Últimas novedades en maquinaria de recolección de grano

Año tras año los fabricantes de cosechadoras van mejorando sus modelos o introduciendo rnaquinria totalmente nuevas para aumentar las capacidades de las mismas o para adaptarse a las necesidades específicas de los agricultores. En este articulo vamos a realizar un repaso a las novedades del mercado de cara a la campana 200

The use of national datasets to baseline science education reform: exploring value-added approaches

This paper uses data from the National Pupil Database to investigate the differences in ‘performance’ across the range of science courses available following the 2006 Key Stage 4 (KS4) science reforms in England. This is a value-added exploration (from Key Stage 3 [KS3] to KS4) aimed not at the student or the school level, but rather at that of the course. Different methodological approaches to carrying out such an analysis, ranging from simple non-contextualized techniques, to more complex fully contextualized multilevel models, are investigated and their limitations and benefits are evaluated. Important differences between courses are found in terms of the typical ‘value’ they add to the students studying them with particular applied science courses producing higher mean KS4 outcomes for the same KS3 level compared with other courses. The implications of the emergence of such differences, in a context where schools are judged to a great extent on their value-added performance, are discussed. The relative importance of a variety of student characteristics in determining KS4 outcomes are also investigated. Substantive findings are that across all types of course, science prior attainment at KS3, rather than that of mathematics or English, is the most important predictor of KS4 performance in science, and that students of lower socio-economic status consistently make less progress over KS4 than might be expected, despite prior attainment being accounted for in the modelling

A non‐contact opto‐electronic sensing device for precision linear and angular positioning of robotic manipulators

A non‐contacting optical sensor is devised to monitor the position and orientation of a robot end‐effector or grasped object within fine limits of accuracy. This enables fine alignment of tools or parts with respect to assembly fixtures, thus rendering precision assembly tasks to be performed in a dexterous manner. The sensor is capable of detecting linear displacements of the order of 5 µm or better and angular misalignments down to 5 seconds of arc. The principle of differential detection is employed which reduces the undesired effects of noise and fluctuations in the source intensity

Analysis of lubricated contact in continuously variable transmissions (CVT)

This paper presents a tribological model for a toroidal CVT. The model predicts the lubricant film thickness, viscous and boundary generated friction and the spin power loss in the contact. This is in order to evaluate the effect of different parameters on the efficiency and durability of the CVT system. An optimisation study is carried out to ascertain the effect of contact surface materials, lubricant rheology and contact geometry upon power loss and maximum generated contact pressure. The results show that numerically, even if the contact pressure cannot be significantly reduced, the contact spin power loss can be reduced by as much as 24%., thus improving system efficienc

Not all surveillance data are created equal—A multi‐method dynamic occupancy approach to determine rabies elimination from wildlife

1. A necessary component of elimination programmes for wildlife disease is effective surveillance. The ability to distinguish between disease freedom and non‐detection can mean the difference between a successful elimination campaign and new epizootics. Understanding the contribution of different surveillance methods helps to optimize and better allocate effort and develop more effective surveillance programmes. 2. We evaluated the probability of rabies virus elimination (disease freedom) in an enzootic area with active management using dynamic occupancy modelling of 10 years of raccoon rabies virus (RABV) surveillance data (2006–2015) collected from three states in the eastern United States. We estimated detection probability of RABV cases for each surveillance method (e.g. strange acting reports, roadkill, surveillance‐trapped animals, nuisance animals and public health samples) used by the USDA National Rabies Management Program. 3. Strange acting, found dead and public health animals were the most likely to detect RABV when it was present, and generally detectability was higher in fall– winter compared to spring–summer. Found dead animals in fall–winter had the highest detection at 0.33 (95% CI: 0.20, 0.48). Nuisance animals had the lowest detection probabilities (~0.02). 4. Areas with oral rabies vaccination (ORV) management had reduced occurrence probability compared to enzootic areas without ORV management. RABV occurrence was positively associated with deciduous and mixed forests and medium to high developed areas, which are also areas with higher raccoon (Procyon lotor) densities. By combining occupancy and detection estimates we can create a probability of elimination surface that can be updated seasonally to provide guidance on areas managed for wildlife disease. 5. Synthesis and applications. Wildlife disease surveillance is often comprised of a combination of targeted and convenience‐based methods. Using a multi‐method analytical approach allows us to compare the relative strengths of these methods, providing guidance on resource allocation for surveillance actions. Applying this multi‐method approach in conjunction with dynamic occupancy analyses better informs management decisions by understanding ecological drivers of disease occurrence

