Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Onderwijsconcepten en professionele ontwikkeling van leraren vanuit praktijktheoretisch perspectief
    Vries, Y. de - \ 2004
    Wageningen University. Promotor(en): Martin Mulder, co-promotor(en): D. Beijaard. - [s.l.] : S.n. - ISBN 9789058089571 - 184
    lerarenopleiding - beroepsopleiding (hoger) - onderwijsmethoden - leertheorie - docenten - onderwijzen - oefening - theorie - nederland - professionaliteit - ontwikkeling - vakbekwaamheid - teacher training - professional education - teachers - teaching - teaching methods - learning theory - professionalism - development - professional competence - practice - theory - netherlands
    The focus of the study reported on in this dissertation is research among teachers with respect to their educational concepts and the extent to which their theories change or develop in the course of teachers' careers. The research is done from a practical knowledge perspective in which what teachers themselves regard as important in education and in teaching, plays a central role. The main research study focussed on a number of aspects that constitute the core of thinking about education; i.e., the aim of education, the content of education, and the role of the teacher and that of the pupil in the educational process. By means of interviews and observation in the classroom these aspects were studied. The results show that the teachers' educational concepts are strongly related to personal and context factors like experiences during childhood; the their education, working experience, the pupils they teach, the school organization, the subjects the teachers teach and social developments. In the second, complementary study, the focus was on the teachers' practical theories about how pupils learn, and on the extent to which these theories change or develop in the course of teachers' careers. The data indicate that all the teachers changed or developed their practical theory with respect to learning by pupils to a greater or lesser degree. As in the main study, personal and contextual factors played a role in the changes in, and development of, these theories. The teacher's own 'drive' to learn, the extent of internal or external steering, and the motivation to learn are important personal factors. Experiences gained in educational practice and the school organization are important context factors.
    CoP op Alterra; use the world around as a learning resource and be a learning resource for the world
    Kersten, P.H. ; Kranendonk, R.P. - \ 2002
    Wageningen : Alterra (Alterra-rapport 546) - 151
    kennis - ontwikkeling - managementbenaderingen - theorie - informatieverspreiding - kennistheorie - kennismanagement - kennisoverdracht - maatschappijwetenschappen - sociologie - knowledge - development - diffusion of information - management philosophies - theory - theory of knowledge
    Uitleg van het begrip Community of Practice (CoP). Het proces van kennisontwikkeling, zoals dat door Etienne Wenger is ontwikkeld
    Op zoek naar magische momenten in de ruimtelijke planvorming; deskstudie voor de etudes uit de nota "Natuur voor mensen, mensen voor natuur"
    Kersten, P.H. ; Eekhout, M.J.J. ; Kranendonk, R.P. ; Poel, K.R. de; Geenen, J.J.N. - \ 2001
    Wageningen : Alterra (Alterra-rapport 366) - 166
    ruimtelijke ordening - ontwerp - acteurs - gevalsanalyse - planning - theorie - landelijk gebied - landschapsarchitectuur - natuur - physical planning - design - actors - case studies - planning - theory
    Architectuur voor een 'standaard raamwerk water'; toepasbaar bij modelstudies in het waterbeheer
    Wal, T. van der - \ 1999
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 32 (1999)22. - ISSN 0166-8439 - p. 46 - 47.
    waterbeheer - hydrologie - theorie - methodologie - modellen - computer software - toepassingen - computers - ontwerp - systemen - automatisering - programmeren - integraal waterbeheer - software-ontwikkeling - water management - hydrology - theory - methodology - models - computer software - applications - computers - design - systems - automation - programming - integrated water management - software engineering
    Uitleg over de achtergronden en de architectuur van het in ontwikkeling zijnde 'Standaard Raamwerk Water'. Het wordt een gemeenschappelijk raamwerk voor alle modelapplicaties in het integraal waterbeheer
    Management, structuur en cultuur : over het gebruik van organisatietheorieën in Breda
    Polling, J. - \ 1999
    Agricultural University. Promotor(en): J.C. van Dalen. - S.l. : [s.n.] - ISBN 9789058080967 - 251
    overheidsorganisaties - organisatieontwikkeling - organisaties - theorie - verandering - bedrijfsvoering - overheid - plaatselijk bestuur - geschiedenis - nederland - noord-brabant - organisatie - government organizations - organizational development - organizations - theory - change - management - public authorities - local government - history - netherlands - noord-brabant - organization

    This book deals with organizational change in two different ways. One way is the historical description of several attempts to implement organizational change in one particular organization. That organization is the local civil service of Breda, a city in the southern part of the Netherlands with a history that goes back to the thirteenth century. This book covers the period of about thirty years from 1965 until 1996. In this period Breda had between 120.000 and 130.000 inhabitants and the civil service varied between 1200 and 1800 employees. The historical description focuses not only on the changes as such but also on the situation that existed when the attempts to change were undertaken (the environmental conditions). Main goal in this part of the study is to create a basis for an answer to the question: What factors or conditions were decisive for the claimed success of the changes that took place in 1992, where similar attempts at earlier dates seemed to have failed?

