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- 2019
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Journal article (peer-reviewed)
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| 2. |
- Duev, Dmitry, et al.
(author)
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Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique: A test case of the Mars Express Phobos fly-by
- 2016
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 593:A34
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Journal article (peer-reviewed)abstract
- The closest ever fly-by of the Martian moon Phobos, performed by the European Space Agency's Mars Express spacecraft, gives a unique opportunity to sharpen and test the Planetary Radio Interferometry and Doppler Experiments (PRIDE) technique in the interest of studying planet-satellite systems. Aims. The aim of this work is to demonstrate a technique of providing high precision positional and Doppler measurements of planetary spacecraft using the Mars Express spacecraft. The technique will be used in the framework of Planetary Radio Interferometry and Doppler Experiments in various planetary missions, in particular in fly-by mode. Methods. We advanced a novel approach to spacecraft data processing using the techniques of Doppler and phase-referenced very long baseline interferometry spacecraft tracking. Results. We achieved, on average, mHz precision (30 mu m/s at a 10 s integration time) for radial three-way Doppler estimates and sub-nanoradian precision for lateral position measurements, which in a linear measure (at a distance of 1.4 AU) corresponds to similar to 50 m.
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| 3. |
- Fu, L., et al.
(author)
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Microstructure and tribological properties of Cr3C2/Ni3Al composite materials prepared by hot isostatic pressing (HIP)
- 2017
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In: Materials and Design. - : Elsevier BV. - 1873-4197 .- 0264-1275. ; 115:115, s. 203-212
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Journal article (peer-reviewed)abstract
- Ni3Al-based composites with different Cr3C2 contents were fabricated by the hot isostatic pressing (HIP) technique.The microstructure, phase constitution, and tribological properties of the composites were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and pin-on-disk wear tests. The results revealed that the strengthening phase is distributed homogeneously in the Ni3Al matrix. During the HIP process, M7C3 (M = Cr, Fe) is formed by diffusion of Fe, C, and Cr to the interface between the Cr3C2 particles and Ni3Al matrix. The diffusion process binds the phases and is important for improving the wear resistance of Cr3C2/Ni3Al composites. The wear measurements demonstrated that micro-cutting and fatigue wear are the dominant mechanisms for this tribological pair. The wear resistance of Cr3C2/Ni3Al composites is significantly improved by the addition of Cr3C2 particles.When the content of Cr3C2 is within a certain range, the wear resistance of Cr3C2/Ni3Al composites increases as the Cr3C2 content increases. However, the addition of excess Cr3C2 (for example, 24 vol% in this work) could lead to a decrease in the wear resistance of the composites. In addition, the average friction coefficients and wear of the counterpart decrease with increasing Cr3C2 addition.
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| 4. |
- Fu, L., et al.
(author)
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Effects of Cr3C2 content and temperature on sliding friction and wear behaviors of Cr3C2/Ni3Al composite materials
- 2018
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In: Wear. - : Elsevier BV. - 0043-1648. ; 414-415, s. 163-173
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Journal article (peer-reviewed)abstract
- Chromium carbide (Cr3C2)-reinforced Ni3Al matrix composites, which possess excellent high-temperature strength and wear resistance, are considered as potential high-temperature wear-resistant materials. In this study, effects of Cr3C2content on the friction and wear properties of Cr3C2/Ni3Al composites and their counterpart gray cast iron disks were investigated at different temperatures. The worn surface morphologies of the Cr3C2/Ni3Al composites and gray cast iron disks were analyzed to understand their wear mechanisms. The analysis results showed that in the Ni3Al matrix composites, a combination of abrasive wear and adhesive wear occurred at room temperature, whereas adhesive wear was severer at 200 °C. Furthermore, the optimum Cr3C2contents of the Cr3C2/Ni3Al composites were found to be 18 vol% and 12 vol% at room temperature and 200 °C, respectively. The volume loss of the composites increased with an increase in the fraction of the Cr3C2strengthening phase at 350 °C. The wear resistance of the gray cast iron disks decreased with an increase in temperature. In contrast, the wear resistance of the Ni3Al matrix composites increased with an increase in temperature. This increased wear resistance of the composites is attributed to the transformation of their wear mechanism with increasing temperature.
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| 5. |
- Garcaa-Fernandez, Angel F., et al.
(author)
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Gaussian implementation of the multi-Bernoulli mixture filter
- 2019
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In: FUSION 2019 - 22nd International Conference on Information Fusion.
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Conference paper (peer-reviewed)abstract
- This paper presents the Gaussian implementation of the multi-Bernoulli mixture (MBM) filter. The MBM filter provides the filtering (multi-target) density for the standard dynamic and radar measurement models when the birth model is multi-Bernoulli or multi-Bernoulli mixture. Under linear/Gaussian models, the single target densities of the MBM mixture admit Gaussian closed-form expressions. Murty's algorithm is used to select the global hypotheses with highest weights. The MBM filter is compared with other algorithms in the literature via numerical simulations.
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| 6. |
- Gray, Victor, 1988, et al.
