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.

    We have a manual that explains all the features 

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    "Versmering kan erger zijn dan verdichting"; interview met Bert Vermeulen
    Dwarswaard, A. ; Vermeulen, G.D. - \ 2014
    BloembollenVisie 2014 (2014)26 december. - ISSN 1571-5558 - p. 14 - 15.
    landbouwtechniek - uitrusting - benodigde machines - grondbewerking - bodemstructuur na grondbewerking - bodemverdichting - trekkers - gewicht - akkerbouw - bloembollen - agricultural engineering - equipment - machinery requirements - tillage - tilth - soil compaction - tractors - weight - arable farming - ornamental bulbs
    De belangstelling voor de bodem neemt snel toe in de bloembollensector. Om die reden startte BloembollenVisie een tweede serie artikelen over dit onderwerp. In deze negende aflevering staat de relatie tussen machines en grond centraal. Onderzoeker Bert Vermeulen van Plant Research International uit Wageningen schetst een genuanceerd beeld van bodemverdichting.
    Palletkist met een golfbodem bespaart energie
    Wildschut, J. - \ 2014
    BloembollenVisie 2014 (2014)297. - ISSN 1571-5558 - p. 22 - 22.
    bloembollen - opslag - ventilatie - palletkisten - energiebesparing - uitrusting - ornamental bulbs - storage - ventilation - pallet boxes - energy saving - equipment
    Bij het drogen en bewaren van bloembollen in palletkisten bepalen het vermogen, de eigenschappen van de ventilator en de totale weerstand die luchtstroom ondervindt de luchtopbrengst van de ventilator in de systeemwand. Een onderdeel van die totale weerstand is de geperforeerde bodemplaat van de palletkist.
    Waterstof maken van etensresten : Wageningen UR Food & Biobased Research
    Claassen, Pieternel - \ 2013
    hydrogen - biofuels - innovations - research projects - biobased economy - equipment - public-private cooperation - Netherlands
    Simultaneous sulfate reduction and metal precipitation in an inverse fluidized bed reactor
    Villa Gomez, D.K. - \ 2013
    Wageningen University. Promotor(en): Piet Lens, co-promotor(en): Karel Keesman. - [S.l.] : S.n. - ISBN 9789461737410 - 194
    wervelbedden - uitrusting - sulfaatreductie - chemische precipitatie - metalen - fluidized beds - equipment - sulfate reduction - chemical precipitation - metals
    Inventarisatie emissies en geluidsoverlast van mestbewerkingsinstallaties en eventuele maatregelen
    Buisonjé, F.E. de; Melse, R.W. ; Mosquera Losada, J. ; Verdoes, N. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 703) - 30
    mestverwerking - emissie - ammoniak - stankemissie - broeikasgassen - geluid - geluidshinder - fijn stof - uitrusting - manure treatment - emission - ammonia - odour emission - greenhouse gases - noise - noise pollution - particulate matter - equipment
    In this report the knowledge on emissions and noise from manure treatment techniques is summarized.
    Slimmer CO2-doseren, levert de teler veel op : moderne tools helpen bij beslissingen
    Heuvelink, E. ; Kierkels, T. - \ 2013
    Onder Glas 10 (2013)8. - p. 20 - 21.
    glastuinbouw - groenten - kasgewassen - kooldioxide - selectieve toediening - dosering - uitrusting - besluitvorming - gebruiksefficiëntie - greenhouse horticulture - vegetables - greenhouse crops - carbon dioxide - selective application - dosage - equipment - decision making - use efficiency
    Zo lang de WKK toch draaide voor de teruglevering van stroom, was de CO2- voorziening geen punt van discussie. Maar die tijd is voorbij. Als je voor CO2 moet betalen, komt de vraag op: kan het niet wat minder? Maar eigenlijk is dat de verkeerde benadering. Niet minder doseren, maar slimmer. En waarschijnlijk kom je dan toch uit op een lager verbruik.
    Onderzoek naar de affecten van de aanleg van damwanden en grondverdichting op tandwalvissen in het Dolfinarium Harderwijk
    Haan, D. de - \ 2013
    IJmuiden : IMARES (Report / IMARES Wageningen UR C020/13) - 62
    dammen - uitrusting - zeezoogdieren - dierentuindieren - simulatie - diergedrag - dierenwelzijn - geluiden - veluwe - walvissen - oscillatie - dams - equipment - marine mammals - zoo animals - simulation - animal behaviour - animal welfare - sounds - veluwe - whales - oscillation
    Voor het vaststellen van de effecten van de aanleg van damwandinstallaties en grondverdichting als onderdelen van het grootschalig bouwplan Waterfront Harderwijk van de gemeente Harderwijk werden op vijf verschillende locaties van het bouwplan installaties gesimuleerd en de geluidseffecten daarvan in vier verschillende bassins op het terrein van het dolfinarium simultaan gemeten. Het onderzoek naar de effecten van het trilgeluid was beperkt tot de bassins waar bruinvissen en tuimelaars werden gehouden. Omdat er tijdens de proeven sterke reacties van haaien en roggen in het roggenbasin werden waargenomen, zijn in dit rapport enkele mitigerende maatregelen voor deze diersoorten opgenomen.
    Energieopslag maakt duurzame energie voorspelbaar
    Terbijhe, A. ; Verbruggen, T. ; Veth, J. de; Pukala, P. - \ 2012
    Lelystad : Praktijkonderzoek Plant & Omgeving B.V. ACRRES - 68
    duurzame energie - opslag - energie - kosten-batenanalyse - rentabiliteit - proeven op proefstations - accu's - uitrusting - windenergie - zonne-energie - sustainable energy - storage - energy - cost benefit analysis - profitability - station tests - batteries - equipment - wind power - solar energy
    De verdiencapaciteit van de WindAccu zit in de electriciteitsmarkt (APX/ENDEX en PV/Onbalans) en transportvoordeel of besparing op energiebelasting, afhankelijk van de situatie. Er zijn 2 cases uitgewerkt in dit rapport. Het eerste betreft het akkerbouwbedrijf van familie de Jong, met zonpv en wind, de ander de onderzoekslocatie van Wageningen UR in Lelystad. Na een grondige analyse van de (markt) mogelijkheden is de conclusie helaas de volgende. Batterijen voor opslag van elektrische energie zijn zonder uitzondering nog te duur om zonder aanvullende inkomsten rendabel te zijn. Stel dat de kostendaling die zich in de PV-sector heeft voorgedaan, exemplarisch is voor de kostendaling van batterijen, dan is er voldoende verdiencapaciteit in de electriciteitsmarkt en kostenbesparing om bij de juiste randvoorwaarden duurzame energie rendabeler te maken.
    Factfinding dropkeel tbv refit Tridens (vanuit visserij onderzoek perspectief)
    Veenstra, F.A. ; Fassler, S.M.M. - \ 2011
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C074/11) - 39
    onderwaterakoestiek - uitrusting - schepen - aquatische ecosystemen - monitoring - visserijbeheer - underwater acoustics - equipment - ships - aquatic ecosystems - monitoring - fishery management
    Het gebruik van onderwater acoustics wordt steeds belangrijker in de komende jaren. Steeds vaker wordt het hele ecosysteem in overweging genomen in het proces van het vaststellen van duurzame exploitatieniveaus voor vissoorten. Zo´n ´ecosysteem-benadering´ in het visserijbeheer zal sterk afhankelijk zijn van surveys die het hele ecosysteem onderzoeken, van plankton onder aan de voedselketen tot vis en andere marine predatoren aan de top daarvan. Akoestische methoden kunnen hierin voorzien, want daarmee kunnen in korte tijd grote zeegebieden intensief worden onderzocht. Gebruik van verschillende frequenties helpt om organismen in het echogram te identificeren en moderne kwantitatieve multi-beam echosounders kunnen een groot watervolume scannen. Momenteel loopt Nederland achter bij andere landen voor wat betreft het gebruik van hydro-akoetische apparatuur en technieken. De onderzoeksschepen van Noorwegen, Ierland, Frankrijk en Schotland zijn al uitgerust met 4-6 verschillende akoestische frequenties, waardoor gemakkelijk en betrouwbaard vis kan worden geïdentificeerd. Daarnaast zijn multi-beam echosounders, die per seconde tot 500 akoestische signalen uitzenden in gebruik op o.a. de Noorse ´G.O. Sars´. Dergelijke apparatuur is onmisbaar als het hele ecosysteem moet worden onderzocht. In 2012 zal een mogelijke refit plaatsvinden van de Tridens. Ter onderbouwing van 'nut en noodzaak' om bij deze refit ook dit schip met een dropkeel uit te rusten (een dropkeel is een stalen druppelvormige constructie die tot enkele meters onder het schip kan worden uitgeschoven en die plaats biedt aan meerdere transducers en een multibeam echosounder tegelijkertijd), heeft IMARES naar aanleiding van een helpdeskvraag van de afdeling AKV van het Ministerie van EL&I van 17-20 mei 2011 een technische factfinding missie naar Noorwegen georganiseerd. In dit rapport wordt hiervan verslag gedaan.
    Proefbedrijf faciliteiten
    PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2011
    Lelystad : PPO AGV
    proefbedrijven - landbouwkundig onderzoek - bodemtypen - faciliteiten en installaties - professionele dienstverlening - uitrusting - pilot farms - agricultural research - soil types - facilities and structures - professional services - equipment
    De business unit Akkerbouw, Groene ruimte en Vollegrondsgroente van Praktijkonderzoek Plant & Omgeving (PPO AGV) is dé partner als het gaat om praktijkgericht onderzoek en innovaties. Resultaten uit strategisch en fundamenteel onderzoek worden door ons praktijk- en toepassingsrijp gemaakt. Daarmee positioneren wij ons als brug tussen wetenschap en praktijk. Wij ontwikkelen en leveren nieuwe, direct toepasbare kennis en passen deze toe in samenwerking met onze partners. Dit zijn ondernemers of instituten die werkzaam zijn in de agrarische sector. Het werkveld is de akkerbouw, vollegrondsgroenten en multifunctionele landbouw.
    Monovergisting op boerderijniveau
    Ellen, H.H. ; Verstappen-Boerekamp, J.A.M. ; Timmerman, M. - \ 2010
    Wageningen UR Livestock Research
    varkenshouderij - varkensmest - mestvergisting - biogas - proefboerderijen - proefbedrijven - installatie - uitrusting - biobased economy - pig farming - pig manure - manure fermentation - biogas - experimental farms - pilot farms - installation - equipment - biobased economy
    De laatste jaren heeft mestvergisting in Nederland een grote vlucht genomen. Er worden steeds meer mestvergistinginstallaties gebouwd en veehouders beseffen meer en meer de energetische waarde van de aanwezige mestvoorraad. Grote co-vergistinginstallaties zijn echter voor veel veehouders geen optie, omdat ze erg groot moeten zijn om economisch rendabel te draaien. De vraag naar kleinschalige mestvergisters wordt daardoor steeds groter. Op Varkensproefbedrijf Sterksel heeft men daarom een minivergister en een minigasturbine geplaatst. Ook een mini-wkk zal worden geplaatst. Door de lage onderhoudskosten is de minigasturbine al op lage vermogens rendabel. De minivergister wordt doorontwikkeld om de uitspoeling van bacteriën te verminderen, waardoor de verblijftijd verkort kan worden, waardoor een kleinere (en dus goedkopere) vergister kan volstaan. Bij een minibiogasinstallatie, gecombineerd met een minigasturbine of mini-wkk is het niet noodzakelijk om coproducten te kopen en is het concept meer gericht op het energetisch gesloten maken van het varkensbedrijf.
    Final report on household and institutional biogas : technical performance & economic potential
    Anonymous, - \ 2010
    Nairobi : Carbon Africa - 17 p.
    biobased economy - biogas - organisch afval - kenya - uitrusting - gistingstanken - economische haalbaarheid - opbrengsten - biobased economy - biogas - organic wastes - kenya - equipment - digesters - economic viability - yields
    This report gives an overview of the technical performance for the ARTI compact biogas system in Nairobi and of the potential economic savings therein, and provides a preliminary analysis of the “gas for cash” business concept in Kenya.
    Speciale lens zet zonnestraling om in hoogwaardige warmte : tweede generatie energieproducerende kassen in aantocht - interview met Piet Sonneveld
    Kierkels, T. ; Sonneveld, P.J. - \ 2008
    Onder Glas 2008 (2008)6/7. - p. 86 - 87.
    kassen - zonne-energie - uitrusting - energieomzetting - elektriciteit - fotovoltaïsche cellen - innovaties - glastuinbouw - duurzame energie - greenhouses - solar energy - equipment - energy conversion - electricity - photovoltaic cells - innovations - greenhouse horticulture - sustainable energy
    Energieproducerende kassen van de eerste generatie kennen een belangrijk nadeel. De geproduceerde energie (warmte) is laagwaardig en daarom beperkt bruikbaar. Wageningen UR Glastuinbouw werkt samen met partners aan de tweede generatie. Die zet zonnestraling, die de plant toch niet gebruikt om in elektriciteit. Hiervoor wordt gebruik gemaakt van verschillende principes: Fresnellenzen, regelbare lamellen en speciale folies
    Toezicht op minimum maaswijdte
    Machiels, M.A.M. ; Marlen, B. van; Densen, W.L.T. van - \ 2008
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C001/08) - 16
    visserij - vis vangen - uitrusting - vistuig - netten - regelingen - wetgeving - bemonsteren - Nederland - fisheries - fishing - equipment - fishing gear - nets - regulations - legislation - sampling - Netherlands
    De vangst en sterfte van vis wordt hoofdzakelijk bepaald door de maaswijdte (of maasopening) in de kuil van het gebruikte visnet. Meting van maaswijdte is niet eenvoudig en de huidige regelgeving is aan kritiek onderhevig. Dit heeft geleid tot de ontwikkeling van een nieuw meetprotocol en meetinstrument. De visserij op tong met 80 mm en een minimummaat van 24 cm is gevoelig voor een juiste vaststelling van de maaswijdte van de kuil. Dit rapport behandelt statistische en juridische aspecten van de huidige regelgeving en de eventuele invoering van de nieuwe OMEGA-maaswijdtemeter.
    Gerichte visserij op wolhandkrab in het IJsselmeer, een onderzoek naar vangstmethoden en bijvangsten
    Leijzer, T.B. ; Aarts, G.M. ; Kampen, J. van - \ 2008
    IJmuiden : IMARES (Rapport / Wageningen IMARES C088/08) - 27
    visserij - vis vangen - krabben (schaaldieren) - decapoda - vistuig - uitrusting - netten - bijvangst - fisheries - fishing - crabs - decapoda - fishing gear - equipment - nets - bycatch
    Vissers van het IJsselmeer hebben eind 2007; begin 2008 een onderzoek uitgevoerd naar de effectiviteit en bijvangsten van een gerichte visserij op wolhandkrab met behulp van aangepaste fuiken.
    Ontwikkeling van een monstertuig voor bestandsopnames van mesheften
    Craeymeersch, J.A.M. ; Stralen, M.R. van; Wijsman, J.W.M. ; Kesteloo, J.J. ; Perdon, K.J. ; Mesel, I.G. de - \ 2007
    Yerseke : IMARES (Rapport / Wageningen IMARES C084/07) - 25
    schaal- en schelpdierenvisserij - schaaldieren - ensis - kustwateren - visbestand - visstand - inventarisaties - monstertrekkers - uitrusting - shellfish fisheries - shellfish - ensis - coastal water - fishery resources - fish stocks - inventories - samplers - equipment
    Ten behoeve van het beleid voor de visserij inventariseert Wageningen IMARES in opdracht van het ministerie van LNV sinds 1995 jaarlijks de verspreiding en het bestand van een aantal schelpdieren in de Nederlandse kustzone. De laatste jaren is de aandacht vooral op mesheften komen te liggen. De daarbij gebruikte monstertuigen zijn echter niet geschikt voor een goede inventarisatie van mesheften, omdat deze dieren veel dieper in het sediment voorkomen dan de bemonsterde diepte (7910cm). Daardoor is het niet mogelijk een goed en kwantitatief beeld te krijgen van de bestandsdynamiek, de visserijdruk of de relatie tussen mesheften, vissers en vogels.
    Groene energie uit koeienmest : mestvergisten is pas interessant bij 130 tot 150 melkkoeien en co-vergisting
    Booij, A. - \ 2005
    Veeteelt 22 (2005)7. - ISSN 0168-7565 - p. 60 - 61.
    melkveehouderij - dierlijke meststoffen - verwerking - fermentatie - gistingstanken - economische haalbaarheid - agrarische bedrijfsvoering - bedrijfsresultaten in de landbouw - uitrusting - mestverwerking - mestvergisting - biobased economy - energieproductie in de landbouw - dairy farming - animal manures - processing - fermentation - digesters - economic viability - farm management - farm results - equipment - manure treatment - manure fermentation - biobased economy - agricultural energy production
    In 6 verschillende scenario's zijn de kosten, opbrengsten en terugverdientijd van een mestvergistingsinstallatie berekend, waarbij de grootte van de vergister en de hoeveelheid energierijke toevoegstof, zoals mais, varieerde
    Er zit toekomst in de gesloten kas
    Raaphorst, M.G.M. - \ 2005
    Groenten en Fruit. Algemeen 2005 (2005)18. - ISSN 0925-9694 - p. 20 - 21.
    gesloten systemen - teelt onder bescherming - klimaatregeling - warmtepompen - kooldioxide - gewasopbrengst - duurzaamheid (sustainability) - uitrusting - glastuinbouw - closed systems - protected cultivation - air conditioning - heat pumps - carbon dioxide - crop yield - sustainability - equipment - greenhouse horticulture
    Nadat in proeven van het PPO in Naaldwijk was aangetoond dat telen in een gesloten kas de productie met meer dan 20 procent kan verhogen, zetten de ondernemers van pruimtomtatenbedrijf Themato in Berkel en Rodenrijs zo'n kas op. Onderzoekers van PPO volgen de verrichtingen van de gesloten kas op de voet en zien de toekomst van deze kas met vertrouwen tegemoet
    Nieuw proces maakt continue extractie mogelijk : eerste installatie binnen twee tot vijf jaar op de markt
