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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Model selection with a common structure : Tomato crop growth models
Kuijpers, Wouter J.P. ; Molengraft, Marinus J.G. van de; Mourik, Simon van; ’t Ooster, Albertus van; Hemming, Silke ; Henten, Eldert J. van - \ 2019
Biosystems Engineering 187 (2019). - ISSN 1537-5110 - p. 247 - 257.
Common structure - Model selection - Tomato crop growth models

Crop modelling is an essential part of biosystems engineering; selecting or developing a crop model for a specific application, having its requirements and desires, is difficult if not impossible without the required domain knowledge. This paper presents a fundamentally different model selection approach based on biological functionalities. This is enabled by a common structure, which allows for a combining of components, yielding new models. This increased design space allows the development of models which are better suited to the application than the original models. The use of a common structure, and its potential, are demonstrated by a use-case involving the selection of a tomato crop model for a model-based control application, but the rationales and methodologies can apply to other crops and applications as well. In this paper, 27 valid model combinations have been created from 4 models. In the use-case presented, the models are compared to data originating from a real system. The predictive performance of a model is quantified by the Root-Mean-Squared-Error (RSME) between the predictions and data. One trade-off is model accuracy versus computational speed. With the model set used, a 13% decrease in RSME was obtained by allowing a 7.5% increase in model computation time compared to one of the original models.

Greenhouse horticulture : Technology for optimal crop production
Stanghellini, C. ; Ooster, A. van 't; Heuvelink, E. - \ 2019
Wageningen : Wageningen Academic Publishers - ISBN 9789086863297 - 300 p.
This book provides an integrated approach to crop growth and development and the technical aspects of greenhouse cultivation and climate management. It combines an analysis of the relationship between crop production and ambient climate with an explanation of the processes that determine the climate in a protected environment. With the ability to modify the environment comes the need for growers to strike a balance between the costs and benefits of technology. This book outlines the methods and gives several examples of how to make 'optimal' choices about technology. Sustainable management of shoot and root environment is discussed, as well as the pros and cons of vertical farming. The processes addressed in this book, like crop growth, energy balance and mass exchange, apply to any kind of greenhouse. Therefore, in spite of the word 'technology', this is not a book about high-tech greenhouses only. 'Greenhouse horticulture' is an easy-to-read textbook for all those interested in protected cultivation, from university students and teachers to professional advisers in the field and managers of horticultural companies.
Discrete event simulation of crop operations in sweet pepper in support of work method innovation
Ooster, Bert van 't; Aantjes, Wiger ; Melamed, Z. - \ 2017
Acta Horticulturae 1154 (2017). - ISSN 0567-7572 - p. 145 - 153.
Brief of requirements - Greenhouse horticulture - GWorkS - Operations research

Greenhouse Work Simulation, GWorkS, is a model that simulates crop operations in greenhouses for the purpose of analysing work methods. GWorkS is a discrete event model that approaches reality as a discrete stochastic dynamic system. GWorkS was developed and validated using cut-rose as a case crop for which two cultivation systems exist, the path-based system and the mobile cultivation system. The focus of this paper is horizontal extension of GWorkS to sweet pepper, which is characterised by high crop-related labour effort and costs. For sweet pepper, international research aiming at automation of sweet pepper harvest is ongoing. Dynamic process simulation and analysis may contribute strongly to economic and technical constraints for the design of new work methods. The most important crop operation in sweet pepper cultivation, harvesting, was pre-modelled in IDEF3 process analysis. The mathematical structure of the GWorkS model is described, as well as specific model adaptations for sweet pepper and inputs determined from labour registration data and video recordings at a sweet pepper grower. Data were analysed for two growers producing different pepper cultivars. Model simulations were performed for one grower. Dynamic simulation results were used to derive technical and economic requirements as numerical constraints for the design of work method innovation.

