions and speeds from the machine PLC. It sends stop signals directly to servos when a collision is detected. From simulation testing it was determined that model complexity has a large effect on performance, but using a more powerful computer, and developing a better 3D model exporting algorithm could improve performance significantly. Physical testing demonstrated accuracy and reliability, with reasonable response times. With limited optimization conducted for individual axes during testing, the performance of the test system showed great promise for further development, including an auto-tuning mode which will measure the dynamics of each axis to find the best response parameters for each. Work will continue on this system until a commercial product is realized

Planetary Boundaries and the Doughnut frameworks: A review of their local operability

The concept of Planetary Boundaries has sparked debate around tipping points and the limits of the Earth System for over a decade. Among the most investigated aspects is how to downscale this global concept to a country level, to make it operative at scales at which decisions are taken and policies applied. Specifically how to achieve applicability locally while keeping global relevance, however, remains unclear. The same is true for the "Doughnut" concept, which builds on the Planetary Boundaries framework and adds a social component to create a "Safe and Just Operating Space" (SJOS) within which humanity should live. This paper reviews these two concepts in detail, focusing on their local operability. Synthesis of the literature reveals that, during the downscaling process, either the global meaning of the Planetary Boundaries or the local characteristics of a country are lost. Further, the SJOS remains a very theoretical concept because a match does not exist between the Planetary Boundaries and the social components of the Doughnut. Identification of this problem therefore suggests that future work should calculate the Planetary Boundaries globally for each ecosystem first, and then downscale them by country. In this way, the global relevance of the Planetary Boundaries would hold, and the framework could apply to local policies. Furthermore, the ecosystem services could link the Planetary Boundaries with the social aspects of the Doughnut, and hence contribute to understanding why a country lies within or outside the SJOS

Potential carbon loss from Scottish peatlands under climate change

Open Access via Springer Compact Agreement. Acknowledgements: This work was possible thanks to a Studentship from the Macaulay Development Trust.Peer reviewedPublisher PD

Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

Changes in grazing management are believed to be responsible for declines in populations of birds breeding in grassland over the last decades. The relationships between grazing management regimes, vegetation structure and composition and the availability of invertebrate food resources to passerine birds remain poorly understood. In this Study, we investigated the foraging site selection of meadow pipits (Anthus pratensis L.) breeding in high intensity sheep-grazed plots or low intensity mixed (i.e. sheep and cattle)-grazed plots. We sampled above-ground invertebrates, measured vegetation height and density and conducted a vegetation survey in areas where meadow pipits were observed to forage and areas that were randomly selected. Birds foraged in areas with a lower vegetation height and density and in areas containing a lower proportion of the dominant, tussock-forming grass species Molinia caerulea. They did not forage in areas with a total higher invertebrate biomass but at areas with preferred vegetation characteristics invertebrate biomass tended to be higher in foraging sites than random sites. The foraging distance of meadow pipits was higher in the intensively grazed plots. Our findings support the hypothesis that resource-independent factors such as food accessibility and forager mobility may determine patch selection and are of more importance as selection criteria than food abundance per se. Food accessibility seems to become an even more important selection criterion under high grazing intensity, where prey abundance and size decrease. In our upland grazing system, a low intensity, mixed grazing regime seems to provide a more suitable combination of sward height, plant diversity, structural heterogeneity and food supply for meadow pipit foraging activity compared to a more intensive grazing regime dominated by sheep. (c) 2009 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved

Facilitation and sustainable agriculture: a mechanistic approach to reconciling crop production and conservation