    Groote, Y. de; Giezen, F.E. - \ 2004
    Elsevier Voedingsmiddelen Industrie 5 (2004)6. - ISSN 1570-6907 - p. 30 - 32.
    extractie - verwerking - uitpersing - reologie - fysica - uitrusting - mengapparaten - voedseltechnologie - productieprocessen - extraction - processing - extrusion - rheology - physics - equipment - agitators - food technology - production processes
    Een Europees consortium van bedrijven en kennisinstellingen ontwikkelde binnen het EU-project C-REX een nieuw proces voor het continu extraheren van waardevolle of ongewenste stoffen uit grondstoffen. Een patentaanvraag is door Agrotechnology & Food Innovations uit Wageningen ingediend
    Verder op zoek naar een wildredder: verdiepend onderzoek naar mogelijkheden voor de ontwikkeling van een nieuwe wildredder
    Bruin, B.M.H. de; Damminga, D.J. ; Walle, T. van der; Wiersma, E.R. - \ 2004
    Wageningen : Wageningen UR, Wetenschapswinkel (Rapport / Wetenschapswinkel Wageningen UR 201) - ISBN 9789067547826 - 60
    limosa limosa - vogels - agrarische bedrijfsvoering - uitrusting - detectors - reddingsmiddelen - wildbescherming - bedreigde soorten - nederland - weidevogels - limosa limosa - birds - farm management - equipment - detectors - safeners - wildlife conservation - endangered species - netherlands - grassland birds
    Warmtewisselaars met gekromde buizen
    Kelder, J.D.H. ; Klerk, S. de - \ 2004
    Voedingsmiddelentechnologie 37 (2004)13. - ISSN 0042-7934 - p. 14 - 16.
    warmteuitwisseling - voedseltechnologie - uitrusting - automatisering - thermisch rendement - reologie - vloeistoffen (liquids) - stroming - heat exchange - food technology - equipment - automation - thermal efficiency - rheology - liquids - flow
    Ultra High Temperature (UHT) sterilisation is a commonly applied technique to preserve liquid food products. Stork Food & Dairy Systems has marketed coiled tubular UHT-sterilisers. For viscous and especially for gelatinising foods (e.g. custard and pudding) spiral sterilisers bring superior performance. Heat transfer greatly increases and required temperatures are attained faster, thus reducing processing time. Coiled sterilisers are therefore shorter and more compact, minimising the loss of quality factors due to the heat treatment. Finally, gelatinisation occurs rapidly and uniformly, and de reduced thermo-mechanical stresses enable a potentially lower amount of starch needed to obtain a target consistency
    20 mestverwerkingssystemen op een rij
    Buisonjé, F.E. de - \ 2003
    Praktijkkompas. Varkens 17 (2003)3. - ISSN 1570-8578 - p. 22 - 22.
    mest - dierlijke meststoffen - stalmest - dierlijk afval - afvalverwerking - verwerking - behandeling - systemen - uitrusting - mestverwerking - manures - animal manures - farmyard manure - animal wastes - waste treatment - processing - treatment - systems - equipment - manure treatment
    ASG, divisie Praktijkonderzoek heeft in opdracht van VROM en InfoMil een twintigtal mestverwerkingssystemen beschreven. Zie ook de website van InfoMil (www.infomil.nl). Deze worden regelmatig bijgewerkt aan de hand van nieuwe informatie en mogelijke technische wijzigingen aan de installaties.
    Voorlichting op basis van onderzoek : 1e update en uitbreiding
    Rijssel, E. van; Ploeger, C. - \ 2000
    Aalsmeer : Proefstation voor Bloemisterij en Glasgroente, Vestiging Aalsmeer (Rapport / Proefstation voor Bloemisterij en Glasgroente 272) - 151
    energiebehoud - teelt onder bescherming - kassen - voorlichting - documentatie - overzichten - informatie - uitrusting - landbouwvoorlichting - glastuinbouw - energy conservation - protected cultivation - greenhouses - extension - documentation - reviews - information - equipment - agricultural extension - greenhouse horticulture
    Toepassingsmogelijkheden mestbewerking op varkenshouderijbedrijven
    Verdoes, N. ; Melse, R. - \ 2000
    Praktijkonderzoek varkenshouderij 14 (2000)6. - ISSN 1382-0346 - p. 13 - 13.
    varkenshouderij - varkensmest - mest - verwerking - uitrusting - mestverwerking - pig farming - pig manure - manures - processing - equipment - manure treatment
    Het Praktijkonderzoek Varkenshouderij leidt het project 'Toepassingsmogelijkheden mestbewerking opvarkenshouderijbedrijven', dat mestbewerkingsinstallaties onderzoekt op twaalf praktijkbedrijven.
    Extruder goed toepasbaar voor continue extractie en deegkneden
    Stegeman, D. ; Luyten, H. - \ 2000
    Voedingsmiddelentechnologie 33 (2000)7. - ISSN 0042-7934 - p. 30 - 32.
    uitpersing - verwerking - broodbereiding - brood - vloeistofmechanica - prestatieniveau - kwaliteit - reologie - visco-elasticiteit - uitrusting - voedselindustrie - voedseltechnologie - productieprocessen - machines - extrusion - processing - breadmaking - bread - fluid mechanics - performance - quality - rheology - viscoelasticity - equipment - food industry - food technology - production processes - machines
    De voortdurende ontwikkeling van de apparatuur zorgt voor een continue uitbreiding van de toepassingsmogelijkheden van de extrusietechnologie. De werking van het extrusie-extractieproces is behandeld en schematisch weergegeven
    Ex-post evaluatie van een gasmotorwarmtepomp op een glastuinbouwbedrijf
    Haastert, M. van - \ 2000
    Den Haag : LEI - ISBN 9789052426297 - 47
    kassen - verwarming - stookkosten - verwarmingssystemen - uitrusting - warmtepompen - warmtewisselaars - verwarmingsapparatuur - economische analyse - kosten-batenanalyse - greenhouses - heating - heating costs - heating systems - equipment - heat pumps - heat exchangers - heaters - economic analysis - cost benefit analysis
    Hydrometry
    Boiten, W. - \ 2000
    Rotterdam [etc.] : Balkema - ISBN 9789054104193 - 246
    meting - doorstroommeters - vloeistofmechanica - kanalen, klein - waterpassen - ontladingen - instrumenten (meters) - meetopeningen - uitrusting - measurement - flow meters - fluid mechanics - channels - level gauges - discharges - instruments - measuring orifices - equipment
    Met ontvochtiger blijft warmte binnen
    Campen, J.B. - \ 1999
    Groenten en Fruit. Vakdeel glasgroenten (1999)14. - ISSN 1380-3573 - 17
    klimaat - vochtigheid - uitrusting - energiebehoud - technische informatie - glastuinbouw - climate - humidity - equipment - energy conservation - technical information - greenhouse horticulture
    Schematisch ontwerp van ontvochtiger van IMAG-DLO. Gecombineerd stoken en ventileren om de luchtvochtigheid te verlagen kost veel energie. Door een deel van de energie terug te winnen met een ontvochtiger, kan het energieverbruik in kassen verminderen
    Helft veldspuiten vertoont gebreken
    Vries, R.L. de - \ 1998
    Landbouwmechanisatie 49 (1998)3. - ISSN 0023-7795 - p. 24 - 25.
    gewasbescherming - uitrusting - spuitapparaten - componenten - landbouwwerktuigen - boerderij uitrusting - gereedschappen - onderhoud - service - regulatie - wetgeving - beleid - duitsland - plant protection - equipment - sprayers - components - farm machinery - farm equipment - tools - maintenance - servicing - regulation - legislation - policy - germany
    Microorganisms in Foods 6: Microbial Ecology of Food Commodities.
    Schothorst, M. van - \ 1997
    London : Blackie Academic & Professional - ISBN 9780751404302 - 615
    voedselindustrie - voedseltechnologie - micro-organismen - bacteriën - classificatie - taxonomie - dierlijke producten - bacteriologie - kiemgetal - voedselinspectie - microbiologie - voedingsmiddelen - voedselbewaring - groenteproducten - opslag - plantaardige producten - microbiële ecologie - methodologie - biologische technieken - experimenten - uitrusting - voedselmicrobiologie - voedselproducten - landbouwproducten - voedselbesmetting - toxische stoffen - xenobiotica - haccp - food industry - food technology - microorganisms - bacteria - classification - taxonomy - animal products - bacteriology - bacterial count - food inspection - microbiology - foods - food preservation - vegetable products - storage - plant products - microbial ecology - methodology - biological techniques - experiments - equipment - food microbiology - food products - agricultural products - food contamination - toxic substances - xenobiotics - haccp
    Biopreservation in modified atmosphere packaged vegetables
    Bennik, M.H.J. - \ 1997
    Agricultural University. Promotor(en): F.M. Rombouts; L.G.M. Gorris. - S.l. : Bennik - ISBN 9789054858089 - 96
    uitrusting - verpakking - verpakkingsmaterialen - verpakken - planten - dieren - behoud - machines - equipment - packaging - packaging materials - packing - plants - animals - preservation - machines

