Search

Your search keyword '"Verboven, Pieter"' showing total 751 results
Start Over Author "Verboven, Pieter"
751 results on '"Verboven, Pieter"'

205. Localization of (photo)respiration and CO2 re-assimilation in tomato leaves investigated with a reaction-diffusion model

Author

Berghuijs, Herman N.C., Yin, Xinyou, Ho, Quang Tri, Retta, Moges A., Verboven, Pieter, Nicolaï, Bart M., Struik, Paul C., Berghuijs, Herman N.C., Yin, Xinyou, Ho, Quang Tri, Retta, Moges A., Verboven, Pieter, Nicolaï, Bart M., and Struik, Paul C.

Abstract

The rate of photosynthesis depends on the CO2 partial pressure near Rubisco, Cc, which is commonly calculated by models using the overall mesophyll resistance. Such models do not explain the difference between the CO2 level in the intercellular air space and Cc mechanistically. This problem can be overcome by reaction-diffusion models for CO2 transport, production and fixation in leaves. However, most reaction-diffusion models are complex and unattractive for procedures that require a large number of runs, like parameter optimisation. This study provides a simpler reaction-diffusion model. It is parameterized by both leaf physiological and leaf anatomical data. The anatomical data consisted of the thickness of the cell wall, cytosol and stroma, and the area ratios of mesophyll exposed to the intercellular air space to leaf surfaces and exposed chloroplast to exposed mesophyll surfaces. The model was used directly to estimate photosynthetic parameters from a subset of the measured light and CO2 response curves; the remaining data were used for validation. The model predicted light and CO2 response curves reasonably well for 15 days old tomato (cv. Admiro) leaves, if (photo)respiratory CO2 release was assumed to take place in the inner cytosol or in the gaps between the chloroplasts. The model was also used to calculate the fraction of CO2 produced by (photo)respiration that is re-assimilated in the stroma, and this fraction ranged from 56 to 76%. In future research, the model should be further validated to better understand how the re-assimilation of (photo)respired CO2 is affected by environmental conditions and physiological parameters.

Published
2017

206. Cross-scale modelling of transpiration from stomata via the leaf boundary layer

Author

Defraeye, Thijs, Derome, Dominique, Verboven, Pieter, Carmeliet, Jan, Nicolai, Bart, Defraeye, Thijs, Derome, Dominique, Verboven, Pieter, Carmeliet, Jan, and Nicolai, Bart

Abstract

Background and Aims Leaf transpiration is a key parameter for understanding land surface-climate interactions, plant stress and plant structure-function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2-5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5-10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be significantly erroneous

Published
2017

207. DEM-CFD of cooling of packed fruit using 3D shape models

Author

Gruyters, Willem, Rogge, Seppe, Vanmaercke, Simon, Delele, Mulugeta Admasu, Ramon, Herman, Verboven, Pieter, and Nicolai, Bart

Subjects
Apples, Packaging, Cooling efficiency, Randomised stacking, CAD models, Precooling
Abstract

Cooling of freshly harvested produce is crucial for maintaining a high product quality for a prolonged storage period and to reduce postharvest losses. Modelling the cooling process of packed horticultural produce provides a means for improving package designs and cooling operations. In this work, a methodology to more accurately model the cooling process of randomly stacked produce in packages is presented. First, a validated geometrical 3D shape model generator of apple fruit is used to create realistic CAD models. The generator also considers the biological variability of the produce shape to create a database of more than 100 representative fruits of each cultivar. A discrete element model (DEM) then randomly selects surface meshed bodies from the database to simulate the gravitational packing of produce in a designated box or bin. The resulting stacking pattern of the produce is used to generate a computational fluid dynamics (CFD) model. The CFD model solves the airflow, heat and mass transfer through the packages to evaluate the aerodynamic and cooling performance of packages under different conditions and configurations. The difference between using actual 3D fruit shapes and an approach using equivalent spheres is demonstrated in a simulation study of forced airflow cooling of apple fruit (cv. Braeburn) packed in a “Supervent” telescopic corrugated fibreboard package under typical precooling conditions. The results are analysed in terms of pressure drop characteristics, velocity profiles and distribution of cooling rates expressed by local surface heat transfer coefficients. ispartof: CIGR AgEng conference location:Aarhus, Denmark date:26 Jun - 29 Jun 2016 status: accepted

Published
2016

208. Fast X-ray computed tomography via image completion

Author

Alves Pereira, Luis F., Janssens, Eline, Van Dael, Mattias, Verboven, Pieter, Nicolaï, Bart, Cavalcanti, George D.C., Ing Ren, Tsang, and Sijbers, Jan

Subjects
Physics, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, ComputingMethodologies_COMPUTERGRAPHICS
Abstract

Reconstructing adequate Computed Tomography (CT) images from very few X-ray projections is a hot topic in many applications. Such technology would lead to a new generation of much faster X-ray CT scanners. We propose a solution that uses a training set of conventionally reconstructed CT images to predict the interior of a target object given a fast reconstruction from very few X-ray projections. We claim that such prediction can be of sufficient quality to be used in applications that requires a high throughput.