Stochastic control of crop growth, a simulation study
Mourik, S. van; Vellekoop, Michel ; Beveren, P.J.M. van; Ooster, A. van 't; Henten, E.J. van - \ 2016
In: Proceedings of the International Conference on Agricultural Engineering, Aarhus, Denmark. -
stochastic control - Crop growth simulation model - climate change - metamodel - Regression analysis - LINTUL2
Assessment of porous media instead of slatted floor for modelling the airflow and ammonia emission in the pit headspace
Yin, Shuo ; Ooster, Bert van 't; Ogink, Nico W.M. ; Groot Koerkamp, Peter W.G. - \ 2016
Computers and Electronics in Agriculture 123 (2016). - ISSN 0168-1699 - p. 163 - 175.
Ammonia emission - Computational fluid dynamics (CFD) - Modelling - Porous media - Slatted floor - Turbulence

In order to reduce the emission, proper understanding of the transportation behaviour of gaseous ammonia inside the slurry pit is required. Numerical simulation by the aid of computational fluid dynamics (CFD) technique can be used for this purpose. However, direct modelling of slatted floors is complicated and may be replaced by the porous media model (PMM) as shown in earlier studies. The objective of our study is to improve the quality of simulation results by PMM, and to assess the effects of air velocity above the slatted floor (as affected by wind), pit headspace height (as affected by amount of slurry in the pit) and sidewall height (as affected by the dairy house sidewall) on the airflow features inside the pit and ammonia emission from the pit. Three different CFD models of a slatted floor were developed to evaluate whether porous media is capable to represent a slatted floor for modelling the airflow inside and ammonia emission from the slurry pit, and to study the effect of turbulence treatment in the porous media on the modelling results: a slatted floor model (SFM) which models the slatted floor as it is, a turbulent porous media model (PMM-T) and a laminar porous media model (PMM-L). Both PMM-T and PMM-L represent the slatted floor by porous media, the PMM-T assumes turbulent airflow and the PMM-L assumes laminar airflow in the porous media. The SFM was verified for a dataset acquired from a 1:8 scale wind tunnel model of the slurry pit. Results showed that the PMM (PMM-T and PMM-L) were able to predict both the airflow features inside the slurry pit and the ammonia emission from the slurry pit if the resistance parameters and flow regime of the porous media were properly set. In comparison to the SFM, the PMM-T predicted the flow pattern better, but overestimated the turbulence intensity and the consequent emission rate. PMM-L performed better in predicting the ammonia emission rate because of the relatively accurate prediction of turbulence intensity. Simulation results also showed that the ammonia emission rate increased with a higher mean airflow velocity, a smaller headspace height and the presence of sidewalls.