    The other way to treat organizational change in this study is induced by the question: Which organization theory or theories were used in the reorganizations described in the historical part? In order to obtain an answer to this question it was necessary to go into the character of organizations theory - which is thought to be a body of knowledge - and into the relevancy of organizations theory for practical use - which is thought to be small. A theoretical model for research is proposed in part 2. This model is based upon three major assumptions.

    guidelines and directions derived from organizations theory are insufficient to support organizational change in practice. This causes "changers" (those who initiate the desired change) to develop their own, "private" organization theory. An important part of this study is concerned with the reconstruction of those private theories.the private theories of changers are expressed one way or another in the documents used to realise the desired organizational change. In the addendum to this study quotes from the documents used are translated into "central concepts" of the changers. These central concepts are considered to be the framework of the private organization theories.organizational change is realised on one or more of three organizational dimensions: management, structure and culture. These dimensions are influenced strongly by environmental factors. Technologic possibilities available, the actual economic situation, prevailing social values and political and governmental conditions are considered to be the most important environmental conditions.

    The last section of part 2 (chapter 6) gives a short analysis of the specific character of Dutch local government and public service. In the local civil service the position of the town clerk in most cities has evolved to that of city manager in the period considered.

    The historical account in part 3 is subdivided into 5 chapters, the first being a short and global sketch of the history of the Netherlands since World War II in order to give a general background for the developments in Breda. Each of the other four give a description of one of the successive attempts to reorganize the civil service of Breda. In these chapters attention is also given to several problems of local policy that filled, for the most part, the political agenda.

    In part 4, the model developed in part 2 is applied on documents used to realise the desired changes described in part 3. The private theories for each period are reconstructed and compared to the general organization theory existing at the time. An important aspect of this analysis is that private and general organization theory and the desired and realised organization are described in terms of the three dimensions (management, structure and culture) of the proposed referential model in part 2. Each chapter of part 4 closes with a summary of conclusions with respect to that period.

    General conclusions derived from the whole study and a few suggestions for further research are gathered in part 5. The most important conclusions can be presented in the following statements.

    Writers on organizations agree to a large extent on the fact that environmental conditions have a bearing on the structure and functioning of organizations. Many of them even agree on the fact that organizations theories are influenced by the economic and social forces of their time. Nevertheless proposed organization theories hardly ever try to specify the situation in which they are developed.An explanation for this lack of attention may be found in the emphasis on comparative analysis of organizational research. In comparing organizations in a specific historical period, technological economic, social and political conditions can be viewed as the same for all organizations at the time. In that case those environmental conditions have no bearing on the results of the research and need not be made explicit.Organizational change can be considered as change on the three dimensions: management, structure and culture. In the case observed in this study the same set of rather simple rules was used for creating change in each of the four successive periods on the dimensions management: (replace sitting managers) and structure (enhance line-staff relations, put together what belongs together; though criteria to do this differ from period to period; and decrease span of control).The most important motive to introduce large scale changes in the case observed, therefore, seems to be the need to change organizational culture. In the case considered, the organization started with a power oriented culture. The first attempt on change tried to implement a role oriented culture but failed for the most part as a result of the existing power structure.

    The second attempt was accompanied by the wave of democratization of the late sixties and early seventies which undermined the power structure in the organization. The rather low pressure on reinforcing role relations, except for those belonging to project management, caused a major shift towards a task culture in which hardly anybody seemed to have authority. In this situation project management played a major role.

    In the third attempt, under pressure of the economic recession, legitimate authority, the political power of mayor and aldermen, reinforced a strong role culture. As a result of this change the existing structural elements of project management were practically eliminated. The position of the chief executive level (the town clerk) was weak.

    In the fourth attempt power shifted from the political to the chief executive level. This shift was enabled by the weak political position of mayor and aldermen and the authority bestowed on the town clerk.

