Comparison of GOCE-GPS gravity fields derived by different approaches

Several techniques have been proposed to exploit GNSS-derived kinematic orbit information for the determination of long-wavelength gravity field features. These methods include the (i) celestial mechanics approach, (ii) short-arc approach, (iii) point-wise acceleration approach, (iv) averaged acceleration approach, and (v) energy balance approach. Although there is a general consensus that—except for energy balance—these methods theoretically provide equivalent results, real data gravity field solutions from kinematic orbit analysis have never been evaluated against each other within a consistent data processing environment. This contribution strives to close this gap. Target consistency criteria for our study are the input data sets, period of investigation, spherical harmonic resolution, a priori gravity field information, etc. We compare GOCE gravity field estimates based on the aforementioned approaches as computed at the Graz University of Technology, the University of Bern, the University of Stuttgart/Austrian Academy of Sciences, and by RHEA Systems for the European Space Agency. The involved research groups complied with most of the consistency criterions. Deviations only occur where technical unfeasibility exists. Performance measures include formal errors, differences with respect to a state-of-the-art GRACE gravity field, (cumulative) geoid height differences, and SLR residuals from precise orbit determination of geodetic satellites. We found that for the approaches (i) to (iv), the cumulative geoid height differences at spherical harmonic degree 100 differ by only ≈10 % ; in the absence of the polar data gap, SLR residuals agree by ≈96 % . From our investigations, we conclude that real data analysis results are in agreement with the theoretical considerations concerning the (relative) performance of the different approaches.

Rules to limit snacking in front of the TV and childhood BMI status: Findings from the "Fun Families Study"

Childhood obesity is increasing at epidemic rates, and thus there is a need to target appropriate childhood behaviors that contribute to obesity. Many factors contribute to childhood weight status. The aim of this study was to look at relationships between parental rules to limit snacking while watching television and childhood weight status. The study looked at the presence of the behavior of snacking while watching television yesterday, congruence between child- and parent-reported perception of the presence of rules to limit snacking while watching television, and parent-reported frequency of children following rules to limit snacking while watching television. The outcomes were examined in a multi-ethnic population of children ages 6 to 9 years in Southeast Texas.^ This study was a cross-sectional secondary data analysis of the pilot program, Fun Families. This study examined baseline data from 202 parent-child dyads, which included both the control ( N= 101) and intervention groups (N= 101). Data were gathered using validated questions that were administered to 6-9 year old children and their primary caregiver (referred to as parent in the rest of the discussion) in Southeast Texas, between 2006 and 2008. The main study outcome was childhood weight status based on CDC BMI-for-age categories. The independent variables are (1) the presence of parental rules to limit snacking while watching television, (2) the congruence between child and parent about the presence of rules to limit snacking while watching television, and (3) the parent-reported frequency of the child following the rules to limit snacking while watching television. Chi-Square analyses were used to determine if weight status was different for (1) children who reported rules to limit snacking yesterday, (2) children who reported snacking, (3) children whose parents reported rules were present, and (4) those who had rule congruence with the parents not. Chi-Square analyses also examined if there was a difference in the presence of snacking behavior for children who reported rules, for children whose parents reported rules, and for those children who had congruence about rules. Linear regressions were used to determine if any of the studied variables predicted increased weight status or reported snacking while watching television yesterday.^ This study found that child-reported snacking yesterday was significantly different for children who reported rules (4.12, p= 0.04). Child-reported rules was significantly associated with (p= -0.14, α= 0.04) and predicted child-reported snacking yesterday (R 2 0.021, p= 0.04, t= -2.04, 95% CI -0.31, -0.01). There was statistical significant incongruence between child and parent perception about the presence of rules to limit snacking yesterday (15.06, p= 0.00). For this population, parent education level was significantly associated with child-reported rules (r= -0.16, p= 0.02), child-reported snacking yesterday (r= -0.15, p= 0.04), and parent-reported frequency of child following rules to limit snacking (r= 0.29, p= -0.01). Parent-reported speaking another language besides English at home was significantly associated with parent-reported rules (r= 0.17, p= 0.02).^ Although the studied variables did not show any significant associations or predictors for childhood weight status, the significant discord between parent and child perception about the presence of rules provides valuable information to future interventions that aim to reduce childhood weight status. Including the creation and enforcement of parental rules in interventions to reduce childhood weight status will be beneficial for future studies.^

Techniques for Area Discretization and Coverage in Aerial Photography for Precision Agriculture employing mini quad-rotors

Remote sensed imagery acquired with mini aerial vehicles, in conjunction with GIS technology enable a meticulous analysis from surveyed agricultural sites. This paper sums up the ongoing work in area discretization and coverage with mini quad-­?rotors applied to Precision Agriculture practices under the project RHEA.