    Recent trends in food preservation are the use of mild preservation techniques, such as modified atmosphere (MA) packaging and refrigeration, to prolong the shelflife of foods without affecting the fresh character of the product. This has resulted in the development of a new generation of chill stored, minimally processed foods, such as vegetables that are packaged under reduced oxygen (0 2 ) and elevated carbon dioxide (C0 2 ) concentrations. These gas atmospheres in combination with refrigerated storage conditions reduce the respiration rates of these products, and can limit the growth of endogenous spoilage bacteria, thereby rendering prolonged shelflives as compared with storage under ambient conditions. Although MA packaged vegetables have a fair safety record, they may incidently harbor foodborne pathogens. Especially the outgrowth of psychrotrophic (cold tolerant) pathogens can be considered a safety concern, but quantitative data on their growth under MA conditions that are suitable for produce are essentially lacking. Detailed information on the outgrowth of both pathogens and vegetable-associated spoilage bacteria under these conditions may give better insight into possible antagonistic action of competing microflora on the growth of pathogens, and the development of adequate countermeasures toward their growth to hazardous levels.

    One of the objectives of the studies that are described in this thesis was to obtain information on the impact of refrigerated MA storage conditions on the growth of microorganisms on minimally processed, MA packaged produce. Since our initial studies substantiated the possible hazard which can be posed by psychrotrophic pathogens, the use of biopreservation for adequate control of these microorganisms was investigated. In this respect, we have focused on lactic acid bacteria (LAB) because they occur naturally on fresh and minimally processed vegetables, and are able to produce a variety of antimicrobial substances, amongst which bacteriocins.

    Chapter 1 gives a short introduction on the technology of MA packaging of minimally processed vegetables and their current microbiological safety and quality status. Furthermore, the possible role of LAB as biopreservation agents in foods is addressed with special emphasis on those strains that are able to produce bacteriocins. The characteristics and mode of action of different bacteriocins that are produced by LAB are described, as well as aspects which are relevant to the application of these antimicrobial compounds or their producing organisms as food preservatives.

    Detailed information on the impact of refrigerated MA storage on the population dynamics of the endogenous microflora on vegetables is limited. Therefore, the prevailing epiphytic microorganisms on model produce ( i.e . chicory endive, and mungbean sprouts) were identified before and after MA storage. Subsequently, the growth characteristics of the predominant spoilage bacteria were determined under MA conditions ( Chapter 2 ). It was found that the major strains on both products were Enterobacteriaceae and Pseudomonas species. There were changes in the prevalent species on chicory endive before and after MA storage, but this was not observed for mungbean sprouts. To quantify the influence of C0 2 and 0 2 on the growth of the individual spoilage bacteria, a model agar system was developed that mimicked the in situ growth of bacteria on the surface of vegetables. The analysis of the growth of the predominant strains under controlled 0 2 and C0 2 concentrations at 8°C indicated that, in general, lag times were not present under the various conditions tested, and that the maximum population sizes were not affected. However, the maximum specific growth rates generally decreased with increasing C0 2 concentrations, which was independent of the 0 2 concentrations applied. This effect was more pronounced for Pseudomonas species than for Enterobacteriaceae. Representatives of the former subpopulation already showed significantly reduced maximum specific growth rates at C0 2 concentrations that are suitable for MA packaged vegetables.

    In Chapter 3 , the effects of different 0 2 and C0 2 concentrations on the growth of Aeromonas hydrophila, Yersinia enterocolitica, L. monocytogenes, and a cold tolerant strain of Bacillus cereus were quantified in the above mentioned model agar system at 8°C. Again, the maximum specific growth rates of the various microorganisms decreased significantly with increasing C0 2 concentration, while the maximum population densities were not affected and lag times were not observed. Extrapolation of the results from the model system to MA packaged vegetables suggested that growth of the above pathogens may occur at 8°C to the same maximum population densities as compared to ambient conditions, but at 10 to 20% lower maximum specific growth rates. Because we have shown that MA packaging can only moderately retard the growth of psychrotrophic pathogens, these bacteria can be considered a safety hazard to which countermeasures need to be developed.

    L. monocytogenes is a relevant psychrotrophic pathogen on minimally processed vegetables that requires adequate control measures. This Gram-positive bacterium can be inhibited by a number of bacteriocins that are produced by LAB. Thus, biopreservation using bacteriocin producing LAB strains may effectively prevent the growth of this bacterium, and possibly other psychrotrophic pathogens. With respect to practical application, an effort was made to obtain bacteriocinogenic LAB from minimally processed vegetables since these strains might be best adapted to the specific conditions under which their antimicrobial activity is required. Out of a total of 890 LAB isolates from mungbean sprouts and chicory endive, only nine strains were found to produce bacteriocins ( Chapter 4 ). Three of these strains exhibited antimicrobial activity towards a wide variety of Gram- positive bacteria, including the foodborne pathogens L.monocytogenes, and nonproteolytic Clostridium botulinum. Two of these bacteriocinogenic isolates were identified as Pediococcus parvulus on the basis of fermentation patterns and ribotyping. Recombinant DNA experiments revealed the presence of the pediocin PA-1 gene in both LAB strains, and further biochemical analysis confirmed the production of pediocin PA-1 in absence of other bacteriocins.