    Modelstructuren voor het schatten van het volume c.q. gewicht van komkommers met computer vision
    Langers, R.A. - \ 1998
    Wageningen : IMAG-DLO (Nota / Dienst Landbouwkundig Onderzoek, Instituut voor Milieu- en Agritechniek P98-25) - 20
    cucumis sativus - komkommers - plantenfysiologie - plantenanatomie - plantenmorfologie - modellen - theorie - onderzoek - machine vision - cucumis sativus - cucumbers - plant physiology - plant anatomy - plant morphology - models - theory - research - machine vision
    STIMEST versie 1.0 : een model voor mineralenstromen en mestbewerking op vleesvarkensbedrijven
    Adriaenssens, R.S. ; Willers, H.C. ; Lamaker, E.J.J. - \ 1998
    Wageningen : IMAG-DLO (Nota / Dienst Landbouwkundig Onderzoek, Instituut voor Milieu- en Agritechniek P 98-14) - 25
    mest - vloeibare meststoffen - rundveedrijfmest - varkens - zoötechniek - mineralen - voedingsfysiologie - modellen - theorie - onderzoek - mestoverschotten - mestverwerking - manures - liquid manures - cattle slurry - pigs - zootechny - minerals - nutrition physiology - models - theory - research - manure surpluses - manure treatment
    Duurzaam gewasproductiesysteem voor de toekomst
    Bakker, J.C. - \ 1998
    Agrabeton 8 (1998)1. - ISSN 0167-3246 - p. 4 - 4.
    duurzaamheid (sustainability) - kassen - forceren van planten - landbouw - klimaatverandering - natuurlijke hulpbronnen - hulpbronnengebruik - bescherming - herstel - theorie - ontwerp - toekomst - sustainability - greenhouses - forcing - agriculture - climatic change - natural resources - resource utilization - protection - rehabilitation - theory - design - future
    Korte presentatie van een concept dat aan de Duurzame Technologische Ontwikkeling (DTO) moet kunnen voldoen. Omdat het een ontwerp voor de toekomst betreft wordt het ook wel afgekort tot 'KAS 2020'
    Global optimization at work
    Hendrix, E.M.T. - \ 1998
    Agricultural University. Promotor(en): P. van Beek; A.J.M. Beulens. - Renkum : Hendrix - ISBN 9789054858744 - 248
    modellen - theorie - wiskundige modellen - onderzoek - wetenschap - models - theory - mathematical models - research - science

    In many research situations where mathematical models are used, researchers try to find parameter values such that a given performance criterion is at an optimum. If the parameters can be varied in a continuous way, this in general defines a so-called Nonlinear Programming Problem. Methods for Nonlinear Programming usually result in local optima. A local optimum is a solution (parameter values) which is the best with respect to values in the neighbourhood of that solution, not necessarily the best over the total admissible, feasible set of all possible parameter values, solutions.

    For mathematicians this results in the research question: How to find the best, global optimum in situations where several local optima exist?, the field of Global Optimization (GLOP). Literature, books and a specific journal, has appeared during the last decades on the field. Main focus has been on the mathematical side, i.e. given assumptions on the structure of the problems to be solved and specific global optimization methods and properties are derived. Cooperation between mathematicians and researchers (in this book called 'the modeller' or 'the potential user'), who saw global optimization problems in practical problems has lead to application of GLOP algorithms to practical optimization problems. Some of those can be found in this book. In this book we started with the question:

    Given a potential user with an arbitrary global optimization problem, what route can be taken in the GLOP forest to find solutions of the problem?

    From this first question we proceed by raising new questions. In Chapter 1 we outline the target group of users we have in mind, i.e. agricultural and environmental engineers, designers and OR workers in agricultural science. These groups are not clearly defined, nor mutually exclusive, but have in common that mathematical modelling is used and there is knowledge of linear programming and possibly of combinatorial optimization.

    In general, when modellers are confronted with optimization aspects, the first approach is to develop heuristics or to look for standard nonlinear programming codes to generate solutions of the optimization problem. During the search for solutions, multiple local optima may appear. We distinguished two major tracks for the path to be taken from there by the potential user to solve the problem. One track is called the deterministic track and is discussed in Chapters 2, 3 and 4. The other track is called the stochastic track and is discussed in Chapters 5 and 6. The two approaches are intended to reach a different goal.