(author)
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CdS/ZnS core-shell nanocrystal photosensitizers for visible to UV upconversion
- 2017
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In: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6539 .- 2041-6520. ; 8:8, s. 5488-5496
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Journal article (peer-reviewed)abstract
- Herein we report the first example of nanocrystal (NC) sensitized triplet-triplet annihilation based photon upconversion from the visible to ultraviolet (vis-to-UV). Many photocatalyzed reactions, such as water splitting, require UV photons in order to function efficiently. Upconversion is one possible means of extending the usable range of photons into the visible. Vis-to-UV upconversion is achieved with CdS/ZnS core-shell NCs as the sensitizer and 2,5-diphenyloxazole (PPO) as annihilator and emitter. The ZnS shell was crucial in order to achieve any appreciable upconversion. From time resolved photoluminescence and transient absorption measurements we conclude that the ZnS shell affects the NC and triplet energy transfer (TET) from NC to PPO in two distinct ways. Upon ZnS growth the surface traps are passivated thus increasing the TET. The shell, however, also acts as a tunneling barrier for TET, reducing the efficiency. This leads to an optimal shell thickness where the upconversion quantum yield (Phi(UC)') is maximized. Here the maximum Phi(UC)' was determined to be 5.2 +/- 0.5% for 4 monolayers of ZnS shell on CdS NCs.
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| 7. |
- He, Y., et al.
(author)
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Combined effects of trapped energetic ions and resistive layer damping on the stability of the resistive wall mode
- 2016
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In: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 23:1
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Journal article (peer-reviewed)abstract
- A dispersion relation is derived for the stability of the resistive wall mode (RWM), which includes both the resistive layer damping physics and the toroidal precession drift resonance damping from energetic ions in tokamak plasmas. The dispersion relation is numerically solved for a model plasma, for the purpose of systematic investigation of the RWM stability in multi-dimensional plasma parameter space including the plasma resistivity, the radial location of the resistive wall, as well as the toroidal flow velocity. It is found that the toroidal favorable average curvature in the resistive layer contributes a significant stabilization of the RWM. This stabilization is further enhanced by adding the drift kinetic contribution from energetic ions. Furthermore, two traditionally assumed inner layer models are considered and compared in the dispersion relation, resulting in different predictions for the stability of the RWM.
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| 8. |
- Liu, Ya, 1991, et al.
(author)
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Surface modification of graphene for use as a structural Fortifier in water-borne epoxy coatings
- 2019
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In: Coatings. - : MDPI AG. - 2079-6412. ; 9:11
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Journal article (peer-reviewed)abstract
- Graphene, the typical two-dimensional sp2 hybridized carbon allotrope, is widely used as a filler for improving the mechanical performance of polymers. However, its superhydrophobic surface makes it a big challenge to obtain stable graphene dispersions, especially in water-borne systems. On the contrary, graphene oxide (GO) shows excellent dispersibility in water, but strong oxidants and acids destroy its structure and degrade its mechanical properties. This largely limits its application in water-borne coatings. In this work, graphene from mechanical exfoliation was surface modified by p-aminophenol derived diazonium salt to achieve a homogenous dispersion. Moreover, the hydroxyl groups in p-aminophenol are able to combine with epoxy resins during the curing process to improve mechanical performance of the final coatings. The result shows that functionalized graphene shows a lower coefficient of friction and better abrasion resistance compared to GO.
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| 9. |
- McGinn, Steven, et al.
(author)
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New Technologies for DNA analysis-A review of the READNA Project.
- 2016
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In: New Biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784.
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Research review (peer-reviewed)abstract
- The REvolutionary Approaches and Devices for Nucleic Acid analysis (READNA) project received funding from the European Commission for 4 1/2 years. The objectives of the project revolved around technological developments in nucleic acid analysis. The project partners have discovered, created and developed a huge body of insights into nucleic acid analysis, ranging from improvements and implementation of current technologies to the most promising sequencing technologies that constitute a 3(rd) and 4(th) generation of sequencing methods with nanopores and in situ sequencing, respectively.
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| 10. |
- Wu, L. F., et al.
(author)
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Ground State Host-Guest Interactions upon Effective Dispersion of Regioregular Poly(3-hexylthiophene) in Poly(9,9-dioctylfluorene-alt-benzothiadiazole)
- 2015
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In: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 48:24, s. 8765-8772
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Journal article (peer-reviewed)abstract
- Regioregular poly(3-hexylthiophene), (rr-P3HT), is widely regarded as an archetypical semiconducting electron-donor polymer in bulk heterojunction solar cells, mainly due to its notable exciton and charge transport properties. Conversely, its use in photonic/lighting devices received little interest owing to its low emission quantum yield in the solid state, related to its large tendency to self-organize into lamellar domains with highly nonemissive character. We present experimental evidence pointing to a large miscibility of P3HT in poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), accompanied by mutual pi-pi interactions. Concomitant to this effect, the emission properties of P3HT:F8BT blends, which are attributed to heterogeneous interchain complexes, experience a significant improvement, with photoluminescence quantum efficiency (PLQE) values approaching 25% (almost a 7-fold efficiency enhancement with respect to neat/aggregated rr-P3HT). Our results open up new prospects for improved photonic properties through appropriate control of interchain interactions.
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