An investigation of passive control methods for shock-induced separation at hypersonic speeds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76765/1/AIAA-1992-2725-533.pd

Evapotranspiration from an Olive Orchard using Remote Sensing-Based Dual Crop Coefficient Approach

A remote sensing-based approach to estimate actual evapotranspiration (ET) was tested in an area covered by olive trees and characterized by Mediterranean climate. The methodology is a modified version of the standard FAO-56 dual crop coefficient procedure, in which the crop potential transpiration, Tp, is obtained by directly applying the Penman-Monteith (PM) equation with actual canopy characteristics (i.e., leaf area index, albedo and canopy height) derived from optical remote sensing data. Due to the minimum requirement of in-situ ancillary inputs, the methodology is suitable also for applications on large areas where the use of tabled crop coefficient values become problematic, due to the need of corrections for specific crop parameters, i.e., percentage of ground cover, crop height, phenological cycles, etc. The methodology was applied using seven airborne remote sensing images acquired during spring-autumn 2008. The estimates based on PM approach always outperforms the ones obtained using simple crop coefficient constant values. Additionally, the comparison of simulated daily evapotranspiration and transpiration with the values observed by eddy correlation and sap flow techniques, respectively, shows a substantial agreement during both dry and wet days with an accuracy in the order of 0.5 and 0.3 mm d−1, respectively. The obtained results suggest the capability of the proposed approach to correctly partition evaporation and transpiration components during both the irrigation season and rainy period also under conditions of significant reduction of actual ET from the potential one

Comparison of SWAP and FAO Agro-Hydrological Models to Schedule Irrigation of Wine Grape

This paper compares two agro-hydrological models that are used to schedule irrigation of a typical Mediterranean crop. In particular, a comparison between the Food and Agriculture Organization (FAO) model, which uses a black box approach, and the soil-water-atmosphere-plant (SWAP) model, which is based on the numerical analysis of Richards' equation, are shown for wine grape. The comparison was carried out for the 2005 and 2006 irrigation seasons and focused on hydrological balance components and on soil water contents. Next, the ordinary scheduling parameters were identified so that the performance of the two models, which aimed to evaluate the seasonal water requirements and the irrigation times, could be assessed. In the validation phase, both of the models satisfactorily simulated the soil water content, and comparable values of cumulative evapotranspiration were obtained. With the goal of recognizing the crop water stress condition in the field, the original algorithm of the FAO model was modified. This research provided evidence of how the two agrohydrological models, although characterized by different approaches in modeling the phenomena, showed a similar behaviour when used for scheduling irrigation under soil water deficit conditions. © 2012 American Society of Civil Engineers

Detecting crop water status in mature olive groves using vegetation spectral measurements

Full spectral measurements (350-2500nm) at tree canopy and leaf levels and the corresponding leaf water potentials (LWP) were acquired in an olive grove of Sicily, at different hours of the day, during summer season 2011. The main objective of the work was to assess, on the basis of the experimental data-set, two different approaches to detect crop water status in terms of LWP. Specifically, using existing families of Vegetation Indices (VIs) and applying Partial Least Squares Regression (PLSR) were optimised and tested. The results indicated that a satisfactory estimation of LWP at tree canopy and leaf levels can be obtained using vegetation indices based on the near infrared-shortwave infrared (NIR-SWIR) domain requiring, however, a specific optimisation of the corresponding "centre-bands". At tree canopy level, a good prediction of LWP was obtained by using optimised indices working in the visible domain, like the Normalized Difference Greenness Vegetation Index (NDGI, RMSE=0.37 and R2=0.57), the Green Index (GI, RMSE=0.53 and R2=0.39) and the Moisture Spectral Index (MSI, RMSE=0.41 and R2=0.48). On the other hand, a satisfactory estimation of LWP at leaf level was obtained using indices combining SWIR and NIR wavelengths. The best prediction was specifically found by optimising the MSI (RMSE of 0.72 and R2=0.45) and the Normalized Difference Water Index (NDWI, RMSE=0.75 and R2=0.45). Even using the PLSR technique, a remarkable prediction of LWP at both tree canopy and leaf levels was obtained. However, this technique requires the availability of full spectra with high resolution, which can only be obtained with handheld spectroradiometers or hyper-spectral remote sensors

Assessing agro-hydrological models to schedule irrigation for crops of Mediterranean enviroment

