[en] A method of estimating a power system's electromechanical mode shape and coherence from time synchronized phasor measurements is presented. The approach uses a parametric estimate of the transfer function (TF) between signals at different buses throughout the power system. The relationship between the TF and mode shape and coherence is reviewed. A non-causal autoregressive exogenous (ARX) model is used in a least squares (LS) minimization to estimate the TF parameters and to estimate the magnitude squared coherence function. The method is applied to both a simulated system and measured data from the western North American power system and is compared to the traditional Welch periodogram averaging approach.

[en] A search for the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model with a warped extra dimension is performed in the dielectron and diphoton channels. The data set used for the search corresponds to 5.4 fb^-1 of data from p(bar p) collisions at a center-of-mass energy of 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron between July 2002 and Summer 2009. We search for resonances in the invariant mass spectrum of two electromagnetic showers from the decay of the graviton to either electron-positron pairs or photon pairs. To optimize the sensitivity, the dielectron and diphoton channels are analyzed separately, then the results are combined together in the end. We also investigate whether, due to the unique spin-2 nature of the graviton, the angular distribution of the final state particles can be used to significantly enhance the sensitivity of the search. We set 95% confidence level upper limits on the graviton production cross section times branching fraction into electron-positron pairs of between ∼ 7 fb and ∼ 0.5 fb for a range of graviton masses from 220 GeV and 1050 GeV, respectively. Compared with Randall-Sundrum model predictions, these results correspond to lower limits on the lightest graviton mass between 440 GeV and 1040 GeV, for the dimensionless graviton coupling to the Standard Model fields k/(bar M)_Pl in the range from 0.01 to 0.1. In addition, for coupling k/(bar M)_Pl of 0.01, gravitons with masses between 460 GeV and 560 GeV are also excluded at 95% confidence level. These results represent the most sensitive limits to date.

[en] Front tracking algorithms have generally assumed that the computational medium is divided into piece-wise smooth subdomains bounded by interfaces and that strong wave interactions are solved via Riemann solutions. However, in multi-dimensional cases, the Riemann solution of multiple shock wave interactions are far more complicated and still subject to analytical study. For this reason, it is very desirable to be able to track contact discontinuities only. A new numerical algorithm to couple a tracked contact surface and an untracked strong shock wave are described. The new tracking algorithm reduces the complication of computation, and maintains the sharp resolution of the contact surface. The numerical results are good. (authors)

[en] Highlights: • A composite anode with endogenous Fe-Ni alloy nanoparticles has been prepared. • The redox reversibility of the anode has been confirmed by XRD. • The E_a of H_2 oxidation at the anode is much smaller than that at Ni-YSZ anode. • A ScSZ supported cell achieves MPD of 0.71 Wcm"−"2 and R_p of 0.16 Ω cm"2 at 800 °C. • The single cell shows stable output during 105 h testing at 800 °C 0.7 V in wet H_2". - Abstract: A redox reversible composite anode with Fe-Ni alloy nanoparticles in situ growth on SrLaFeO_4-type and LaFeO_3-type oxide substrates has been prepared for intermediate temperature solid oxide fuel cell (IT-SOFC) by reducing perovskite precursor La_0_._4Sr_0_._6Fe_0_._7_5Ni_0_._1Nb_0_._1_5O_3_-_δ (LSFNNb) in wet H_2 at 900 °C for 1 h. The anode has shown an excellent electrochemical catalytic activity for oxidation of hydrogen with much smaller E_a (25.1 ∼ 68.9 kJ mol"−"1) than the value (>160 kJ mol"−"1) at Ni-YSZ anode. A scandium stabilized zirconia (ScSZ) electrolyte supported SOFC with the anode achieves maximum power densities of 0.71, 0.52, 0.35, and 0.21 W cm"−"2 at 800, 750, 700 and 650 °C, respectively in wet H_2 (3% H_2O), and the corresponding R_p of 0.16, 0.21, 0.35, and 0.60 Ω cm"2 under OCV. Moreover, the single cell shows stable power output during ∼105 h operation at 800 °C under 0.7 V in wet H_2 after a initial degradation, indicating that R-LSFNNb is an excellent candidate as anode of IT-SOFC.

[en] Objective: To evaluate the effect of automatic tube modulation on imaging quality and lesion revealed in infant brain. Methods: The infant patients of 200 cases were divided into four groups according to the values of SD (2.5, 2.75, 3.0, 4.0), 50 cases in each group. They were performed with the automatic tube current modulation scanning in brain. The imaging quality and radiation dose were analyzed. Results: When the values of SD were 2.5, 2.75, 3.0 and 4.0, the high values of CTDI_vol were 60.0, 49.8, 42.9 and 25.8 mGy, respectively. The effective doses were (3.27±1.01), (2.78±0.85), (2.40±0.74) and (1.49±0.45) mSv·mGy^-1·cm^-1, respectively. There was significant difference among those groups (F=48.99, P<0.05). The excellent imaging qualities were 100%, 96%, 70% and 20%, 12 cases were neonate in SD 2.5 group. In SD 2.75 group, the imaging quality of neonate (2 cases) were all fine. In SD 3.0 group, the imaging quality was not ideal for the ages less than 1 year. In SD 4.0 group, when the infants aged over 2 years and 6 months, or with the larger head circumference, their imaging quality were all excellent. Conclusions: The individual application of ATCM could obtain the best balance among imaging quality, radiation dose and diagnostic quality. The SD 2.5, 2.75, 3.0 and 4.0 might be suitable to infants of newborn, 1 month to 1 year old, 1 to 3 years, the larger head circumference and part of the reviewed cases. (authors)