    The third broad spectrum bacteriocin-producing strain was identified as Enterococcus mundtii ( Chapter 5 ). Its bacteriocin was purified to homogeneity and characterized. Elucidation of the complete primary amino acid sequence revealed a novel bacteriocin of 43 amino acids (M r 4287.2), designated as mundticin, that belongs to the class IIa bacteriocins of LAB. Other LAB that produce this class of antimicrobial peptides have previously been isolated from a wide variety of meat and dairy products, and their apparent wide-spread occurrence in foods may allow for the selection of strains that are ecologically adapted to specific food environments.

    As further described in Chapter 5 , mundticin exhibited bactericidal activity towards L.monocytogenes, and was shown to dissipate the membrane potential of whole cells, and to deplete their intracellular ATP pools. Mundticin was selected as a prototype of class IIa bacteriocins to investigate the biophysical properties of this peptide by molecular computer analysis. It was found that mundticin and related bacteriocins, contain a central α-helical region that was predicted to insert at an angle of 30 to 50° in a simulated hydrophobic/hydrophilic interface. This oblique insertion is proposed to cause a destabilisation of the phospholipid bilayer and facilitate the insertion and/or aggregation of monomers into functional pores in the cytoplasmic membrane. This concept is of interest for the rational design of bacteriocins with, for example, better biopreservation properties.

    For the effective application of bacteriocins as biopreservation agents, it is essential to gain more insight into the variation in the susceptibility of Gram-positive bacteriocins towards bacteriocins. The comprehensive study that is described in Chapter 6 addresses several factors which are associated with the natural variability in the bacteriocin-sensitivity of closely related non- bacteriocinogenic LAB. Two sets of strains for which the minimal inhibitory concentrations for nisin and pediocin PA-1 differed 100 to 1000-fold were compared. Our data provide evidence that the association of bacteriocins with the cell membrane and their subsequent insertion into the membrane take place in a similar way for cells that have a high or a low natural bacteriocin tolerance. For insensitive strains, the overall constitution of the membrane, rather than the mere membrane fluidity, may preclude the formation of pores with sufficient diameters and lifetimes to ultimately cause cell death. Further analysis of this phenomena may require more attention for the structural role of proteins in biological membranes.

    The last part of this dissertation comprises a study on the potential of the vegetable- associated bacteriocin-producing bacteria and mundticin to act as biopreservation agents on refrigerated, MA-stored vegetables ( Chapter 7 ). Both P. parvulus strains were found to be unsuitable for this purpose, due to the lack of bacteriocin production at 4 and 8°C. By contrast, E. mundtii displayed a number of characteristics that favor an application as a biopreservative agent, such as limited acid production, production of a bacteriocin with anti-listeria activity at low temperatures, and high growth rates under MA conditions. Despite these properties, this strain failed to effectively inhibit the growth of L. monocytogenes on fresh mungbean sprouts. This is probably not due to a lack of in situ bacteriocin production, but rather the result of proteolytic degradation of mundticin or the growth of L. monocytogenes cells that are resistant to mundticin. Experiments with mundticin in a washing step and as a component of a coating were successful and warrant further research on the potential of this compound as a natural preservative agent for minimally processed vegetables.

    In conclusion, this dissertation has contributed to a better understanding of the microbiological characteristics of minimally processed vegetables that are stored under MA conditions. A general concern for the possible outgrowth of psychrotrophic pathogens on MA stored vegetables was substantiated by our investigations, which stresses that hygienic cultivation and processing conditions of this type of products remain indispensable. Although bacteriocins cannot be used as the sole preservatives to enhance the safety of refrigerated MA-stored minimally processed vegetables, they can contribute to tackle safety problems that may arise from certain cold tolerant, Grampositive pathogens.

    Benutting van het afvalwater van een melkveebedrijf voor het spoelen van de mestgangen : een orienterend onderzoek = Use of waste water from a dairy farm for flushing alleys : a preliminary research
    Kroodsma, W. ; Bleijenberg, R. ; Lent, A.J.H. van - \ 1996
    Wageningen : IMAG-DLO (Rapport / Dienst Landbouwkundig Onderzoek, Instituut voor Milieu- en Agritechniek 96-09) - ISBN 9789054061458 - 16
    landbouw - schoonmaken - schoonmaakgereedschap - melkvee - melkveehouderij - uitrusting - rioolwater - scheren - stallen - wassen (activiteit) - afvalwater - agriculture - cleaning - cleaning equipment - dairy cattle - dairy farming - equipment - sewage - shearing - stalls - washing - waste water
    Desinfectie van bedrijfsvreemd materiaal door blootstelling aan UV-C
    Roelofs, P.F.M.M. - \ 1996
    Rosmalen : Praktijkonderzoek varkenshouderij (Proefverslag / Praktijkonderzoek Varkenshouderij P1.166) - 28
    uitrusting - schoonmaken - wassen (activiteit) - scheren - stallen - varkensstallen - woningen - desinfectie - ontsmettingsmiddelen - steriliseren - ultraviolette straling - equipment - cleaning - washing - shearing - stalls - pig housing - dwellings - disinfection - disinfectants - sterilizing - ultraviolet radiation
    Waterverbruik schoonspuiten melkstallen
    Verstappen-Boerekamp, J.A.M. ; Wolters, G.M.V.H. - \ 1996
    Lelystad : Praktijkonderzoek Rundvee, Schapen en Paarden (Publicatie / Praktijkonderzoek Rundvee, Schapen en Paarden (PR) 114) - 17
    melkmachines - melkstandinrichtingen - uitrusting - schoonmaken - wassen (activiteit) - scheren - hergebruik van water - schadepreventie - milking machines - milking parlours - equipment - cleaning - washing - shearing - water reuse - loss prevention
    In deze publicatie wordt het onderzoek naar het waterverbruik en de gebruikte methodiek voor het schoonspuiten van de melkstal beschreven en de mogelijkheden die er zijn om het waterverbruik te verminderen.
    Reductie ammoniakemissie door stalen roostervloer
    Kant, P.P.H. - \ 1996
    Lelystad : Praktijkonderzoek Rundvee, Schapen en Paarden (Publicatie / Praktijkonderzoek Rundvee, Schapen en Paarden (PR) 110) - 20
    luchtverontreiniging - ammoniak - emissie - vervluchtiging - rundvee - uitrusting - schoonmaken - wassen (activiteit) - scheren - air pollution - ammonia - emission - volatilization - cattle - equipment - cleaning - washing - shearing
    De roosterelementen hadden een doorlaat van 52,5 %. De dieren liepen voorzichtiger dan normaal op de betonnen roosters. De stalen roosters reduceerden de ammoniak-emissie met 52 % in vergelijking met de betonnen roosters.
    Rubber trekker zorgt voor minder water bij schoonspuiten melkstal
    Verstappen-Boerekamp, J.A.M. - \ 1996
    Praktijkonderzoek Rundvee, Schapen en Paarden. Praktijkonderzoek 9 (1996)3. - ISSN 1386-8470 - p. 26 - 28.
    schoonmaken - uitrusting - schadepreventie - melkstandinrichtingen - scheren - wassen (activiteit) - watergebruik - cleaning - equipment - loss prevention - milking parlours - shearing - washing - water use
    Een eenvoudige manier om water te besparen is gebruik van een rubber trekker vóórdat wordt schoongespoten.
    Performance indicators for the statistical evaluation of digital image classifications
    Urso, G. D'; Menenti, M. - \ 1996
    ISPRS Journal of Photogrammetry and Remote Sensing 51 (1996)2. - ISSN 0924-2716 - p. 78 - 90.
    uitrusting - afbeelden - fotointerpretatie - remote sensing - equipment - imagery - photointerpretation - remote sensing
    A statistical procedure is proposed to evaluate the algorithms for the numerical classification of images. The approach is based on the derivation of performance indicators from measurements of signature separability and thresholding analysis. Although these measurements are not new in image processing techniques, they are used in this study in an original way for the comparison of outputs resulting from different classification criteria. The theoretical description of the method suggested is followed by its practical application to a case-study for mapping crop coefficients in an irrigation district.
    Growth and death of animal cells in bioreactors
    Martens, D.E. - \ 1996
    Agricultural University. Promotor(en): J. Tramper; C.D. de Gooijer. - S.l. : Martens - ISBN 9789054855934 - 222
    weefselkweek - celkweek - meristemen - zoölogie - chemische reacties - uitrusting - biotechnologie - chemische industrie - biochemie - tissue culture - cell culture - meristems - zoology - chemical reactions - equipment - biotechnology - chemical industry - biochemistry - cum laude

