| 1. |
- Schaap, M., et al.
(författare)
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Standardized evaluation methodology and reference database for evaluating coronary artery centerline extraction algorithms
- 2009
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Ingår i: Medical Image Analysis. - : Elsevier. - 1361-8415 .- 1361-8423. ; 13:5, s. 701-714
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Tidskriftsartikel (refereegranskat)abstract
- Efficiently obtaining a reliable coronary artery centerline from computed tomography angiography data is relevant in clinical practice. Whereas numerous methods have been presented for this purpose, up to now no standardized evaluation methodology has been published to reliably evaluate and compare the performance of the existing or newly developed coronary artery centerline extraction algorithms. This paper describes a standardized evaluation methodology and reference database for the quantitative evaluation of coronary artery centerline extraction algorithms. The contribution of this work is fourfold: (1) a method is described to create a consensus centerline with multiple observers, (2) well-defined measures are presented for the evaluation of coronary artery centerline extraction algorithms, (3) a database containing 32 cardiac CTA datasets with corresponding reference standard is described and made available, and (4) 13 coronary artery centerline extraction algorithms, implemented by different research groups, are quantitatively evaluated and compared. The presented evaluation framework is made available to the medical imaging community for benchmarking existing or newly developed coronary centerline extraction algorithms.
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| 2. |
- Reischer, G. H., et al.
(författare)
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Performance Characteristics of qPCR Assays Targeting Human- and Ruminant-Associated Bacteroidetes for Microbial Source Tracking across Sixteen Countries on Six Continents
- 2013
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:15, s. 8548-8556
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Tidskriftsartikel (refereegranskat)abstract
- Numerous quantitative PCR assays for microbial fecal source tracking (MST) have been developed and evaluated in recent years. Widespread application has been hindered by a lack of knowledge regarding the geographical stability and hence applicability of such methods beyond the regional level. This study assessed the performance of five previously reported quantitative PCR assays targeting human-, cattle-, or ruminant-associated Bacteroidetes populations on 280 human and animal fecal samples from 16 countries across six continents. The tested cattle-associated markers were shown to be ruminant-associated. The quantitative distributions of marker concentrations in target and nontarget samples proved to be essential for the assessment of assay performance and were used to establish a new metric for quantitative source-specificity. In general, this study demonstrates that stable target populations required for marker-based MST occur around the globe. Ruminant-associated marker concentrations were strongly correlated with total intestinal Bacteroidetes populations and with each other, indicating that the detected ruminant-associated populations seem to be part of the intestinal core microbiome of ruminants worldwide. Consequently tested ruminant-targeted assays appear to be suitable quantitative MST tools beyond the regional level while the targeted human-associated populations seem to be less prevalent and stable, suggesting potential for improvements in human-targeted methods.
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| 3. |
- Abdelhameed, A. H., et al.
(författare)
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Cryogenic characterization of a LiAlO2 crystal and new results on spin-dependent dark matter interactions with ordinary matter: CRESST Collaboration
- 2020
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:9
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a first cryogenic characterization of a scintillating LiAlO2 single crystal is presented. The results achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut fur Kristallzuchtung (IKZ) have been tested to study different properties at cryogenic temperatures. Firstly, two 2.8 g twin crystals were used to build different detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of LiAlO2 at cryogenic temperatures. The second achieved an energy threshold of (213.02 +/- 1.48) eV which allows setting a competitive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses between 350 MeV/c2 and 1.50 GeV/c2. Secondly, a detector module with a 373 g LiAlO2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazionali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux monitor for low-background experiments.
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| 4. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Binder, Christian, et al.
(författare)
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Experimental Study on Pressure Losses in Circular Orifices for the Application in Internal Cooling Systems
- 2015
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Ingår i: Journal of turbomachinery. - : ASME Press. - 0889-504X .- 1528-8900. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- The cooling air flow in a gas turbine is governed by the flow through its internal passages and controlled by restrictors such as circular orifices. If the cooling air flow is incorrectly controlled, the durability and mechanical integrity of the whole turbine may be affected. Consequently, a good understanding of the orifices in the internal passages is important. This study presents experimental results for a range of pressure ratios and length-to-diameter ratios common in gas turbines including even very small pressure ratios. Additionally, the chamfer depth at the inlet was also varied. The results of the chamfer depth variation confirmed its beneficial influence on decreasing pressure losses. Moreover, important effects were noted when varying more than one parameter at a time. Besides earlier mentioned hysteresis at the threshold of choking, new phenomena were observed, e.g. a rise of the discharge coefficient for certain pressure and length-to-diameter ratios. A correlation for the discharge coefficient was attained based on the new experimental data with a generally lower error than previous studies.
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| 6. |
- Grosselindemann, C., et al.
