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Owen, C.C. (author)The imminence of anthropogenic climate change has motivated a global energy transition towards sustainable power generation. Offshore wind—an important contributor to the energy transition—is expanding, not only in turbine size and number of installations, but also into regions with harsher environmental conditions. One of those conditions in...doctoral thesis 2024
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Hammer, T.C. (author), Hendrikse, H. (author)Drifting sea ice failing in crushing against vertically-sided offshore structures can cause ice-induced vibrations. Offshore structures are typically founded on slender structures to minimize the load effect of waves and currents. In combination with large top masses, those offshore structures often provide sufficient compliance for ice-induced...conference paper 2023
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Hammer, T.C. (author), Willems, Tom (author), Hendrikse, H. (author)For offshore wind farms which are planned in sub-arctic regions like the Baltic Sea and Bohai Bay, support structure design has to account for load effects from dynamic ice-structure interaction. There is relatively high uncertainty related to dynamic ice loads as little to no load- and response data of offshore wind turbines exposed to...journal article 2023
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Pan, S. (author), An, Xiaomeng (author), Yu, Zheru (author), Jiang, H. (author), Makinwa, K.A.A. (author)This article presents the design and implementation of a compact CMOS RC frequency reference. It consists of a frequency-locked loop (FLL) that locks the period of a voltage-controlled oscillator (VCO) to the time an RC network takes to charge to a reference voltage. Conventionally, an RC time constant with a near-zero temperature coefficient...journal article 2023
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Hendrikse, H. (author), Hammer, T.C. (author), van den Berg, M.A. (author), Willems, Tom (author), Owen, C.C. (author), van Beek, C. (author), Ebben, Nick J.J. (author), Puolakka, Otto (author), Polojärvi, Arttu (author)Basin tests were performed at the Aalto Ice Tank to gather data on ice-structure action and interaction from ice failing against a vertically sided cylindrical pile. The tests were performed with a real-time hybrid test setup, which combined physical and numerical components to simulate a range of test structures in real-time. The dataset...journal article 2022
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Gürleyük, C. (author), Pan, S. (author), Makinwa, K.A.A. (author)This article presents a 16-MHz RC frequency reference implemented in a standard 180-nm CMOS process. It consists of a frequency-locked loop (FLL) in which the output frequency of a digitally controlled oscillator (DCO) is locked to the frequency-phase characteristic of a Wien bridge RC filter. Since it is made from on-chip resistors and...journal article 2022
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van den Berg, M.A. (author), Owen, C.C. (author), Hendrikse, H. (author)This study analyses the results from basin tests with a vertically sided cylindrical pile loaded by ice failing in crushing. Tests were performed with a ‘rigid’ structure and with structural models representing a series of single-degree-of-freedom (SDOF) oscillators covering a wide range of mass, frequency, and damping values. The structural...journal article 2022
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Hendrikse, H. (author), Hammer, T.C. (author), Owen, C.C. (author), van den Berg, M.A. (author), van Beek, C. (author), Polojärvi, Arttu (author), Puolakka, Otto (author), Willems, Tom (author)With the recent surge in development of offshore wind in the Baltic Sea, Bohai Sea and other ice-prone regions, a need has arisen for new basin tests to qualify the interaction between offshore wind turbines and sea ice. To this end, a series of model tests was performed at the Aalto ice basin as part of the SHIVER project. The tests were aimed...conference paper 2022
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Choi, Woojun (author), Angevare, J. (author), Park, Injun (author), Makinwa, K.A.A. (author), Chae, Youngcheol (author)This article presents an energy-efficient dual- RC frequency reference intended for wireless sensor nodes. It consists of a digital frequency-locked loop (FLL) in which the frequency of a digitally controlled oscillator (DCO) is locked to a temperature-independent phase shift derived from two different RC poly-phase filters (PPFs). Phase...journal article 2022
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Koreman, Dion (author)With the Paris climate accords signed in 2016, most countries have committed themselves to ambitious climate targets during the next decades. One of these targets is a dramatic increase in the overall energy portfolio's market share of renewable energies. This increase in renewable market share will, for a large part, consist of newly built...master thesis 2020
