Recursos de colección

University of Twente Publications (59.861 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 7.277

  1. Distortion compensator (10 June 2013)

    Sakamoto, Kazuma; Nauta, Bram
    PROBLEM TO BE SOLVED: To improve distortion compensation accuracy of a power amplifier. SOLUTION: An LMS algorithm using a feedback signal that is an output signal of a power amplifier 1 input via an attenuator 15 and pseudorandom data calculates a delay of an input signal to the power amplifier 1. A delay of an input signal to the power amplifier 1 is adjusted on the basis of the calculated delay to match timing of the input signal to the power amplifier 1 with a feedback signal including a fractional delay, and the delay-adjusted input signal where the timing is matched is used...

  2. Frequency synthesiser

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram
    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an input of the digital controlled oscillator, the feedback loop configured to provide the digital control word to the input of the digital controlled oscillator from an error derived from an input frequency control word (FCW) and the output signal; and a duty cycle module connected to the digital controlled oscillator and the feedback loop, the...

  3. Self-Explanations in Game-Based Learning: From Tacit to Transferable Knowledge

    Vrugte, Judith ter; Jong, Ton de
    Game-based learning is often considered to be an effective instructional approach, but the effects of game-based learning are varied and far from optimal. Aside from many features and characteristics that might affect the results of game-based learning, we conjecture that games generally thrive on experiential learning and that experiential learning does increase knowledge, but that this knowledge is often implicit. We note that though implicit knowledge is certainly valuable, that in general explicit knowledge is considered more desirable in education, because it is more accessible and promotes transfer. It is suggested that explicit knowledge does not always automatically follow from...

  4. The Role of Surprise in Game-Based Learning for Mathematics

    Wouters, Pieter; Oostendorp, Herre van; Vrugte, Judith ter; Vandercruysse, Sylke; Jong, Ton de; Elen, Jan
    In this paper we investigate the potential of surprise on learning with prevocational students in the domain of proportional reasoning. Surprise involves an emotional reaction, but it also serves a cognitive goal as it directs attention to explain why the surprising event occurred and to learn for the future. Experiment 1 - comparing a surprise condition with a control condition - found no differences, but the results suggested that surprise may be beneficial for higher level students. In Experiment 2 we combined Expectancy strength (Strong vs. Weak) with Surprise (Present vs. Absent) using higher level students. We found a marginal...

  5. Instruction Based on Computer Simulations and Virtual Laboratories

    Jong, Ton de

  6. Improvement of Inquiry in a Complex Technology-Enhanced Learning Environment

    Pedaste, Margus; Kori, Külli; Maeots, Mario; Jong, Ton de
    Inquiry learning is an effective approach in science education. Complex technology-enhanced learning environments are needed to apply inquiry worldwide to support knowledge gain and improvement of inquiry skills. In our study, we applied an ecology mission in the SCY-Lab learning environment and tested with 54 students (aged 14–18 years) how its rich technology and complexity could be applied in supporting students’ general inquiry knowledge, transformative inquiry skills, and domain-related knowledge. Reflection questions were applied in supporting inquiry. In this article, we show how different skills and knowledge improved and how these are related with each other.

  7. Distortion compensator (4 July 2013)

    Sakamoto, Kazuma; Nauta, Bram
    PROBLEM TO BE SOLVED: To improve the accuracy of distortion compensation of a power amplifier. SOLUTION: An LMS algorithm using a feedback signal that is an output signal of a power amplifier 1 input via an attenuator 17 and pseudorandom data calculates a delay of an input signal to the power amplifier 1 and a delay of the feedback signal. Specifically, the delays of the input signal and feedback signal are calculated such that the delay of the input signal is only an integer delay. An input signal to the power amplifier 1 is adjusted on the basis of the calculated delay, and...

  8. Distortion compensator (13 June 2013)

    Sakamoto, Kazuma; Nauta, Bram
    PROBLEM TO BE SOLVED: To improve distortion compensation accuracy of a power amplifier. SOLUTION: An LMS algorithm using a feedback signal that is an output signal of a power amplifier 1 input via an attenuator 17 and pseudorandom data calculates a delay of an input signal to the power amplifier 1 and a delay of the feedback signal. Specifically, the delays of the input signal and feedback signal are calculated such that the delay of the input signal is only an integer delay. An input signal to the power amplifier 1 is adjusted on the basis of the calculated delay, and a delay...

