80 research outputs found

    On Polya\u27s Orchard Problem

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    In 1918 Polya formulated the following problem: ``How thick must the trunks of the trees in a regularly spaced circular orchard grow if they are to block completely the view from the center? (Polya and Szego [2]). We study a more general orchard model, namely any domain that is compact and convex, and find an expression for the minimal radius of the trees. As examples, solutions for rhombus-shaped and circular orchards are given. Finally, we give some estimates for the minimal radius of the trees if we see the orchard as being 3-dimensional

    Investigating HLB control strategies using Genetic Algorithms: A two-orchard model approach with ACP Dispersal

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    This study focuses on the use of genetic algorithms to optimize control parameters in two potential strategies called mechanical and chemical control, for mitigating the spread of Huanglongbing (HLB) in citrus orchards. By developing a two-orchard model that incorporates the dispersal of the Asian Citrus Psyllid (ACP), the cost functions and objective function are explored to assess the effectiveness of the proposed control strategies. The mobility of ACP is also taken into account to capture the disease dynamics more realistically. Additionally, a mathematical expression for the global reproduction number (R0R_{0}) is derived, allowing for sensitivity analysis of the model parameters when ACP mobility is present. Furthermore, we mathematically express the cost function and efficiency of the strategy in terms of the final size and individual R0R_{0} of each patch (i.e., when ACP mobility is absent). The results obtained through the genetic algorithms reveal optimal parameters for each control strategy, providing valuable insights for decision-making in implementing effective control measures against HLB in citrus orchards. This study highlights the importance of optimizing control parameters in disease management in agriculture and provides a solid foundation for future research in developing disease control strategies based on genetic algorithms

    SIMLIDAR Simulation of LiDAR performance in artificially simulate orchards

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    SIMLIDAR is an application developed in Cþþ that generates an artificial orchard using a Lindenmayer system. The application simulates the lateral interaction between the artificial orchard and a laser scanner or LIDAR (Light Detection and Ranging). To best highlight the unique qualities of the LIDAR simulation, this work focuses on apple trees without leaves, i.e. the woody structure. The objective is to simulate a terrestrial laser sensor (LIDAR) when applied to different artificially created orchards and compare the simulated characteristics of trees with the parameters obtained with the LIDAR. The scanner is mounted on a virtual tractor and measures the distance between the origin of the laser beam and the nearby plant object. This measurement is taken with an angular scan in a plane which is perpendicular to the route of the virtual tractor. SIMLIDAR determines the distance measured in a bi-dimensional matrix N M, where N is the number of angular scans and M is the number of steps in the tractor route. In order to test the data and performance of SIMLIDAR, the simulation has been applied to 42 different artificial orchards. After previously defining and calculating two vegetative parameters (wood area and wood projected area) of the simulated trees, a good correlation (R2 ¼ 0.70e0.80) was found between these characteristics and the wood area detected (impacted) by the laser beam. The designed software can be valuable in horticulture for estimating biomass and optimising the pesticide treatments that are performed in winter

    Leap of Faith: Intelligent Design\u27s Trajectory after Dover

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    Juglans regia L., phenotypic selection and assessment of genetic variation within a simulated seed orchard

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    Noble hardwoods are very important for the Italian furniture industry. Since 1985, approximately 170,000 ha have been planted in Italy with noble hardwoods. Among them, about 50% of species are represented by walnuts. Walnut (Juglans regia L.), not native in Italy, has been the focus of a substantial research effort for breeding and improvement programmes. The priority has been to preserve the in situ genetic resource still existing after intensive felling. Phenotypes suitable for timber production showing important traits such as straight stem, nice branch architecture, dominance and adaptation (phenology) have needed to be developed and selected. In order to reach this goals, selection of valuable progenies and the evaluation of the interaction genotype x environment, methods based essentially on a multi-trait Selection Index, were developed. Studies have been undertaken also to measure the variation of phenological traits, more correlated to traits valuable for architecture; in addition, neutral markers were used to assess genetic variation among different intensities of the adopted selections. The individual genetic component was found to be higher than at the inter-population level. Results showed that a hypothetical seed orchard made with progenies selected by morphology, phenology and genetic traits could provide material with a good performance and supply a variability similar to larger populations as the total plantation or the pseudo-natural system chosen for comparison

    Monitoring of Artificial Nests in Horticultural Ecosystems-Observation of Woodpeckers Ethology

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    In order to increase the integrated protection of horticultural ecosystems by using the biological fight, the installation on artificial nests, is an important measure to help the insectivore birds. In a research program, a number of 166 artificial nets for Passeriformes birds were installed in different ecosystems as parks, botanical gardens and orchards in the South-Eastern part of Romania. During the nests monitoring period an interesting, but in the same time warring phenomenon, was noticed: a certain number of artificial nets were prayed by woodpeckers, especially by Dendrocopos major (Great Spotted Woodpecker). In Romania, all the ten European woodpecker species are nesting, nine being sedentary and one (Jynx torquilla) migratory, leaving the country in autumn. Woodpeckers in general, are very useful in woody plant biological protection, having a predominant insectivore nutrition and being the only one to keep under control the insects that are leaving on, inside and under the trees bark. The paper presents some data regarding the woodpeckers ethology in the studied ecosystems. More research are needed to understand the woodpeckers behaviour and to find protection methods of useful birds' nests against the woodpeckers attack. Keywords: useful birds;  Dendrocopos major;  Dendrocopos syriacus;  Passer montanus;  Picus viridis
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