Development of a robotic detection system for greenhouse pepper plant diseases

Automation of disease detection and monitoring can facilitate targeted and timely disease control, which can lead to increased yield, improved crop quality and reduction in the quantity of applied pesticides. Further advantages are reduced production costs, reduced exposure to pesticides for farm workers and inspectors and increased sustainability. Symptoms are unique for each disease and crop, and each plant may suffer from multiple threats. Thus, a dedicated integrated disease-detection system and algorithms are required. The development of such a robotic detection system for two major threats of bell pepper plants: powdery mildew (PM) and Tomato spotted wilt virus (TSWV), is presented. Detection algorithms were developed based on principal component analysis using RGB and multispectral NIR-R-G sensors. High accuracy was obtained for pixel classification as diseased or healthy, for both diseases, using RGB imagery (PM: 95%, TSWV: 90%). NIR-R-G multispectral imagery yielded low classification accuracy (PM: 80%, TSWV: 61%). Accordingly, the final sensing apparatus was composed of a RGB sensor and a single-laser-beam distance sensor. A relatively fast cycle time (average 26.7 s per plant) operation cycle for detection of the two diseases was developed and tested. The cycle time was mainly influenced by sub-tasks requiring motion of the manipulator. Among these tasks, the most demanding were the determination of the required detection position and orientation. The time for task completion may be reduced by increasing the robotic work volume and by improving the algorithm for determining position and orientation.     

Coherent optical spectroscopy of a strongly driven quantum dot

Quantum dots are typically formed from large groupings of atoms and thus may be expected to have appreciable many-body behavior under intense optical excitation. Nonetheless, they are known to exhibit discrete energy levels due to quantum confinement effects. We show that, like single-atom or single-molecule two- and three-level quantum systems, single semiconductor quantum dots can also exhibit interference phenomena when driven simultaneously by two optical fields. Probe absorption spectra are obtained that exhibit Autler-Townes splitting when the optical fields drive coupled transitions and complex Mollow-related structure, including gain without population inversion, when they drive the same transition. Our results open the way for the demonstration of numerous quantum level-based applications, such as quantum dot lasers, optical modulators, and quantum logic devices.     

Segmentation and motion parameter estimation for robotic Medjoul-date thinning

Precision Agriculture - Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automation can significantly reduce labor and improve efficiency. An image processing...     

Homoeothermy and growth rate in the fowl

Observations on growth rates and diurnal changes in colonic temperatures were made on seven groups of 30 to 50 White Plymouth Rock x Cornish chicks aged between 6 and 8 weeks. Ambient air temperature ranged from 22 °C to 35 °C.

Colonic temperatures in the morning (08.00 to 09.00 h) and growth rates were within the normal range. A slight hyperthermia was evident from 13.00 to 14.00 h.

Morning colonic temperatures were not correlated with the later increments in body temperatures. This suggests that the set‐point temperature for thermo‐regulatory control differs between individuals.

Growth rates were not correlated with the morning colonic temperature, except in one group; they were, however, significantly correlated with the diurnal fluctuation in colonic temperature in all groups. These results suggest that the maintenance of a constant body temperature is essential for a normal growth rate.

The variation in thermoregulatory ability accounted for 31 to 71% of the total variation in growth rate.