[en] Objective: To compare the test bolus technique with the bolus tracking technique for dual-energy CT pulmonary angiography in patients suspected of pulmonary embolism (PE). Methods: A total of 60 patients were randomized into 2 groups: bolus tracking technique group (group B, n = 30) and test bolus technique group (group T, n = 30). A standard dual-energy CT pulmonary angiography (CTPA) was performed after injection of 60 ml contrast medium followed by 35 ml saline chaser at a speed of 4 ml/s. Attenuation profiles of different vascular segments (the subclavian vein, superior vena cava, left atrium, pulmonary trunk, S1 and S10 pulmonary artery) and enhancement value of lung parenchyma were measured to evaluate the timing techniques. The overall image quality of CTPA and pulmonary perfusion were analyzed by two radiologists. SPSS 19.0, Student t test, ANOVA test, Chi-Square test, Mann-Whitney U test and Kappa test were used for the statistic analysis. Results The attenuation of the subclavian vein [(1042 ± 639), (2200 ± 724) HU, F = 43.196, P = 0.001 ], superior vena cava [(529 ± 237), (904 ± 329) HU, F = 25.654, P = 0.001], pulmonary trunk [(325 ± 112), (383 ± 69) HU, F = 5.94, P = 0.018], S1 pulmonary artery [(320 ± 118), (385 ± 73) HU, F = 6.549, P =0.013], S10 pulmonary artery [(307 ± 78), (360 ± 82) HU , F = 6.658, P = 0.012 ] in group B were lower than those in group T, while the attenuation of the left atrium in group B was higher than that in group T [(270 ± 53), (219 ± 57) HU, F = 12.823, P = 0.001]. The percentage of pulmonary arteries exceeding optimal attenuation (> 250 HU) in groups B was lower than that in group T [n = 21(70.0%), n = 29(96.7%), χ² = 5.88, P < 0.05]. The enhancement value of pulmonary parenchyma in group B was lower than that in group T (the right lung (29 ± 8)vs(34 ± 8) HU, -2.401, P = 0.020; the left lung (30 ± 7)vs(36 ± 9)HU, t = -2.493, P = 0.016; total (30 ± 7)vs(35 ± 8) HU, t = -2.495, 016). The image quality of CTPA in group B was poorer than that in group T (U = 619.5, P < 0.05 = 0.708), while the artifacts of lung perfusion image in group B was less than that in group T (U = 162.5, P < 0.05, Kappa = 0.796). Conclusion: The test bolus technique has a better image quality of CT pulmonary angiography and a higher lung perfusion blood volume compared with the bolus tracking technique by using 60 ml contrast medium and 35 ml saline. (authors)

[en] By studying uranium metallogenic character, it is pointed out that the uranium mineralization in this area is controlled jointly by migmatite zone of metamorphic schist, transitional facies of the granite body edge, later veins, structural system and hydrothermal alteration. The prospecting criteria in this area of uranium, such as rock marks, structural sign, altered signs and radiological signs, were pointed out. It is indicated that the key regions which could be found altered cataclastic rock type uranium deposits in Qimantage area are the edges of granites both sides of Qimantage backbone fault. (authors)

[en] The paleo-landmass and its margin are important uranium metallogenic regions. Statistics show that 47% uranium deposits are located in the paleo-landmass or its margin in China. In response to these phenomena,a series of data investigation have been carried out to preliminarily summarize the relationship between paleo-landmass and uranium mineralization. On one hand, the paleo-landmass is believed to be the oldest mature crust and has the high uranium content Which can provide the material source for uranium mineralization. On the other hand, there existed significant crust-mantle circulation and frequent magmatic-hydrothermal activities around the paleo-landmass which are favorable for uranium mineralization. These factors make the paleo-landmass and its margins become the uranium concentration area and control the space-time distribution of uranium deposits to some extent. (authors)

[en] Transparent glass ceramics embedded with YbOF: Er${}^{3+}$ nanocrystals were successfully prepared by melt quenching and cooling methods. The structure and morphology of the YbOF nanocrystals were confirmed by X-ray diffraction, selected area electron diffraction, and transmission electron microscopy. The significant enhancement of upconversion luminescence confirms the doping of Er${}^{3+}$ into the precipitated YbOF nanocrystals. Furthermore, the temperature dependence of the upconversion luminescence was systematically investigated using the fluorescence intensity ratio (FIR) technique under 980 nm excitation. The FIR of the two thermally coupled energy levels of Er${}^{3+}$ ion was validated to be suitable used as temperature probes. The maximum thermal relative sensitivity is about 1.02% K${}^{-<!--\; ???\; -->1}$ at 300 K. The results indicate that glass ceramics embedded with YbOF: Er${}^{3+}$ nanocrystals can be used as candidates for temperature sensing.