Despite in Mediterranean environment water resources for irrigation are limited, water management for agriculture is often practiced ignoring principles of environmental sustainability. Objective of the paper is to asses the possibility of using agro-hydrological models for irrigation scheduling, in order to optimize the water use efficiency. The results of a comparison between the numerical SWAP model and the functional model proposed by FAO to estimate water requirements in two typical arboreal Mediterranean Crops (grapevine and olive) are showed. In the initial phase of the research, involving both irrigation seasons 2005 and 2006, after a preliminary analysis of soil hydraulic and biophysical plant parameters, two intensive field measurements campaigns were carried out to measure the soil water content at different depths, to proceed to the validation of both the models. Validation of the model was carried out by means of the comparison between measured and predicted soil water content. Finally different irrigation scheduling options were examined, in order to compare the scheduled irrigation times with those planned by the farmers. The results of investigations evidenced that FAO model simulates reliably the values of average water content of the soil profile, even if a certain overestimation of evapotranspiration fluxes can be observed with the FAO 56 model compared with SWAP. Consequently, the FAO model anticipates the starting date for irrigation obtained with SWAP, but, in terms of seasonal water requirements, the estimates determined by the two modes did not result significantly different

Retinal vessel local tortuosity under a macula-to-optic disc central-framing change

Some ocular and cardiovascular diseases can be detected through the increased tortuosity of retinal blood vessels. Objective tortuosity measures can be obtained from digital image analysis of a retinography. This study tested a set of local tortuosity indices under a change in the frame center (macula, optic disc) of the eye fundus image. We illustrate the effects of such a change on 40 pairs of vessels evaluated with eight tortuosity indices. We show that the frame center change caused significant differences in the mean values of the vast majority of the tortuosity indices analyzed. The index defined as the ratio of the curvature to the arc length of a vessel segment proved to be the most robust in relation to a frame center change. Experimental results obtained from the analysis of clinical images are provided and discussed.This research was funded by Agencia Estatal de Investigación of the Spanish Government, grant number PID2020-114582RB-I00/AEI/10.13039/501100011033.Peer ReviewedPostprint (published version

Combined use of eddy covariance and sap flow techniques for partition of ET fluxes and water stress assessment in an irrigated olive orchard

Correct estimation of crop actual transpiration plays a key-role in precision irrigation scheduling, since crop growth and yield are associated to the water passing through the crop. Objective of the work was to assess how the combined use of micro-meteorological techniques (eddy covariance, EC) and physiological measurements (sap flow, SF) allows a better comprehension of the processes involving in the Soil-Plant-Atmosphere continuum. To this aim, an experimental dataset of actual evapotranspiration, plant transpiration, and soil water content measurements was collected in an olive orchard during the midseason phenological period of 2009 and 2010. It was demonstrated that the joint use of EC and SF techniques is effective to evaluate the components of actual evapotranspiration in an olive orchard characterized by sparse vegetation and a significant fraction of exposed bare soil. The availability of simultaneous soil water content measurements allowed to estimate the crop coefficients and to assess a simple crop water stress index, depending on actual transpiration that can be evaluated even in the absence of direct measurements of actual transpiration. The crop coefficients experimentally determined resulted very similar to those previously evaluated; in particular, in the absence of water stress, a seasonal average value of about 0.65 was obtained for the "single" crop coefficient, whereas values of a 0.34 and 0.41 were observed under limited water availability in the root zone. The comparison between the values of crop water stress index evaluated during the investigated periods evidenced systematically lower values (less crop water stress) in the first year compared to the second, according to the general trend of soil waters content in the root zone. Further researches are however necessary to extent the experimental dataset to periods characterized by values of soil evaporation higher than those observed, in order to verify the crop coefficients even under different conditions than those investigated. © 2012 Elsevier B.V

Perfil fenólico de aceites de oliva vírgenes obtenidos de selecciones avanzadas en un programa de mejora