  9. Current source array

    Cathelin, Andreia; Nauta, Bram
    A Silicon On Insulator current source array includes input control for receiving a control voltage, a first reference input for receiving a first reference voltage, and a second reference input for receiving a second reference voltage. A chain of several Silicon On Insulator MOS transistors, of the same type, have control electrodes all connected to the input control, first conduction electrodes are all connected to the first reference input, and second conduction electrodes are respectively connected to the second reference input through several load circuits respectively configured to be traversed by several currents when the several transistors are ON upon...

  10. Amplification variable factor amplifier

    Akitsugu, Oshita; Nauta, Bram
    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and can vary an amplification factor of the input signal in response to an amplification factor control signal. An amplification factor monitor circuit 12 is comprised of a circuit which is equivalent with a predetermined circuit included in the Gilbert type amplification factor variable amplifier 11 and has a predetermined amplification factor, and outputs a voltage corresponding to that...

  11. Disadvantages of online support groups for people with arthritis, fibromyalgia and breast cancer disproved

    Kraan, C.F.; Taal, E.; Drossaert, C.H.C.; Lebrun, C.E.I.; Smit, W.M.; Seydel, E.R.; Laar, M.A.F.J. van de
    INTRODUCTION: People in stressful circumstances, such as serious health conditions, often turn to support groups. With the increase in the availability and popularity of internet, the possibility has arisen to join support groups online. Various authors have raised attention for potential disadvantages of these groups, such as the lack of control of the quality of the information, criticism on health care services, delay of responses to questions, expression of negative emotions, reinforcement of negative emotions and negative remarks to other participants. However, data are scarce. PURPOSE: To explore to what extent potential disadvantages actually occur in online support groups. In addition, we examined...

  12. Ion-step method for surface potential sensing of silicon nanowires

    Chen, Songyue; Nieuwkasteele, Jan W. van; Berg, Albert van den; Eijkel, Jan C.T.
    This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected. Thus, a change of conductance through the Si-NWs is measured. The surface potential on the Si-NW gate is changed from negative for a bare SiO2 surface to neutral/ positive when there is poly-L-lysine adsorption at certain pH, which also indicates a shift of point-of-zero charge pH after surface modification. This change is measured by...

  13. Electrochemical protein cleavage in a microfluidic cell with integrated boron doped diamond electrodes

    Brink, Floris T.G. van den; Zhang, Tao; Ma, Liwei; Bomer, Johan; Odijk, Mathieu; Olthuis, Wouter; Permentier, Hjalmar P.; Bischoff, Rainer; Berg, Albert van den
    Specific electrochemical cleavage of peptide bonds at the C-terminal side of tyrosine and tryptophan generates peptides amenable to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for protein identification. To this end we developed a microfluidic electrochemical cell of 160 nL volume that combines a cell geometry optimized for a high electrochemical conversion efficiency (>95%) with an integrated boron doped diamond (BDD) working electrode offering a wide potential window in aqueous solution and reduced adsorption of peptides and proteins. Efficient cleavage of the proteins bovine insulin and chicken egg white lysozyme was observed at 4 out of 4 and 7 out of...

  14. Wireless receiver with high linearity

    Lien, Yuan-Ching; Tenbroek, Bernard Mark; Klumperink, Eric; Nauta, Bram
    A wireless receiver with high linearity, having an out-band signal bypass filter, a mixer, and a baseband circuit. The out-band signal bypass filter has a first terminal and a second terminal respectively receiving a positive differential signal and a negative differential signal from a former-stage circuit, and the out-band signal bypass filter provides an out-band signal bypass path from the first terminal to the second terminal. The mixer receives a filtered signal from the out-band signal bypass filter. The baseband circuit is coupled to the mixer for generation of an in-phase signal and a quadrature phase signal.