Non invasive moisture measurement in agricultural fiel using a rolling spherical robot

Irrigation management in large crop fields is a very important practice. Since the farm management costs and the crop results are directly connected with the environmental moisture, water control optimization is a critical factor for agricultural practices, as well as for the planet sustainability. Usually, the crop humidity is measured through the water stress index (WSI), using imagery acquired from satellites or airplanes. Nevertheless, these tools have a significant cost, lack from availability, and dependability from the weather. Other alternative is to recover to ground tools, such as ground vehicles and even static base stations. However, they have an outstanding impact in the farming process, since they can damage the cultivation and require more human effort. As a possible solution to these issues, a rolling ground robot have been designed and developed, enabling non-invasive measurements within crop fields. This paper addresses the spherical robot system applied to intra-crop moisture measurements. Furthermore, some experiments were carried out in an early stage corn field in order to build a geo-referenced WSI map.

Risk analysis for UAV safe operations: a rationalization for an agricultural environment

The road to the automation of the agricultural processes passes through the safe operation of the autonomous vehicles. This requirement is a fact in ground mobile units, but it still has not well defined for the aerial robots (UAVs) mainly because the normative and legislation are quite diffuse or even inexistent. Therefore, to define a common and global policy is the challenge to tackle. This characterization has to be addressed from the field experience. Accordingly, this paper presents the work done in this direction, based on the analysis of the most common sources of hazards when using UAV's for agricultural tasks. The work, based on the ISO 31000 normative, has been carried out by applying a three-step structure that integrates the identification, assessment and reduction procedures. The present paper exposes how this method has been applied to analyze previous accidents and malfunctions during UAV operations in order to obtain real failure causes. It has allowed highlighting common risks and hazardous sources and proposing specific guards and safety measures for the agricultural context.

Comparación de desempeño de una cámara de profundidad comercial y un LIDAR en explotaciones agrícolas.

Este estudio presenta una comparativa entre un LIDAR modelo LMS-111 (Sick Ltd.) y una cámara de profundidad de uso doméstico: Kinect (Microsoft Corporation), orientada a determinar las condiciones de uso de uno y otro sensor, así como sus ventajas e inconvenientes cuando son empleados en condiciones de campo, en una explotación agrícola. Para ello se realizaron diversos ensayos en una parcela experimental del CSIC-CAR de Arganda del Rey, España. Para los ensayos ambos sensores fueron instalados en un tractor operado remotamente diseñado y construido en el marco del proyecto europeo RHEA. Dicho tractor realizó dos recorridos diferentes: el primero se efectuó en paralelo a un muro y el segundo paralelo a una hilera de olivos. El primer ensayo se realizó con el propósito de cuantificar la uniformidad de las mediciones de ambos sensores y el segundo para validar los resultados en un cultivo real. Los recorridos se realizaron empleando cuatro marchas diferentes, con el objetivo de determinar si los diferentes regímenes de operación del motor influyen sobre la precisión de los sensores. Los resultados muestran que el LIDAR posee un mayor alcance máximo de medición, pero una resolución menor frente a Kinect, muestran además que el LIDAR puede ser operado a cualquier hora del día y condición meteorológica, mientras que Kinect, no puede operar en exteriores, salvo en horas del día con baja intensidad lumínica. Por otra parte la gran desventaja del LIDAR es su coste, 30 veces más alto que Kinect.

On the acquisition of high-resolution maps with open source software and commercials off-the-shelf quad-rotors

Mosaics are high-resolution images obtained aerially and employed in several scientific research areas, such for example, in the field of environmental monitoring and precision agriculture. Although many high resolution maps are obtained by commercial demand, they can also be acquired with commercial aerial vehicles which provide more experimental autonomy and availability. For what regard to mosaicing-based aerial mission planners, there are not so many - if any - free of charge software. Therefore, in this paper is presented a framework designed with open source tools and libraries as an alternative to commercial tools to carry out mosaicing tasks.

What is the optimal stitching orientation from an aerial survey perspective?

