Papers by maurice van der beek
Proceedings of SPIE, Aug 28, 2008
One of the big advantages of polymer optics is the possibility of integrating several functions i... more One of the big advantages of polymer optics is the possibility of integrating several functions into one component. These functions can range from mechanical reference datums all the way to micro channels in "lab-on-chip" type of applications. In this paper an overview on several design- and manufacturing principles of such integrated components will be given. Furthermore the next steps in
Nowadays, semi-crystalline polymers are widely used in many product applications that display hig... more Nowadays, semi-crystalline polymers are widely used in many product applications that display high dimensional accuracy and stability. However, the relationship between processing conditions and the main property determining macroscopic shrinkage, i.e. specific volume, is still not understood in sufficient detail to predict the resulting dimensions of a product dependent on the selected material and chosen processing conditions. In this thesis, the dependence of the specific volume of crystallizing polymers on the thermomechanical history as experienced during processing is investigated. Emphasis is placed on selecting and reaching those processing conditions that are relevant for industrial processing operations such as injection molding and extrusion. To extent the interpretation of the results obtained on the development of specific volume, structure properties of the resulting crystalline morphology are investigated using wide angle X-ray diffraction (WAXD) in combination with s...
Dilatometer for measuring shrinkage or expansion of a sample and system, comprising the dilatomet... more Dilatometer for measuring shrinkage or expansion of a sample and system, comprising the dilatometer and the sample, wherein the dilatometer is provided with a first and second member which, in combination, define a chamber for the sample, wherein the dilatometer is arranged to apply a relative movement of the first and second member with respect to each other for shearing the sample, and wherein the chamber is provided with a structure for, in use, mechanically engaging the sample for substantially preventing a relative movement of the first member with respect to a first-member-facing-part of the sample and a relative movement of the second member with respect to a second-member-facing-part of the sample, in a direction substantially parallel to the relative movement of the first and second member
Introduction The heterogeneous microstructure of semi-crystalline polymers strongly depends on th... more Introduction The heterogeneous microstructure of semi-crystalline polymers strongly depends on the thermal-mechanical history experienced during processing. For the prediction of material properties that are closely related to this microstructure, such as specific volume (figure 1), a realistic computational model is required. Therefore, a novel experimental set-up is developed that provides the input data for this model as a function of the thermal-mechanical history.
Citation for published version (APA): van der Beek, M. H. E. (1994). Influence of the pulse shape... more Citation for published version (APA): van der Beek, M. H. E. (1994). Influence of the pulse shape on the flow field in a three dimensional model of the human carotid artery bifurcation (LDA experiments). (DCT rapporten; Vol. 1994.067). Technische Universiteit Eindhoven.
Novel Optical Systems Design and Optimization XI, 2008
One of the big advantages of polymer optics is the possibility of integrating several functions i... more One of the big advantages of polymer optics is the possibility of integrating several functions into one component. These functions can range from mechanical reference datums all the way to micro channels in "lab-on-chip" type of applications. In this paper an overview on several design- and manufacturing principles of such integrated components will be given. Furthermore the next steps in
Macromolecules, 2006
ABSTRACT
Macromolecules, 2006
ABSTRACT
Macromolecular Materials and Engineering, 2005
Journal of Biomechanics, 1996
Laser Doppler anemometer (LDA) experiments were performed to gain quantitative information on the... more Laser Doppler anemometer (LDA) experiments were performed to gain quantitative information on the differences between the large-scale flow phenomena in a non-stenosed and a stenosed model of the carotid artery bifurcation. The influence of the presence of the stenosis was compared to the effect of flow pulse variation to evaluate the feasibility of early detection of stenosis in clinical practice. Three-dimensional Plexiglass models of a non-stenosed and a 25% stenosed carotid artery bifurcation were perfused with a Newtonian fluid. The flow conditions approximated physiological flow. The results of the velocity measurements in the non-stenosed model agreed with the results from previous hydrogen-bubble visualization. A shear layer separated the low-velocity area near the non-divider wall from the high-velocity area near the divider wall. In this shear layer, vortex formation occurred during the deceleration phase of the flow pulse. The instability of this shear layer dictated the flow disturbances. The influences of the mild stenosis, located at the non-divider wall, was mainly limited to the stability of the shear layer. No disturbances were found downstream of the stenosis near the non-divider wall. Using a pulse wave with an increased systolic deceleration time, the velocity distribution showed an extended region with reversed flow, a more pronounced shear layer and increased vortex strength. From these measurements it is obvious that the influence of the presence of a mild stenosis, mainly limited to the stability of the shear layer, can hardly be distinguished from the effects of a variation of the flow pulse. From this it can be concluded that methods for detection of mild stenosis, using solely the large-scale flow phenomena, as can be measured by ultrasound or MRI techniques, will hardly have any clinical relevance.
Laser Doppler anemometer (LDA) experiments were performed to gain quantitative information on the... more Laser Doppler anemometer (LDA) experiments were performed to gain quantitative information on the differences between the large-scale flow phenomena in a non-stenosed and a stenosed model of the carotid artery bifurcation. The influence of the presence of the stenosis was compared to the effect of flow pulse variation to evaluate the feasibility of early detection of stenosis in clinical practice. Three-dimensional Plexiglass models of a non-stenosed and a 25% stenosed carotid artery bifurcation were perfused with a Newtonian fluid. The flow conditions approximated physiological flow. The results of the velocity measurements in the non-stenosed model agreed with the results from previous hydrogen-bubble visualization. A shear layer separated the low-velocity area near the non-divider wall from the high-velocity area near the divider wall. In this shear layer, vortex formation occurred during the deceleration phase of the flow pulse. The instability of this shear layer dictated the flow disturbances. The influences of the mild stenosis, located at the non-divider wall, was mainly limited to the stability of the shear layer. No disturbances were found downstream of the stenosis near the non-divider wall. Using a pulse wave with an increased systolic deceleration time, the velocity distribution showed an extended region with reversed flow, a more pronounced shear layer and increased vortex strength. From these measurements it is obvious that the influence of the presence of a mild stenosis, mainly limited to the stability of the shear layer, can hardly be distinguished from the effects of a variation of the flow pulse. From this it can be concluded that methods for detection of mild stenosis, using solely the large-scale flow phenomena, as can be measured by ultrasound or MRI techniques, will hardly have any clinical relevance.
Uploads
Papers by maurice van der beek