bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing soil erosion rates in cultivated areas of Navarre (Spain)
Authors: De Santisteban L. M. , Casalí J. , López J. J. 
Published: November 2005

AbstractAlthough there is much evidence of intense soil erosion in cultivated areas of Navarre (Spain), information on it is currently scarce. Rill and ephemeral gully volumes can be used as a guide to minimum erosion rates. With the main purpose of determining the annual soil loss rates in cultivated areas of central Navarre, a detailed assessment of rainfall and of rill and gully erosion was made in 19 small catchments from October 1999 to September 2001. Seventeen of them were randomly selected, and were cultivated with winter cereals, vineyards or sunflowers. The other two catchments were selected to represent partially uncultivated lands abandoned for ten years. Channel cross‐sections were measured by using a 1‐m‐wide micro‐topographic profile meter, describing 632 cross‐sections and processing information from 31 600 pins. Erosive events happened every year in the three study areas. For cereal catchments, soil losses occurred in only one or two rainfall events each year, usually at the end of autumn and in some summers, with high erosion rates (0·20–11·50 kg m−2 a−1). In vineyards, soil losses occurred several times per year, and in any season. This is attributed to the small percentage of surface covered by the crop throughout the year. Again, high erosion rates were found (0·33–16·19 kg m−2 a−1), with ephemeral gully erosion causing more loss than rill erosion. No‐till is proposed as an effective conservation measure. From this large data set, it can be stated that rill erosion and ephemeral gully erosion are widespread in Mediterranean regions, and that much more attention should be paid to the problem. Abandoned fields showed very high erosion rates (16·19 kg m−2 a−1 on average), suggesting that the abandonment of marginal lands without implementing any erosion control can lead to severe erosion rates. Copyright © 2005 John Wiley & Sons, Ltd.
Channel head location and characteristics using digital elevation models
Authors: Hancock G. R. , Evans K. G. 
Published: November 2005

AbstractThe drainage network is the conduit through which much surface water and sediment are routed within a catchment. In a catchment, the position of where hillslopes begin and channels end has long been considered the position of transition between diffusive processes upslope and the more incisive fluvial processes downslope. Consequently, understanding channel head location is an important issue in understanding catchment hydrology and geomorphology. This study examines channel head position and characteristics in a catchment in Arnhem Land, Northern Territory, Australia. In this study the position of channel heads was mapped within the catchment and plotted on a reliable digital elevation model of the catchment. It was found that the majority of channel heads have relatively small source areas and that graphical catchment descriptors, such as the area–slope relationship and cumulative area distribution, can provide reliable measures of the field position of the heads of first‐order streams and the transition from hillslope to channel. The area–slope relationship and cumulative area distribution are also shown to be good tools for determining digital elevation model grid size which can capture hillslope detail and the transition from hillslope to channel. Copyright © 2005 John Wiley & Sons, Ltd.
Rotor resistance tuning for indirect stator flux orientated induction motor drive based on MRAS scheme
Authors: Koubaa Yassine , Boussak Mohamed 
Published: November 2005

AbstractIn this paper, the indirect stator flux orientated controlled (ISFOC) induction motor drive is presented. In order to eliminate the effect of parameter variation on the ISFOC induction motor drive, an adaptation algorithm for tuning the rotor resistance is proposed. Based on the model reference adaptive system (MRAS) scheme, the rotor resistance is tuned to obtain an exact ISFOC induction motor drive. The integral plus proportional (IP) speed controller is designed using a model‐based analytical method in order to obtain a speed step response without overshoot. The reference and adjustable models, developed in the stationary stator reference frame, are used in the MRAS scheme to estimate induction rotor resistance from measured terminal voltages and currents. The major contributions of this work are: first, taking into account the variations of the rotor resistance during start‐up and normal operations; and second, the IP gains speed controller and PI gains current controller are calculated and tuned at each sampling time according to the new estimated rotor resistance. Computer simulation results show the satisfactory behaviour of the proposed identification method. Copyright © 2005 John Wiley & Sons, Ltd.
Implementation of a dual vector control strategy in a doubly‐fed machine drive
Authors: Azaza Henda , Masmoudi Ahmed 
Published: November 2005