Mosaicing is a technique that allows obtaining a large high resolution image by stitching several images together. These base images are usually acquired from an elevated point of view. Until recently, low-altitude image acquisition has been performed typically by using using airplanes, as well as other manned platforms. However, mini unmanned aerial vehicles (MUAV) endowed with a camera have lately made this task more available for small for cicil applications, for example for small farmers in order to obtain accurate agronomic information about their crop fields. The stitching orientation, or the image acquisition orientation usually coincides with the aircraft heading assuming a downwards orientation of the camera. In this paper, the efect of the image orientation in the eficiency of the aerial coverage path planning is studied. Moreover, an algorithm to compute an optimal stitching orientation angle is proposed and results are numerically compared with classical approaches.

Planificación y supervisión de flotas de robots autónomos en tareas agrícolas

El control seguro y efectivo de las malas hierbas según los principios establecidos por la Agricultura de Precisión requiere una tecnología específica, avanzada y de coste asumible dentro de los márgenes de beneficio. El uso de plataformas móviles autónomas tanto terrestres como aéreas equipadas con sistemas de percepción innovadores, sistemas inteligentes de toma de decisión y herramientas que permitan la aplicación precisa de los tratamientos herbicidas, reduce el coste asociado a la operación así como los potenciales daños ambientales y el riesgo para los agricultores. Varios son los grupos internacionales de investigación dedicados al desarrollo de tecnologías basadas en sistemas robóticos capaces de optimizar las operaciones complejas implicadas en este tipo de tratamientos de precisión. El desarrollo de sistemas autónomos de ayuda al tratamiento preciso, tanto de cultivos extensivos (malas hierbas) como de leñosos, es el objetivo principal del proyecto RHEA (Robot Fleets for Highly Effective Agriculture and Forestry Management), financiado por el 7º Programa Marco de la CE y dirigido a minimizar los insumos (agroquímicos, combustible, etc.) a la vez que garantizar la calidad y seguridad del producto así como cubrir totalmente el campo independientemente del tamaño que éste tenga. RHEA propone utilizar una flota de robots pequeños/medianos tanto aéreos como terrestres para la inspección/monitorización y posterior aplicación de fitosanitarios, lo que presenta múltiples ventajas frente al tratamiento basado en la habitual máquina de mayores dimensiones y más tradicional. Entre otras, una flota de robots de tamaño pequeño/mediano reduce el impacto sobre la compactación del suelo e interactúa de un modo más seguro con los operarios, ya que la detección e interacción se puede distribuir en varios sistemas de detección y gestión de fallos como los propuestos en la presente tesis. El trabajo de investigación presentado en esta tesis se ha desarrollado dentro de este proyecto europeo y está relacionado con el diseño, desarrollo y evaluación del nivel más alto de la arquitectura RHEA, en otras palabras, con los tres aspectos fundamentales para conseguir que los robots de la flota ejecuten el trabajo eficientemente y sin intervención humana, es decir, con la planificación, la supervisión y la gestión completa e integrada de las tareas de inspección y tratamiento...

America learns to play; a history of popular recreation, 1607-1940.

Bibliography: p. 375-390.

The presidential campaign of 1832,

Published also as Johns Hopkins university studies in historical and political science, ser. XL, no. 1.

Doing educational research in Bangladesh: challenges in applying Western research methodology

Research methods are closely linked to specific cultures (Kee, 2004). Recognition of cultural values in the knowledge generation process is important if researchers are to produce culturally diverse interpretations of reality that facilitate meaningful progression. Asian scholars often depend on Western theories for understanding issues and creating knowledge in their own contexts (Papoutsaki, 2006). Many scholars relate this influence of the West on the non-West to neocolonization (Nguyen et al., 2009), neo-imperialism (Balogh, 1962) and globalization (Rizvi, 2004; Campbell, 2012). Scholars also see this influence as a unidirectional cultural flow, from 'the West' to 'the Rest' (Rizvi, 2004, p. 159). Such Western influences on knowledge-generating practices often pose challenges for researchers fro1n non-Western, particularly Asian, contexts when they employ Western methodologies in their own contexts. These challenges are embedded in differences in cultural values, beliefs and norms, as well as differences in orientation to research, because each society is unique in character and has specific knowledge needs that are culturally appropriate. Societal and local knowledge is, essentially, a contributory factor if research is to be locally appropriate and globally acceptable (Ma Rhea, 2004).