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Ding, Ming (author), Zhou, Zhihao (author), Traferro, Stefano (author), Liu, Yao Hong (author), Bachmann, Christian (author), Sebastiano, F. (author)This paper presents a wakeup timer in 40-nm CMOS for Internet-of-Things (IoT) applications based on a bang-bang Digital-intensive Frequency-Locked Loop (DFLL). A self-biased Σ Δ Digitally Controlled Oscillator (DCO) is locked to an RC time constant via a feedback loop consisting of a single-bit chopped comparator and a digital loop filter,...journal article 2020
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Preda, Valeria (author)Smart temperature sensors can be used for the temperature compensation of micro-electromechanical (MEMS) frequency references. From the different types of CMOS temperature sensors, resistor-based sensors are currently the most energy-efficient. However, compared with bipolar transistor (BJT)-based temperature sensors, resistors suffer from...master thesis 2019
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Hendrikse, H. (author), Koot, Jasper (author)Ice-induced vibrations have to be considered in the design of vertically sided offshore structures which may encounter drifting sea or lake ice during their lifetime. One particular aspect is the contribution of ice-induced vibrations to the fatigue of such structures. Estimation of the duration of events is often difficult, due to limited...conference paper 2019
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Lee, Yongtae (author), Choi, Woojun (author), Kim, Taewoong (author), Song, Seungwoo (author), Makinwa, K.A.A. (author), Chae, Youngcheol (author)This letter describes a compact resistor-based temperature sensor intended for the thermal monitoring of microprocessors and DRAMs. It consists of an RC poly phase filter (PPF) that is read out by a frequency-locked loop (FLL) based on a dual zero-crossing (ZC) detection scheme. The sensor,fabricated in 65-nm CMOS,occupies 5800 μm<sup>2</sup>...conference paper 2019
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Willems, Tom (author), Hendrikse, H. (author)Offshore wind turbines at locations where sea or lake ice is present need to be designed to withstand ice-induced loading. For vertical-sided support structures, such as monopiles, the effects of ice-induced vibrations need to be considered in the design. Current practice is either to use approaches provided in design standards, or for example...conference paper 2019
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Hendrikse, H. (author)The second edition of the ISO19906 design standard contains changes in the informative appendix concerning dynamic ice actions. Challenges in application of the previous approach and advances in understanding of the dynamic ice-structure interaction process were the main motivation for the revision. The new guideline provides relevant...conference paper 2019
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Abramian, A. (author), Vakulenko, Sergei A. (author), van Horssen, W.T. (author)In this paper, a new simple oscillator model is considered describing ice-induced vibrations of upstanding, water-surrounded, and bottom-founded offshore structures. Existing models are extended by taking into account deformations of an ice floe and a moving contact interaction between an ice rod, which is cut out from the floe, and the...journal article 2019
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Lee, Yongtae (author), Choi, Woojun (author), Kim, Taewoong (author), Song, Seungwoo (author), Makinwa, K.A.A. (author), Chae, Youngcheol (author)This letter describes a compact resistor-based temperature sensor intended for the thermal monitoring of microprocessors and DRAMs. It consists of an RC poly phase filter (PPF) that is read out by a frequency-locked loop (FLL) based on a dual zero-crossing (ZC) detection scheme. The sensor, fabricated in 65-nm CMOS, occupies 5800 μ m2 and...journal article 2019
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Hendrikse, H. (author), Nord, Torodd S. (author)Interaction of sea or lake ice with vertically sided offshore structures may result in severe structural vibrations commonly referred to as ice-induced vibrations. With the surge in offshore wind developments in sub-arctic regions this problem has received increased attention over the last decade, whereas traditionally the topic has been mainly...journal article 2019
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Nord, Torodd S. (author), Samardžija, Ilija (author), Hendrikse, H. (author), Bjerkås, Morten (author), Høyland, Knut V. (author), Li, Hongtao (author)The signature and occurrence of frequency lock-in (FLI) vibrations of full-scale offshore structures are not well understood. Although several structures have experienced FLI, limited amounts of time histories of the responses alongside measured met-ocean data are available in the literature. This paper presents an analysis of 61 measured...journal article 2018
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