AbstractThe paper deals with the control of a variable speed drive made up of a doubly‐fed motor (DFM) and a rotor converter including two current‐regulated voltage inverters connected through a DC link: the rotor‐side inverter and the line‐side one. Two vector control strategies are implemented using electrical variables expressed in the frame held by the DFM stator flux. High transient and steady‐state performances of the DFM have been gained, thanks to the implementation of the stator‐flux‐oriented control in the rotor‐side inverter even though the flux loop lacks accuracy, while a unity overall power factor operation has been achieved with the implementation of a (P,Q) vector control strategy in the line‐side inverter. Copyright © 2005 John Wiley & Sons, Ltd.
Design and comparison of different flux‐switch synchronous machines for an aircraft oil breather application
Authors: Amara Yacine , Hoang Emmanuel , Gabsi Mohamed , Lécrivain Michel , Allano Sylvain 
Published: November 2005

AbstractThis paper presents a design procedure of a flux–switch synchronous machine for an aircraft oil breather application. This work is part of a European project called ‘Power Optimised Aircraft’. The aim of this project is to replace some mechanical equipment by electromechanical devices to improve performance and reduce power consumption. The structure under study was developed at SATIE laboratory and it is based on the flux‐switch principle. The permanent magnets are located in the stator, and the rotor is entirely passive. The study described in this paper is limited to the electromagnetic design. Copyright © 2005 John Wiley & Sons, Ltd.
On the reduction of the commutation frequency in DTC: a comparative study
Authors: Ben Salem F. , Yangui A. , Masmoudi A. 
Published: November 2005

AbstractThe paper deals with a comparison between three DTC strategies: (i) the original one introduced by Takahashi which is based on an empirical approach, (ii) a strategy based on an analytical approach which takes into account the torque dynamic considering four quadrant operation, and (iii) an extension of the second approach considering twelve ‘active’ voltage space vectors. It has been found that a reduction of the commutation frequency has been gained going from the first strategy to the third one. This opens up crucial efficiency benefits, as far as the commutation losses in the inverter are considerably reduced. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical convergence of the MPFA O‐method and U‐method for general quadrilateral grids
Authors: Aavatsmark I. , Eigestad G. T. 
Published: November 2005

AbstractControl‐volume discretization methods are applicable for problems that require good numerical approximations of fluxes. Here, a class of flux‐continuous discretization methods, denoted multipoint flux approximation methods (MPFA), is discussed, and two different approaches are derived. The resulting discrete equations use pressures as the only unknowns, and the fluxes will be given explicitly as weighted sums of the discrete pressures. The two methods are denoted the O‐method and the U‐method, respectively, and differ in the way that continuity requirements are embedded in the discrete equations. Numerical tests are provided for smooth problems and problems with discontinuous coefficients for both the O‐method and the U‐method. Convergence rates of the methods are indicated through numerical experiments on smooth and rough grids. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical boundary conditions for globally mass conservative methods to solve the shallow‐water equations and applied to river flow
Authors: Burguete J. , García‐Navarro P. , Murillo J. 
Published: November 2005

AbstractA revision of some well‐known discretization techniques for the numerical boundary conditions in 1D shallow‐water flow models is presented. More recent options are also considered in the search for a fully conservative technique that is able to preserve the good properties of a conservative scheme used for the interior points. Two conservative numerical schemes are used as representatives of the families of explicit and implicit numerical methods. The implementation of the different boundary options to these schemes is compared by means of the simulation of several test cases with exact solution. The schemes with the global conservation boundary discretization are applied to the simulation of a real river flood wave leading to very satisfactory results. Copyright © 2005 John Wiley & Sons, Ltd.
Boundary element solution of unsteady magnetohydrodynamic duct flow with differential quadrature time integration scheme
Authors: Bozkaya C. , Tezer‐Sezgin M. 
Published: November 2005

