Joan Rosell

Real-Time Tree-Foliage Surface Estimation Using a Ground Laser Scanner

The optimization of most pesticide and fertilizer applications is based on overall grove conditions. In this paper, we propose a measurement system to estimate the foliage surface of a tree crop. The system is based on a ground laser scanner that estimates the volume of the trees and then extrapolates their leaf area using simple and fast algorithms to allow true real-time operation. Tests with pear trees demonstrated that the relation between the volume and the foliage can be interpreted as linear with a coefficient of correlation (R) of 0.81, and the foliage surface can be estimated from this volume with an average error less than 6%.

Airborne spray drift measurement using passive collectors and lidar Systems

Minimization of the risk associated with spray applications requires a proper understanding of the spray drift phenomenon. This fact has led to the development of several techniques to measure the deposition on horizontal surfaces as well as the airborne spray profiles. Assessment of airborne spray drift is particularly difficult because this phenomenon is subject to variable micrometeorological conditions. However the monitoring of airborne drift has a great importance since it can be carried over long distances. This paper reviews main sampling techniques currently used to asses the airborne spray drift, based on passive collectors and tracers. Theoretical principles that determine the efficiency of passive samplers are studied as well as the performance of different types of tracers. On the other hand, this paper shows new airborne spray drift assessment techniques based on lidar technology, reviewing its principle of operation as well as its practical application in several spray drift trials. It is concluded that the lidar technique has significant advantages over conventional methods, especially in terms of time consumption and monitoring capabilities. However, the future adoption of lidar technology for airborne spray drift studies will be subjected to the development of lidar instruments really adapted to this application.

Real-Time Tree Foliage Estimation Using a Ground Laser Scanner

The optimization of most pesticide and fertilizer applications is based on overall grove conditions. In this work we propose a measurement system based on a ground laser scanner to estimate the volume of the trees and then extrapolate their foliage surface in real-time. Tests with pear trees demonstrated that the relation between the volume and the foliage can be interpreted as linear with a coefficient of correlation (R) of 0.81 and the foliar surface can be estimated with an average error less than 5%

Distributed and self-adaptive microfluidic cell cooling for CPV dense array receivers

Temperature non uniformities of the CPV receivers lead to mismatch losses. In order to deal with this issue, a cooling device, formed by a matrix of microfluidic cells with individually variable coolant flow rate, has been developed. This device tailors the distribution of the heat extraction capacity over the CPV receiver to the local cooling needs in order to reduce the temperature non uniformities with respect to microchannel devices when submitted to uniform or non-uniform illumination profiles. At equal average temperature of the CPV receiver, power generation applying the matrix of microfluidic cells with individually variable coolant flow rate is 9.7% higher than the one with conventional microchannel technology.

Difficulties on Tree Volume Measurement from a Ground Laser Scanner

The optimization of most pesticide and fertilizer applications is based on overall grove conditions. To this end, a ground laser scanner can be used to estimate the volume of the trees and then extrapolate their foliage surface to control the application dose. In this work we summarize the difficulties involved in this volume measurement. Tests with pear trees demonstrated that volume estimated with a ground laser scanner is very sensitive to errors in the angle of orientation and in the estimated distance to the center of the trees.

Design Of A Hybrid Jet Impingement / Microchannel Cooling Device For Densely Packed PV Cells Under High Concentration

A hybrid jet impingement / microchannel cooling scheme was designed and applied to densely packed PV cells under high concentration. An experimental study allows validating the principles of the design and confirming its applicability to the cited system. In order to study the characteristics of the device in a wide range of conditions, a numerical model was developed and experimentally validated. The results allow evaluating the contributions of the cooling device to the performances of densely packed PV cells under high concentration. The main advantages of the system are related to its compactness, its good capacity of heat extraction associated to relatively low pressure losses and its capability to improve the temperature uniformity of the PV receiver with respect to other cooling schemes. These features improve the net electric output of the whole system and its reliability.