    The deterministic track aims at:

    The global optimum is approximated (found) with certainty in a finite number of steps.

    The stochastic track is understood to contain some stochastic elements and aims at:

    Approaching the optimum in a probabilistic sense as effort grows to infinity.

    Both tracks are investigated in this book from the viewpoint of a potential user corresponding to the way of thinking in Popperian science. The final results are new challenging problems, questions for further research. A side question along the way is:

    How can the user influence the search process given the knowledge of the underlying problem and the information that becomes available during the search?

    The deterministic approach
    When one starts looking into the deterministic track for a given problem, one runs into the requirements which determine a major difference in applicability of the two approaches.

    Deterministic methods require the availability of explicit mathematical expressions of the functions to be optimized.

    In many practical situations which are also discussed in this book, these expressions are not available and deterministic methods cannot be applied. The operations in deterministic methods are based on concepts such as Branch-and-Bound and Cutting which require bounding of functions and parameters based on so-called mathematical structures.

    In Chapter 2 we describe these structures and distinguish between those which can be derived directly from the expressions, such as quadratic, bilinear and fractional functions and other structures which require analysis of the expressions such as concave and Lipschitz continuous functions. Examples are given of optimization problems revealing their structure. Moreover, we show that symmetry in the model formulation may cause models to have more than one extreme.

    In Chapter 3 the relationship between GLOP and Integer Programming (IP) is highlighted for several reasons.

    • Sometimes practical GLOP problems can be approximated by IP variants and solved by standard Mixed Integer Linear Programming (MILP) techniques.
    • The algorithms of GLOP and IP can similarly be classified.
    • The transformability of GLOP problems to IP problems and vice versa shows that difficult problems in one class will not become easier to solve in the other.
    • Analysis of problems, which is common in Global Optimization, can be used to better understand the complexity of some IP problems.

    In Chapter 4 we analyze the use of deterministic methods, demonstrating the application of the Branch-and-Bound concept. The following can be stated from the point of view of the potential user:

    • Analysis of the expressions is required to find useful mathematical structures (Chapter 2). It should be noted that also interval arithmetic techniques can be applied directly on the expressions.
    • The elegance of the techniques is the guarantee that we are certain about the global optimality of the optimum, when it has been discovered and verified.
    • The methods are hard to implement. Thorough use should be made of special data structures to store the necessary information in memory.

    Two cases are elaborated. The quadratic product design problem illustrates how the level of Decision Support Systems can be reached for low dimensional problems, i.e. the number of variables, components or ingredients, is less than 10. The other case, the nutrient problem, shows how by analysis of the problem many useful properties can be derived which help to cut away large areas of the feasible space where the optimum cannot be situated. However, it also demonstrates the so-called Curse of Dimensionality; the problem has so many variables in a realistic situation that it is impossible to traverse the complete Branch-and-Bound tree. Therefore it is good to see the relativity of the use of deterministic methods:

    No global optimization method can guarantee to find and verify the global optimum for every practical situation, within a humans lifetime.

    The stochastic approach
    The stochastic approach is followed in practice for many optimization problems by combining the generation of random points with standard nonlinear optimization algorithms. The following can be said from the point of view of the potential user.

    • The methods require no mathematical structure of the problem and are therefore more generally applicable.
    • The methods are relatively easy to implement.
    • The user is never completely certain that the global optimum has been reached.
    • The optimum is approximated in a probabilistic sense when effort increases to infinity.

    In Chapter 5 much attention is paid to the question what happens when a user wants to spend a limited (not infinite) amount of time to the search for the optimum, preferably less than a humans lifetime:

    What to do when the time for solving the problem is finite?

    First we looked at the information which becomes available during the search and the instruments with which the user can influence the search. It appeared that besides classical instruments which are also available in traditional nonlinear programming, the main instrument is to influence the trade-off between global (random) and local search (looking for a local optimum). This lead to a new question:

    Is there a best way to rule the choice between global and local search, given the information which becomes available?

    Analyzing in a mathematical way with extreme cases lead to the comfortable conclusion that a best method of choosing between global and local search -thus a best global optimization method- does not exist. This is valid for cases where further information (more than the information which becomes available during the search) on the function to be optimized is not available, called in literature the black-box case. The conclusion again shows that mathematical analysis with extreme cases is a powerful tool to demonstrate that so-called magic algorithms -algorithms which are said in scientific journals to be very promising, because they perform well on some test cases- can be analyzed and 'falsified' in the way of Popperian thinking. This leads to the conclusion that:

    Magic algorithms which are going to solve all of your problems do not exist.