Published
2016

210. Deliverable report D4.11 X-ray imaging module ready

Author

Rheinlander, Jorgen, Kahinpour, Bahman, Wouters, Niels, Van Dael, Mattias, Verboven, Pieter, Saeys, Wouter, and Pekkeriet, E.J.

Subjects
GTB Tuinbouw Technologie, Life Science
Published
2016

222. Building a Statistical Shape Model of the Apple from Corresponded Surfaces

Author

Danckaers, Femke, Huysmans, Toon, Van Dael, Mattias, Verboven, Pieter, Nicolai, Bart, and Sijbers, Jan

Subjects
lcsh:Computer engineering. Computer hardware, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, lcsh:TP155-156, lcsh:TK7885-7895, lcsh:Chemical engineering, ComputingMethodologies_COMPUTERGRAPHICS
Abstract

In this paper, a method for building a 3D statistical shape model of the apple is described. The framework consists of two parts. First, a reference surface is registered to each apple surface, derived from 3D CT scans of apples, of the population to obtain meaningful correspondences between the shapes. In the second part, the corresponded surfaces are used to build a statistical shape model from the population of apples. This model maps out the variability within the population and by adapting the shape model parameters, new, realistic surfaces can be obtained. By parameterizing the surface, an apple can be described with a compact set of basis functions, which has applications in surface fitting description, recognition, or meshing, e.g. for storage simulation. The constructed apple shape model is tested on performance and has proven to be a good representation of the population and can be used in many applications.

Published
2015

223. Online Tomato Inspection Using X-Ray Radiographies and 3- Dimensional Shape Models

Author

van Dael, Mattias M., Rogge, Seppe, Verboven, Pieter, Saeys, Wouter, Sijbers, Jan, and Nicolai, Bart

Subjects
lcsh:Computer engineering. Computer hardware, lcsh:TP155-156, lcsh:TK7885-7895, lcsh:Chemical engineering
Abstract

A method is proposed that fits a 3-dimensional shape model (SM) on X-ray radiographies of tomatoes on a conveyor belt to allow for inspection of internal tomato quality using X-ray. For the training of the SM a set of computed tomography (CT) scans is used. From these scans, the surfaces of the fruits are extracted. Corresponding points on all these surfaces are located after which the variation in position of every point can be determined using principal component analysis (PCA). The result of this process is a mean shape with various modes of variation, which represent the variability of the shape. Any shape can then be reconstructed through a linear combination of the mean shape and its modes of variation. During runtime, the contour of every tomato is extracted onto which the SM is fitted. This allows us to accurately estimate tomato volume and 3-dimensional shape, and assess the presence of defects and other unwanted properties from X-ray radiographies in an online application. Results are promising, but show that improvement can be made by simulating radiographs from the shape model and fitting these directly to the measured radiograph.

Published
2015

226. Investigation of the metabolic consequences of impregnating spinach leaves with trehalose and applying a pulsed electric field

Author

Chemical Biology and Drug Discovery, Afd Chemical Biology and Drug Discovery, Sub Molecular Plant Physiology, Molecular Plant Physiology, Dymek, Katarzyna, Panarese, Valentina, Herremans, Els, Cantre, Dennis, Schoo, Rick, Torano, Javier Sastre, Schlupmann, Henriette, Wadso, Lars, Verboven, Pieter, Nicolai, Bart M., Dejmek, Petr, Galindo, Federico Gomez, Chemical Biology and Drug Discovery, Afd Chemical Biology and Drug Discovery, Sub Molecular Plant Physiology, Molecular Plant Physiology, Dymek, Katarzyna, Panarese, Valentina, Herremans, Els, Cantre, Dennis, Schoo, Rick, Torano, Javier Sastre, Schlupmann, Henriette, Wadso, Lars, Verboven, Pieter, Nicolai, Bart M., Dejmek, Petr, and Galindo, Federico Gomez

Published
2016

227. The mechanism of improved aeration due to gas films on leaves of submerged rice

Author

Verboven, Pieter, Pedersen, Ole, Ho, Quang Tri, Nicolai, Bart, and Colmer, Timothy D

