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University of Twente Publications (61.608 recursos)

University of Twente Repository provides publications of UT scientific staff, in many cases full text and publicly available.

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Mostrando recursos 1 - 20 de 27.933

  1. The European university landscape: A micro characterization based on evidence from the Aquameth project

    Daraio, Cinzia; Bonaccorsi, Andrea; Geuna, Aldo; Lepori, Benedetto; Bach, Laurent; Bogetoft, Peter; Cardoso, Margarida F.; Castro-Martinez, Elena; Jongbloed, Ben; et al,
    This paper provides a new and systematic characterization of 488 universities, from 11 European countries: Finland, France, Germany, Hungary, Italy, Netherlands, Norway, Portugal, Spain, Switzerland and UK. Using micro indicators built on the integrated Aquameth database, we characterize the European university landscape according to the following dimensions: history/foundation of university, dynamics of growth, specialization pattern, subject mix, funding composition, offer profile and productivity.

  2. Method to pattern etch masks in two inclined planes for three-dimensional nano- and microfabrication

    Tjerkstra, R. Willem; Woldering, Léon A.; Broek, Johanna M. van den; Roozeboom, Fred; Setija, Irwan D.; Vos, Willem L.
    The authors present a method to pattern etch masks for arbitrary nano- and microstructures on different, inclined planes of a sample. Our method allows standard CMOS fabrication techniques to be used in different inclined planes; thus yielding three-dimensional structures with a network topology. The method involves processing of the sample in a first plane, followed by mounting the prepared sample in a specially designed silicon holder wafer such that the second, inclined plane is exposed to continued processing. As a proof of principle we demonstrate the fabrication of a patterned chromium etch mask for three-dimensional photonic crystals in silicon. The...

  3. Guest editorial: Special issue on selected papers from the IEEE SENSORS 2015 conference

    Jiang, Hongrui; Maeda, Ryutaro; Krijnen, Gijs; Vellekoop, Michel
    Over the years, the IEEE SENSORS Conference has become one of the premier, true international, conferences on anything that has to do with sensors, ranging from principles, design and fabrication to interfacing, data-extraction, applications, etc. The IEEE SENSORS 2015 Conference was held in Bushan, South Korea. The program consisted of 484 papers (249 orals and 235 poster contributions). As has become customary, the tracks chairs were asked to select the approximately 10% best abstract submissions to their track. The authors of these were subsequently invited to contribute an extended manuscript to this Special Issue.

  4. On the small-signal capacitance of RF MEMS switches at very low frequencies

    Wang, Jiahui; Bielen, Jeroen; Salm, Cora; Krijnen, Gijs; Schmitz, Jurriaan
    This paper presents on-wafer capacitance measurements of silicon-based RF MEMS capacitive switches down to frequencies below 1 Hz. The capacitance-voltage (C-V) curve measured at very-low frequency (0.01-10 Hz) deviates from the commonly measured and well-understood high-frequency C-V curve, especially near the pull-in and pull-out voltages. This behavior is explained from the mechanical action of the top electrode. An electrostatic transducer model is used to express the coupling between mechanical and electrical behavior of the device under study. The mechanical action and air damping play an important role at the lower measurement frequencies, as confirmed by vibrometer measurements, FEM modeling and...

  5. A 2D particle velocity sensor with minimal flow disturbance

    Pjetri, Olti; Wiegerink, Remco J.; Krijnen, Gijs J.M.
    A 2D sound particle velocity sensor, consisting of a cross of two connected, heated wires is presented. We developed a fabrication process by which the wires become freely suspended 350 micrometer above the chip surface. This largely eliminates the influence of boundary layer effects and increases the temperature gradient along the wires, both due to the large distance to the silicon substrate. As a result, the sensor has increased sensitivity and reduced power consumption compared with an earlier design. Furthermore, due to the fully symmetrical structure of the sensor, the sensitive directions are exactly orthogonal to each other and have...

  6. A 2D acoustic particle velocity sensor with perfectly orthogonal sensitivity directions

    Pjetri, O.; Wiegerink, R.J.; Lammerink, T.S.J.; Krijnen, G.J.M.
    A two-dimensional acoustic particle velocity sensor as well as the required interfacing electronics have been designed and realized. The novel crossed-wire sensor structure provides a direct two- dimensional measurement and, contrary to current 2D particle velocity sensors, the sensitive directions are exactly orthogonal to each other due to the inherent symmetry of the sensor. This new design of size 1.0 mm × 2.5 mm × 0.5 mm dissipates only half the power required by current one-dimensional particle velocity sensors, has comparable bandwidth at modest 15 dB higher selfnoise. Furthermore, it requires no directivity calibration, which was difficult to achieve in...