    Several side questions derived from the main problem are investigated in this book.

    In Chapter 6 we place the optimization problem in the context of parameter estimation. One practical question is raised by the phenomenon

    Every local search leads to a new local optimum.

    We know from parameter estimation that this is a symptom in so called non-identifiable systems. The minimum is obtained at a lower dimensional surface or curve. Some (non-magic) heuristics are discussed to overcome this problem.

    There are two side questions of users derived from the general remark:

    "I am not interested in the best (GLOP) solution, but in good points".

    The first question is that of Robust Solutions, introduced in Chapter 4, and the other is called Uniform Covering, concerning the generation of points which are nearly as good as the optimum, discussed in Chapter 6.

    Robust solutions are discussed in the context of product design. The robustness is defined as a measure of the error one can make from the solution so that the solution (product) is still acceptable. Looking for the most robust product is looking for that point which is as far away as possible from the boundaries of the feasible (acceptable) area. For the solution procedures, we had a look at the appearance of the problem in practice, where boundaries are given by linear and quadratic surfaces, properties of the product.

    • For linear boundaries, finding the most robust solution is an LP problem and thus rather easy.
    • For quadratic properties the development of specific algorithms is required.

    The question of Uniform Covering concerns the desire to have a set of "suboptimal" points, i.e. points with low function value (given an upper level of the function value); the points are in a so-called level set. To generate "low" points, one could run a local search many times. However, we want the points not to be concentrated in one of the compartments or one sub-area of the level set, we want them to be equally, uniformly spread over the region. This is a very difficult problem for which we test and analyze several approaches in Chapter 6. The analysis taught us that:

    It is unlikely that stochastic methods will be proposed which solve problems in an expected calculation time, which is polynomial in the number of variables of the problem.

    Final result
    Whether an arbitrary problem of a user can be solved by GLOP requires analysis. There are many optimization problems which can be solved satisfactorily. Besides the selection of algorithms the user has various instruments to steer the process. For stochastic methods it mainly concerns the trade-off between local and global search. For deterministic methods it includes setting bounds and influencing the selection rule in Branch-and-Bound. We hope with this book to have given a tool and a guidance to solution procedures. Moreover, it is an introduction to further literature on the subject of Global Optimization.