AbstractA numerical scheme which is a combination of the dual reciprocity boundary element method (DRBEM) and the differential quadrature method (DQM), is proposed for the solution of unsteady magnetohydrodynamic (MHD) flow problem in a rectangular duct with insulating walls. The coupled MHD equations in velocity and induced magnetic field are transformed first into the decoupled time‐dependent convection–diffusion‐type equations. These equations are solved by using DRBEM which treats the time and the space derivatives as nonhomogeneity and then by using DQM for the resulting system of initial value problems. The resulting linear system of equations is overdetermined due to the imposition of both boundary and initial conditions. Employing the least square method to this system the solution is obtained directly at any time level without the need of step‐by‐step computation with respect to time. Computations have been carried out for moderate values of Hartmann number (M⩽50) at transient and the steady‐state levels. As M increases boundary layers are formed for both the velocity and the induced magnetic field and the velocity becomes uniform at the centre of the duct. Also, the higher the value of M is the smaller the value of time for reaching steady‐state solution. Copyright © 2005 John Wiley & Sons, Ltd.
Recent increase in persistence of atmospheric circulation over Europe: comparison with long‐term variations since 1881
Authors: Kyselý Jan , Domonkos Peter 
Published: November 2005

AbstractLong‐term changes in the persistence of atmospheric circulation (measured by the mean residence time of circulation types) over Europe since 1881 are studied using the Hess–Brezowsky classification of Grosswetterlagen. A comprehensive statistical analysis is performed utilizing tests for change points, trends and outliers. The most remarkable feature of the long‐term variations in the persistence of circulation patterns is a general sharp increase from the 1970s to the late 1980s. The shift towards higher persistence is statistically significant in most groups of the types and most seasons and is confirmed by all the statistical tools. The 1986–2000 period is an outlier, and the most pronounced change point in the time series appears in the mid‐1980s. The observed increase in the mean lifetime of the circulation types over European mid‐latitudes seems to be consistent with the idea of global warming, which is likely to shift the areas with the highest baroclinic activity (storm tracks) northwards. The enhanced persistence of the atmospheric circulation may have also supported the more frequent occurrence of temperature and other climatic extremes in Europe recently. Copyright © 2005 Royal Meteorological Society.
Study of the effect of ripening stages and climatic conditions on the physicochemical and sensorial parameters of two varieties of Vitis vinifera L. by principal component analysis: influence on enzymatic browning
Authors: Serrano‐Megías M , Núñez‐Delicado E , Pérez‐López AJ , López‐Nicolás JM 
Published: November 2005

AbstractThe present paper describes the effects of maturation on the physicochemical, biochemical and color components of Napoleon and Dominga grape varieties, and on any differences between them. Climatic conditions were taken into account to explain the results obtained. Protein levels increased during ripening and were correlated with pH. Polyphenoloxidase activity was affected by climatic conditions (rainfall) and increased to a greater degree in Dominga than in Napoleon. Taste tests were conducted to determine the contribution of physicochemical and biochemical parameters to the sensorial properties of the grapes. Principal components analysis showed that parameters were correlated in different ways during the ripening period in Napoleon and Dominga varieties. In Dominga AE were correlated to the b parameter and in Napoleon to the L parameter. Copyright © 2005 Society of Chemical Industry
Impact of grazing on soil biota in a Mediterranean grassland
Authors: Li Q. , Mayzlish E. , Shamir I. , Pen‐Mouratov S. , Sternberg M. , Steinberger Y. 
Published: November 2005

AbstractThe effect of cattle grazing on the soil nematode and protozoan communities, and on microbial biomass, was measured in Israel's northern highlands. Three grazing areas were compared: (1) with 1·1 cow ha−1 y−1; (2) 0·55 cow ha−1 y−1; and (3) control—no grazing for almost 18 years.Soil samples were collected from the upper 10 cm level of each area (n = 24), in autumn, before the onset of the rainy season, in order to analyse soil moisture, organic matter, total nitrogen, microbial biomass, soil respiration, soil free‐living nematodes, as well as ciliate and flagellate populations.Soil microbial biomass and soil free‐living nematodes showed no clear differences in impact between heavy and moderate grazing. However, ciliates and flagellates showed a significant response to different grazing pressures. Copyright © 2005 John Wiley & Sons, Ltd.
Crop and soil variability on terraces in the highlands of SW Uganda
Authors: Siriri D. , Tenywa M. M. , Raussen T. , Zake J. K. 
Published: November 2005