High resolution 3-D imaging via multi-pass SAR

Spaceborne/airborne synthetic aperture radar (SAR) systems provide high resolution two-dimensional terrain imagery. The paper proposes a technique for combining multiple SAR images, acquired on flight paths slightly separated in the elevation direction, to generate high resolution three-dimensional imagery. The technique could be viewed as an extension to interferometric SAR (InSAR) in that it generates topographic imagery with an additional dimension of resolution. The 3-D multi-pass SAR imaging system is typically characterised by a relatively short ambiguity length in the elevation direction. To minimise the associated ambiguities we exploit the relative phase information within the set of images to track the terrain landscape. The SAR images are then coherently combined, via a nonuniform DFT, over a narrow (in elevation) volume centred on the 'dominant' terrain ground plane. The paper includes a detailed description of the technique, background theory, including achievable resolution, and the results of an experimental stud

Determination of firmness in a fruit packing line using a non destructive impact sensor.

The increasing of quality fruit demanded by the consumers is originating an advance in the development and application of sensors capable of measuring parameters of quality (sugar, acids, firmness, etc) on a non destructive way. Some of these sensors are already operative for their use in laboratory and even in lines. The Physical Properties laboratory of the Polytechnic University of Madrid, is developing different sensors for their implementation in lines. One of them is a non destructive impact sensor to measure fruit firmness

Elementos deceleradores para transferencias en ángulo recto en líneas de manipulación de fruta.

Characterization of a 90° Transfer Point in a Fruit Packing Line. Characteristics of the impacts suffered by the fruit on a transfer point of an experimental fruit packing line were analysed. The transfer is made up by two transporting belts at different heights forming an angle of 90°. Different tests were carried out to study the effect of transfer height, velocity, belt structure and padding on the acceleration values recorded by an instrumental sphere (IS 100). Results showed that transfer height and belt structure affect mainly impact values on the belt base, and padding affects mainly impact values registered in lateral impact. Two powered transfer decelerators were tested at the same point with the aim of decreasing impacts suffered by the fruit

The environmental security debate and its significance for climate change

Policymakers, military strategists and academics all increasingly hail climate change as a security issue. This article revisits the (comparatively) long-standing “environmental security debate” and asks what lessons that earlier debate holds for the push towards making climate change a security issue. Two important claims are made. First, the emerging climate security debate is in many ways a re-run of the earlier dispute. It features many of the same proponents and many of the same disagreements. These disagreements concern, amongst other things, the nature of the threat, the referent object of security and the appropriate policy responses. Second, given its many different interpretations, from an environmentalist perspective, securitisation of the climate is not necessarily a positive development

The relationship between birth unit design and safe, satisfying birth: Developing a hypothetical model

Recent advances in cross-disciplinary studies linking architecture and neuroscience have revealed that much of the built environment for health-care delivery may actually impair rather than improve health outcomes by disrupting effective communication and increasing patient and staff stress. This is also true for maternity care provision, where it is suggested that the design of the environment can also impact on the experiences and outcomes for birthing women.The aim of this paper is to describe the development of a conceptual model based on literature and understandings of design, communication, stress and model of care. The model explores potential relationships among a set of key variables that need to be considered by researchers wishing to determine the characteristics of optimal birth environments in relation to birth outcomes for women and infants. The conceptual model hypothesises that safe satisfying birth is reliant on the level of stress experienced by a woman and the staff around her, stress influences the quality of communication with women and between staff, and this process is mediated by the design of the birth unit and model of care.The conceptual model is offered as a starting point for researchers who have an appreciation of the complexity of birth and the ability to bring together colleagues from a range of disciplines to explore the pre-requisites for safe and effective maternity care in new ways. © 2010 Elsevier Ltd