    Keuze van een nieuwe structuur : eindrapport van de Werkgroep Organisatiestructuur : intern rapport
    Anonymous, - \ 1997
    Wageningen : IMAG-DLO (Nota / DLO Instituut voor Milieu- en Agritechniek P 97-13) - 30
    organisaties - theorie - bedrijfsvoering - bestuur - onderzoeksinstituten - proefstations - bedrijfseconomie - organizations - theory - management - administration - research institutes - experimental stations - business management
    Biologische en chemische bestrijding van de gegroefde lapsnuitkever (Otiorhynchus sulcatus)
    Tol, R.W.H.M. van - \ 1997
    Boskoop : Proefstation voor de Boomkwekerij (Rapport / Boomteeltpraktijkonderzoek nr. 50) - 50
    bestrijdingsmethoden - plantenplagen - plantenziekten - geïntegreerde plagenbestrijding - geïntegreerde bestrijding - gewasbescherming - biologische bestrijding - pesticiden - houtachtige planten als sierplanten - rapporten - theorie - systemen - nederland - otiorhynchus sulcatus - wetenschap - control methods - plant pests - plant diseases - integrated pest management - integrated control - plant protection - biological control - pesticides - ornamental woody plants - reports - theory - systems - netherlands - otiorhynchus sulcatus - science
    Speelveld voor nieuwe buitenplaatsen : een verkennende studie naar de invloed van hun variabele eigenschappen op ruimtelijke kwaliteit en rentabiliteit
    Berg, L.M. van den; Wintjes, A.L.W. - \ 1997
    Wageningen : DLO-Staring Centrum (Rapport / DLO-Staring Centrum 511) - 102
    landschap - landschapsbouw - ruimtelijke ordening - landhuizen - theorie - ontwerp - nederland - kastelen - landscape - landscaping - physical planning - country houses - theory - design - netherlands - castles
    Continuous soil maps - a fuzzy set approach to bridge the gap between aggregation levels of process and distribution models
    Gruijter, J.J. de; Walvoort, D.J.J. ; Gaans, P.F.M. van - \ 1997
    Geoderma 77 (1997)2/4. - ISSN 0016-7061 - p. 169 - 195.
    bodemtaxonomie - bodemclassificatie - bodemtypen - theorie - controle - systemen - systeemanalyse - geostatistiek - regeltheorie - soil taxonomy - soil classification - soil types - theory - control - systems - systems analysis - geostatistics - control theory
    Soil maps as multi-purpose models of spatial soil distribution have a much higher level of aggregation (map units) than the models of soil processes and land-use effects that need input from soil maps. This mismatch between aggregation levels is particularly detrimental in the context of precision agriculture. It is argued that, in order to bridge the gap, soil distribution modelling should be based on a new classification paradigm: that of fuzzy set theory. In geographic space, this enables representation of gradual as well as abrupt transitions, i.e., soil distribution models that can predict variables at pedon level. In a case study we used fuzzy k-means with extragrades to derive a continuous classification from data on thicknesses of 25 layers measured in 552 soil profiles. For interpolation of the class memberships we developed a new method, Compositional Kriging, which takes into account that the memberships have the structure of compositional data: they must be positive and add up to a constant (1) for each individual. These conditions were added to the regular Kriging equations. For cartographic representation of the continuous soil distribution models we developed a new technique, the Pixel Mixture technique, by which we generated a large number of small coloured pixels in each raster cell of the map. The colours of the pixels symbolize the classes, and the proportions of iso-coloured pixels in a cell symbolize the grades of the class memberships as predicted for that cell. The combination of continuous classification and Compositional Kriging convincingly bridged the gap between aggregation levels, and with the aid of the Pixel Mixture technique the resulting soil distribution model could also be visualized at the appropriate level of aggregation. The continuous soil map showed both the general landscape structure, as well as the varying degree of variability within the study area. Based on this multi-purpose continuous soil model, functional models of soil processes and land-use effects can be developed.
    Lagekostenbedrijf is een feit
    Ooijen, J.H. van; Braam, C.R. - \ 1997
    Agrabeton 7 (1997)5. - ISSN 0167-3246 - p. 2 - 4.
    kostenanalyse - stallen - bouwmaterialen - beton - asbest - bouwconstructie - constructieonderdelen - structuren - constructie - theorie - ontwerp - cost analysis - stalls - building materials - concrete - asbestos - building construction - structural components - structures - construction - theory - design
    Op de 'Waiboerhoeve', de centrale proefboerderij van het Praktijkonderzoek Rundvee, Schapen en Paarden (PR) in Lelystad, is een zogenoemd lagekostenbedrijf gebouwd. In dit artikel wordt ingegaan op het ontwerp en de uitvoering van enkele betonnen bouwdelen
    Manure Management. Treatment strategies for sustainable agriculture
    Burton, C.H. ; Beck, J. ; Bloxham, P.F. ; Derikx, P.J.L. ; Martinez, J. - \ 1997
    Silsoe : Silsoe Research Institute - ISBN 9780953128204 - 181
    mest - vloeibare meststoffen - rundveedrijfmest - dierlijke meststoffen - drijfmest - organisaties - theorie - bedrijfsvoering - bestuur - duurzaamheid (sustainability) - mestoverschotten - mestverwerking - bedrijfseconomie - manures - liquid manures - cattle slurry - animal manures - slurries - organizations - theory - management - administration - sustainability - manure surpluses - manure treatment - business management
    HOPSY: instrument voor afwegen van beheersalternatieven
    Edelenbosch, N.H. - \ 1997
    Bosbouwvoorlichting 36 (1997)7. - ISSN 0166-8986 - p. 119 - 122.
    bosbouw - opbrengsten - theorie - houtaanwas - staande opstand - bossen - rotaties - aanbodsevenwicht - vraag - aanbod - econometrische modellen - wiskundige modellen - bosbedrijfsvoering - opbrengstregeling - velling - bosexploitatie - forestry - yields - theory - increment - growing stock - forests - rotations - supply balance - demand - supply - econometric models - mathematical models - forest management - yield regulation - felling - forest exploitation
    Prognoses ontwikkeling houtoogst met Hopsy. Het houtoogstprognose-systeem Hopsy is een instrument dat consequenties voor strategische beheerskeuzen voor de toekomstige houtoogst en houtvoorraad laat zien
    Gevraagd: een verbeterd ontwerp
    Guldemond, J.L. - \ 1997
    Groen : vakblad voor groen in stad en landschap 53 (1997)3. - ISSN 0166-3534 - p. 20 - 24.
    ontwerp - onderhoud - bedrijfsvoering - bestrating - wegen - oppervlakten - theorie - design - maintenance - management - pavements - roads - surfaces - theory
    A geo-information theoretical approach to inductive erosion modelling based on terrain mapping units
    Suryana, N. - \ 1997
    Agricultural University. Promotor(en): M. Molenaar; A.C. Imeson. - S.l. : [s.n.] - ISBN 9789054856306 - 234
    bodem - erosie - geografische informatiesystemen - cartografie - theorie - remote sensing - fotointerpretatie - afbeelden - modellen - onderzoek - soil - erosion - geographical information systems - mapping - theory - remote sensing - photointerpretation - imagery - models - research
    Three main aspects of the research, namely the concept of object orientation, the development of an Inductive Erosion Model (IEM) and the development of a framework for handling uncertainty in the data or information resulting from a GIS are interwoven in this thesis. The first and the second aspect of the thesis discuss simultaneously the application of a terrain mapping unit (TA" in hierarhical observational procedures and an IEM in a GIS environment. These aspects were aimed at providing an alternative solution to the traditional approach to data acquisition, data capture and producing aggregated information for a GIS.