Abstract

Some terrestrial wetland plants, such as rice, have super-hydrophobic leaf surfaces which retain a gas film when submerged. O2 movement through the diffusive boundary layer (DBL) of floodwater, gas film and stomata into leaf mesophyll was explored by means of a reaction-diffusion model that was solved in a three-dimensional leaf anatomy model. The anatomy and dark respiration of leaves of rice (Oryza sativa L.) were measured and used to compute O2 fluxes and partial pressure of O2 (pO2 ) in the DBL, gas film and leaf when submerged. The effects of floodwater pO2 , DBL thickness, cuticle permeability, presence of gas film and stomatal opening were explored. Under O2 -limiting conditions of the bulk water (pO2

Published
2014

236. Contrast enhanced imaging of food microstructure with X-Ray microCT

Author

KUL, Wang, Zi, Vancauwenberghe, Valérie, Kerckhofs, Greet, Verboven, Pieter, Nicolai, Bart, EMBO|EMBL Symposium: Seeing is Believing, KUL, Wang, Zi, Vancauwenberghe, Valérie, Kerckhofs, Greet, Verboven, Pieter, Nicolai, Bart, and EMBO|EMBL Symposium: Seeing is Believing

Abstract

The ability to acquire images of intact microstructures of food products is of great benefit to both structural and functional studies related to food processing and preservation. X-Ray microCT is particularly well suited for this purpose as it benefits from both its nondestructive nature as well as the high resolution output. However, fundamental limitation of X-rays results in the inability of CT systems to distinguish between materials with similar atomic composition. In the context of food microstructure studies, this results in the inability to separate otherwise distinctive structures such as dense cell clusters in tissues of fruit or meat. While the medical imaging field have been developing and utilizing contrast agents to combat this limitation, these agents are seldom used outside of medicine. This study explores and demonstrates the value of utilizing contrast enhancing agents for purposes of both cell cluster separation and structure labelling. With the use of commercially available contrast enhancing agents in conjunction with optimized delivery methods, we demonstrate the significant improvement in both cellular and structural separation of both fruit and meat tissue samples. The enhanced separation allows additional software processing in which more accurate 3D models of intact structures can be produced, and thus provide a better foundation for downstream analysis and modeling.

Published
2015

238. Nondestructive quality evaluation and monitoring of Braeburn apples by Spatially Resolved Spectroscopy

Author

Do Trong, Nghia Nguyen, Tsuta, Mizuki, Erkinbaev, Chyngyz, Mathijs, Frank, Moreda Cantero, Guillermo P., Barreiro Elorza, Pilar, Verboven, Pieter, Nicolai, Bart, and Saeys, Wouter

Subjects
Ciencia y Tecnología de Alimentos
Abstract

Contact Spatially Resolved Spectroscopy (SRS) measurements by means of a fiber-optics probe were employed for nondestructive assessment and monitoring of Braeburn apples during shelflife storage. SRS measurements and estimation of optical properties were calibrated and validated by means of liquid optical phantoms with known optical properties and a metamodeling method. The acquired optical properties (absorption and reduced scattering coefficients) for the apples during shelf-life storage were found to provide useful information for nondestructive evaluation of apple quality attributes (firmness and SSC) and for monitoring the changes in their microstructure and chemical composition. On-line SRS measurement was achieved by mounting the SRS probe over a conveyor system

Published
2013

239. Modelling postmortem evolution of pH in beef M. biceps femoris under two different cooling regimes.

Author

Kuffi, Kumsa, Lescouhier, Stefaan, Nicolai, Bart, Smet, Stefaan, Geeraerd, Annemie, and Verboven, Pieter

Abstract

A model based on enzyme kinetics was developed to predict differences in postmortem pH change in beef muscles as affected by cooling rate. For the calibration and validation of the model, pH and temperature measurements were conducted at different positions in M. biceps femoris following conventional carcass cooling or faster cooling of the muscle after hot boning. The glycogen conversion, and, hence, the pH fall, was observed to significantly vary with position and cooling regime but only during the initial hours of cooling. Comparison of the cooling regimes indicated that fast cooling following hot boning avoids heat shortening induced by the combined effect of high temperature and low pH. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

248. Three-dimensional microscale modelling of CO2transport and light propagation in tomato leaves enlightens photosynthesis

Author

Ho, Quang Tri, primary, Berghuijs, Herman N. C., additional, Watté, Rodrigo, additional, Verboven, Pieter, additional, Herremans, Els, additional, Yin, Xinyou, additional, Retta, Moges A., additional, Aernouts, Ben, additional, Saeys, Wouter, additional, Helfen, Lukas, additional, Farquhar, Graham D., additional, Struik, Paul C., additional, and Nicolaï, Bart M., additional

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results