AbstractTerrace benches on the hillslopes of Western Uganda exhibit a crop‐yield gradient: upper portions of terraces produce less than the lower sections. We investigated the soil factors responsible for this yield variation on 30 terraces along 5 toposequences in what was predominantly a Ferralsol. Two levels of spatial analysis were conducted: (1) variation within individual terraces; and (2) differences across hill‐slope positions. A greenhouse experiment further examined this fertility gradient using soils extracted from the upper, middle and lower parts of the terrace. This included a nitrogen (N) treatment of 70 mg N kg−1 soil. In the fields sorghum (Sorghum bicolor) grain yield differed significantly (p ≤ 0·05) across terraces, increasing from 0·4 Mg ha−1 on the upper 40 per cent of terrace to 2·5 Mg ha−1 on the lower 40 per cent. Soil bulk density decreased down the terraces from 1·41 g cm−3 to 1·18 g cm−3, causing an increase of hydraulic conductivity from 1·6 cm h−1 to 7·3 cm h−1, from the upper to the lower part, respectively. Organic carbon (C) and total N increased from upper to lower terrace sections. In the greenhouse, sorghum growing on soils from which the soil physical limitations have been removed did not show significant yield differences across a terrace as observed in the field. Response to N was most pronounced on the upper terrace sections, increasing sorghum dry matter from 3 g pot−1 to 15 g pot−1. On the lower terrace, N amendment increased dry matter from 4 g pot−1 to 11 g pot−1. Technologies to improve the adverse soil physical conditions and the N limitations on upper terrace parts while preventing tillage‐ and soil‐erosion‐induced terrace scouring are required. Copyright © 2005 John Wiley & Sons, Ltd.
Soil erosion and the adaptive cycle metaphor
Authors: Dorren L. K. A. , Imeson A. C. 
Published: November 2005

AbstractThe landscapes that we live in and the changes that they undergo play an important part in the qualities of our lives. They provide natural goods and services of value to us because of the existence of soil, which is a medium between the solid earth and the sphere in which we live our daily life. The medium soil is constantly subject to change and one of the causes is soil erosion. If one tries to understand or to deal with soil erosion it is helpful to consider soil as an integral part of continuously changing landscapes and to be aware of the different functions of a soil in its environmental context at different scales. To clarify this, we present three important concepts. These are: (1) scale/connectivity; (2) change; and (3) resilience. These concepts will be put in an innovative framework called the panarchy theory, which represents a hierarchical structure in which both human and natural systems are linked together in adaptive cycles. Presenting soil erosion in such a framework allows us to link causes and their impacts at different scales. The application of such a framework and the insight obtained could facilitate the assessment of risks and possibilities for sustainable use. Copyright © 2005 John Wiley & Sons, Ltd.
Concise review of interrill erosion studies in SE Spain (Alicante and Murcia): erosion rates and progress of knowledge from the 1980s
Authors: Boix‐Fayos C. , Martínez‐Mena M. , Calvo‐Cases A. , Castillo V. , Albaladejo J. 
Published: November 2005