    Animal-cell cultivation is becoming increasingly important especially for the area of hunian- health products. The products range from vaccines to therapeutic proteins and the cells themselves. The therapeutic application of proteins puts high demands upon their quality with respect to purity and structure. For example, a correct folding and glycosylation is of importance for the activity, the in vivo clearance rate and the possible immunogenicity of the protein, and can often only be obtained by production in animal cells. An important class of proteins produced by animal cells is formed by monoclonal antibodies. Monoclonal antibodies are produced by hybridoma cells and have the capacity to bind very specifically to a particular molecular structure (epitope), a quality that makes them suitable for application in in vivo and in vitro diagnostics, in separation technology and for the in vivo targeting of drugs.

    The occurrence of substantial cell death and the presence of cell debris is a major problem in animal-cell cultivation. It interferes with the attainment of high volumetric productivities and with a proper functioning of the process. In addition, it may affect the quality of the product and cause problems in down-stream processing. Cell death may follow two different pathways, being apoptosis and necrosis, which have very distinct physiological and morphological features. Necrosis is a passive process generally caused by sudden high levels of environmental stress, whereas apoptosis is an active, genetically controlled process induced by mild stress conditions or specific signals from the environment.

    After the introduction in Chapter 1, the application of a general framework for the construction of segregated models is discussed in Chapter 2 with respect to the behaviour of animal-cell populations. For the construction of segregated models, the physiological state of an animal cell must be specified, which is discussed in this chapter with special attention for the experimental verification of the models. Finally, a number of age-structured, segregated models, which are of importance for animal-cell cultivation are reviewed in this chapter.

    The required amounts of animal-cell products are expected to be in the order of kilograms or even tonnes on a yearly basis. In order to produce these amounts, scale-up is necessary, which is most easily done in conventional reactor systems like the stirred-tank, bubble-column, and air-lift reactor. A main problem in the scale-up of these reactors is the supply of sufficient oxygen to the culture, which often requires sparging. Hydrodynamic forces associated with sparging cause cell death. In Chapters 3, 4, and 5 the specific death rate of hybridoma cells in bubble-column and air-lift reactors is studied with the hypothetical-killing-volume theory as a central theme. The hypothetical killing volume is a hypothetical volume associated with an air bubble during its lifetime in the reactor in which all cells are killed. The first-order death-rate constant in bubble- column and air-lift reactors can then be derived to be the product of this hypothetical killing volume and the number of bubbles introduced into the reactor per unit time and per unit reactor volume. The specific death rate of the hybridoma cells in the bubble-column and air-lift reactors is shown to be proportional to the gas flow rate and the reciprocal reactor height. Furthermore, in bubble columns the specific death rate is shown to be proportional to the square of the reciprocal reactor diameter. These results are in accordance with the hypothetical-killing-volume theory. The main cause of cell death is found to be bubble breakup at the surface, although detrimental effects at the sparger cannot be excluded. In Chapter 6 the specific death rate of Vero cells immobilized on microcarriers is shown to be proportional to the gas flow rate. Since the height of the reactor is not varied, it cannot be excluded that in this case also the rising of the bubbles or the associated liquid flow cause cell damage.

    A common method to reduce the detrimental effects of air bubbles is the use of protective additives. In this thesis it is shown that the addition of two such protectants, Pluronic F68 (Chapter 3) and serum (Chapter 4), respectively, reduces the amount of cell death as a consequence of sparging. Furthermore, as demonstrated in Chapter 4, the protective effect of serum has a fast-acting, physical, and a slow-acting, physiological component. In Chapter 5 the effect of the specific growth rate on the specific death rate of cells due to sparging is studied in air-lift loop reactors. Cells with varying specific growth rates are obtained from steady-state continuous cultures run at different dilution rates. Remarkably, the specific death rate of the cells due to sparging decreased as their specific growth rate decreased. Furthermore, in Chapter 6 it is shown that the specific death rate of Vero cells is reduced by immobilisation of the cells inside porous carriers.

    Below a critical dilution rate in continuous culture as well as towards the end of batch cultures, the specific death rate of hybridoma cells increases rapidly. In this case, the cells mainly die through apoptosis as a consequence of substrate depletion and the accumulation of toxic products. In Chapter 7 an age-structured model is developed to describe the rate of apoptosis as a function of the dilution rate in continuous culture. In this model a critical specific growth rate is introduced below which the cells start becoming apoptotic. In addition to the specific deathand growth rate, the average cell volume of the viable cells and the specific consumption and production rates for glucose, glutamine, lactate and ammonia are calculated. The model can reasonably well describe a set of literature data, with respect to the specific growth- and death rate and the concentrations of viable cells, dead cells, glucose, glutamine, lactate, and ammonia. In Chapter 8 the model is extended with equations concerning two hypotheses for the production of monoclonal antibody being:
    (1) Passive release of antibody from dead cells.
    (2) Increased productivity by the apoptotic cells.
    Both hypotheses can describe the increase in productivity at decreasing dilution rates as observed in Chapter 5. Furthermore, the distribution of cells over the different phases of the cell cycle is calculated and the equations for the average cell volume are rewritten in terms of forward scatter as measured by flow cytometry. Model predictions concerning these variables are compared to results obtained in Chapter 5. The G 1 - and G 2 /M-phase fractions are not predicted correctly, which may be caused by a cell-cycle-phase specificity of apoptosis. In addition, a good prediction of all cell-cycle fractions can be obtained if it is assumed that the duration of the G 2 /M phase is not constant, but increases as the specific growth rate decreases from the maximum to its critical value. Furthermore, the calculated fraction of apoptotic cells is shown to be proportional to the forward scatter.

    Cell death associated with sparging may be minimised by:
    (1) Maximizing the amount of oxygen transferred per bubble introduced in the reactor.
    (2) The addition of a shear-protective agent like Pluronic F68 or serum.
    (3) The immobilisation of cells inside porous microcarriers.
    Point one is most easily done by increasing the reactor height and the oxygen tension in the air bubbles. With respect to the second point, it should be mentioned that the additive must be removed from the final product and can cause problems in down-stream processing. This may lead to an increase in the product cost. Finally, in the case of immobilisation of cells inside carriers, transport limitations may occur, which may in turn induce apoptosis. Cell death through apoptosis as caused by low levels of shear, substrate limitation and the presence of toxic products may be reduced through a careful process design and genetic manipulation of the cells.

    Modelling nutrient removal in a sequencing batch reactor with respirometry
    Bernardes, R.S. - \ 1996
    Agricultural University. Promotor(en): W.H. Rulkens; A. Klapwijk. - S.l. : Bernardes - ISBN 9789054854715 - 173
    waterzuivering - verwijdering - chemische reacties - uitrusting - afvalwaterbehandeling - rioolafvalwaterverwijdering - zuiveringsinstallaties - water treatment - removal - chemical reactions - equipment - waste water treatment - sewage effluent disposal - purification plants

    The main objectives of the present thesis can be summarized as: i) the development and validation of simplified mathematical models for activated sludge processes in an SBR treating real domestic wastewater; ii) the application of these simplified models for analysing the respirometric response and for obtaining information about the oxygen uptake for the different processes; iii) the application of the monitored respirometric values for model calibration and determination of parameter values, which are used to predict the processes in the next cycle; iv) the use of models as theoretical background for the development of control strategies for plug-flow systems and for SBR; v) relating the basic time scale for the models to the short term.

