Current established risk assessment methodologies and tools - Ionita, Dan; Hartel, Pieter; Pieters, Wolter; Wieringa, Roel
The technology behind information systems evolves at an exponential rate, while at the same time becoming more and more ubiquitous. This brings with it an implicit rise in the average complexity of systems as well as the number of external interactions. In order to allow a proper assessment of the security of such (sub)systems, a whole arsenal of methodologies, methods and tools have been developed in recent years. However, most security auditors commonly use a very small subset of this collection, that best suits their needs. This thesis aims at uncovering the differences and limitations of the most common Risk...
Design of active N-path filters - Darvishi, Milad; Zee, Ronan van der; Nauta, Bram
Abstract—A design methodology for synthesis of active N-path bandpass filters is introduced. Based on this methodology, a 0.1-to-1.2 GHz tunable 6th-order N-path channel-select filter in 65 nm LP CMOS is introduced. It is based on coupling N-path filters with gyrators, achieving a “flat” passband shape and high out-of-band linearity. A Miller compensation method is utilized to considerably improve the passband shape of the filter. The filter has 2.8 dB NF, +25 dB gain, +26 dBm wideband IIP₃ ( MHz), an out-of-band 1 dB blocker compression point B of +7 dBm (Δf = +50 MHz) and 59 dB stopband rejection. The...
Transient nanobubbles in short-time electrolysis - Svetovoy, Vitaly B.; Sanders, Remco G.P.; Elwenspoek, Miko
Water electrolysis in a microsystem is observed and analyzed on a short-time scale of ∼10 μs. The very unusual properties of the process are stressed. An extremely high current density is observed because the process is not limited by the diffusion of electroactive species. The high current is accompanied by a high relative supersaturation, S > 1000, that results in homogeneous nucleation of bubbles. On the short-time scale only nanobubbles can be formed. These nanobubbles densely cover the electrodes and aggregate at a later time to microbubbles. The effect is significantly intensified with a small increase of temperature. Application of...
A multi-band, high bandwidth, short duration linear chirp generation IC for phased-array applications - Velner, J.; Klumperink, E.A.M.; Nauta, B.; Vliet, F.E. van
This work presents a fully integrated multi-band frequency synthesizer that is capable of creating wide-band linear frequency sweeps of very short duration. The main aim is to create a flexible waveform generation system, requiring distribution of a low frequency reference rather than RF signals. By using a phase-locked loop, frequency multiplication (rather than shifting) occurs. This allows for a narrow band and low frequency reference signal, allowing digital reference generation and thus providing a large degree of flexibility. Chirps with a bandwidth of 1 GHz (in X-band) and duration as short as 10 μs can be created. The chip can...
Chronopotentiometric chloride sensing using transition time measurement - Abbas, Y.; de Graaf, D.B.; Olthuis, W.; van den Berg, A.
Detection of chloride ions is crucial to accurately access the concrete structure durability. The existing electrochemical method of chloride ions detection in concrete, potentiometry, is not suitable for in-situ measurement due to the long term stability issue of conventional reference electrode (RE) inside concrete.
Method for manufacturing a single crystal nanowire - Berg, Albert van den; Bomer, Johan; Carlen, Edwin Thomas; Chen, Songyue; Kraaijenhagen, Roderik Adriaan; Pinedo, Herbert Michael
A method for manufacturing a single crystal nano-structure is provided comprising the steps of providing a device layer with a 100 structure on a substrate; providing a stress layer onto the device layer; patterning the stress layer along the 110 direction of the device layer; selectively removing parts of the stress layer to obtain exposed parts of the device layer; plane dependent etching of the exposed parts of the device layer to obtain an exposed 111 faces of the device layer; thermally oxidizing the exposed 111 face of the device layer and forming a lateral oxidation layer at an interface...
Point of care creatinine measurement for diagnosis of renal disease using a disposable microchip - Ávila Muñoz, Mónica; Floris, Arjan; Staal, Steven; Ríos, Ángel; Eijkel, Jan; Berg, Albert van den
A point-of-care device for the determination of elevated creatinine levels in blood is reported. This device potentially offers a new and simple clinical regime for the determination of creatinine that will give huge time savings and removal of several steps of determination. The test employs a disposable prefilled microchip and the handheld Medimate Multireader®. By optimizing the analytical conditions it was found that the LOD of the proposed method was 87 μM creatinine, close to the normal human serum levels that are in the range of 60 to 100 μM. A statistical analysis of the residual shows a normal distribution,...
Lactate biosensors: current status and outlook - Rassaei, Liza; Olthuis, Wouter; Tsujimura, Seiya; Sudhölter, Ernst J.R.; Berg, Albert van den
Many research efforts over the last few decades have been devoted to sensing lactate as an important analytical target in clinical care, sport medicine, and food processing. Therefore, research in designing lactate sensors is no longer in its infancy and now is more directed toward viable sensors for direct applications. In this review, we provide an overview of the most immediate and relevant developments toward this end, and we discuss and assess common transduction approaches. Further, we critically describe the pros and cons of current commercial lactate sensors and envision how future sensing design may benefit from emerging new technologies.
Sample preconcentration inside sessile droplets using electrowetting - Mampallil, Dileep; Tiwari, D.; Ende, H.T.M. van den; Mugele, F.G.
Electrowetting with alternate voltage (AC) creates azimuthal flow vortices inside sessile droplets. These flow vortices can be controlled by introducing pinning sites at the contact line. When the frequency of the applied AC voltage is gradually ramped from a few hundreds of hertz to a few tens of kilohertz the azimuthal flow vortices contract and move towards the contact line near the pinning site. Dispersed particles in the liquid are collected in the center of these vortices leading to an increase in the local particle concentration by up to more than one order of magnitude. We provide a qualitative explanation...