Summary Food security is currently considered a major global problem. However, increasing intensity of food production in agricultural systems has driven reductions in farmland biodiversity. A major challenge is to enable biodiversity conservation whilst addressing the problem of food security. Here we describe how facilitative plant-plant interactions in crop systems could be used to help strike this balance. An obvious example is that of intercropping systems, where combinations of crop species can – under some circumstances – deliver reduced inputs of agrochemicals (fertilisers, pesticides) per unit yield, with potential knock-on benefits for biodiversity conservation. Other facilitative processes can also play a role in biodiversity conservation. Increased intra-specific crop genetic diversity can help protect crops from pests and diseases. Although overlooked in facilitation research, we argue that the mechanisms operate in a manner which is directly analogous to associational defence against herbivores, a process well-recognised in the facilitation literature. As with intercropping, the benefits to nature conservation arise from reduced pesticide use per unit harvested crop. Crops may have facilitative effects on some arable weed species, particularly those that are currently considered rare in intensive farming systems. Work is in its early stages to understand the underlying mechanisms, but it appears that crops might create niche space to which some weed species are adapted. Increasing plant species diversity through niche space creation may then have cascading benefits for other components of farmland biodiversity. Our new understanding of facilitative processes arising from work on crop systems has lessons for the study of facilitative interactions in natural and semi-natural communities. We argue that, although easier to identify and quantify in crop systems, some of these facilitative processes have to date been overlooked in studies of non-crop systems, and certainly deserve further consideration. Finally we discuss what steps may be needed to move from our understanding of the role of facilitation to the development of new agricultural practice. In some cases the challenge may be one of encouraging uptake of existing practices, and in others more research is needed to understand how new ecological understanding might deliver more sustainable agricultural practice

A new hammer to crack an old nut : interspecific competitive resource capture by plants is regulated by nutrient supply, not climate

Peer reviewedPublisher PD

The role of photograph aesthetics on online review sites:Effects of management- versus traveler-generated photos on tourists’ decision-making

Tourists searching for information about destinations on online review sites areconcurrently exposed to two different photograph aesthetics, professional (produced by destination managers) and amateur (generated by travelers). While the former is glossy and sharp, the latter is often grainy and overexposed. Although aesthetics are important factors in tourist decision-making, the effects of the exposure to both types of photo aesthetics remain largely unexamined. This research investigates how both types of aesthetics, either singularly or in combination, affect a destination’s visual appeal and tourists’ booking intentionsthrough four controlled experiments (N = 1282). Our results show that despite the ‘messy’ beauty in amateur aesthetics, photos with professional aesthetics make a depicted destinationappear more visually appealing, ultimately driving booking intentions. However, the negative effects of amateur aesthetics are mitigated when (i) viewed by risk-averse tourists, (ii) presented alongside positive reviews, and (iii) accompanied by a greater number of professional photos

Cultivar Differences and Impact of Plant-Plant Competition on Temporal Patterns of Nitrogen and Biomass Accumulation

Current niche models cannot explain multi-species plant coexistence in complex ecosystems. One overlooked explanatory factor is within-growing season temporal dynamism of resource capture by plants. However, the timing and rate of resource capture are themselves likely to be mediated by plant-plant competition. This study used Barley (Hordeum sp.) as a model species to examine the impacts of intra-specific competition, specifically inter- and intra-cultivar competition on the temporal dynamics of resource capture. Nitrogen and biomass accumulation of an early and late cultivar grown in isolation, inter- or intra- cultivar competition were investigated using sequential harvests. We did not find changes in the temporal dynamics of biomass accumulation in response to competition. However, peak nitrogen accumulation rate was significantly delayed for the late cultivar by 14.5 days and advanced in the early cultivar by 0.5 days when in intra-cultivar competition; there were no significant changes when in inter-cultivar competition. This may suggest a form of kin recognition as the target plants appeared to identify their neighbors and only responded temporally to intra-cultivar competition. The Relative Intensity Index found competition occurred in both the intra- and inter- cultivar mixtures, but a positive Land Equivalence Ratio value indicated complementarity in the inter-cultivar mixtures compared to intra-cultivar mixtures. The reason for this is unclear but may be due to the timing of the final harvest and may not be representative of the relationship between the competing plants. This study demonstrates neighbor-identity-specific changes in temporal dynamism in nutrient uptake. This contributes to our fundamental understanding of plant nutrient dynamics and plant-plant competition whilst having relevance to sustainable agriculture. Improved understanding of within-growing season temporal dynamism would also improve our understanding of coexistence in complex plant communities