University of Twente Publications
University of Twente Repository provides publications of UT scientific staff, in many cases full text and publicly available.
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3D printing of functional structures - Krijnen, G.J.M.
The technology colloquial known as ‘3D printing’ has developed in such diversity in printing technologies and application fields that meanwhile it seems anything is possible. However, clearly the ideal 3D Printer, with high resolution, multi-material capability, fast printing, etc. is yet to be developed. Nevertheless, one can al- ready start to wonder what possibilities for electrical engineering applications will become available in the near future. Here I try to give a brief and balanced overview of current developments and a few examples of the first small steps towards 3D printed transducers.
An Action Design Research on development and deployment of a computer-based group discussion support tool for achieving consensus and culture change at an educational institution - Lee Mui Suan, Jaclyn; Hillegersberg, Jos van; Kumar, K.
Organisational culture change is a long and complex process that typically takes years to complete and has a very low success rate. This project addresses the problem by the proposed use of an Action Design Research Methodology to build and deploy an IT artifact named Organisational Culture Assessment Instrument-Spilter (OCAI-Spilter) to speed up cultural change while reducing failure rate. OCAI-Spilter should be able to fast-track culture change by addressing the problem of scalability and process losses encountered in most change projects involving large numbers of people. We used an iterative prototyping process to continuously refine the tool in use. We...
IT Governance Maturity: Developing a Maturity Model Using the Delphi Method - Smits, Daniel; Hillegersberg, Jos van
To advance in maturity, organizations should pay attention to both the hard and soft sides of IT governance (ITG). The hard side is related to processes and structure, the soft side to social aspects like behavior and organizational culture. This paper describes a study to develop an ITG maturity model (MM) that includes both. Our research method is based on literature study, the Delphi method and makes use of a Group Decision Support System. We chose to design a focus area MM. In this type of MM maturity is determined by a set of focus areas. The study reveals one...
From traditional to interactive playspaces: automatic analysis of player behavior in the interactive tag playground - Moreno Célleri, Alejandro
Play is an essential activity for the development of children. However, with the emergence of digital games, the way in which games are played has changed significantly. Many digital games promote sedentary gaming habits, or make it difficult for meaningful social interactions to occur. Nevertheless, digital games are capable of keeping players engaged for prolonged periods of time.
Recently, new types of games aim to promote the positive behavior associated with traditional play while retaining the benefits of digital games. This is accomplished by employing sensors and actuators such as cameras or projectors. Would it be possible to leverage these technological...
Microfluidics for medical applications
Lab-on-a-chip devices for point of care diagnostics have been present in clinics for several years now. Alongside their continual development, research is underway to bring the organs and tissue on-a-chip to the patient, amongst other medical applications of microfluidics.
This book provides the reader with a comprehensive review of the latest developments in the application of microfluidics to medicine and is divided into three main sections. The first part of the book discusses the state-of-the-art in organs and tissue on a chip; the second provides a thorough background to microfluidics for medicine, and the third (and largest) section provides numerous examples...
Efficiency of equilibria in uniform matroid congestion games - Jong, Jasper de; Klimm, Max; Uetz, Marc
Network routing games, and more generally congestion games play a central role in algorithmic game theory, comparable to the role of the traveling salesman problem in combinatorial optimization. It is known that the price of anarchy is independent of the network topology for non-atomic congestion games. In other words, it is independent of the structure of the strategy spaces of the players, and for affine cost functions it equals 4/3. In this paper, we show that the dependence of the price of anarchy on the network topology is considerably more intricate for atomic congestion games. More specifically, we consider congestion...
Sustainability strategies in industrial supply networks: an innovation approach concerning environmental and social aspects in the clothing industry - Bommel, Henricus Wilhelmus Maria van
Many different theories are found to explain how industrial companies implement sustainability strategies in their supply networks. However, the question why companies in a similar position choose different strategies remains under discussed. It is this question the research of this study seeks to answer using the clothing industry as an example. The results of a survey performed for this study show that specific innovation characteristics of focal companies are significantly related to the strategies found for improving the social aspects but not for the environmental aspects. These innovation characteristics represent the capability to act. The differences found between the strategies...