AbstractFrom the 1980s onward studies on interrill soil erosion were intensified in SE Spain. The main achievements of the research carried out in the field areas of Alicante and Murcia concern: first, (1) the estimation of erosion rates directly in the field under a wide range of methodologies, different scales and different environmental conditions; (2) estimations based on existing models, such as the USLE, carried out for different subcatchments of the Segura and Júcar catchments; and (3) other parametric and physical event‐based models have also been calibrated and validated.Second, the progress of the knowledge in understanding erosion mechanisms. New and reviewed concepts regarding mainly hydrological behaviour and sediment movement and transport at patch, slope and catchment scale have improved our understanding of soil‐erosion processes in Mediterranean‐type ecosystems. These concepts focus on: (1) the definition of runoff generation models more appropriate to Mediterranean conditions; (2) the definition of thresholds for runoff generation; (3) the definition of models of soil water redistribution within soils and at landscape level; (4) the establishment of conditions and controls for sediment detachment and movement; and (5) the characterization of the change in the controlling factors of soil erosion and degradation under different environmental characteristics (climatic or human‐induced). The insights into soil‐erosion processes obtained and the renewed hydrological and geomorphological concepts achieved can be very valuable for the design of new strategies of erosion management and ecosystems restoration. Copyright © 2005 John Wiley & Sons, Ltd.
The effectiveness of agro‐environmental schemes in reducing erosion
Authors: Arnoldussen A. H. 
Published: November 2005

AbstractAutumn and winter in Norway are the most vulnerable periods for erosion. The government aims to reduce the autumn tillage acreage and keep the soil covered by vegetation as much as possible during the winter period. The farmers get support to plough their land in spring; the level of this support is related to the erosion risk. Also, support is given to several technical measures aimed at preventing eroded material reaching streams and rivers. The Agricultural Environmental Scheme has been successful and Norway has reduced nutrient runoff by nearly 50 per cent as required by the North Sea Agreement. However, more can be achieved. From January 2004 the counties and municipalities can further adapt the Agricultural Environmental Scheme to suit the protection of local watersheds. Copyright © 2005 John Wiley & Sons, Ltd.
Dealing with soil threats in Lower Saxony, Germany
Authors: Gunreben M. 
Published: November 2005

AbstractIn Germany a legal federal framework for soil protection was created in 1998 through the Federal Soil Protection Law. A State Soil Protection Law for Lower Saxony was enacted in 1999 in order to regulate the legal aspects of soil protection in Lower Saxony.The data contained in the soil information system for Lower Saxony (NIBIS®) provide a basis for decision making in state and regional development planning. The NIBIS® plays a significant role as part of the legal framework in respect of soil protection, nature protection and water protection.The main focus of currently existing state and federal acts on soil conservation is on material impacts (heavy metals, organics) rather than non‐material ones. In consideration of this situation and on behalf of Lower Saxony's Department for Environment, the Lower State Agency for Ecology in cooperation with other state agencies responsible for soil protection, is developing a concept to define targets for soil quality in Lower Saxony.Standards and aims of soil quality with regard to the factors of erosion and sealing by construction are described. In the case of water erosion, the concept defines degrees of threat to soil fertility depending on the depth of common rooting. For wind erosion, the concept of ‘tolerable field length’ has been introduced. For soil sealing the measure of building coverage with the main components ‘coverage ratio’ and the ‘floor space ratio’ is of great relevance. Consequently, quality standards have been attributed to both components. Copyright © 2005 John Wiley & Sons, Ltd.
The institutional framework of land‐use decisions
Authors: Bizer K. 
Published: November 2005

AbstractEffective soil‐protection policies should be based on a sound understanding of individual land‐use decisions in order to change it towards more sustainable decisions. This paper argues for the modification of the behavioural model of ‘Homo economicus’ by explicitly allowing for cognitive limits and non‐reflective modes of behaviour in addition to situational utility‐maximizing behaviour. These modifications take into account actual difficulties in changing individual land‐use decisions. While it is possible to adjust behaviour by moral persuasion, consensus‐oriented round‐tables or planning processes, such approaches are unlikely to bring about effective changes in land‐use decisions without changing relative prices. This paper suggests ways to implement a special land‐use tax as a reform model for existing property taxes. Such a land‐use tax applies different rates according to ecological damage. Accordingly, surfaces covered by buildings will pay higher tax rates than free space. Conventional agriculture will pay more than forest areas, and nature reserve areas will be free of charge. Such a land‐use tax, designed as a revenue‐neutral alternative to Germany's property tax, could trigger modest changes in land‐use behaviour in the near future. A general reform of local fiscal relations could increase this effect in the long run. Copyright © 2005 John Wiley & Sons, Ltd.