Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2018
Authors
Synnøve RivedalAbstract
No abstract has been registered
Authors
Synnøve RivedalAbstract
No abstract has been registered
Abstract
The key factor for autonomous navigation is efficient perception of the surroundings,while being able to move safely from an initial to a final point. We deal in this paper with a wheeled mobile robot working in a GPS-denied environment typical for a greenhouse. The Hector Simultaneous Localization and Mapping (SLAM) approach is used in order to estimate the robots’ pose using a LIght Detection And Ranging (LIDAR) sensor. Waypoint following and obstacle avoidance are ensured by means of a new artificial potential field (APF) controller presented in this paper. The combination of the Hector SLAMand the APF controller allows themobile robot to performperiodic tasks that require autonomous navigation between predefined waypoints. It also provides themobile robot with a robustness to changing conditions thatmay occur inside the greenhouse, caused by the dynamic of plant development through the season. In this study, we show that the robot is safe to operate autonomously with a human presence, and that in contrast to classical odometrymethods, no calibration is needed for repositioning the robot over repetitive runs. We include here both hardware and software descriptions, as well as simulation and experimental results.
Abstract
There is increasing evidence that the impact of climate change on the productivity of grasslands will at least partly depend on their biodiversity. A high level of biodiversity may confer stability to grassland ecosystems against environmental change, but there are also direct effects of biodiversity on the quantity and quality of grassland productivity. To explain the manifold interactions, and to predict future climatic responses, models may be used. However, models designed for studying the interaction between biodiversity and productivity tend to be structurally different from models for studying the effects of climatic impacts. Here we review the literature on the impacts of climate change on biodiversity and productivity of grasslands. We first discuss the availability of data for model development. Then we analyse strengths and weaknesses of three types of model: ecological, process-based and integrated. We discuss the merits of this model diversity and the scope for merging different model types.
Authors
Leonardo Ciaccheri Lorenza Tuccio Andrea A. Mencaglia Anna G. Mignani Ewelina Hallmann Kalina Sikorska-Zimny Stanislaw Kaniszewski Michel Verheul Giovanni AgatiAbstract
Non-destructive tools for evaluating the lycopene content in tomatoes are of great interest to the entire fruit chain because of an increasing demand for beneficial health products. With the aim of developing compact low-cost reflectance sensors for lycopene determination, we compared Partial Least Squares (PLS) prediction models by using either directional or total reflectance in the 500–750 nm range. Directional reflectance at 45° with respect to the LED lighting direction was acquired by means of a compact spectrometer sensor. Total reflectance was acquired through a 50-mm integrating sphere connected to a spectrometer. The analysis was conducted on two hydroponic greenhouse cultivated red tomato varieties, namely the large round ‘Dometica’ (average diameter: 57 mm) and the small cherry ‘Juanita’ (average diameter: 26 mm). For both varieties, the spectral variance of directional reflectance was well correlated to that of total reflectance. The performances of the PLS prediction models were also similar, with R2 of cross-validation between 0.73 and 0.81. The prediction error, relative to the mean lycopene content of full ripe tomatoes, was similar: i.e. around 16–17% for both varieties and sensors. Our results showed that directional reflectance measured by means of portable, low-cost and compact LED-based sensors can be used with an adequate precision for the non-destructive assessment of lycopene in tomatoes.
Abstract
Lunch canteens and their salad bars are an important arena for sales and consumption of vegetables including herbs. One major Norwegian canteen operator had a turnover of more than seven thousand tons of fresh vegetables in 2016, with lettuce, tomato, potato, cucumber and bell pepper being the most important species. A typical lunch meal included about 260 g vegetables including potatoes. Vegetables used in 450 canteens were either green, yellow, orange, red, purple/dark or colorless, and consisted of pigments of chlorophylls, carotenoids, anthocyanins and betalains. The total pigment content in the 60 most abundant vegetables was calculated to be 14.5-28.3 mg 100 g-1 FW. Of all vegetables in the canteens, 60% were found to be green. The intake of chlorophyll through one lunch meal was estimated to be 46 mg. Lettuce was found to be the single most important source of chlorophylls as this species was consumed in high amounts and made up 20% of the vegetables in a lunch meal. Carotenoids was found in all colored vegetables except the purple/dark ones and an estimate revealed an intake of 15 mg total carotenoids from lunch vegetables. Tomato was found to be the most important carotenoid source representing 44% of the total intake. Due to high pigment concentrations and popularity of red beets in the salad bars, the intake of betalains through a lunch meal was estimated to be 3 mg, similar to the total intake of anthocyanins from vegetable species.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered