| 1. |
- Lukasch, B., et al.
(författare)
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Major histocompatibility complex genes partly explain early survival in house sparrows
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Environmental factors and genetic incompatibilities between parents have been suggested as important determinants for embryonic mortality and survival. The genetic set-up of the immune system, specifically the highly polymorphic major histocompatibility complex (MHC) may also influence individual resistance to infections. MHC proteins are important for an appropriate adaptive immune response and enable T-cells to separate 'self' from 'non-self'. Here we investigate the importance of MHC functional diversity for early development in birds, more specifically, if offspring survival and body mass or size depends on number of different functional MHC alleles, specific functional MHC alleles or similarity of MHC alleles in the parents. Unhatched eggs are common in clutches of many bird species. In house sparrows (Passer domesticus), embryo and nestling mortality can exceed 50%. To control for environmental factors, our study was carried out on an aviary population. We found that one specific functional MHC allele was associated with reduced nestling survival, which was additionally supported by lower body mass and a smaller tarsus when nestlings have been 6 days old. Another allele was positively associated with tarsus length at a later nestling stage (nestlings 12 days old). These results indicate that MHC alleles might influence pathogen resistance or susceptibility.
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| 2. |
- Bhat, P. Narayana, et al.
(författare)
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THE THIRD FERMI GBM GAMMA-RAY BURST CATALOG : THE FIRST SIX YEARS
- 2016
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics Publishing (IOPP). - 0067-0049 .- 1538-4365. ; 223:2
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Tidskriftsartikel (refereegranskat)abstract
- Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two.-ray bursts (GRBs) every three days. Here, we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years through the middle of 2014 July. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM-detected GRBs. For each GRB, the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50-300 keV energy band where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10 to 1000 keV, exploiting the full energy range of GBM's low-energy [NaI[Tl)] detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fit by a two-component model with short-hard and long-soft bursts than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.
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| 3. |
- Hegde, Gurumurthy, 1979, et al.
(författare)
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Photoalignment Properties of Brilliant Yellow Dye
- 2007
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Ingår i: IDW07. ; 3:LCTP5-1
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Konferensbidrag (refereegranskat)abstract
- Photoalignment properties of commercially available Brilliant Yellow (BY) diazo dye are investigated. By using ozone pre-cleaning procedure we succeeded in deposition of highly uniform BY films on different kinds of inorganic and organic substrates used in LCD manufacturing. Excellent photoalignment of nematic, smectic ferroelectric and reactive liquid crystals (LC) on BY films is observed. This alignment shows extraordinary high photo-and thermal stability. The distinguished alignment properties of this dye extend the field of the sulfuric azo dyes effective for photoalignment.
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| 4. |
- Yu, Yantao, et al.
(författare)
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Experimental study of DOA estimation using a compact monopole array
- 2010
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Ingår i: 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010; Toronto, ON; 11 July 2010 through 17 July 2010. - 9781424449682
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Konferensbidrag (refereegranskat)abstract
- Space-time techniques like MIMO, diversity reception and direction finding all require multiport antenna arrays. In mobile applications, the size-limited platforms demand compact arrays with element spacing significantly smaller than λ/2. The small element spacing introduces strong mutual coupling between the elements of such compact arrays. For application of direction-of-arrival (DOA) estimation using typical DOA estimation algorithms, for example MUSIC [1], the mutual coupling effect between antenna elements significantly contributes to the estimation error. Many compensation methods have been proposed in previous studies [2] -[3]. The most commonly used one is the conventional mutual impedance method (CMIM) proposed in [4] . Recently, a modified concept of mutual impedance in receiving antenna arrays, the receiving mutual impedance, was proposed in [5]. This method is called the receiving mutual impedance method (RMIM). Theoretical studies have shown that much higher accuracies for DOA estimations can be achieved when the mutual coupling in receiving arrays are characterized using the RMIM than the CMIM. The current study is to provide experimental evidence on this. In this paper, a seven-element monopole array with element spacing of 0.2λ was used in the experiments. Both the receiving mutual impedances and the conventional mutual impedances of the array were measured. A series DOA experiments were then performed with one and two signal sources generated by transmitting antennas inside the anechoic chamber. © 2010 IEEE.
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| 5. |
- Yu, Yantao, et al.
(författare)
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Improved DOA Estimations Using the Receiving Mutual Impedances for Mutual Coupling Compensation: An Experimental Study
- 2011
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2248 .- 1536-1276. ; 10:7, s. 2228-2233
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Tidskriftsartikel (refereegranskat)abstract
- An experimental study is performed to investigate the improvement of direction-of-arrival (DOA) estimation using the recently proposed receiving mutual impedances for mutual coupling compensation. A seven-monopole antenna array is constructed and used in DOA estimation employing the MUSIC algorithm. Comparisons are made with the case of using the conventional mutual impedances for mutual coupling compensation. All experiments are carried out inside an anechoic chamber. Results are obtained for one-and two-source experiments which indicate that the performance of DOA estimation in the presence of mutual coupling can be significantly improved when the mutual coupling effect is compensated by using the receiving mutual impedances.
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| 6. |
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| 7. |
- Boatman, Elizabeth M., et al.
(författare)
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Mechanisms of soft tissue and protein preservation in Tyrannosaurus rex
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The idea that original soft tissue structures and the native structural proteins comprising them can persist across geological time is controversial, in part because rigorous and testable mechanisms that can occur under natural conditions, resulting in such preservation, have not been well defined. Here, we evaluate two non-enzymatic structural protein crosslinking mechanisms, Fenton chemistry and glycation, for their possible contribution to the preservation of blood vessel structures recovered from the cortical bone of a Tyrannosaurus rex (USNM 555000 [formerly, MOR 555]). We demonstrate the endogeneity of the fossil vessel tissues, as well as the presence of type I collagen in the outermost vessel layers, using imaging, diffraction, spectroscopy, and immunohistochemistry. Then, we use data derived from synchrotron FTIR studies of the T. rex vessels to analyse their crosslink character, with comparison against two non-enzymatic Fenton chemistry- and glycation-treated extant chicken samples. We also provide supporting X-ray microprobe analyses of the chemical state of these fossil tissues to support our conclusion that non-enzymatic crosslinking pathways likely contributed to stabilizing, and thus preserving, these T. rex vessels. Finally, we propose that these stabilizing crosslinks could play a crucial role in the preservation of other microvascular tissues in skeletal elements from the Mesozoic.
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| 8. |
- Cheng, Yu Ting, et al.
(författare)
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Tuning atom-field interaction via phase shaping
- 2024
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Ingår i: Physical Review A. - 2469-9934 .- 2469-9926. ; 109:2
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Tidskriftsartikel (refereegranskat)abstract
- A coherent electromagnetic field can be described by its amplitude, frequency, and phase. All these properties can influence the interaction between the field and an atom. Here we demonstrate the phase shaping of microwaves that are scattered by a superconducting artificial atom coupled to the end of a semi-infinite one-dimensional transmission line. In particular, we input a weak exponentially rising pulse with phase modulation to a transmon qubit. We observe that atom-field interaction can be tuned from a nearly full interaction (interaction efficiency, i.e., amount of the field energy interacting with the atom, of 94.5 %) to effectively no interaction (interaction efficiency of 3.5 %).
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| 9. |
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| 10. |
- Hettyey, A., et al.
(författare)
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Costs and benefits of defences induced by predators differing in dangerousness
- 2011
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 24:5, s. 1007-1019
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Tidskriftsartikel (refereegranskat)abstract
- While theoretical studies predict that inducible defences should be fine-tuned according to the qualities of the predator, very few studies have investigated how dangerousness of predators, i.e. the rate at which predators kill prey individuals, affects the strength of phenotypic responses and resulting benefits and costs of induced defences. We performed a comprehensive study on fitness consequences of predator-induced responses by involving four predators (leech, water scorpion, dragonfly larva and newt), evaluating costs and benefits of responses, testing differences in dangerousness between predators and measuring responses in several life history traits of prey. We raised Rana dalmatina tadpoles in the presence of free-ranging predators, in the presence of caged predators, and exposed naive and experienced tadpoles to free-ranging predators. Tadpoles adjusted the intensities of their behavioural and morphological defences to predator dangerousness. Survival was lower in the nonlethal presence of the most dangerous predator, while we could not detect costs of induced defences at or after metamorphosis. When exposed to free-ranging predators, small, but not large, tadpoles benefited from exhibiting an induced phenotype in terms of elevated survival when compared to naive tadpoles, but we did not observe higher survival either in tadpoles exhibiting more extreme phenotypes or in tadpoles exposed to the type of predator they were raised with. These results indicate that while predator-induced defences can mirror dangerousness of predators, costs and benefits do not necessarily scale to the magnitude of plastic responses.
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| 11. |
- Joshi, Siddarth Koduru, et al.
(författare)
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Space QUEST mission proposal : experimentally testing decoherence due to gravity
- 2018
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Models of quantum systems on curved space-times lack sufficient experimental verification. Some speculative theories suggest that quantum correlations, such as entanglement, may exhibit different behavior to purely classical correlations in curved space. By measuring this effect or lack thereof, we can test the hypotheses behind several such models. For instance, as predicted by Ralph et al [5] and Ralph and Pienaar [1], a bipartite entangled system could decohere if each particle traversed through a different gravitational field gradient. We propose to study this effect in a ground to space uplink scenario. We extend the above theoretical predictions of Ralph and coworkers and discuss the scientific consequences of detecting/failing to detect the predicted gravitational decoherence. We present a detailed mission design of the European Space Agency's Space QUEST (Space-Quantum Entanglement Space Test) mission, and study the feasibility of the mission scheme.
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| 12. |
- Lin, En-Tzu, et al.
(författare)
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Bayesian analysis on the X-ray spectra of the binary neutron star merger GW170817
- 2019
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Ingår i: Journal of High Energy Astrophysics. - : ELSEVIER SCIENCE BV. - 2214-4048 .- 2214-4056. ; 21, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, we present a Bayesian time-resolved spectral study of the X-ray afterglow datasets of GW170817/GRB17017A observed by the Chandra X-ray Observatory. These include all 12 public datasets, from the earliest observation taken at t similar to 9 d to the newest observation at similar to 359 d post-merger. While our results are consistent with the other works using Cash statistic within uncertainty, the Bayesian analysis we performed in this work have yielded Gaussian-like parameter distributions. We also obtained the parameter uncertainties directly from their posterior probability distributions. We are able to confirm that the power-law photon index has remained constant of Gamma similar to 1.6 throughout the entire year-long observing period, except for the first dataset observed at t = 8.9 d when Gamma = 1.04 +/- 0.44 is marginally harder. We also found that the unabsorbed X-ray flux peaked at t similar to 155 d, temporally consistent with the X-ray flare model suggested recently by Piro et al. (2019). The X-ray flux has been fading since similar to 160 days after the merger and has returned to the level as first discovered after one year. Our result shows that the X-ray spectrum of GW170817/GRB170817A is well-described by a simple power-law originated from non-thermal slow-cooling synchrotron radiation.
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| 13. |
- Liu, H. M., et al.
(författare)
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Microplastics pollution in the rivers of a metropolitan city and its estimated dependency on surrounding developed land
- 2023
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 880
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution and abundance of suspected microplastics (SMPs) in the surface water of a metropolitan city, as represented by four Hong Kong rivers, was studied during the dry season. Shing Mun River (SM), Lam Tsuen River (LT), and Tuen Mun River (TM) are located in urbanized areas, and SM and TM are tidal rivers. The fourth river, Silver River (SR) is situated in a rural area. TM had a significantly higher SMP abundance (53.80 ± 20.67 n/L) than the other rivers. The SMP abundance increased from upstream to downstream in non-tidal rivers (LT and SR), but not in tidal rivers (TM and SM), probably due to the tidal influence and a more homogeneous urban development along the tidal rivers. Inter-site differences in the SMP abundance were strongly correlated with the built area ratio (defined as the percentage of surrounding developed land area), human activities, and the nature of the river. About half (48.72 %) of the SMPs were <250 μm. Fibers and fragments were most abundant (>98 %), with most of them being transparent (58.54 %), black (14.68 %), or blue (12.12 %). Polyethylene terephthalate (26.96 %) and polyethylene (20.70 %) were the most common polymers. However, the MP abundance could be overestimated due to the presence of natural fibers. By contrast, an underestimation of the MP abundance could result from a smaller volume of water samples collected, due to a low filtration efficiency caused by high organic content and particle concentrations in the water. A more effective solid waste management strategy and upgrading of the sewage treatment facilities for removing microplastics are recommended to ameliorate the microplastic pollution in local rivers.
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| 14. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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A Note on the Mutual-Coupling Problems in Transmitting and Receiving Antenna Arrays
- 2009
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Ingår i: IEEE Antennas and Propagation Magazine. - 1045-9243. ; 51:5, s. 171-176
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Tidskriftsartikel (refereegranskat)abstract
- In antenna arrays, mutual coupling between antenna elements is well known as an undesired effect, which degrades the performance of array signal-processing algorithms. The compensation of such an undesired effect has been a popular research topic throughout the years. Various approaches for mutual-coupling compensation have been developed, and they can easily be found in the open literature. In general, the mutual-coupling problems for a transmitting and receiving array are different, even if the physical geometry of the array remains unchanged. However, it seems that antenna engineers are not well aware of such differences in the analysis of receiving antenna arrays. In this note, the mutual-coupling problems in transmitting and receiving antenna arrays are revisited. The differences between the mutual coupling and mutual impedances for transmitting and receiving antenna arrays are explained. It is concluded that the mutual-coupling problems of transmitting and receiving arrays are in general different, and hence different mutual impedances should be used for mutual-coupling analysis and compensation.
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| 15. |
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| 16. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Direction-of-Arrival Estimation of Closely Spaced Emitters Using Compact Arrays
- 2013
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2013, s. Art. no. 104848-
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Tidskriftsartikel (refereegranskat)abstract
- Performance evaluation of direction-of-arrival (DOA) estimation algorithms has continuously drawn significant attention in the past years. Most previous studies were conducted under the situation that antenna element separation is about half wavelength in order to avoid the appearance of grating lobes. On the other hand, recent developments in wireless communications have favoured the use of portable devices that utilize compact arrays with antenna element separations of less than half wavelength. Performance evaluation of DOA estimation algorithms employing compact arrays is an important and fundamental issue, but it has not been fully studied. In this paper, the performance of the matrix pencil method (MPM) that applies to DOA estimations is investigated through Monte Carlo simulations. The results show that closely spaced emitters can be accurately resolved using linear compact array with an array aperture as small as around half wavelength.
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| 17. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Effect of mutual coupling on the performance of Direction-of-arrival estimation of compact array
- 2010
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Ingår i: 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010; Toronto, ON; 11 July 2010 through 17 July 2010. - 9781424449682
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Konferensbidrag (refereegranskat)abstract
- With the recent advancement in microwave hardware, there has been significant focus on developing compact antenna arrays with element separation less than half wavelength. Direction-of-arrival (DOA) estimation is an important application for antenna arrays but yet not much work has been done on DOA estimation using compact arrays. In particular, as the element separation becomes smaller, the undesirable mutual coupling effect between antenna elements becomes much stronger which can significantly degrade the accuracy of DOA estimation. © 2010 IEEE.
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| 18. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Effective mutual coupling compensation for direction-of-arrival estimations using a new, accurate determination method for the receiving mutual impedance
- 2010
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Ingår i: Journal of Electromagnetic Waves and Applications. - 1569-3937 .- 0920-5071. ; 24:2-3, s. 271-281
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Tidskriftsartikel (refereegranskat)abstract
- Performance degradation due to the mutual coupling effect of antenna arrays in direction-of-arrival (DOA) estimations has been well known, and many mutual coupling compensation methods have been proposed throughout the years. In particular, the mutual coupling effect becomes significant when the antenna elements are closely spaced, which is difficult to compensate. In this paper, a new, accurate method is introduced to determine the receiving mutual impedances of antenna arrays with closely spaced omni-directional antenna elements. This new method uses a number of plane wave sources coming from different directions to determine the receiving mutual impedances of a particular antenna element with all other antenna elements in the array in a single step. This step is repeated for all the antenna elements in the array, and the full mutual impedance matrix of the array is thus obtained. Using the Matrix Pencil Method (MPM), DOA estimations using eight-element arrays were used to demonstrate the validity and accuracy of this new method.
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| 19. |
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| 20. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Improved mutual coupling compensation in compact antenna arrays
- 2010
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Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 4:10, s. 1506-1516
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Tidskriftsartikel (refereegranskat)abstract
- A new method for the characterisation of receiving mutual impedances of compact arrays with omnidirectional antenna elements is proposed. Based on a large number of incident waves coming from different directions, the new method is able to calculate the receiving mutual impedances of omni-directional antennas based on a system of equations that characterise the received terminal voltages at different incident wave directions. In the new method, the receiving mutual impedances of all the antenna elements are calculated together in a single equation with the scattering effect from all antenna elements in the array being taken into account. Compared to the previous methods for the characterisation of the receiving mutual impedances, the new method preserves the boundary conditions of the original electromagnetic problem and produces much more accurate results on receiving mutual impedances, especially for compact antenna arrays. Direction finding examples based on the new method demonstrate its superior performance over existing methods.
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| 21. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Mutual Coupling Compensation for Direction-of-Arrival Estimations Using the Receiving-Mutual-Impedance Method
- 2010
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2010
-
Tidskriftsartikel (refereegranskat)abstract
- A short review of the receiving-mutual-impedance method (RMIM) for mutual coupling compensation in direction finding applications using linear array is conducted. The differences between the conventional-mutual-impedance method (CMIM) and RMIM, as well as the three different determination methods for receiving mutual impedance (RMI), will be discussed in details. As an example, direction finding with better accuracies is used for demonstrating the superiority of mutual coupling compensation using RMIM.
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| 22. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Mutual Coupling Compensation of Compact Antenna Array for Direction-of-Arrivals Estimations
- 2010
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Ingår i: 4th International Conference on Signal Processing and Communication Systems. - 9781424479078 ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- Mutual coupling is well known as an undesirable effect as it degrades the performance of most array signal processing algorithm. Such undesirable effect becomes significant when the antenna element spacing becomes small, which is the case for compact antenna array. Throughout the years, extensive studies from signal processing and communication society have been conducted to compensate such undesirable effect. In this paper, a new method for the determination of receiving mutual impedances of omni-directional antenna elements is proposed. The new method is able to compensate such undesirable effect for compact array. Numerical examples of using the new method for the determinations receiving mutual impedances for some monopole arrays are given, which aims to show the differences between the old and new methods. DOA estimation examples with better accuracies demonstrate the superior mutual coupling characterization performance of the new receiving mutual impedance determination method over existing methods.
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| 23. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Mutual Coupling in Antenna Arrays 2011
- 2012
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2012, s. Art. no. 715138-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 24. |
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| 25. |
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