5,010 research outputs found
Comparative feasibility study of a 30 MW disruptive floater solution with a 15 MW PivotBuoy and a benchmark 15 MW semi-submersible floater in the Bay of Biscay
No full textThis paper investigates the technical, life cycle, and economic feasibility of a 30 MW upscaled downwind turbine, comparing it to a 15 MW X1 Wind PivotBuoy downwind turbine and a benchmark 15 MW IEA Umaine VolturnUS-S upwind turbine in the 450 MW Sud de la Bretagne I wind farm site. The study is significant due to the rising energy demand, the potential for decreasing the levelized cost of energy with increased turbine size, and the optimized use of space. The size limit of current upwind turbine designs could be addressed using a downwind turbine solution.The research is conducted by modelling the global dynamic response of the structure using OpenFAST and computing the natural frequencies and stresses using a finite element model. A lifecycle analysis is performed to identify potential pitfalls and bottlenecks by analysing the individual lifecycle phases. The economic feasibility is assessed by simulating the annual energy production using TOPFARM and utilizing structural analysis and lifecycle assessment to quantify capital, operational, and abandonment expenditures. Based on the annual energy production and the performance indicators the levelized cost of energy is calculated.The findings indicate that while the global stability is within boundaries, the stress in members is too high with a simple scale-up of the proposed design. Bottlenecks are found in lifting operations and supply chain readiness. The levelized cost of energy and capital expenditure increased due to substructure self-weight, rendering the proposed 30 MW scale-up currently unfeasible when compared to the other two wind farms.These findings are important as they demonstrate that the 15 MW X1 Wind PivotBuoy is not scalable without design changes. The levelized cost of energy does not decrease with an increased floater solution. The 15 MW X1 Wind PivotBuoy downwind turbine seems more economically viable, making it a more interesting option for future development.Civil Engineerin
Dual-band Butler matrix for WLAN systems
No full textThis paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe
Dual-band Butler matrix for WLAN systems
No full textThis paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe
Dual-band Butler matrix for WLAN systems
Get PDFThis paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe
Short-circuit characteristics of superconducting permanent magnet generators for 10 MW wind turbines
No full textSuperconducting permanent magnet generators (SCPMGs) are a potential candidate for 10 MW direct-drive wind turbine applications. This paper presents two 10 MW SCPMG designs using MgB<sub>2</sub> cables for the armature winding and investigates the short-circuit characteristics of the designed SCPMGs. The first part of the results shows that the SCPMGs can double the shear stress of a conventional low-speed permanent magnet (PM) generator (from 65 kPa to 130 kPa) whilst avoiding demagnetization of the PMs in rated-load operation. However, the power factor has to drop to a range of 0.7-0.8. The second part of the results shows that during a sudden three-phase short circuit, the superconducting armature winding is prone to quench and the PMs are likely to be demagnetized in both proposed designs.Accepted Author ManuscriptTransport Engineering and Logistic
The E-Butler Service, or Has the Age of Electronic Personal Decision Making Assistants Arrived?