    The starting points for the model development and simplification were: i) the Activated Sludge Model No. 1, for carbon oxidation, nitrification and denitrification; and ii) the Activated Sludge Model No. 2, for biological phosphorus removal .

    In this study an SBR pilot plant was used and seen as a model for a plug-flow system. During the two and a half years of operation, the plant underwent three different technological phases. The first phase began with the removal of organics and nitrification. Denitrification was incorporated in the second phase. The last phase included biological phosphorus removal.

    In the first phase, two simplified mathematical activated sludge models are presented. The first model gives the response of the respiration rate in an SBR with nitrification, the oxidation of readily biodegradable matter, and endogenous respiration during one cycle. This model is used to predict the respiration rate during a complete SBR cycle. For this, it uses parameter values calibrated during the previous cycle, some default values and information about the ammonia concentration in the influent. The endogenous respiration rate is described with an exponential equation. The second model is used to predict the changes in nitrification capacity after a change in the loading rate and/or sludge wastage rate. For model calibration and validation, an SBR pilot plant receiving domestic wastewater was operated for nine weeks.

    In the second phase, a mathematical model is presented for the behaviour of the respiration rate and nitrate removal in an SBR with nitrification, denitrification and carbon oxidation. This model is based on the response of the respiration rate measured during nitrification and carbon oxidation and the nitrate removal rate during the post-denitrification period. For model calibration and validation, an SBR pilot plant receiving domestic wastewater was operated for three months. The respiration rate was used to calibrate several parameters of the model.

    In the third phase, a mathematical model for an activated sludge SBR with nitrification, denitrification, carbon oxidation and phosphate removal is presented. This model is based on the response of the respiration rate measured during nitrification, carbon oxidation and phosphate removal, together with the behaviour of phosphate and acetate as proposed in the Activated Sludge Model No. 2. For model calibration and validation, an SBR pilot plant receiving settled domestic wastewater plus acetic acid solution was operated for five months.

    In all the three phases the model for the respiration rate ( r ) in an SBR during one cycle, including nitrification, oxidation of readily biodegradable matter, endogenous respiration and a fraction for the respiration rate for phosphorus uptake, gives a good simulation of the measured respiration rate. A good prediction of the total oxygen consumption and distribution during one cycle is found from a simulation, using parameters calculated from the previous cycle together with the variables from the influent. Therefor this model can be used in control strategies as long as it is used for a short time- scale. During long-term operation, parameter variation is significant and too complex to be predicted. In the particular case of nitrification capacity variation in an SBR during long-term operation, the model can explain the variation trend but cannot explain the abrupt changes.

    Simplified mathematical models for the activated sludge process on the bases of the respiration rate are validated. On short-time scale, the models give a good response prediction of the activated sludge process feed with wastewater. The models are good tools for control strategies, however periodical parameter calibration is needed.

    De urease - activiteit en de ammoniakemissie in varkensstallen met een mestschuifsysteem onder de roostervloer = Urease activity and ammonia emission in piggeries with a manure-scraper system below the slatted floor
    Elzing, A. ; Commissaris, A.C.H.M. ; Oosthoek, J. - \ 1995
    Wageningen : IMAG-DLO (Rapport / Instituut voor Milieu- en Agritechniek 94-34) - ISBN 9789054061007 - 48
    luchtverontreiniging - ammoniak - schoonmaken - schoonmaakgereedschap - emissie - enzymen - uitrusting - fermentatie - vloeren - roostervloeren - varkensstallen - scheren - stallen - vervluchtiging - wassen (activiteit) - air pollution - ammonia - cleaning - cleaning equipment - emission - enzymes - equipment - fermentation - floors - grid floors - pig housing - shearing - stalls - volatilization - washing
    Inrichting afdeling heeft invloed op reinigbaarheid
    Roelofs, P. ; Plagge, G. - \ 1995
    Praktijkonderzoek varkenshouderij 9 (1995)4. - ISSN 1382-0346 - p. 8 - 10.
    huisvesting, dieren - schoonmaken - uitrusting - vloeren - roostervloeren - hygiëne - varkensstallen - varkens - scheren - stallen - wassen (activiteit) - water - watervoorziening - watergebruik - arbeidskunde - waterzuivering - animal housing - cleaning - equipment - floors - grid floors - hygiene - pig housing - pigs - shearing - stalls - washing - water - water supply - water use - work study - water treatment
    Onderzoek op het Varkensproefbedrijf te Raalte toont aan dat de inrichting van stallen de reinigbaarheid beonvloedt. Werktijd, waterverbruik en hygiëne kunnen verbeteren als bij bouw of renovatie rekening wordt gehouden met reinigbaarheid.
    Invloed mestspleet en roosteruitvoering op hokbevuiling en kreupelheid
    Vrielink, M. - \ 1995
    Praktijkonderzoek varkenshouderij 9 (1995)3. - ISSN 1382-0346 - p. 17 - 17.
    huisvesting, dieren - botziekten - schoonmaken - uitrusting - vloeren - roostervloeren - hygiëne - varkens - scheren - stallen - diergeneeskunde - wassen (activiteit) - animal housing - bone diseases - cleaning - equipment - floors - grid floors - hygiene - pigs - shearing - stalls - veterinary science - washing
    Een mestspleet heeft geen invloed op het aantal vleesvarkens met kreupelheid. Verder blijkt bij een mestspleet minder hokbevuiling op te treden. Metalen roosters geven duidelijk minder hokbevuiling dan betonroosters.
    Verbouw biggenopfokstal (1)
    Altena, H. - \ 1995
    Praktijkonderzoek varkenshouderij 9 (1995)2. - ISSN 1382-0346 - p. 2 - 3.
    schoonmaken - uitrusting - kraamstallen - vloeren - roostervloeren - bedrijfsvoering - nederland - biggen - varkens - scheren - stallen - duurzaamheid (sustainability) - wassen (activiteit) - cleaning - equipment - farrowing houses - floors - grid floors - management - netherlands - piglets - pigs - shearing - stalls - sustainability - washing
    In de biggenopfokstal op het Varkensproefbedrijf in Raalte worden vijf afdelingen verbouwd. De opzet hierbij is om tegen minimale kosten het Groen Label te verkrijgen.
    Assessment of the capabilities of multi-temporal ERS-1 SAR data to discriminate between agricultural crops
    Schotten, C.G.J. ; Rooy, W.W.L. van; Jansen, L.L.F. - \ 1995
    International Journal of Remote Sensing 16 (1995)14. - ISSN 0143-1161 - p. 2619 - 2637.
    toepassingen - akkerbouw - uitrusting - veldgewassen - afbeelden - landgebruik - fotointerpretatie - ruimtelijke ordening - remote sensing - zonering - applications - arable farming - equipment - field crops - imagery - land use - photointerpretation - physical planning - remote sensing - zoning
    The capability of ERS-1 SAR precision data to discriminate between crop types for land cover inventory purposes at the earliest stage in the growing season was assessed using a field-based classification. The objectives were tested for an agriculturalregion in the Netherlands, where twelve crop types are found. Fourteen ERS-1 SAR images were available for this area, covering the 1992 growing season (May to November). The field-based classification yielded an overall classification accuracy of 80% with the optimal data set. The stage at which the crop types could be assessed depended on the crop. Cereals could be discriminated in May, potatoes and rape-seed in May and June.
    Mechanisatiemogelijkheden bij diepstrooiselsystemen in varkensstallen
    Maljaars, J.M. ; Vermeulen, G.D. ; Sprong, M.C. - \ 1995
    Wageningen : IMAG-DLO - ISBN 9789054061151 - 50
    schoonmaken - schoonmaakgereedschap - uitrusting - ligstro - varkensstallen - scheren - wassen (activiteit) - cleaning - cleaning equipment - equipment - litter - pig housing - shearing - washing
    Two-stage baculovirus production in insect-cell bioreactors
    Lier, F. van - \ 1995
    Agricultural University. Promotor(en): J. Tramper; J.M. Vlak. - S.l. : Van Lier - ISBN 9789054853978 - 184
    baculovirus - kernpolyedervirussen - experimenten - weefselkweek - celkweek - chemische reacties - uitrusting - biologische bestrijding - virussen - organismen ingezet bij biologische bestrijding - baculovirus - nuclear polyhedrosis viruses - experiments - tissue culture - cell culture - chemical reactions - equipment - biological control - viruses - biological control agents

    Baculoviruses are insect-pathogenic viruses with a narrow host range. The viruses can be an alternative to chemical insecticides. From research aimed at improving the efficacy of the viruses in insect control another application evolved: the use of the baculovirus to express foreign proteins in insect cells. To produce large amounts of baculovirus or baculovirus- expressed proteins, large-scale culture and subsequent infection of insect cells is necessary. Chapter 1 of this thesis reviews the research on factors influencing insect-cell culture and infection and the status of production with insect-cell cultures.

