4,374 research outputs found
Microseisms generated by super typhoon Megi in the western Pacific Ocean
Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 9518–9529, doi:10.1002/2017JC013310.Microseisms generated by the super typhoon Megi (13–24 October 2010) were detected on both land-based and island-based seismic stations. We applied temporal frequency spectrum analysis to investigate the temporal evolution of the microseisms. When Megi was over the deep basins of the Philippine Sea, only weak microseisms with short-period double frequency (SPDF, ∼0.20–0.40 Hz) were observed. However, after Megi traveled into the shallower waters of the South China Sea, microseisms with both long-period double frequency (LPDF, ∼0.12–0.20 Hz) and SPDF were recorded. The excitation source regions of the microseisms were analyzed using seismic waveform records and synthetic modeling in frequency domain. Results reveal that part of the LPDF microseisms were excited in coastal source regions, while the intensity of both LPDF and SPDF microseisms correlated well with the distance from seismic stations to the typhoon center. Synthetic computations of equivalent surface pressure and corresponding microseisms show that the wave-to-wave interaction induced by coastal reflection has primary effects on microseismic frequency band of ∼0.10–0.20 Hz. The coastal generation of the dispersive LPDF microseisms is also supported by the observation of ocean swells induced by Megi through the images of C-band ENVISAT-ASAR satellite during its migration process. Two source regions of the microseisms during the life span of Megi are finally distinguished: One was mainly located in the left-rear quadrant of the typhoon center that generated both LPDF and SPDF microseisms at shallow seas, while the other one was near the coasts that generated mostly LPDF microseisms.National Natural Science Foundation of China Grant Numbers: 41104027, 91628301, U1606401, 41676044;
Natural Science Foundation of Zhejiang Province Grant Number: LZ14D060001;
Opening Fund of SKLGED Grant Number: SKLGED2013-1-7-E;
Chinese Academy of Sciences Grant Numbers: Y4SL021001, Y6YB011001, QYZDY-SSW-DQC0052018-06-0
Dichlorido(4,5-diazafluoren-9-one-κ2 N,N′)palladium(II)
The structure of the title compound, [PdCl2(C11H6N2O)], shows a nearly square-planar geometry for the PdII atom within a Cl2N2 donor set
A call for leadership and management competency development for directors of medical services—evidence from the Chinese public hospital system
Background: A competent medical leadership and management workforce is key to the effectiveness and efficiency of health service provision and to leading and managing the health system reform agenda in China. However, the traditional recruitment and promotion approach of relying on clinical performance and seniority provides limited incentive for competency development and improvement. Methods: A three-component survey including the use of a validated management competency assessment tool was conducted with Directors of Medical Services (n = 143) and Deputy Directors of Medical Services (n = 152) from three categories of hospital in Jinan, Shandong Province, China. Results: The survey identified the inadequacy of formal and informal management training received by hospital medical leaders before commencing their management positions and confirms that the low self-perceived competency level across two medical management level and three hospitals was beyond acceptable. The study also indicates that the informal and formal education provided to Chinese medical leaders have not been effective in developing the required management competencies. Conclusions: The study suggests two system level approaches (health and higher education systems) and one organization level approach to formulate overall medical leadership and management workforce development strategies to encourages continuous management competency development and self-improvement among clinical leaders in China
Joint Location Sensing and Channel Estimation for IRS-Aided mmWave ISAC Systems
In this paper, we investigate a self-sensing intelligent reflecting surface
(IRS) aided millimeter wave (mmWave) integrated sensing and communication
(ISAC) system. Unlike the conventional purely passive IRS, the self-sensing IRS
can effectively reduce the path loss of sensing-related links, thus rendering
it advantageous in ISAC systems. Aiming to jointly sense the
target/scatterer/user positions as well as estimate the sensing and
communication (SAC) channels in the considered system, we propose a two-phase
transmission scheme, where the coarse and refined sensing/channel estimation
(CE) results are respectively obtained in the first phase (using scanning-based
IRS reflection coefficients) and second phase (using optimized IRS reflection
coefficients). For each phase, an angle-based sensing turbo variational
Bayesian inference (AS-TVBI) algorithm, which combines the VBI, messaging
passing and expectation-maximization (EM) methods, is developed to solve the
considered joint location sensing and CE problem. The proposed algorithm
effectively exploits the partial overlapping structured (POS) sparsity and
2-dimensional (2D) block sparsity inherent in the SAC channels to enhance the
overall performance. Based on the estimation results from the first phase, we
formulate a Cram\'{e}r-Rao bound (CRB) minimization problem for optimizing IRS
reflection coefficients, and through proper reformulations, a low-complexity
manifold-based optimization algorithm is proposed to solve this problem.
Simulation results are provided to verify the superiority of the proposed
transmission scheme and associated algorithms
Magnetic properties of a novel Pr Fe Ti phase
In a systematic study of the (Pr1−xTix)Fe5 alloy series, the (Pr0.65Ti0.35)Fe5 alloy has been
found to have a dominant phase with either the rhombohedral Th2Zn17 structure or the
newly discovered Nd2(Fe,Ti)19 (S. J. Collocott, R. K. Day, J. B. Dunlop, and R. L. Davis,
in Proceedings of the Seventh International Symposium on Magnetic Anisotropy and
Coercivity in R‐T Alloys, Canberra, July 1992, p. 437) structure, depending on the
annealing procedure. Powder‐x‐ray‐diffraction patterns and scanning electron
microscopy show that the sample annealed at a temperature of 850 °C followed by
1000 °C has the 2:17 structure whereas annealing at 1000 °C directly leads to the new
2:19 structure. Energy‐dispersive x‐ray analysis yields Pr:Fe:Ti ratios of 10.7:86.2:3.1
for the Pr2(Fe,Ti)17 phase and 9.2:85.9:4.9 for the Pr2(Fe,Ti)19 phase.
57
Fe Mössbauer
spectroscopy (at 295 K) gives values for the average
57
Fe hyperfine field of 15.7 T for the
2:17 phase and 17.5 T for the 2:19 phase, respectively
Retinal Fundus Image Registration via Vascular Structure Graph Matching
Motivated by the observation that a retinal fundus image may contain some unique geometric structures within
its vascular trees which can be utilized for feature matching, in this paper, we proposed a graph-based registration
framework called GM-ICP to align pairwise retinal images. First, the retinal vessels are automatically detected and
represented as vascular structure graphs. A graph matching is then performed to find global correspondences between
vascular bifurcations. Finally, a revised ICP algorithm incorporating with quadratic transformation model is used at
fine level to register vessel shape models. In order to eliminate the incorrect matches from global correspondence
set obtained via graph matching, we proposed a structure-based sample consensus (STRUCT-SAC) algorithm. The
advantages of our approach are threefold: (1) global optimum solution can be achieved with graph matching; (2)
our method is invariant to linear geometric transformations; and (3) heavy local feature descriptors are not required.
The effectiveness of our method is demonstrated by the experiments with 48 pairs retinal images collected from
clinical patients
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