Monitoring vooroeververdediging Oosterschelde en Westerschelde 2014
Tangelder, M. ; Heuvel-Greve, M.J. van den; Kluijver, M. de; Glorius, S.T. ; Jansen, H.M. - \ 2015
Yerseke : IMARES (Rapport / IMARES C102/15) - 141
oeverbescherming van rivieren - dijken - steenwerk - staal - aquatische ecosystemen - biota - metalen - ecotoxicologie - oosterschelde - westerschelde - nederland - riverbank protection - dykes - stonework - steel - aquatic ecosystems - metals - ecotoxicology - eastern scheldt - western scheldt - netherlands
Rijkswaterstaat bestort de vooroevers voor de dijken in de Ooster- en Westerschelde om de waterveiligheid te kunnen blijven waarborgen. Voor deze bestortingen wordt gebruik gemaakt van staalslakken, breukstenen en zeegrind. Om de gevolgen van het bestorten voor het plaatselijke onderwaterleven inzichtelijk te maken wordt monitoring uitgevoerd door IMARES in opdracht van Rijkswaterstaat. Hierbij wordt onderzoek gedaan naar hard substraat soorten (planten en dieren gevestigd op de harde oever), zacht substraat soorten (dieren die in het sediment op de vooroever leven) en mogelijke uitloging van zware metalen vanuit de vooroeverbestorting naar planten en dieren
Monitoring vooroever Schelphoek Building for Nature proefvlak 2014 - 2017: voortgangsrapportage ontwerp vooroeverbestorting en T0-meting (T2014) epifauna en infauna
Tangelder, M. ; Ysebaert, T. ; Oijen, T. van; Kluijver, M. de - \ 2015
Yerseke : IMARES (Rapport / IMARES Wageningen UR C112/15) - 38
oeverbescherming van rivieren - oevers - fauna - benthos - oeverecosystemen - monitoring - natuurtechniek - zeeuwse eilanden - oosterschelde - riverbank protection - shores - riparian ecosystems - ecological engineering - eastern scheldt
Rijkswaterstaat voert vooroeverbestortingen uit op het deel van de dijk dat onder water ligt in de Ooster- en Westerschelde. Dit is nodig om de stabiliteit van de dijk en daarmee de waterveiligheid te kunnen blijven garanderen. Eerst werd hierbij alleen op veiligheidsdoelen gelet. Nieuw inzicht is echter dat je door gebruik van bepaalde materialen ook de natuur kunt faciliteren, dit principe wordt ‘Building for Nature’ genoemd. In 2014 is bij de oostelijke strekdam van locatie Schelphoek in de Oosterschelde een bestorting van zeegrind uitgevoerd. Doel van dit onderzoek is om de rekolonisatie en ontwikkeling van hard substraat soorten (epifauna) en soorten die leven in het sediment (infauna) op de nieuwe bestorting van breuksteen, zandsteen en zeegrind bij de locatie Schelphoek gedurende drie jaar na bestorting te volgen (2015-2017) en te vergelijken met de situatie voor bestorten (T0-situatie in 2014). Voorliggend rapport betreft een tussenrapportage met (1) een beschrijving van het ontwerp van de vooroeverbestorting en (2) een beschrijving van de T0-situatie in 2014 vóór het aanleggen van de vooroeverbestorting.
Model-based analysis of skill oriented labour management in a multi-operations and multiworker static cut rose cultivation system
Ooster, A. van 't; Bontsema, J. ; Henten, E.J. van; Hemming, S. - \ 2015
Biosystems Engineering 135 (2015)July. - ISSN 1537-5110 - p. 87 - 102.
discrete-event simulation - harvest operations
Worldwide competitive challenges urge growers to further improve operational performance. In this paper, the objective ‘model-based analysis and improvement of the operation of horticultural production systems’ was narrowed to ranking simulated labour management scenarios in a multi-operations and multi-worker static cut-rose cultivation system. Eight scenarios with worker skill as a central theme were simulated including a practical labour management scenario applied by a Dutch cut-rose grower. The GWorkS-model was prepared for simulation of disbudding and bending in addition to harvest, three crop operations representing over 90% of crop-bound labour time, as well as for full scale simulation of the greenhouse using all workers and equipment. The sub-models on disbudding and bending were verified using data acquired in practice. Both processes were reproduced accurately. The model study on work scenarios showed that labour organisation choices might yield up to 5 s per harvested rose difference in total labour time for harvest, bending and disbudding between the best and worst scenario, which is equivalent to 7.1 € m-2 labour costs difference per year. Scenarios pointed out that working with low skilled, low paid workers is not effective. Specialised workers were most time effective, -17.5% compared to the reference, but overall a permanent team of skilled generalists ranked best in a multi-factorial assessment. Reduced crop operation diversity per day improved labour organisational outputs but ranked almost the same as the reference. The reference scenario was outranked by 5 scenarios. Overall, the GWorkS-model provided clear answers to research questions using the full complexity of crop operations.
A model based method for evaluation of crop operation scenarios in greenhouses
Ooster, A. van 't - \ 2015
Wageningen University. Promotor(en): Eldert van Henten, co-promotor(en): Jan Bontsema; Silke Hemming. - Wageningen : Wageningen University - ISBN 9789462573024 - 169
kastechniek - glastuinbouw - simulatie - discrete simulatie - simulatiemodellen - arbeid (werk) - rozen - greenhouse technology - greenhouse horticulture - simulation - discrete simulation - simulation models - labour - roses


This research initiated a model-based method to analyse labour in crop production systems and to quantify effects of system changes in order to contribute to effective greenhouse crop cultivation systems with efficient use of human labour and technology. This method was gradually given shape in the discrete event simulation model GWorkS, acronym for Greenhouse Work Simulation. Model based evaluation of labour in crop operations is relatively new in greenhouse horticulture and could allow for quantitative evaluation of existing greenhouse crop production systems, analysis of improvements, and identification of bottlenecks in crop operations. The modelling objective was a flexible and generic approach to quantify effects of production system changes. Cut-rose was selected as a case-study representative for many cut-flowers and fruit vegetables.

The first focus was a queueing network model of the actions of a worker harvesting roses in a mobile cultivation system. Data and observations from a state-of-art mobile rose production system were used to validate and test the harvesting model. Model experiments addressed target values of operational parameters for best system performance. The model exposed effects of internal parameters not visible in acquired data. This was illustrated for operator and gutter speed as a function of crop yield. The structure and setup of the GWorkS model was generic where possible and system specific where inevitable.