(författare)
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Impact of CeCo-Coated Metallic Interconnectors on SOCs Towards Performance, Cr-Oxide-Scale, and Cr-Evaporation
- 2024
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Ingår i: Journal of the Electrochemical Society. - 1945-7111 .- 0013-4651. ; 171:5
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Tidskriftsartikel (refereegranskat)abstract
- The performance of a solid oxide cell (SOC) depends on the operating environment. Regarding single cell tests with ideal contacting (gold, platinum, nickel meshes) and inert flow fields (Al2O3), performance is limited by intrinsic losses in the cell. Contact losses and poisoning effects are minimized. In a SOC-stack with metallic interconnectors, performance is affected by contact resistances, chromium (Cr) evaporation, and limitations in gas supply. Here, 1 cm2 single cells were tested with a stack-like contact applying metallic flow fields made from three different steel grades (Crofer 22 APU, AISI 441, UNS S44330) with and without a cerium-cobalt PVD-coating. Cell performance and losses were analyzed by IV-characteristics, impedance spectroscopy, and DRT analysis. For all uncoated interconnectors, significant performance losses due to increased contact losses and air electrode polarization were observed, which is attributed to Cr-oxide scale formation on the metallic interconnectors and Cr-poisoning of the air electrode as revealed by scanning electron microscopy-energy-dispersive X-ray spectroscopy. A CeCo-coating leads to similar oxide scales irrespective of the substrate material. Moreover, with the coating the electrochemical performance drastically improved due to decreased contact losses and an effective blocking of Cr-evaporation leading to a cell performance close to the ideal case for all three steel grades.
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| 7. |
- Bauer, K., et al.
(författare)
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Welcome message from the PADE chairs
- 2013
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Ingår i: Welcome message from the PADE chairs (Editorial). - : IEEE Computer Society. - 9781479905379 ; , s. lxi-lxii
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Cibiraite, D., et al.
(författare)
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Thermal noise-limited sensitivity of FET-based terahertz detectors
- 2017
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Ingår i: 2017 International Conference on Noise and Fluctuations, ICNF 2017, Vilnius, Lithuania, 20-23 June 2017.
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Konferensbidrag (refereegranskat)abstract
- Here we present a detailed study on estimation of noise-dependent parameters, such as signal-to-noise ratio (SNR) or noise equivalent power (NEP), of field-effect-transistor based terahertz detectors (TeraFETs). Commonly, these parameters are estimated from a well-known assumption, that detector's performance is limited by the thermal noise of transistor's channel. However, practice shows that the influence of other noise sources or transient effects is considerable. We summarize TeraFET noise measurements performed on different material systems based transistors, such as AlGaN/GaN, AlGaAs/GaAs, silicon CMOS, and monolayer graphene. We have achieved a good agreement between thermal noise and measured data. However, attention has to be paid to gate leakage currents and slow defect charging and discharging effects, which can strongly influence TeraFET's performance estimation.
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| 9. |
- Hanssen-Bauer, O. W., et al.
(författare)
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Comparison of three DWM-based wake models at above-rated wind speeds
- 2023
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Ingår i: WAKE CONFERENCE 2023. - : Institute of Physics Publishing (IOPP).
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Konferensbidrag (refereegranskat)abstract
- In this study we investigate three mid-fidelity wind turbine wake models based on the dynamic wake meandering (DWM) model principle, and compare their performance with a reference dataset, produced with large-eddy simulations using the actuator line model. The models are compared with respect to flow field, power, and loads on a row of four 5MW reference turbines experiencing above-rated wind conditions. In general, the DWM models show fairly good agreement with large-eddy simulation for the time-averaged flow fields, blade forces and power, with increasing differences along the turbine row. Also when comparing fatigue loads of blade root moments, the differences between the models increase further into the row, with deviations up to 25 % of the reference case. However, while the development in blade root moment fatigue along the turbine row is predominantly driven by the energy content at the frequency corresponding to the turbine's rotational period (1P) for the DWM models, the large-eddy simulation results suggest that the key drivers for the blade root and tower loads are the increase in meandering and energy at higher frequencies (> 1P) deeper into the turbine row. For the tower loads, the DWM models highly underestimate the fatigue for the waked turbines. From these results, we suggest priorities for future model developments so that robust model implementations can be used in wind farm design and operation.
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| 10. |
- Leisawitz, David, et al.
(författare)
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The origins space telescope
- 2019
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11115
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Konferensbidrag (refereegranskat)abstract
- The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid-and far-infrared wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of Herschel, the largest telescope flown in space to date. After a 3 1/2 year study, the Origins Science and Technology Definition Team will recommend to the Decadal Survey a concept for Origins with a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (MISC-T) will measure the spectra of transiting exoplanets in the 2.8-20 μm wavelength range and offer unprecedented sensitivity, enabling definitive biosignature detections. The Far-IR Imager Polarimeter (FIP) will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer (OSS) will cover wavelengths from 25-588 μm, make wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The telescope has a Spitzer-like architecture and requires very few deployments after launch. The cryo-thermal system design leverages JWST technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins' natural backgroundlimited sensitivity.
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