Past, current and future water footprints, water scarcity and virtual water flows in China - Zhuo, La
The increasing water consumption as a result of population growth and economic development, especially in fast growing developing countries, puts an increasing strain on the sustainable use of the globe’s finite freshwater resources and poses a key challenge for the future. The objective of the thesis is to evaluate past, current and future water footprints (WFs), water scarcity and virtual water (VW) flows at both river basin and national level in China, focusing on the agricultural sector, high spatial resolution modelling, uncertainties, inter- and intra-annual variation and benchmarks.
A case study for the Yellow River Basin (YRB) for 1996-2005 show...
Adsorption at solid-liquid interfaces studied with surface sensitive techniques - Wang, Lei
In this thesis, we investigated the adsorption of both organic and inorganic molecules at (aqueous) liquid-solid interfaces in the context of low salinity water flooding in enhanced oil recovery with various surface sensitive techniques and microfluidics.
With ellipsometry, we are the first to quantitatively detect ion adsorption at silica-water interfaces. The combination with microfluidics and ellipsometry, enables us to conduct screening studies efficiently. As we develop a concentration gradient generator which creates a dilution series offering parallelization. With Quartz Crystal Microbalance (QCM), hexanoate adsorption at silica, alumina and gibbsite (each of them bearing a certain similarity to clays as...
An experimental comparison of path planning techniques applied to micro-sized magnetic agents - Scheggi, S.; Misra, S.
Micro-sized agents can be used in applications suchas microassembly, micromanipulation, and minimally invasive surgeries. Magnetic agents such as paramagnetic microparticles can be controlled to deliver pharmaceutical agents to difficult-toaccess regions within the human body. In order to autonomously move these microparticles toward a target/goal area, an obstaclefree path must be computed using path planning algorithms. Several path planning algorithms have been developed in the literature, however, to the best of our knowledge, only few have been employed in an experimental scenario. In this paper we perform an experimental comparison of six path planning algorithms when applied to the motion control...
Center of mass velocity based predictions in balance recovery following pelvis perturbations during human walking - Vlutters, M.; Asseldonk, E.H.F. van; Kooij, H. van der
In many simple walking models foot placement dictates the center of pressure location and ground reaction force components, whereas humans can modulate these aspects after foot contact. Because of the differences, it is unclear to what extend predictions made by models are valid for human walking. Yet, both model simulations and human experimental data have previously indicated that the center of mass (COM) velocity plays an important role in regulating stable walking.
Here, perturbed human walking was studied for the relation of the horizontal COM velocity at heel strike and toe-off with the foot placement location relative to the COM, the...
The spatial relation between early and delayed responses evoked by single pulse electrical stimulation in pre-surgical evaluation of epilepsy patients - Blooijs, D. van; Huiskamp, G.; Hebbink, J.; Klooster, M. van 't; Meijer, H.; Gils, S. van; Gosselaar, P.; Leijten, F.
Purpose: Single pulse electrical stimulation (SPES) assists delineating epileptogenic tissue during long-term intracranial monitoring for pre-surgical evaluation. The SPES protocol consists of systematic stimulation of neighboring electrode pairs and analysis of responses in all other electrodes. SPES evokes early (ER) and delayed (DR) responses. DRs occur in epileptogenic tissue, but are stochastic: 10 stimuli are needed to reliably establish a response. ERs occur in healthy and diseased tissue and require only a single stimulus. We studied the spatial relation between ERs and DRs. If it is possible to predict DRs from ERs, this might improve the efficiency of SPES.