The generic concept was tested by transferring GWorkS to harvesting a greenhouse section in a static growing system for cut-roses and extending it with navigation in the greenhouse, product handling, and multiple operator activity (up to 3 workers). Also for rose harvesting in a static growing system, the model reproduced harvesting accurately. A seven workday validation for an average skilled harvester showed a relative root mean squared error (RRMSE) under 5% for both labour time and harvest rate. A validation for 96 days with various harvesters showed a higher RRMSE, 15.2% and 13.6% for labour time and harvest rate respectively. This increase was mainly caused by the absence of model parameters for individual harvesters. Work scenarios were simulated to examine effects of skill, equipment, and harvest management. For rose yields of 0.5 and 3 harvested roses per m2, harvest rate was 346 and 615 stems h-1 for average skilled harvesters, 207 and 339 stems h-1 for new harvesters and 407 and 767 stems h-1 for highly skilled harvesters. Economic effects of trolley choice are small, 0-2 € per 1000 stems and two harvest cycles per day was only feasible if yield quality effects compensate for extra costs of 0.2-1.1 eurocents per stem.

In a sensitivity analysis and uncertainty analysis, parameters with strong influence on labour performance in harvesting roses in a static system were identified as well as effects of parameter uncertainty on key performance indicators. Differential sensitivity was analysed, and results were tested for linearity and superposability and verified using the robust Monte Carlo method. The model was not extremely sensitive for any of the 22 tested input parameters. Individual sensitivities changed with crop yield. Labour performance was most affected by greenhouse section dimensions, single rose cut time, and yield. Throughput was most affected by cut time of a single rose, yield, number of harvest cycles, greenhouse length and operator transport velocity. In uncertainty analysis the coefficient of variation for the most important outputs labour time and throughput is around 5%. The main sources of model uncertainty were in parallel execution of actions and trolley speed. The uncertainty effect of these parameters in labour time, throughput and utilisation of the operator is acceptably small with CV less than 5%. The combination of differential sensitivity analysis and Monte Carlo analysis gave full insight in both individual and total sensitivity of key performance indicators.

To realise the objective of model based improvement of the operation of horticultural production systems in resources constrained system, the GWorkS-model was extended for simultaneous crop operations by multiple workers analysis. This objective was narrowed down to ranking eight scenarios with worker skill as a central theme including a labour management scenario applied in practise. The crop operations harvest, disbudding and bending were considered, which represent over 90% of crop-bound labour time. New sub-models on disbudding and bending were verified using measured data. The integrated scenario study on harvest, disbudding and bending showed differences between scenarios of up to 5 s per harvested rose in simulated labour time and up to 7.1 € m-2 per year in labour costs. The simulated practice of the grower and the scenario with minimum costs indicated possible savings of 4 € m-2 per year, which equals 15% of labour cost for harvest, disbudding and bending. Multi-factorial assessment of scenarios pointed out that working with low skilled, low paid workers is not effective. Specialised workers were most time effective with -17.5% compared to the reference, but overall a permanent team of skilled generalists ranked best. Reduced diversity in crop operations per day improved labour organisational outputs but ranked almost indifferent. The reference scenario was outranked by 5 scenarios.

Discrete event simulation, as applied in the GWorkS-model, described greenhouse crop operations mechanistically correct and predicts labour use accurately. This model-based method was developed and validated by means of data sets originating from commercial growers. The model provided clear answers to research questions related to operations management and labour organisation using the full complexity of crop operations and a multi-factorial criterion. To the best of our knowledge, the GWorkS-model is the first model that is able to simulate multiple crop operations with constraints on available staff and resources. The model potentially supports analysis and evaluation of design concepts for system innovation.

