Search results for: Matthijs Langelaar

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Langelaar</title> <meta name="description" content="Search results for: Matthijs Langelaar"> <meta name="keywords" content="Matthijs Langelaar"> <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no"> <meta charset="utf-8"> <link href="https://cdn.waset.org/favicon.ico" type="image/x-icon" rel="shortcut icon"> <link href="https://cdn.waset.org/static/plugins/bootstrap-4.2.1/css/bootstrap.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/plugins/fontawesome/css/all.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/css/site.css?v=150220211555" rel="stylesheet"> </head> <body> <header> <div class="container"> <nav class="navbar navbar-expand-lg navbar-light"> <a class="navbar-brand" href="https://waset.org"> <img src="https://cdn.waset.org/static/images/wasetc.png" alt="Open Science Research Excellence" title="Open Science Research Excellence" /> </a> <button class="d-block d-lg-none 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action="https://publications.waset.org/abstracts/search"> <div id="custom-search-input"> <div class="input-group"> <i class="fas fa-search"></i> <input type="text" class="search-query" name="q" placeholder="Author, Title, Abstract, Keywords" value="Matthijs Langelaar"> <input type="submit" class="btn_search" value="Search"> </div> </div> </form> </div> </div> <div class="row mt-3"> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Commenced</strong> in January 2007</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Frequency:</strong> Monthly</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Edition:</strong> International</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Paper Count:</strong> 3</div> </div> </div> </div> <h1 class="mt-3 mb-3 text-center" style="font-size:1.6rem;">Search results for: Matthijs Langelaar</h1> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">3</span> Modeling, Topology Optimization and Experimental Validation of Glass-Transition-Based 4D-Printed Polymeric Structures</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Sara%20A.%20Pakvis">Sara A. Pakvis</a>, <a href="https://publications.waset.org/abstracts/search?q=Giulia%20Scalet"> Giulia Scalet</a>, <a href="https://publications.waset.org/abstracts/search?q=Stefania%20Marconi"> Stefania Marconi</a>, <a href="https://publications.waset.org/abstracts/search?q=Ferdinando%20Auricchio"> Ferdinando Auricchio</a>, <a href="https://publications.waset.org/abstracts/search?q=Matthijs%20Langelaar"> Matthijs Langelaar</a> </p> <p class="card-text"><strong>Abstract:</strong></p> In recent developments in the field of multi-material additive manufacturing, differences in material properties are exploited to create printed shape-memory structures, which are referred to as 4D-printed structures. New printing techniques allow for the deliberate introduction of prestresses in the specimen during manufacturing, and, in combination with the right design, this enables new functionalities. This research focuses on bi-polymer 4D-printed structures, where the transformation process is based on a heat-induced glass transition in one material lowering its Young鈥檚 modulus, combined with an initial prestress in the other material. Upon the decrease in stiffness, the prestress is released, which results in the realization of an essentially pre-programmed deformation. As the design of such functional multi-material structures is crucial but far from trivial, a systematic methodology to find the design of 4D-printed structures is developed, where a finite element model is combined with a density-based topology optimization method to describe the material layout. This modeling approach is verified by a convergence analysis and validated by comparing its numerical results to analytical and published data. Specific aspects that are addressed include the interplay between the definition of the prestress and the material interpolation function used in the density-based topology description, the inclusion of a temperature-dependent stiffness relationship to simulate the glass transition effect, and the importance of the consideration of geometric nonlinearity in the finite element modeling. The efficacy of topology optimization to design 4D-printed structures is explored by applying the methodology to a variety of design problems, both in 2D and 3D settings. Bi-layer designs composed of thermoplastic polymers are printed by means of the fused deposition modeling (FDM) technology. Acrylonitrile butadiene styrene (ABS) polymer undergoes the glass transition transformation, while polyurethane (TPU) polymer is prestressed by means of the 3D-printing process itself. Tests inducing shape transformation in the printed samples through heating are performed to calibrate the prestress and validate the modeling approach by comparing the numerical results to the experimental findings. Using the experimentally obtained prestress values, more complex designs have been generated through topology optimization, and samples have been printed and tested to evaluate their performance. This study demonstrates that by combining topology optimization and 4D-printing concepts, stimuli-responsive structures with specific properties can be designed and realized. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=4D-printing" title="4D-printing">4D-printing</a>, <a href="https://publications.waset.org/abstracts/search?q=glass%20transition" title=" glass transition"> glass transition</a>, <a href="https://publications.waset.org/abstracts/search?q=shape%20memory%20polymer" title=" shape memory polymer"> shape memory polymer</a>, <a href="https://publications.waset.org/abstracts/search?q=topology%20optimization" title=" topology optimization"> topology optimization</a> </p> <a href="https://publications.waset.org/abstracts/132462/modeling-topology-optimization-and-experimental-validation-of-glass-transition-based-4d-printed-polymeric-structures" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/132462.