    The third aspect discusses the application of standard deviation, probability of misclassification, membership degree and plausibility reasoning for handling error and uncertainty associated with data inputs and information outputs handled by a GIS in general and into and from the Indonesian Field Engineering Design Plan (FEDP) in particular. It is aimed mainly at establishing a framework for representing uncertainty in geographical data manipulation. GIS logical models, the characteristics of logical GIS models, types of uncertainty including error due to variability, imprecision, ambiguity and a proposed conceptual framework based on the concept of certainty factors are discussed.

    The research involved the establishment of stable basic mapping units that allow the definition of repeatable and hierarchical observational procedures. This solution was addressed especially to the situation when sophisticated software and good quality data are not available. In this research, TMUs are defined as areas with a particular combination of geology, geomorphology, morphometry and soil characteristics, usually obtained by interpretation of aerial photo or SPOT images. Terrain areas having similar relief characteristics are identified, delineated and verified in the field. The delineated TMUs represent natural divisions of the terrain often with distinct boundaries.

    Attributes associated with the established TMUs were selected and used to clasify TMUs. A classification hierarchy of TMU was established in the fight of object oriented modelling including abstraction, inheritance, aggregation and association of terrain objects. The hierarchy has three levels, namely level +1 (superclass level refered to as TMU), level 0 (class level refered to as sub TMU) and level -1 (elementary object refered to as subsub TMU). A lower level in the classification hierarchy represents more refined or specialised information.

    The well known deductive erosion model, the Universal Sod Loss Equation (USLE) is incomplete in predicting spatial erosion processes. More sophisticated models (i.e. CREAMS, ANSWERS, EPIC, WEPP, GAMES) have failed to account for the complexity of erosion processes and there are no means for validation of model predictions. An alternative to the problem is suggested through an inductive (bottom-up) approach. This approach involves an Inductive Erosion Model (IEM), which was built on observations including dynamic (resilience) and static (inertia) site specific erosion influencing factors in one or more sample areas, made on site at the farmer's field level which is the best functional unit to describe erosion class at local level. An IEM model therefore is region specific. Once an IEM is built and tested for each type of TMU then it can be incorporated within the GIS environment as an acceptable means to predict safely the severity of sod erosion for the entire study area. Erosion severity classes predicted by an IEM are considered as active or dynamic attributes of the established TMUs. By definition TMU provides inherently erosion influencing factors, so called terrain characteristics including morphometry, geology, soil and ground cover. An IEM is intended to predict homogeneous erosion severity classes, related to TMUs at different aggregation or hierarchical levels. The aggregation levels are related to point observations, farmers field level (FFL) and larger parts of the terrain. The discussion of this aspect is focused on the role of the TMU in the observational procedure providing input for an IEM.

    The established hierarchical mapping units served as a basis for inductive erosion modelling, incorporating expert knowledge-based inference rules. The inductive erosion modelling followed a multi-scale approach and was implemented in a GIS environment. Application of the concepts of regionalization, observed pattern, and decision rules in predicting and modelling purposes are discussed. At regional level patterns associated with the main erosive processes such as sheet, rill, gully and ravine features are generally still identifiable on the aerial photos at scale 1 : 50 000. However, more detailed information on these types of active process at local level can be obtained only by more detailed study, i.e., erosion study at the FFL. In this regard, the FFL is considered as a suitable basic functional unit to describe erosion at local level.