  15. Ultrasensitive DNA detection based on two-step quantitative amplification on magnetic nanoparticles

    Jin, Mingliang; Liu, Xia; Berg, Albert van den; Zhou, Guofu; Shui, Lingling
    Sensitive detection of a specific deoxyribo nucleic acid (DNA) sequence is important for biomedical applications. In this report, a two-step amplification strategy is developed based on magnetic nanoparticles (MNPs) to achieve ultrasensitive DNA fluorescence detection. The first level amplification is obtained from multiple binding sites on MNPs to achieve thousands of probe DNA molecules on one nanoparticle surface. The second level amplification is gained by enzymatic reaction to achieve fluorescence signal enhancement. MNPs functionalized by probe DNA (DNAp) are bound to target DNA (t-DNA) molecules with a ratio of 1:1 on a substrate with capture DNA (DNAc). After the MNPs...

  16. Random telegraph signal phenomena in avalanche mode diodes: application to SPADs

    Agarwal, V.; Annema, A.J.; Dutta, S.; Hueting, R.J.E.; Nanver, L.K.; Nauta, B.
    The current-voltage (IV ) dependency of diodes close to the breakdown voltage is shown to be governed by Random Telegraph Signal (RTS) phenomena. We present a technology independent approach to accurately characterize the bias dependent statistical RTS properties and show that these can fully describe the steep IV -dependency in avalanche. The statistical properties also allow to more accurately describe e.g. the value of the self sustaining avalanche current that is crucial in designing optical detection systems using avalanche photo diodes or single photon avalanche diodes (SPADs). More accurate modelling is shown to allow improving on e.g. count rates, dead...

  17. Structure and dynamics of confined alcohol-water mixtures

    Bampoulis, P.; Witteveen, J.P.; Kooij, E.S.; Lohse, D.; Poelsema, B.; Zandvliet, H.J.W.
    The effect of confinement between mica and graphene on the structure and dynamics of alcohol–water mixtures has been studied in situ and in real time at the molecular level by atomic force microscopy (AFM) at room temperature. AFM images reveal that the adsorbed molecules are segregated into faceted alcohol-rich islands on top of an ice layer on mica, surrounded by a pre-existing multilayer water-rich film. These faceted islands are in direct contact with the graphene surface, revealing a preferred adsorption site. Moreover, alcohol adsorption at low relative humidity (RH) reveals a strong preference of the alcohol molecules for the ordered...

  18. Self-similar decay of high Reynolds number Taylor-Couette turbulence

    Verschoof, R.A.; Huisman, S.G.; Veen, R.C.A. van der; Sun, C.; Lohse, D.
    We study the decay of high-Reynolds-number Taylor-Couette turbulence, i.e., the turbulent flow between two coaxial rotating cylinders. To do so, the rotation of the inner cylinder (Re i =2×10 6 , the outer cylinder is at rest) is stopped within 12 s, thus fully removing the energy input to the system. Using a combination of laser Doppler anemometry and particle image velocimetry measurements, six decay decades of the kinetic energy could be captured. First, in the absence of cylinder rotation, the flow-velocity during the decay does not develop any height dependence in contrast to the well-known Taylor vortex state. Second,...

  19. Flanders: Regional Organization of Water and Drought and Using Data as Driver for Change

    Trölzsch, Jenny; Vidaurre, Rodrigo; Bressers, Hans; Browne, Alison; La Jeunesse, Isabelle; Lordkipanidze, Maia; Defloor, Willem; Maetens, Willem; Cauwenberghs, Kris
    This chapter presents a summary of the analysis results of the governance of drought-related issues in the Flanders region of Belgium. In the context of the Interreg IV-B project DROP, a team of researchers from four universities and knowledge institutes visited Flanders twice to perform interviews with authorities and stakeholders (October 2013 and May 2014). The visit was supported by colleagues at the Flemish Environment Agency (Vlaamse Milieumaatschappij, VMM). The exchange was held in the form of individual and group interviews and workshops with stakeholders including representatives from different institutions and sectors, e.g. from the drinking water company, national and...

  20. Towards a Drought Policy in North-West European Regions?

    Larrue, Corinne; Bressers, Nanny; Bressers, Hans
    This chapter proposes a comparative approach of the drought governance context in the six regions studied. In sum, the governance context for drought resilience policies and measures in most of the regions studied can be regarded to currently be “intermediate”. The implementation of the governance assessment tool does not allow a clear picture of the drought and water scarcity governance context in those NW regions. The governance appears to be half capable of providing a favourable context in terms of the actors and decision levels involved in all of the regions, but does not provide a favourable context to develop...

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