Stability and interactions in mixed monolayers of fatty acid derivatives on artificial sea water - Brzozowska, A.M.; Mugele, F.; Duits, M.H.G.
We studied the formation and stability of fatty acid and derivatives films on aqueous sub-phases by means of Langmuir trough experiments. Films were prepared from pure stearic acid (SA), stearyl amine (SAm) and 12-phenyldodecanoic acid (PDA), and from binary systems of SA with either SAm or PDA. For the aqueous sub-phase, multicomponent salt solutions (‘Artificial Sea Water’) at various concentrations (cASW, 0–100%) and pH values (3–7) were explored. SAm and SA differ most strongly at pH 7, where they can dissociate into oppositely charged species. For SA:SAm mixtures at this pH, pressure-area isotherms indicate mixing on a molecular scale. Increase...
Building upon what is already there: The role of prior knowledge, background information, and scaffolding in inquiry learning - Wecker, C.; Lazonder, A.W.; Chiu, J.L.; Madeira, C.; Slotta, J.D.; Mulder, Y.G.; Jong, T. de; Rachel, A.; Wiesner, H.; Heran-Dorr, E.; Fischer, F.; Reimann, P.
Prior knowledge is one of the most important factors for learning. During the iterative cycles of inquiry learning, learners' prior domain knowledge is modified, refined, and further developed, provided that learners act upon self-assessments of their understanding and that they can actually think of appropriate hypotheses. Furthermore, knowledge about inquiry strategies influences the quality of the learners' inquiry activities, and the lack there of requires compensatory support. This symposium brings together recent work about the role of prior knowledge for inquiry learning and ways to compensate for the lack of it. The four papers focus on the role of learners'...
Sieving of Hot Gases by Hyper-Cross-Linked Nanoscale-Hybrid Membranes - Raaijmakers, M.J.T.; Hempenius, M.A.; Schön, P.M.; Vancso, G.J.; Nijmeijer, A.; Wessling, M.; Benes, N.E.
Macromolecular networks consisting of homogeneously distributed covalently bonded inorganic and organic precursors are anticipated to show remarkable characteristics, distinct from those of the individual constituents. A novel hypercross-linked ultrathin membrane is presented, consisting of a giant molecular network of alternating polyhedral oligomeric silsesquioxanes and aromatic imide bridges. The hybrid characteristics of the membrane are manifested in excellent gas separation performance at elevated temperatures, providing a new and key enabling technology for many important industrial scale applications.
Buoyancy driven convection in vertically shaken granular matter: experiment, numerics, and theory - Eshuis, P.G.; Weele, J.P. van der; Alam, M.; Gerner, H.J. van; Hoef, M.A. van der; Kuipers, J.A.M.; Luding, S.; Meer, D. van der; Lohse, D.
Buoyancy driven granular convection is studied
for a shallow, vertically shaken granular bed in a quasi
2D container. Starting from the granular Leidenfrost state,
in which a dense particle cluster floats on top of a dilute
gaseous layer of fast particles (Meerson et al. in Phys RevLett
91:024301, 2003; Eshuis et al. in Phys Rev Lett 95:258001,
2005), we witness the emergence of counter-rotating convection
rolls when the shaking strength is increased above a critical
level. This resembles the classical onset of convection—at
a critical value of the Rayleigh number—in a fluid heated
from below. The same transition, even quantitatively, is
seen in molecular dynamics simulations, and explained by
a hydrodynamic-like model...
Frequency limitations of first-order gm-RC all-pass delay circuits - Garakoui, Seyed Kasra; Klumperink, Eric A.M.; Nauta, Bram; Vliet, Frank E. van
All-pass filter circuits can implement a time delay but, in practice, show delay and gain variations versus frequency, limiting their useful frequency range. This brief derives analytical equations to estimate this frequency range, given a certain maximum allowable budget for variation in delay and gain. We analyze and compare two well-known gm - RC first-order all-pass circuits, which can be compactly realized in CMOS technology and relate their delay variation to the main pole frequency. Modeling parasitic poles and putting a constraint on gain variation, equations for the maximum achievable pole frequency and delay variation versus frequency are derived. These...
Towards minimum achievable phase noise of relaxation oscillators - Geraedts, Paul F.J.; Tuijl, Ed (A.J.M.) van; Klumperink, Eric A.M.; Wienk, Gerard J.M.; Nauta, Bram
A relaxation oscillator design is described, which has a phase noise rivaling ring oscillators, while also featuring linear frequency tuning. We show that the comparator in a relaxation-oscillator loop can be prevented from contributing to 1/f2 colored phase noise and degrading control linearity. The resulting oscillator is implemented in a power efficient way with a switched-capacitor circuit. The design results from a thorough analysis of the fundamental phase noise contributions. Simple expressions modeling the theoretical phase noise performance limit are presented, as well as a design strategy to approach this limit. To verify theoretical predictions, a relaxation oscillator is implemented...
Multi-Band linear chirp generation based on a type-III PLL - Velner, J.; Klumperink, E.A.M.; Nauta, B.; Vliet, F.E. van
A type-III PLL is used to generate linear frequency ramps with 386 kHz RMS frequency error in L-band (3088 kHz in X-band) and 10% fractional bandwidth. Pulse durations can be as low as 10 μs without performance degradation. The system covers the L-, S-, C- and X-bands. A programmable output driver delivering −17.9 to +4.9 dBm differentially is included on chip. The system is fully integrated using a 250 nm SiGe BiCMOS process.