    Instead of using probability reasoning, which must follow statistical constraints, production rules allow the introduction of a Certainty Factor (CF) for handling both uncertainty in data, models and the resulting information. The C17 can be obtained as a subjective judgment made by experts and comes naturally to experts either in inferring underlying processes or estimating quality of data and models being used. With special reference to the situation when all procedures and techniques for determining probability and obtaining quantitative information particularly in data poor environment are unlikely to be performed, this study demonstrated sufficiently the application of the concept of CF.

    In the fight of evidence theory, an IEM for predicting erosion severity at a specific TMU was built as a function of various certainty factors of spatial erosion influencing factors. The certainty factor has a value between -1 and +1 and its value indicates the estimated change in belief of allocation of a TMU to a particular erosion class as evidence (from maps, air photos, field observations etc.) is gathered, for each contributing factor. The erosion severity class to which a TMU is finally allocated is the one with overall certainty factor closest to +1. It is proposed as a method of handling uncertain information caused by incompleteness such as inferences established and derived by experts from a set of observations including the effect of causal relationships among various uncertain evidences.

    Hydrodynamics, sediment transport and light extinction off Cape Bolinao, Philippines
    Rivera, P.C. - \ 1997
    Agricultural University. Promotor(en): L. Lijklema; W. van Vierssen. - Rotterdam : Balkema - ISBN 9789054104087 - 244
    delta's - estuaria - hydraulica - hydrodynamica - rivieren - waterlopen - kanalen - water - geologische sedimentatie - kusten - modellen - theorie - onderzoek - oceanografie - deltas - estuaries - hydraulics - hydrodynamics - rivers - streams - canals - water - geological sedimentation - coasts - models - theory - research - oceanography

    Observational and numerical modelling studies of the hydrodynamics, sediment transport, and light extinction were undertaken in the marine environment around Cape Bolinao in the Lingayen Gulf (Northwest Philippines). Abundant with ecologically important seagrasses and benthic organisms, Cape Bolinao is presently threatened with siltation and eutrophication problems. For this reason intensive field measurements of relevant enviromnental variables which include currents, tides, temperature, salinity, total suspended solids (TSS), ash-free dry weight (AFDW), sedimentation flux, grain size distribution and organic content of bottom sediments, gilvin absorption, phytoplankton concentration, and light extinction were executed from August 1993 to June 1995. Laboratory experiments were simultaneously undertaken to determine the sedimentation and light extinction characteristics of various sediment fractions. Using time series and regression analyses, the results were analyzed and presented. A set of numerical models were developed and applied in the area around Cape Bolinao and the Lingayen Gulf. A prognostic model for the hydrodynamics, driven by realistic wind and tide forces, was developed independently for the cape (fine-resolution model) and the gulf (coarse resolution model). An operational open boundary condition based on the method of wave propagation is discussed. The hydrodynamical predictions were used, in conjunction with a diagnostic surface wave model, to force the suspended sediment transport model. The transport model, which is based on the time-dependent advection-diffusion equation, is third order accurate in space and time. For a realistic description of the suspended sediment transport process in Cape Bolinao, resuspension and sedimentation fluxes were included in the numerical model using existing parameterizations. The predicted suspended sediment concentrations were used in a diagnostic model for light extinction. This later model is based on the assumption that the contributions of the optically active components to the attenuation of the photosynthetically available radiation (PAR) are linearly additive. Calibration of the numerical models using field observations produced a set of parameter values which is deemed representative for the area of investigation. Using these parameter values, the overall model predictions were in good agreement with field observations. Finally, using the integrated model, the impact of river sediment loads (treated as a conservative tracer) in the Bolinao reef system was quantified.

    Non-timber forest products of East Kalimantan : Potentials for sustainable use.
    Valkenburg, J.L.C.H. van - \ 1997
    Wageningen : Tropenbos Foundation - ISBN 9789051130300 - 202
    bosbouw - bosproducten - bosbedrijfsvoering - theorie - duurzaamheid (sustainability) - opbrengsten - flora - plantengeografie - kalimantan - borneo - ericaceae - sierplanten - bosproducten anders dan hout - forestry - forest products - forest management - theory - sustainability - yields - flora - phytogeography - kalimantan - borneo - ericaceae - ornamental plants - non-wood forest products
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