[en] Objective: To investigate the incident body surface dose level of subjects caused by X-ray examinations in Jiangxi province in 2017, and to elaborate the current situation of medical radiation of X-ray diagnosis in Jiangxi province. Methods: 20 hospitals were randomly selected from 6 prefecture-level cities, Nanchang, Shangrao, Ganzhou, Pingxiang, Yichun and Jiujiang to measure ESD values of different irradiation sites of 1 273 examined individuals by using thermoluminescence dosimeters. Results: In 2017, the ESD values range of subjects caused by computer X-ray photography (CR) and digital X-ray photography (DR) in Jiangxi province was 0.08 ∼ 17.81 mGy and 0.04 ∼ 30.91 mGy, respectively. The entrance surface doses to adult patients from X-ray examinations were 0.07 ∼ 2.40 mGy for chest AP, 0.13 ∼ 7.27 mGy for chest LAT, 0.33 ∼ 23.29 mGy for lumbar spine AP, 0.62 ∼ 30.91 mGy for lumbar spine LAT, 0.09 ∼ 1.69 mGy for cervical spine AP, 0.10 ∼ 1.79 for cervical spine LAT, 0.29 ∼ 23.46 mGy for pelvic and hip joint, respectively. Conclusion: 75% percentile of ESD to chest LAT was higher than the guidance levels of medical radiation exposure. The ESD values of some exposed parts decreased significantly compared with the survey during the 9 th National Five-Year Plan period. The ESD values caused by DR photography is higher than CR, and measures should be taken to reduce the radiation dose of subjects caused by DR photography. (authors)

[en] Objective: To assess the CT and MRI features of endodermal sinus tumors of vagina in infants. Methods: The CT and MRI of pathologically confirmed endodermal sinus tumors of vagina in eight infants were analyzed retrospectively. Results: Endodermal sinus tumor of vagina showed a large soft tissue mass similar-circular, and the density was inhomogeneous All cases are Endodermal sinus tumor of vagina appeared as a large round soft tissue mass with heterogeneous density, variable necrosis and cystic degeneration on unenhanced CT. The tumor had heterogeneous low to intermediate T₁ and slightly high T₂ signal intensities. Heterogeneous enhancement especially peripherally was noted on both CT and MRI. Conclusions: The CT and MRI features of heterogeneously enhancing vaginal mass with necrosis and cystic degeneration in the setting of elevated a-fetoprotein level suggest diagnosis of endodermal sinus tumor. MRI is superior to CT in showing surrounding tumor infiltration and tumor recurrence. (authors)

[en] 30 cases of primary liver cancer and 30 cases benign liver disorders are studied with radioimmunoassay AFP and pisum sativum agglutinin by affinity crossed immunoelectrophoresis autoradiography (PSA-AFF-CIEA). The results show that differentiation of primary liver cancer from benign liver disorders seems to be difficult by determination of total amount of serum AFP. However, human AFP can be separated into two variants PSA bound AFP and PSA unbound AFP with PSA-AFF-CIEA. The percentage of PSA bound AFP is significantly higher in the presence of primary liver cancer (41.26% +- 19.47) than in benign liver disorders (15.96% +- 12.09%, P<0.001). The results possess higher clinical value to diagnose the positive lower level of primary liver cancer and benign liver disorders by using PSA-AFF-CIEA

[en] Objective: To analyze and evaluate the problems existing in the plane layout of radiation protection control effect evaluation stage of a hospital PET/CT center construction project, and to propose the importance of occupational hazard radiation protection evaluation, especially the pre-evaluation. Method: The layout of the PET/CT workplace was analyzed and evaluated on the basis of on-site verification and in accordance with relevant laws, regulations and standards. Results: The layout of the PET/CT center was unreasonable, including: the site layout was not arranged from the low activity area to the high activity area, the sanitary passage was not set, the dedicated channel for transport of radioactive drugs and waste was not set. Conclusion: The reasonable layout of nuclear medicine workplace is the premise to ensure the optimization of radiation protection, and the pre-evaluation of occupational hazard radiation protection is the key to determine whether the layout is reasonable or not. (authors)

[en] Many astronomical observations have confirmed the existence of dark matter in the universe. According to the constraints on the properties of dark matter, the most attractive candidate is the 'weakly interacting massive particles (WIMPs)', and most experiments looking for dark matter are trying to find the signals of WIMPs. In this paper we describe the three main methods to detect WIMPs and their respective merits and demerits; the emphasis is on colliders and in particular the Large Hadron Collider (LHC). The latest observations and most recently defined constraints on the properties of dark matter based on the LHC results are described in detail. (authors)