4,083 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
Effect of hyaluronic acid molecular weight on the morphology of quantum dot-hyaluronic acid conjugates
No full textThe morphological analysis of novel quantum dot-hyaluronic acid (QDot-HA) conjugates was carried outwith a transmission electron microscope (TEM). Adipic acid dihydrazide-modified HA (HA-ADH) was synthesized and conjugated to quantum dots (QDots) having carboxyl terminal ligands which were activated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS). HA molecules with a molecular weight (MW) of 20 K, 234 K and 3000 K were used to investigate the effect of MW on the morphology of QDot-HA conjugates. The TEM micrographs of QDot-HA conjugates showed branched and multi-layered chain type morphology formed by inter- and intra-molecular conjugation of QDots to HA molecules. The size of QDot-HA conjugate increased with the MW of HA. QDot-HA conjugate could be successfully used for real-time bio-imaging of HA derivatives in nude mice. The novel QDot-HA conjugate will be further used to investigate the biological roles of HA with a different MW in the body. (c) 2007 Published by Elsevier B.V.X1126sciescopu
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
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
Observation of a stationary double transport barrier in KSTAR
No full textWe have observed a stationary high confinement regime with a double transport barrier (DTB), including both internal and edge transport barriers (ITB and ETB) but without edge-localized modes (ELMs), in KSTAR. The ELM-free DTB phase has high thermal confinement comparable to typical H-mode operation in KSTAR. We investigated the characteristics of the DTB phase through various analyses. Transport analysis shows a reduction of ion heat diffusivity to near neoclassical level after the transition from the ELMy H-mode phase to the DTB phase. This result supports the formation of an ion ITB during the DTB phase. Furthermore, we observed that the DTB phase had an edge thermal transport barrier in the ion temperature profile, comparable to that of the H-mode, without a particle transport barrier at the edge. Peeling-ballooning stability analysis indicates that a lower pressure gradient due to density decrease in the DTB phase is mainly responsible for the ELM-free operation. Linear gyrokinetic analysis shows that the real frequency of the most unstable mode in the core region ( = 0.32–0.47) is in the ion diamagnetic direction at both H-mode and DTB phases. At the DTB phase, the linear growth rate inside the ITB is reduced by 50% compared to the ITB foot, while the reduction is not shown at the H-mode phase. Further investigation including nonlinear effects will be needed to better understand the unique operation mode, which can contribute to applying the physical mechanism to fusion reactors in the future
Target Specific Tumor Treatment by VEGF siRNA Complexed with Reducible Polyethyleneimine-Hyaluronic Acid Conjugate
No full textTarget specific delivery of small interfering RNA (siRNA) has been regarded as one of the most important technologies for the development of siRNA therapeutics. In this work, non-toxic low molecular weight (MW) polyethyleneimine (PEI, 2000 Da) was cross-linked with cystamine bisacrylamide (CBA) to prepare reducible PEI-SS in the body. Then, PEI-SS was conjugated with hyaluronic acid (HA) in the form of block-copolymer to enhance serum stability and facilitate target specific cellular uptake of siRNA by HA receptor mediated endocytosis. The cytotoxicity of (PEI-SS)-b-HA conjugate appeared to be negligible likely due to the degradation of PEI-SS to low MW PEI in the cytosol. Flow cytometric and confocal microscopic analyses confirmed the HA receptor mediated endocytosis of siRNA/(PEI-SS)-b-HA complex. The siRNA/(PEI-SS)-b-HA complex demonstrated an excellent in vitro gene silencing efficiency in the range of 50-80% reducing the mRNA expression level in the absence and presence of 50 vol% serum. Moreover, intra-tumoral injection of vascular endothelial growth factor (VEGF) siRNA/(PEI-SS)-b-HA complex resulted in dramatically inhibited tumor growth with reduced VEGF mRNA and VEGF levels in the tumors. (C) 2010 Elsevier Ltd. All rights reserved.X119699sciescopu
Data from echolocation convergence study
No full textThe data in this folder accompany the publication:
Thomas GWC and Hahn MW. 2015 Determining the null model for detecting adaptive convergence from genomic data: a case study using echolocating mammals. Molecular Biology and Evolution.
The files in this repository are:
1.alignments:The 6,400 amino acid alignments (in fasta format) of the 9 mammals used in this study along with the ancestral states as inferred by PAML.
2.species_tree.nwkThe newick formatted species tree inferred from the original alignments with RAxML and average consensus. Internal nodes have been labeled to correspond with the labels of the ancestral state sequences from the alignments
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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