Schorherstel in de Ooster- en Westerschelde met gebruik van schorrenmatten
Tangelder, M. ; Dalen, J. van; Ijzerloo, L. van; Ysebaert, T. - \ 2015
Yerseke : IMARES (Rapport / IMARES Wageningen UR C024/15) - 54
wetlands - kweldergronden - herstel - dijken - bekledingen - habitat vernietiging - natuurtechniek - oosterschelde - westerschelde - salt marsh soils - rehabilitation - dykes - linings - habitat destruction - ecological engineering - eastern scheldt - western scheldt
Projectbureau Zeeweringen verbetert de dijkbekledingen langs de Oosterschelde en Westerschelde. Daarbij kan helaas niet voorkomen worden dat kwetsbare schorren en slikken verstoord en deels vernietigd worden tijdens de dijkverbeteringswerkzaamheden. Het doel van deze studie was om na te gaan onder welke omstandigheden herstel en groei van schorvegetatie in dijkwerkstroken en pionierzones mogelijk is door het aanplanten van Engels Slijkgras (Spartina anglica) in zogenaamde kokosmatten. Het basiskokosmateriaal fungeert als substraat en bescherming tegen erosie voor de jonge planten gedurende de eerste groeiperiode totdat ze goed geworteld zijn in de bodem.
GWorks model simuleeert gewashandelingen in kassen
Bontsema, Jan ; Ooster, Bert van 't - \ 2014
Simulation Analysis of Sweet Pepper Harvesting Operations
Elkoby, Z. ; Ooster, A. van 't; Edan, Y. - \ 2014
In: Advances in Production Management Systems. Innovative and Knowledge-Based Production Management in a Global-Local World. - Berlin : Springer Verlag - p. 441 - 448.
Greenhouse crop production requires extensive manual labor. The objective of this research is to analyze different work methods for harvesting in sweet pepper greenhouses. Operations research of harvesting work methods for a Dutch and Israeli sweet pepper greenhouse was performed. An existing discrete event simulation model on the crop handling processes inside a greenhouse, GWorkS, was used to simulate harvesting of sweet peppers in both countries. Results of simulation of one day showed that the model estimates harvesting time with an accuracy of 92% for NL data and 96% for IL data. The data analysis showed differences between the greenhouses in the existing harvesting procedures, logistic operations and data collection.
Monitoring vooroeververdediging Oosterschelde 2013
Tangelder, M. ; Schellekens, T. ; Kluijver, M. de; Heuvel-Greve, M.J. van den - \ 2014
Yerseke : IMARES (Rapport / IMARES Wageningen UR C102/14) - 62
oeverbescherming van rivieren - bekledingen - steenwerk - flora - fauna - zware metalen - mossels - oesters - ecotoxicologie - oosterschelde - monitoring - riverbank protection - linings - stonework - heavy metals - mussels - oysters - ecotoxicology - eastern scheldt
Dit rapport beschrijft de uitkomsten van de eco(toxico)logische monitoring van de vooroeververdediging in de Oosterschelde. Aanleiding hiervoor is dat Rijkswaterstaat sinds 2009 op locaties met voortschrijdende erosie in de Ooster- en Westerschelde bestortingen met staalslakken en breuksteen uitvoert op de vooroever van de dijken om de veiligheid tegen overstromingen te kunnen blijven garanderen. Het doel van deze monitoring is het bepalen van de samenstelling en biodiversiteit van de aanwezige levensgemeenschappen op harde en zachte substraten, en de bepaling van de gehalten aan zware metalen in mosselen en oesters op de nieuwe vooroever en referentie-locaties. Dit is in 2013 gedaan voor de locatie Zeelandbrug (oost/midden/west), waar voor het vierde opeenvolgende jaar is gemonitord na de bestorting in 2009. Daarnaast is de nulsituatie in kaart gebracht voor de locatie Zierikzee die in 2014 bestort zal worden. Ook zijn er verschillende referentie-locaties in de Oosterschelde meegenomen.
Simulation of harvest operations in a static rose cultivation system
Ooster, A. van 't; Bontsema, J. ; Henten, E. van; Hemming, S. - \ 2014
Biosystems Engineering 120 (2014). - ISSN 1537-5110 - p. 34 - 46.