  7. Recent developments in bio-inspired sensors fabricated by additive manufacturing technologies

    Krijnen, Gijs J.M.; Sanders, Remco G.P.
    In our work on micro-fabricated hair-sensors, inspired by the flow-sensitive sensors found on crickets, we have made great progress. Initially delivering mediocre performance compared to their natural counter parts they have evolved into capable sensors with thresholds roughly a factor of 30 larger than of their natural equivalents. Due to this disparity, and also instigated by our work on fly-halteres inspired rotation rate sensors and desert locust ear-drum mimicking membrane struc- tures, we have analysed the differences in performance between natural and man-made sensors. We conclude that two major drawbacks of main-stream micro-fabrication are the lack of easily applicable soft...

  8. An improved analytical model for carrier multiplication near breakdown in diodes

    Hueting, Raymond J.E.; Heringa, Anco; Boksteen, Boni K.; Dutta, Satadal; Ferrara, Alessandro; Agarwal, Vishal; Annema, Anne Johan
    The charge carrier contributions to impact ionization and avalanche multiplication are analyzed in detail. A closed-form analytical model is derived for the ionization current before the onset of breakdown induced by both injection current components. This model shows that the ratio of both injection current components affects the multiplication factor at relatively low fields before breakdown, but does not affect the reverse breakdown voltage. Furthermore, the model indicates that in case the ionization coefficients of electrons and holes are quite different in value, which depends upon the semiconductor material, the ionization coefficient of the charge carrier with the highest value...

  9. SU-8 micro Coriolis mass flow sensor

    Monge, Rosa; Groenesteijn, Jarno; Alveringh, Dennis; Wiegerink, R.J.; Lötters, Joost; Fernandez, Luis J.
    Abstract This work presents the modelling, design, fabrication and test of the first micro Coriolis mass flow sensor fully fabricated in SU-8 by photolithography processes. The sensor consists of a channel with rectangular cross-section with inner opening of 100 μm × 100 μm and is actuated at resonance by Lorentz forces. Metal tracks for the actuation current are deposited on top of the chip. The chip has been tested over a flow range of 0–800 mg/min in the case of water and 0–650 mg/min for isopropyl alcohol (IPA) to confirm that the sensor measures true mass flow (at the maximum...

  10. Precision in harsh environments

    French, Paddy; Krijnen, Gijs; Roozeboom, Fred
    Microsystems are increasingly being applied in harsh and/or inaccessible environments, but many markets expect the same level of functionality for long periods of time. Harsh environments cover areas that can be subjected to high temperature, (bio)-chemical and mechanical disturbances, electromagnetic noise, radiation, or high vacuum. In the field of actuators, the devices must maintain stringent accuracy specifications for displacement, force, and response times, among others. These new requirements present additional challenges in the compensation for or elimination of cross-sensitivities. Many state-of-the-art precision devices lose their precision and reliability when exposed to harsh environments. It is also important that advanced sensor...

  11. Validation of automatic joint space width measurements in hand radiographs in rheumatoid arthritis

    Schenk, Olga; Huo, Yinghe; Vincken, Koen L.; Laar, Mart A. van de; Kuper, Ina H.H.; Slump, Kees C.H.; Lafeber, Floris P.J.G.; Bernelot Moens, Hein J.
    Computerized methods promise quick, objective, and sensitive tools to quantify progression of radiological damage in rheumatoid arthritis (RA). Measurement of joint space width (JSW) in finger and wrist joints with these systems performed comparable to the Sharp–van der Heijde score (SHS). A next step toward clinical use, validation of precision and accuracy in hand joints with minimal damage, is described with a close scrutiny of sources of error. A recently developed system to measure metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints was validated in consecutive hand images of RA patients. To assess the impact of image acquisition, measurements on radiographs...

  12. Computer game-based mathematics education: Embedded faded worked examples facilitate knowledge acquisition

    Vrugte, Judith ter; Jong, Ton de; Vandercruysse, Sylke; Wouters, Pieter; Oostendorp, Herre van; Elen, Jan
    This study addresses the added value of faded worked examples in a computer game-based learning environment. The faded worked examples were introduced to encourage active selection and processing of domain content in the game. The content of the game was proportional reasoning and participants were 12- to 15-year-old students from prevocational education. The study compared two conditions in which students worked with the environment with faded worked examples (n = 49) or without worked examples (n = 44). The students who received the faded worked examples performed better on a posttest measuring their proportional reasoning skills, and this performance was...

  13. Measurement model choice influenced randomized controlled trial results

    Gorter, Rosalie; Fox, Jean-Paul; Apeldoorn, Adri; Twisk, Jos
    Objective In randomized controlled trials (RCTs), outcome variables are often patient-reported outcomes measured with questionnaires. Ideally, all available item information is used for score construction, which requires an item response theory (IRT) measurement model. However, in practice, the classical test theory measurement model (sum scores) is mostly used, and differences between response patterns leading to the same sum score are ignored. The enhanced differentiation between scores with IRT enables more precise estimation of individual trajectories over time and group effects. The objective of this study was to show the advantages of using IRT scores instead of sum scores when analyzing RCTs. Study...