    One of the production strategies reviewed in chapter 1 is a continuous two-stage bioreactor configuration. In the first reactor cells are cultured and the effluent is led to second reactor where the cells are infected with the baculovirus. The first results reported with this system showed two disadvantages. The number of cells infected was relatively small and production in the infection reactor was limited to about one month.

    To increase the number of infected cells the residence time distribution in the infection reactor was altered (chapter 2). The infection reactor was replaced by two infection reactors in series, each containing half the volume of the original infection reactor. Therefore, the mixing characteristics of the infection part of the production system became more plug-flow like. This resulted in a higher number of cells which produced polyhedra (encapsulated virus). However, the time during which the cells in the infection reactors produced polyhedra was diminished to about two weeks.

    To gain more insight in the decrease of production a recombinant virus was used in a study described in chapter 3. In this recombinant virus the polyhedrin gene (coding for the major protein in the virus matrix) was replaced by the lacZ gene of Escherichia coli. Production of β- galactosidase in a continuous two-reactor configuration gave analogous results to production with the wild-type virus. Production was maintained for about four weeks then it rapidly decreased. Upon restriction enzyme analysis it was shown that the decrease of β-galactosidase resulted from the disappearance of the gene from the virus population rather than inactivation of the gene.

    Research at the department of Virology of the Agricultural University of Wageningen revealed that the reduction of production resulted from the occurrence of defective mutants of the baculovirus. These defective virus lack the polyhedrin-promoter driven gene and became predominant in the bioreactor due to interference with the replication of non-mutated virus.

    On the defective viruses another highly expressed gene, the p10 gene, was found to be still present. A recombinant virus containing the lacZ from E. coli under control of the p10 promoter was used in the study described in chapter 4. The recombinant virus produced both polyhedra and β-galactosidase in a continuous bioreactor system. Again production lasted for about four weeks both for polyhedra and β-galactosidase This indicates that the presence of the p10-promoter driven gene per se is not enough for recombinant protein production.

    In chapter 5 a model is presented which describes the kinetics of virus infection. Besides the infectious virus particles and the defective mutants, a third virus type is taken into account. This so-called abortive virus is capable of blocking an entry site of a cell but is not leading to production of new virus particles. By assuming a limited amount of entry sites on an insect cell it was possible to calculate when production of infectious virus decreased. The model indicates that the build-up of defective viruses can be postponed by keeping the number of infectious viruses per cell low. A way of accomplishing this is the use of repeated batch infections.

    In chapter 6 experiments with repeated (fed-)batch infections are presented. These experiments confirmed calculations with the model. A production involving a series of batch infections resulted in prolongation of production time to 60 days.

    The application of the baculovirus expression vector in the light of the findings described in the thesis is discussed in chapter 7.

    Design, characterization and application of the multiple air-lift loop bioreactor
    Bakker, W.A.M. - \ 1995
    Agricultural University. Promotor(en): J. Tramper; C.D. de Gooijer; H.H. Beeftink. - S.l. : Bakker - ISBN 9789054854791 - 172
    chemische reacties - uitrusting - chemische eigenschappen - automatische regeling - instrumentatie - systemen - zuurstof - monoclonale antilichamen - hybridoma's - chemical reactions - equipment - chemical properties - automatic control - instrumentation - systems - oxygen - monoclonal antibodies - hybridomas

    A new bioreactor is introduced: the Multiple Air-lift Loop reactor (MAL). The MAL consists of a series of air-lift loop reactors within one vessel. With the MAL, a new type of geometry for air-lift reactors with an internal loop is introduced. This new geometry was characterized with respect to hydrodynamics, mixing and oxygen transfer. The hydrodynamics were described by an existing model. Hydrodynamics, mixing and oxygen transfer in the new reactor configuration were comparable to that in conventional air-lifts with an internal loop.

    The design and use of the MAL as a reactor cascade, to approximate plug-flow behaviour, were studied. Biological model systems were used to compare the reactor series to a single vessel. These model systems included immobilized invertase and nitrifying bacteria. With the immobilized invertase it was shown that a threecompartment MAL gives an improved substrate conversion when compared to a single vessel of the same overall volume. This could be described with a previously developed model. Also for the immobilized nitrifying bacteria improved substrate conversion was shown in the comparison between a series and a single vessel. Free suspended hybridomas were used for monoclonal antibody (MAb) production. It was shown that reactor series can be useful research tools for kinetic studies. In the second vessel in the series conditions were obtained that can hardly be reached in a single vessel. Not only growth, but also death could be studied under stable conditions. A model was derived that describes hybridoma growth and their MAb production.

    Vessels in a series can be of equal volume, but very often unequal volumes can be more advantageous. Therefore, choosing the appropriate reactor volumes is an important design step, which is discussed for different applications. Finally, a general procedure for choosing the optimal bioreactor cascade configuration for any application is given.

    Een beslissingsondersteunend model voor de vervangingsinvestering van een machine of werktuig
    Schoorlemmer, H.B. ; Krikke, A.T. - \ 1994
    In: Jaarboek 1993-1996 : verslagen van afgesloten onderzoeksprojecten op de regionale onderzoekcentra en het PAGV. Akkerbouw Lelystad : Proefstation voor de Akkerbouw en de Groenteteelt in de Vollegrond [etc.] (Publikatie / Proefstation voor de Akkerbouw en de Groenteteelt in de Vollegrond, Regionale Onderzoekcentra No. 70a-81A) - p. 207 - 211.
    afschrijving - kosten - besluitvorming - depreciatie - uitrusting - boerderij uitrusting - landbouwwerktuigen - onderhoud - vervanging - service - gereedschappen - arbeidsleven - machines - amortization - costs - decision making - depreciation - equipment - farm equipment - farm machinery - maintenance - replacement - servicing - tools - working life - machines
    De relevante aspecten m.b.t. een vervangingsinvestering worden in kaart gebracht. Tevens worden de beperkingen besproken van de gebruikelijke wijze van bepaling van het vervangingsmoment. Vervolgens wordt een op het PAGV ontwikkeld model beschreven dat primair bedoeld is de individuele ondernemer te ondersteunen bij de vervangingsafweging van een specifieke machine of werktuig. De kostenoverwegingen en de fiscale aspecten worden in dit model geintegreerd
    Remsystemen voor landbouwwagens = Braking systems for farm trailers
    Straelen, B.C.P.M. van - \ 1994
    Wageningen : IMAG-DLO (Rapport / DLO, Instituut voor Milieu- en Agritechniek 94-12) - ISBN 9789054060819 - 66
    remmen - afremmen - karren - componenten - uitrusting - systemen - trailers - voertuigen - brakes - braking - carts - components - equipment - systems - trailers - vehicles
    Planning van de vervangingsinvestering van een machine of werktuig
    Schoorlemmer, H.B. ; Krikke, A.T. ; Zwanepol, S. - \ 1993
    Lelystad : PAGV (Publikatie / Proefstation voor de Akkerbouw en de Groenteteelt in de Vollegrond nr. 68) - 67
    afschrijving - depreciatie - economische hulpbronnen - boerderij uitrusting - landbouwwerktuigen - agrarische bedrijfsvoering - agrarische bedrijfsplanning - vervanging - arbeidsleven - uitrusting - machines - amortization - depreciation - economic resources - farm equipment - farm machinery - farm management - farm planning - replacement - working life - equipment - machines
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