[en] This paper introduces the development processes of database for the evaluation of national uranium resources potential in the aspects of database structure, map edit, data entry and data checkup. The database has been build-up with the integration technology of organization, storage and management, which is important and significant for future data management and dynamic evaluation of national uranium resources potential. (authors)

[en] GIS evaluation system for sandstone-type uranium deposits is based on uranium geology, it consists of data management, analysis, visualization etc. This paper introduces the study and development of GIS evaluation system for sandstone-type uranium deposits, and describes the main functions of the system, such as data management, bore hole data analysis, spatial data analysis, metallogenic prognosis, information extraction and so on. (authors)

[en] Modal parameter identification is a mature technology. However, there are some challenges in its practical applications such as the identification of vibration systems involving closely spaced modes and intensive noise contamination. This paper proposes a new time-frequency method based on intrinsic chirp component decomposition (ICCD) to address these issues. In this method, a redundant Fourier model is used to ameliorate border distortions and improve the accuracy of signal reconstruction. The effectiveness and accuracy of the proposed method are illustrated using three examples: a cantilever beam structure with intensive noise contamination or environmental interference, a four-degree-of-freedom structure with two closely spaced modes, and an impact test on a cantilever rectangular plate. By comparison with the identification method based on the empirical wavelet transform (EWT), it is shown that the presented method is effective, even in a high-noise environment, and the dynamic characteristics of closely spaced modes are accurately determined.

[en] A nonlinear dynamic model of a one-dimensional photonic crystal nanocavity resonator is presented. It considers the internal tensile stress and the geometric characteristics of a photonic crystal with rectangular (and circular) holes. The solution of the dynamic model shows that the internal tensile stress can suppress the hardening and softening behaviors of the resonator. However, the stress can reduce the amplitude, which is not conducive to an improvement of the sensitivity of the sensor. It is demonstrated that with an optimized beam length, the normalized frequency drift of the beam can be stabilized within 1% when the optical power increases from 2 mW to 6 mW. When the hole size of the resonator beam is close to the beam width, its increase can lead to a sharp rise of the resonant frequency and the promotion of hardening behavior. Moreover, the increase in the optical power initially leads to the softening behavior of the resonator followed by an intensification of the hardening behavior. These theoretical and numerical results are helpful in understanding the intrinsic mechanism of the nonlinear response of an optomechanical resonator, with the objective of avoiding the nonlinear phenomena by optimizing key parameters.

[en] This paper introduced the research idea of data management and application system for the evaluation of national uranium resources potential from aspects of requirement analysis, system design, function structure and etc. The system has been constructed on GIS platform with the basic function of management of spatial database, entry, edit, visual querying and output. (authors)

[en] This paper presents characterization and modeling for viscoelastic hysteresis exhibited by dielectric elastomer actuator (DEAs). Firstly, output–input characteristics in terms of hysteresis, asymmetry and output nonlinearity are quantitatively described by proposed indicators. Their variations with the excitation frequency are investigated, revealing significant asymmetric property and strong frequency-dependence. Next, the Hammerstein model with a cascaded structure is proposed for viscoelastic hysteresis description. A modified Prandtl–Ishlinskii model, representing the static nonlinear element, is employed to characterize the asymmetric property of static hysteresis, while a finite-impulse-response based adaptive filter as the linear part captures the dynamic effect. The hysteresis loops of DEAs under the input voltages with different frequencies, waveforms and amplitudes are experimentally measured and compared with those predicted results. The relative error in terms of root-mean-square value ranges from 1.92% to a maximum of 5.53% over a wide frequency range of 0.1–10 Hz, demonstrating the effectiveness of the proposed model of rate-dependent hysteresis in DEAs. This work can be useful to promote the applications of DEAs to soft robotics and haptics. (paper)