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.
2021
Authors
El Houssein Chouaib HarikAbstract
One of the goals in adopting more sustainable agricultural practices is to reduce green-house-gas emissions from current practices by replacing fossil-fuel-based heavy machinery with lighter, electrical ones. In a not-so-distant scenario where a single farmer owns a fleet of small electrical tractors/robots that can operate in an autonomous/semi-autonomous manner, this will bring along some logistic challenges. It will be highly impractical that the farmer follows each time a given vehicle moves to the charging point to manually charge it. We present in this paper the design and implementation of an autonomous charging station to be used for that purpose. The charging station is a combination of a holonomic mobile platform and a collaborative robotic arm. Vision-based navigation and detection are used in order to plug the power cable from the wall-plug to the vehicle and back to the wall-plug again when the vehicle has recharged its batteries or reached the required level to pursue its tasks in the field. A decision-tree-based scheme is used in order to define the necessary pick, navigate, and plug sequences to fulfill the charging task. Communication between the autonomous charging station and the vehicle is established in order to make the whole process completely autonomous without any manual intervention. We present in this paper the charging station, the docking mechanism, communication scheme, and the deployed algorithms to achieve the autonomous charging process for agricultural electrical vehicles. We also present real experiments performed using the developed platform on an electrical robot-tractor.
Abstract
In developing countries, over 50% of horticultural crops are lost after harvesting due to absense of or poor postharvest cold storage facilities. Cold storage facility is a critical component of the food supply chain and food security because it can extend the storage period of the perishable products; avoid glut and post-harvest losses, reducing transport bottlenecks. The objective of the study was to design and construct an evaporative cooling system to store horticultural products in a wide range of climatic conditions in Ethiopia. The design integrates direct evaporative cooling system and indirect evaporative cooling system with technical improvements and re-arrangements for continuous operation and handling purpose. After the design and construction work of the cooler was completed, its performance was tested and evaluated without product load at maximum mean annual temperature for five days. Finally, the performance and effect of the cooler on tomato shelf life and quality was evaluated by storing fresh tomatoes inside the cooler shelves. For comparison (control group), randomly selected fresh tomatoes were stored in a basket, which is a standard method that retailer display tomatoes in the market in the study area. A portable evaporative cooler was constructed from locally available and used materials and integrated with new temperature and relative humidity sensors. It had a capacity of 260 Kg (573.2 lb). The evaporative cooler resulted in a reduction in the maximum ambient temperature from 32.8°C (91.6°F) to 23.5°C (74.3°F) in the cooler. As the ambient temperature drops to 21.8°C (71.4°F), the temperature in the cooler reduced to 15°C (59°F). The cooler stabilized the relative humidity between 77- 88%. The newly designed and constructed evaporative cooler reduced the postharvest loss of tomato from 80 % in a traditional basket to 5% in the evaporative cooler. The cooler reduced the postharvest loss of tomato by 94%. It maintained the quality of the fresh tomatoes. In conclusion what we showed in this study was that we have refined the design and constructed a low cost and effective cooling system that can be used by poor retailers of vegetables and fruits. Evaporative cooler is an old and forgotten technology, if the design and construction are refined, it can be used to regulate temperature and relative humidity and used in different purposes especially for those who cannot afford to buy modern thermal regulation technologies.
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Authors
Arne SteffenremAbstract
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Authors
Sophie Mentzel Merete Grung Knut-Erik Tollefsen Marianne Stenrød Karina Petersen S. Jannicke MoeAbstract
Conventional environmental risk assessment of chemicals is based on a calculated risk quotient, representing the ratio of exposure to effects of the chemical, in combination with assessment factors to account for uncertainty. Probabilistic risk assessment approaches can offer more transparency by using probability distributions for exposure and/or effects to account for variability and uncertainty. In this study, a probabilistic approach using Bayesian network modeling is explored as an alternative to traditional risk calculation. Bayesian networks can serve as meta-models that link information from several sources and offer a transparent way of incorporating the required characterization of uncertainty for environmental risk assessment. To this end, a Bayesian network has been developed and parameterized for the pesticides azoxystrobin, metribuzin, and imidacloprid. We illustrate the development from deterministic (traditional) risk calculation, via intermediate versions, to fully probabilistic risk characterization using azoxystrobin as an example. We also demonstrate the seasonal risk calculation for the three pesticides.
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Claire CoutrisAbstract
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