Labour is the most dominant cost factor in Dutch cut-rose production. To improve crop production systems and labour management, a generic process modelling approach was developed enabling the impact of different scenarios on labour productivity to be assessed. The crop production system with crop handling processes is defined as a stochastic discrete event system. This paper demonstrates the model flexibility and transferability by adapting an existing model developed for a mobile rose production system to a model for a static growing system for cut roses. The paper describes the adaptation process. The adapted model was validated for the harvest process at a 3.6 ha production site in the Netherlands. Work scenarios were simulated to examine effects of skill, equipment, and harvest management. The model reproduces the harvest process accurately. A seven workday validation for an average skilled harvester showed a relative root mean squared error (RRMSE) under 5% for both labour time and harvest rate. A validation over 96 days for various harvesters showed a higher RRMSE, 15.2% and 13.6% for labour time and harvest rate respectively, mainly caused by the absence of model parameters for individual harvesters. The model was successfully used in scenario studies and indicated that worker skill was an important cost factor, differences associated with harvest trolley type are small, and that an extra harvest cycle per day is only feasible when compensated by product price. Overall, the generic model concept performs well for a static growing system when extended with system specific properties and process elements. (C) 2013 IAgrE. Published by Elsevier Ltd. All rights reserved.
Sensitivity analysis of a stochastic discrete event simulation model of harvest operations in a static rose cultivation system
Ooster, A. van 't; Bontsema, J. ; Henten, E.J. van; Hemming, S. - \ 2013
Biosystems Engineering 116 (2013)4. - ISSN 1537-5110 - p. 457 - 469.
Greenhouse crop system design for maximum efficiency and quality of labour is an optimisation problem that benefits from model-based design evaluation. This study focussed on the harvest process of roses in a static system as a step in this direction. The objective was to identify parameters with strong influence on labour performance as well as the effect of uncertainty in input parameters on key performance indicators. Differential sensitivity was analysed and results were tested for model linearity and superposability and verified using the robust Monte Carlo analysis method since in the literature, performance and applicability of differential sensitivity analysis has been questioned for models with internal stochastic behaviour. Greenhouse section length and width, single rose cut time, and yield influence labour performance most, but greenhouse section dimensions and yield also affect the number of harvested stems directly. Throughput, i.e. harvested stems per second, being the preferred metric for labour performance, is most affected by single rose cut time, yield, number of harvest cycles per day, greenhouse length and operator transport velocity. The model is insensitive for a of lognormal distributed stochastic variables describing the duration of low frequent operations in the harvest process, like loading and unloading rose nets. In uncertainty analysis, the coefficient of variation for the most important outputs, labour time and throughput, is around 5%. Total sensitivity as determined using differential sensitivity analysis and Monte Carlo analysis essentially agreed. The combination of both methods gives full insight into both individual and total sensitivity of key performance indicators. (C) 2013 IAgrE. Published by Elsevier Ltd. All rights reserved.
Variatie gehalte zware metalen op locatie Zeelandbrug en toxiciteit molybdeen - data rapport
Glorius, S.T. ; Heuvel-Greve, M.J. van den; Foekema, E.M. - \ 2013
Den Helder : IMARES (Rapport / IMARES Wageningen UR C105/13) - 24
laboratoriummethoden - aquatische ecologie - ecotoxicologie - zware metalen - laboratory methods - aquatic ecology - ecotoxicology - heavy metals
Om met zekerheid vast te kunnen stellen dat er geen negatieve effecten optreden op het mariene milieu n.a.v. de oever-verdediging in Ooster- en Westerschelde is door Rijkswaterstaat in 2009 een monitoringsprogramma opgezet. Vanwege kostenoverwegingen zijn monitoringsactiviteiten in 2012 ingeperkt. Wel zijn op de Zeelandbrug (Oosterschelde) mosselen (Mytilus edulis) en Japanse oesters (Crassostrea gigas) bemonsterd om inzicht te verkrijgen in gehalten aan zware metalen tweeëneenhalf tot drie jaar na het aanbrengen van de vooroeververdediging. Dit rapport beschrijft het resultaat van de verschillende toxiciteitstesten die uitgevoerd zijn in het laboratorium van IMARES Den Helder. Daarnaast worden de resultaten van de metaalanalyses in mosselen en oesters bemonsterd op de Zeelandbrug besproken waarbij ingegaan wordt op de jaarlijkse variatie in metaalconcentratie een mogelijke trend in de tijd.
Data rapport: Het effect va vooroeververdediging op bodemorganismen in de Oosterschelde: 2012
Brink, A.M. van den; Hartog, E. ; Kluijver, M. de - \ 2013
Yerseke : IMARES (Rapport / IMARES Wageningen UR C101/13) - 52