Get PDFThis paper describes an Electronic Butler (or e-Butler) that provides a customer-centric personalized
shopping services to its subscribers across a wide range of products. This service is provided by
identifying individual customer's shopping needs from the comprehensive purchasing history of that
person and providing purchasing recommendations or direct purchasing decisions for the customer. e-
Butler service consists of two components -- the Personal Shopping Assistant (PSA) service that provides
purchasing recommendations to the customer and the Magic Wand (MW) service that directly makes
purchases it believes the customer needs without any prior consultations with the customer. In order to
understand how PSA and MW services of e-Butler are related to the existing one-to-one marketing and
recommender systems, a general framework classifying various personalized shopping services is
presented that clearly delineates PSA and MW services from these existing systems. Moreover, the paper
presents an architecture of the e-Butler service, explains what its business value is, discusses its
feasibility, and describes what needs to be done to make it a successful service.Information Systems Working Papers Serie
An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants
No full textAluminum Nitride (AlN) Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) are gaining interest for biomedical implant power due to biocompatibility and lowtemperature processing. However, due to the low piezoelectric coefficient of AlN PMUTs, storage capacitors are often used to accumulate ultrasonic power transferred over an extended time. The accumulated energy is then used to power a DC load, which leads to a long start-up time, and insufficient duty cycle for some applications. We present an ultrasonically powered system for biomedical implants capable of delivering mW-range instantaneous power to DC loads, without pre-storing it. The system features a 25 mm2 AlN PMUT, an inductive matching network, and an application-specific power management integrated circuit(ASIC). For an acoustic intensity of 360 mW/cm2 at the surface of the PMUT, an open-circuit voltage of 1.11 V and an aperture efficiency of 30.5 % are measured. Furthermore, by connecting a series-matching inductor to the PMUT, the highest-reported power delivered to the load (PDL) of 6.4 mW is measured over an optimal load of 7.6 Ω. Finally, together with the ASIC and at the intensity of 108 mW/cm2, our system delivers 1.04 mW DC power to a 3.3 kΩ load, which is over two orders of magnitude higher than the previously reported average DC power for AlN PMUTs.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Bio-ElectronicsElectronic Components, Technology and Material
Compact high-power tunable three-level operation of double cladding Nd-doped fiber laser
Get PDFWe present a compact high-power continuous-wave tunable neodymium-doped double cladding fiber laser operating on three-level 4F3/2 - 4I9/2 transition with a maximum output power up to 810 mW. At 926.7 nm, it has a maximum slope efficiency of 49.3% against absorbed 808-nm pump. By compressing the fiber Bragg grating, 15-nm tuning range is achieved
Tyrosine phosphorylation of myosin heavy chain during skeletal muscle differentiation: an integrated bioinformatics approach
No full textBackground: Previously it has been shown that insulin-mediated tyrosine phosphorylation of myosin heavy chain is concomitant with enhanced association of C-terminal SRC kinase during skeletal muscle differentiation. We sought to identify putative site(s) for this phosphorylation event.Results: A combined bioinformatics approach of motif prediction and evolutionary and structural analyses identified tyrosines163 and 1856 of the skeletal muscle heavy chain as the leading candidate for the sites of insulin-mediated tyrosine phosphorylation.Conclusion: Our work is suggestive that tyrosine phosphorylation of myosin heavy chain, whether in skeletal muscle or in platelets, is a significant event that may initiate cytoskeletal reorganization of muscle cells and platelets. Our studies provide a good starting point for further functional analysis of MHC phosphor-signalling events within different cells.<br/
Inversion of coseismic deformation due to the 8th February 2016, Mw 4.2 earthquake at Los Humeros (Mexico) inferred from DInSAR
No full textOn the 8th of February 2016, a Mw 4.2 earthquake was detected inside the Los Humeros caldera, located in the eastern sector of the Trans-Mexican Volcanic Belt. The event occurred after a sharp increase in the injection rate at the Los Humeros Geothermal Field and it was recorded by the seismic monitoring network of the power plant. The earthquake was felt by the local population and it caused damage in the power plant infrastructure. The focal mechanism solution of a previous study based on seismological data shows a reverse movement with a minor left-lateral component: Mw=4.2, depth=1500m, strike=169°, dip=61°, rake=42°. We have performed a geodetic and geomechanical analysis of the seismic source event based on ground deformation inferred from DInSAR. We used ascending and descending Sentinel-1 differential interferograms to retrieve the horizontal and vertical components of the co-seismic deformation. Subsequently, we inverted the estimated deformation to obtain the solution of an activated fault using the Okada model. These results shed light on the geomechanical aspects of the event and can help to understand the effects of field operations interacting with pre-existing structural features and active tectonic processes in the Los Humeros caldera.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mathematical Geodesy and Positionin
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