Adoption of web-based group decision support systems: Experiences from the field and future developments - Hillegersberg, Jos van; Koenen, Sebastiaan
While organizations have massively adopted enterprise information systems to support business processes, business meetings in which key decisions are made about products, services and processes, are usually held without much support of information systems. This is remarkable as group decision support systems (GDSS) seems to fit for this purpose. They have existed for decades and modern versions benefit of web-based technologies, enabling low cost anyplace, any time and device independent meeting support. In this exploratory case research, we study nine organizations in four different adoption categories to learn more about the reasons for the relatively slow adoption of web-based GDSS....
Waiting Time from Diagnosis to Treatment has no Impact on Survival in Patients with Esophageal Cancer - Visser, E.; Leeftink, A.G.; Rossum, P.S.N. van; Siesling, S.; Hillegersberg, R. van; Ruurda, J.P.
Waiting time from diagnosis to treatment has emerged as an important quality indicator in cancer care. This study was designed to determine the impact of waiting time on long-term outcome of patients with esophageal cancer who are treated with neoadjuvant therapy followed by surgery or primary surgery.
Patients who underwent esophagectomy for esophageal cancer at the University Medical Center Utrecht between 2003 and 2014 were included. Patients treated with neoadjuvant therapy followed by surgery and treated with primary surgery were separately analyzed. The influence of waiting time on survival was analyzed using Cox proportional hazard analyses. Kaplan–Meier curves for short (<8...
Risk of regional recurrence in triple-negative breast cancer patients: a Dutch cohort study - Roozendaal, Lori M. van; Smit, Leonie H.M.; Duijsens, Gaston H.N.M.; Vries, Bart de; Siesling, Sabine; Lobbes, Marc B.I.; Boer, Maaike de; Wilt, Johannes H.W. de; Smidt, Marjolein L.
Triple-negative breast cancer is associated with early recurrence and low survival rates. Several trials investigate the safety of a more conservative approach of axillary treatment in clinically T1-2N0 breast cancer. Triple-negative breast cancer comprises only 15 % of newly diagnosed breast cancers, which might result in insufficient power for representative results for this subgroup. We aimed to provide a nationwide overview on the occurrence of (regional) recurrences in triple-negative breast cancer patients with a clinically T1-2N0 status. For this cohort study, 2548 women diagnosed between 2005 and 2008 with clinically T1-2N0 triple-negative breast cancer were selected from the Netherlands Cancer...
Routing policies for a partially observable two-server queueing system - Ellens, Wendy; Kovács, Péter; Núñez-Queija, Rudesindo; Berg, Hans van den
We consider a queueing system controlled by decisions based on partial state information. The motivation for this work stems from road traffic, in which drivers may, or may not, be subscribed to a smartphone application for dynamic route planning. Our model consists of two queues with independent ex-ponential service times, serving two types of jobs. Arrivals occur according to a Poisson process; a fraction of the jobs (type X) is observable and controllable. At all times the number of X jobs in each queue and their individual po-sitions are known. Upon its arrival a router decides which queue the next...
Ambiguity resolution in a Neural Blackboard Architecture for sentence structure - Velde, Frank van der; Kamps, Marc de
We simulate two examples of ambiguity resolution found in human language processing in a neural blackboard architecture for sentence representation and processing. The architecture also accounts for a related garden path effect. The architecture represents and processes sentences in terms of neuronal assemblies, related to the words and the structure of the sentence. The assemblies are simulated as Wilson-Cowan neuronal populations. During sentence processing predictions are generated in the architecture about the remaining structure of the sentence. In the course of processing, the resulting sentence (structure) and word representations in the architecture interact in a dynamical competition. These interactions produce...
A Semantic Map for Evaluating Creativity - Velde, Frank van der; Wolf, Roger A.; Schmettow, Martin; Nazareth, Deniece S.
We present a semantic map of words related with creativity. The aim is to empirically derive terms which can be used to rate processes or products of computational creativity. The words in the map are based on association studies performed by human subjects and augmented with words derived from the literature (based on human raters). The words are used in a card sorting study to investigate the way they are categorized by human subjects. The results are arranged in a heat map of word relations based on a hierarchical cluster analysis. The cluster analysis and a principal component analysis provide...