The evaluation of the phenolic composition in advanced selections in breeding programs constitutes the first approach for selecting genotypes with improved olive oil quality. In this work, the influence of genotype and ripening index on the phenolic profile of olive oils from advanced selections in comparison to their genitors was studied. Fruit samples were collected in genotypes from crosses between ‘Arbequina’ × ‘Picual’, ‘Picual’ × ‘Arbequina’ and ‘Frantoio’ × ‘Picual’ at five dates from 1st October to 26th November 2009. Characterization of the phenolic profile was performed by liquid–liquid extraction with 60:40 (v/v) methanol–water and subsequent chromatographic analysis with absorption and fluorescence detection in a sequential configuration. A dual effect of genotype and fruit ripening on the phenolic profile has been observed with more pronounced genetic influence in both total (34.73% and 20.45%, respectively) and individual phenols (16.99% to 49.25% and 1.58% to 23.77%, respectively). A higher degree of variability between genotypes at early ripening stages was also observed (p<0.05). The obtained results also allow identification of selections with high content of total and individual phenols. These results suggest a strategy based on early harvesting of fruits (at the first three ripening indexes) for better comparison and selection of genotypes in further crosses in olive breeding programs aiming at improving the quality of virgin olive oil.La evaluación de la composición fenolica en selecciones avanzadas en programas de mejora constituye el primer paso para la selección de genotipos cuyos aceites son de mejor calidad. Se ha estudiado la influencia del genotipo y del índice de madurez en el perfil fenólico del aceite de oliva de selecciones avanzadas en comparación con sus genitores. Se recogieron muestras de genotipos obtenidos de cruzamientos entre 'Arbequina' × 'Picual', 'Picual' × 'Arbequina' y 'Frantoio' × 'Picual' en cinco fechas entre el 1 de octubre y el 26 noviembre de 2009. Se realizó la caracterización del perfil fenólico por extracción líquido–líquido con metanol–agua al 60:40 (v/v) seguido de un análisis cromatográfico con detección por absorción y fluorescencia en una configuración secuencial. Los resultados obtenidos mostraron un mayor grado de variabilidad entre genotipos en las primeras etapas de maduración de los frutos (p<0.05), así como el efecto de la madurez de los frutos y del genotipo en el perfil fenólico, con una influencia genética más pronunciada tanto para fenoles totales (34.73% and 20.45%, respectivamente) como individuales (entre 16.99% y 49.25% y entre 1.58% y 23.77%, respectivamente). Los resultados obtenidos han permitido la identificación de selecciones con alto contenido en fenoles totales e individuales. Ambos resultados sugieren una estrategia basada en la evaluación de los fenoles totales e individuales en las primeras etapas de la maduración para comparar y seleccionar genotipos en programas de mejora por cruzamiento encaminados a mejorar la calidad del aceite de oliva virgen

Los estándares para el diseño y implementación de entornos de enseñanza-aprendizaje en red

El objetivo de esta comunicación es presentar un resumen de la situación actual en el marco de la creación, aceptación y adopción de estándares para el diseño e implementación de Entornos Tecnológicos de Enseñanza-Aprendizaje. En este sentido, se presenta la arquitectura LTSA, base de un futuro estándar internacional para este tipo de entornos. También se analiza la especificación IMS, como muestra de una de las pocas implementaciones actuales de estos conceptos. Finalmente, se realiza una comparación entre la estructura organizativa IMS para un centro formativo virtual con la correspondiente a la Universidad en España, concluyendo que los estándares tecnológicos se inspiran en planteamientos de la Organización Escolar.The aim of this paper is to present an overview of the current situation in the process of development, acceptance and adoption of International Standards for the design and implementation of Learning Technology Systems. In that sense we introduce the LTSA architecture as the basis for a future international standard for this kind of environments. We analyse also the IMS specification as the most used model for the implementation of these concepts. Finally, we do a comparison between the IMS structure for virtual centres and the structure of the Spanish University, concluding that all these technological standards are mainly based on educational organization concepts

Centennial olive trees as a reservoir of genetic diversity

Background and AimsGenetic characterization and phylogenetic analysis of the oldest trees could be a powerful tool both for germplasm collection and for understanding the earliest origins of clonally propagated fruit crops. The olive tree (Olea europaea L.) is a suitable model to study the origin of cultivars due to its long lifespan, resulting in the existence of both centennial and millennial trees across the Mediterranean Basin.MethodsThe genetic identity and diversity as well as the phylogenetic relationships among the oldest wild and cultivated olives of southern Spain were evaluated by analysing simple sequence repeat markers. Samples from both the canopy and the roots of each tree were analysed to distinguish which trees were self-rooted and which were grafted. The ancient olives were also put into chronological order to infer the antiquity of traditional olive cultivars.Key ResultsOnly 9·6 % out of 104 a priori cultivated ancient genotypes matched current olive cultivars. The percentage of unidentified genotypes was higher among the oldest olives, which could be because they belong to ancient unknown cultivars or because of possible intra-cultivar variability. Comparing the observed patterns of genetic variation made it possible to distinguish which trees were grafted onto putative wild olives.ConclusionsThis study of ancient olives has been fruitful both for germplasm collection and for enlarging our knowledge about olive domestication. The findings suggest that grafting pre-existing wild olives with olive cultivars was linked to the beginnings of olive growing. Additionally, the low number of genotypes identified in current cultivars points out that the ancient olives from southern Spain constitute a priceless reservoir of genetic diversity