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">208</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">2</span> Dow Polyols near Infrared Chemometric Model Reduction Based on Clustering: Reducing Thirty Global Hydroxyl Number (OH) Models to Less Than Five</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Wendy%20Flory">Wendy Flory</a>, <a href="https://publications.waset.org/abstracts/search?q=Kazi%20Czarnecki"> Kazi Czarnecki</a>, <a href="https://publications.waset.org/abstracts/search?q=Matthijs%20Mercy"> Matthijs Mercy</a>, <a href="https://publications.waset.org/abstracts/search?q=Mark%20Joswiak"> Mark Joswiak</a>, <a href="https://publications.waset.org/abstracts/search?q=Mary%20Beth%20Seasholtz"> Mary Beth Seasholtz</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Polyurethane Materials are present in a wide range of industrial segments such as Furniture, Building and Construction, Composites, Automotive, Electronics, and more. Dow is one of the leaders for the manufacture of the two main raw materials, Isocyanates and Polyols used to produce polyurethane products. Dow is also a key player for the manufacture of Polyurethane Systems/Formulations designed for targeted applications. In 1990, the first analytical chemometric models were developed and deployed for use in the Dow QC labs of the polyols business for the quantification of OH, water, cloud point, and viscosity. Over the years many models have been added; there are now over 140 models for quantification and hundreds for product identification, too many to be reasonable for support. There are 29 global models alone for the quantification of OH across > 70 products at many sites. An attempt was made to consolidate these into a single model. While the consolidated model proved good statistics across the entire range of OH, several products had a bias by ASTM E1655 with individual product validation. This project summary will show the strategy for global model updates for OH, to reduce the number of models for quantification from over 140 to 5 or less using chemometric methods. In order to gain an understanding of the best product groupings, we identify clusters by reducing spectra to a few dimensions via Principal Component Analysis (PCA) and Uniform Manifold Approximation and Projection (UMAP). Results from these cluster analyses and a separate validation set allowed dow to reduce the number of models for predicting OH from 29 to 3 without loss of accuracy. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=hydroxyl" title="hydroxyl">hydroxyl</a>, <a href="https://publications.waset.org/abstracts/search?q=global%20model" title=" global model"> global model</a>, <a href="https://publications.waset.org/abstracts/search?q=model%20maintenance" title=" model maintenance"> model maintenance</a>, <a href="https://publications.waset.org/abstracts/search?q=near%20infrared" title=" near infrared"> near infrared</a>, <a href="https://publications.waset.org/abstracts/search?q=polyol" title=" polyol"> polyol</a> </p> <a href="https://publications.waset.org/abstracts/107706/dow-polyols-near-infrared-chemometric-model-reduction-based-on-clustering-reducing-thirty-global-hydroxyl-number-oh-models-to-less-than-five" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/107706.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">135</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">1</span> Kinetics of Phytochemicals and Antioxidant Activity during Thermal Treatment of Cape Gooseberry (Physalis peruviana L)</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Mary-Luz%20Olivares-Tenorio">Mary-Luz Olivares-Tenorio</a>, <a href="https://publications.waset.org/abstracts/search?q=Ruud%20Verkerk"> Ruud Verkerk</a>, <a href="https://publications.waset.org/abstracts/search?q=Matthijs%20Dekker"> Matthijs Dekker</a>, <a href="https://publications.waset.org/abstracts/search?q=Martinus%20A.%20J.%20S.%20van%20Boekel"> Martinus A. J. S. van Boekel</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Cape gooseberry, the fruit of the plant Physalis peruviana L. has gained interest in research given its contents of promising health-promoting compounds like contents. The presence of carotenoids, ascorbic acid, minerals, polyphenols, vitamins and antioxidants. This project aims to study thermal stability of 尾-carotene, ascorbic acid, catechin and epicatechin and antioxidant activity in the matrix of the Cape Gooseberry. Fruits were obtained from a Colombian field in Cundinamarca. Ripeness stage was 4 (According to NTC 4580, corresponding to mature stage) at the moment of the experiment. The fruits have been subjected to temperatures of 40, 60, 80, 100 and 120掳C for several times. 尾-Carotene, ascorbic acid, catechin and epicatechin content were assessed with HPLC and antioxidant activity with the DPPH method. 尾-Carotene was stable upon 100掳C, and showed some degradation at 120掳C. The same behavior was observed for epicatechin. Catechin increased during treatment at 40掳C, at 60掳C it remained stable and it showed degradation at 80掳C, 100掳C and 120掳C that could be described by a second order kinetic model. Ascorbic acid was the most heat-sensitive of the analyzed compounds. It showed degradation at all studied temperatures, and could be described by a first order model. The activation energy for ascorbic acid degradation in cape gooseberry was 46.0 kJ/mol and its degradation rate coefficient at 100 掳C was 6.53 x 10-3 s-1. The antioxidant activity declined for all studied temperatures. Results from this study showed that cape gooseberry is an important source of different health-promoting compounds and some of them are stable to heat. That makes this fruit a suitable raw material for processed products such as jam, juices and dehydrated fruit, giving the consumer a good intake of these compounds. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=goldenberry" title="goldenberry">goldenberry</a>, <a href="https://publications.waset.org/abstracts/search?q=health-promoting%20compounds" title=" health-promoting compounds"> health-promoting compounds</a>, <a href="https://publications.waset.org/abstracts/search?q=phytochemical" title=" phytochemical"> phytochemical</a>, <a href="https://publications.waset.org/abstracts/search?q=processing" title=" processing"> processing</a>, <a href="https://publications.waset.org/abstracts/search?q=heat%20treatment" title=" heat treatment"> heat treatment</a> </p> <a href="https://publications.waset.org/abstracts/33670/kinetics-of-phytochemicals-and-antioxidant-activity-during-thermal-treatment-of-cape-gooseberry-physalis-peruviana-l" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/33670.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">452</span> </span> </div> </div> </div> </main> <footer> <div id="infolinks" class="pt-3 pb-2"> <div class="container"> <div style="background-color:#f5f5f5;" class="p-3"> <div class="row"> <div class="col-md-2"> <ul class="list-unstyled"> About <li><a href="https://waset.org/page/support">About Us</a></li> <li><a href="https://waset.org/page/support#legal-information">Legal</a></li> <li><a target="_blank" rel="nofollow" href="https://publications.waset.org/static/files/WASET-16th-foundational-anniversary.pdf">WASET celebrates its 16th foundational 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Search results for: Matthijs Langelaar