  14. Employee participation, performance metrics, and job performance: A survey study based on self-determination theory

    Groen, Bianca A.C.; Wouters, Marc J.F.; Wilderom, Celeste P.M.
    Suitable and valid operational performance metrics are important means to translate an organization’s strategy into action. However, developing high-quality operational metrics is challenging because such metrics need the right degree of context specificity to be meaningful to the managers and employees who will use them. We investigated whether managers consider metrics that have been co-developed with operational employees to be of higher quality and, in turn, whether they use these metrics more—and whether this use is linked to greater employee job performance. On the basis of self-determination theory, we investigated if different uses of performance metrics have different effects. We...

  15. The importance of the technologically able social innovators and entrepreneurs: A US National Laboratory Perspective

    Chavez, Victor A.; Stinnett, Regan; Tierney, Robert; Walsh, Steven
    A country's National Innovation Policies (NIP) often center on military, energy or other national security missions. Yet many countries' NIPs have resulted in tremendous societal benefit through both planned and unplanned action not associated with these goals. Socially important technology product platforms often are developed at facilities that are part of National Innovation Systems. Yet the policies that govern Social Entrepreneurial Action (SEA) at these facilities are unclear. If there is not a place for SEA in these facilities for technology transfer practice then there is cause for concern. Here we add to the growing literature on SEA by utilizing the...

  16. Early career burnout among Dutch nurses: A process captured in a Rasch model

    Vos, Jan Alexander de; Brouwers, Andre; Schoot, Tineke; Pat-El, Ron; Verboon, Peter; Näring, Gerard
    This study investigates burnout among Dutch nursing graduates as a process by testing a sequential-developmental model. A sample of 237 respondents was recruited from a population of Dutch early career nurses. Burnout was measured with the Dutch version of the Maslach Burnout Inventory Human Services Survey (MBI-HSS, Maslach & Jackson, 1981; Schaufeli & van Dierendonck, 2000). First, the dimensionality was tested with confirmatory factor analysis. A resulting one-dimensional model with exhaustion and depersonalisation was then analysed using a Rasch rating scale measurement model. Rasch analysis showed that these data adhered well to a sequential-developmental model. Burnout among early career nurses...

  17. Bridging the Gap Between Revealed and Stated Preferences in Flood-prone Housing Markets

    Koning, Koen de; Filatova, Tatiana; Bin, Okmyung

  18. Increased environmental sensitivity in high mathematics performance

    Schwabe, I.; Boomsma, D.I.; Berg, S.M. van den
    Results of international comparisons of students in studies such as PISA (Program for International Student Assessment) and TIMSS (Trends in International Mathematics and Science Study) are often taken to indicate that mathematical education in Dutch schools is not appropriate for mathematically talented students. However, there has been no empirical study yet that investigated this hypothesis. If indeed, Dutch students with a genetic predisposition for high mathematical ability are not nurtured to their full potential, their mathematics performance should be more affected by environmental factors than that of children with a genetic predisposition for low mathematical ability. In behaviour genetics such...

  19. Institutional determinants of power sector reform in Pakistan

    Ullah, Kafait; Arentsen, Maarten J.; Lovett, Jon C.
    The electricity supply sector in Pakistan has performed poorly in recent years. Reforms were introduced in the mid-1990s to improve the sector, but progressed slowly with no significant impacts on pre-reform performance. This study uses new institutional economics as a theoretical basis to elucidate reasons for the failure of power sector reforms in Pakistan to make improvements. Interviews with 23 experts using Q-methodology generated 215 statements that were used as a Q concourse. Of these, 51 statements were selected for the Q sample and ranked by 34 respondents depending on their importance. Analysis revealed four important discourses on the determinants...

  20. The value of participatory development to support antimicrobial stewardship with a clinical decision support system

    Beerlage-de Jong, Nienke; Wentzel, Jobke; Hendrix, Ron; Gemert-Pijnen, Lisette van
    Background Current clinical decision support systems (CDSSs) for antimicrobial stewardship programs (ASPs) are guideline- or expert-driven. They are focused on (clinical) content, not on supporting real-time workflow. Thus, CDSSs fail to optimally support prudent antimicrobial prescribing in daily practice. Our aim was to demonstrate why and how participatory development (involving end-users and other stakeholders) can contribute to the success of CDSSs in ASPs. Methods A mixed-methods approach was applied, combining scenario-based prototype evaluations (to support verbalization of work processes and out-of-the-box thinking) among 6 medical resident physicians with an online questionnaire (to cross-reference findings of the prototype evaluations) among 54 Dutch physicians. Results The prototype...

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