oeverbescherming van rivieren - bodemecologie - oosterschelde - kustbeheer - delta's - zeeland - riverbank protection - soil ecology - eastern scheldt - coastal management - deltas
De stromingen in de Ooster-en Westerschelde zorgen lokaal voor erosie van oevers en geulwanden. Om dat proces tegen te gaan worden, op die locaties waar deze erosie de stabiliteit van de waterkering in gevaar brengt of de reeds bestaande oeverwerken ondermijnt, oevers beschermd door “bestortingen” uit te voeren. . In 2012 is geen volledige monitoring van alle locaties gepland, maar is besloten om op één locatie een vinger aan de pols te houden om de ontwikkeling van planten, dieren en metalen te kunnen blijven volgen. Het gaat hierbij om de locatie Zuidhoek - De Val / Zeelandbrug. Het doel van deze monitoring is het bepalen van de samenstelling en biodiversiteit van de aanwezige levensgemeenschappen op harde en zachte substraten, en de bepaling van de gehalten aan zware metalen in mosselen en oesters
Model maakt afwegingen over efficiëntie en automatisering mogelijk
Kierkels, T. ; Ooster, A. van 't - \ 2012
Onder Glas 4 (2012). - p. 30 - 31.
tuinbouwbedrijven - arbeid (werk) - werkorganisatie - arbeidsproductiviteit - efficiëntie - bedrijfskosten - modellen - glastuinbouw - economische analyse - rozen - snijbloemen - tomaten - groenten - market gardens - labour - organization of work - labour productivity - efficiency - operating costs - models - greenhouse horticulture - economic analysis - roses - cut flowers - tomatoes - vegetables
Arbeid is de grootste kostenpost op het gemiddelde tuinbouwbedrijf. Toch bestond er nog geen instrument om efficiënte arbeidsinzet en automatisering door te rekenen. Agrotechnoloog Bert van ’t Ooster brengt daar verandering in. Het simulatie- en analysemodel GWorkS werkt al voor rozen en trostomaat.
GWorkS, nieuwe ontwerptool voor simulatie van arbeid in de glastuinbouw en van geautomatiseerde teeltsystemen
Ooster, Bert van 't - \ 2012
greenhouse horticulture - production processes - cropping systems - automation - ornamental horticulture - cultural methods - decision support systems - models
Model study on applicability of a semi closed greenhouse concept in Almeria: Effects on greenhouse climate, crop yield and resource use efficiency
Ooster, A. van 't; Ieperen, W. van; Kalaitzoglou, P. - \ 2012
In: XXVIII International Horticultural Congress on Science and Horticulture, Lisbon, Portugal, August 22-27, 2010. - Lisabon Portugal : ISHS - ISBN 9789066057241 - p. 51 - 58.
The application of climate control equipment is becoming increasingly popular in Mediterranean protected horticulture. New climate control techniques reduce ventilation requirement and, thus, increase the benefits of carbon dioxide fertilization. Moreover, temperature extremes are prevented. Improvements on the controllability of the greenhouse climate can enhance production in terms of quantity and increase the water use efficiency at the same time. Those benefits must balance the costs associated with the use of climate control equipment. In an attempt to design and evaluate a semi-closed greenhouse system suitable for application in the Mediterranean area, benefits and problems for this climatic region were revealed. This paper presents a theoretical design study and analysis to assess the viability of a semi-closed greenhouse concept in the Mediterranean climate region. Nine greenhouse concepts were generated for Almeria (36° NL) and evaluated afterwards by a panel of experts. One concept received on-average highest score. This concept was a sustainable energy driven greenhouse using biomass and green electricity to run a compressor heat pump. Ventilation decision was based on the trade-off between cooling costs and yield loss at suboptimal temperatures. The concept was evaluated more systematically in a simulation study that contributed to design consistency and assessed greenhouse performance with respect to constraints and targets set in design requirements. From the simulations it was concluded that the selected sustainable energy driven semi-closed greenhouse that uses wind power and optionally biomass to run a compressor heat pump to heat, cool and dehumidify the greenhouse drastically reduced water use, the use of fossil energy and CO2 emission compared to a conventional greenhouse. Investment and operational costs of the technologically advanced equipment used, were compensated by a higher crop production, thus predicting economic feasibility.
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