[en] The design of the plasma density feedback control system (PDFCS) is described. The design requirements of the feedback control system including hardware and software are proposed to approach the plasma density reference value and then a discussion of 'how to realize the feedback control' is given. The experimental results show that the feedback control system satisfies the real-time and stable control. (authors)

[en] The vacuum system for HL-2A was built in 2003. The test results indicated that this system is feasible. It consists of three main parts: a pumping system, a pumping divertor and a glow discharge cleaning (GDC) system. For the pumping system, there are three main functions: (1) evacuating the vacuum vessel thus to produce an ultra high vacuum, (2) removal of impurities released during baking and (3) pumping during GDC. The pumping divertor controls the particles at the plasma edge and the GDC system provides a clean wall conditioning. During the first campaign of physical trial experiment on HL-2A, the ultimate pressure reached 4.6 x 10^-6 Pa, and the total leakage and outgassing rate in 12 hours was 1.8 x 10^-5 Pa·m³/s, which is close to that of ASDEX. (authors)

[en] The gas analysis and testing system of quadrupole mass spectrometer was designed to research leak calibration, discrimination between helium and deuterium, and leak testing technology. The paper describe the structure of vacuum chamber, selection of pumping equipment, choice of measuring instruments, and working mode of control protection subsystem. The performance experiments of the system, including ultimate vacuum, mass spectrometric analysis of residual gas, leak and outgassing rate, and performance of mass spectrometer, are given. The experimental results show that the gas analysis and testing system satisfies our design requirements. (authors)

[en] The performance test of gas pressure measuring and analysis system for quadrupole mass spectrometer was carried out. The ultimate vacuum is 7.3 × 10"-"7 Pa after the system was baked, and total leak rate is 3.84 × 10"-"9 Pa·m"3·s"-"1. The pressure relationship between upper and lower chamber is linear dependence. So is the relationship of the helium leak rate and partial pressure. The results meet the design requirements of dynamic flow conductance, and provide basic conditions for mass spectrograph analysis. (authors)

[en] In this Letter, we introduce a new method of image stacking to directly study the undetected but possible γ-ray point sources. Applying the method to the Australia Telescope 20 GHz Survey sources which have not been detected by Large Area Telescope on the Fermi Gamma-ray Space Telescope, we find that the sources contribute (10.5 ± 1.1)% and (4.3 ± 0.9)% of the extragalactic gamma-ray background (EGB) and have a very soft spectrum with the photon indices of 3.09 ± 0.23 and 2.61 ± 0.26 in the 1-3 GeV and 3-300 GeV energy ranges, respectively. In the 0.1-1 GeV range, they probably contribute a larger fraction to the EGB, but it is not quite certain. It may not be appropriate to assume that the undetected sources have similar properties to the detected sources.

[en] The basic design of a reliable vacuum system for the HL-2A tokamak is presented. It consists of the main pumping system, pumping divertor and glow discharge cleaning (GDC) system. The main pumping system provides the pumping capability for the high vacuum of chamber, outgassing by baking and GDC. The pumping divertor initially realizes the pumping and control of edge particles in tokamak discharge. The GDC system ensures the good wall condition of the device. The preliminary operation and the data obtained with these systems are also presented. The base pressure is 4.6 x 10^-6 Pa, in the preliminary physical experiment operation of the HL-2A tokamak, and the total leak and outgassing rates of vacuum chamber is below 1.8 x 10^-5 Pa·m³·s^-1 in 12 hours. (author)

[en] The external Compton (EC) model is used to study the high energy emission of some blazars, in which the external photon field is considered to dominate inverse Compton radiation. We explore the properties of the external photon field through analyzing the FERMI LAT bright AGN sample within three months of the start of operations in sky-survey mode. In the sample, assuming the high energy radiation of low synchrotron peaked blazars is from the EC process, we find that the external photon parameter U_ext/ν_ext may not be a constant. Calculating synchrotron and inverse Compton luminosity from the quasi-simultaneous broadband spectral energy distributions, we find that they have an approximately linear relation. This indicates that the ratio of external photon and magnetic energy density is a constant in the comoving frame, implying that the Lorentz factor of the emitting blob depends on the external photon field and magnetic field. The result gives a strong constraint on the dynamic jet model.

[en] Objective: To explore the value of the dual-source dual-energy CT iodine imaging on blood flow characteristics of liver hydatid(HAE). Methods: A retrospective analysis of pre-operative dualsource dual-energy CT including a conventional abdominal scan and 3 phasic scans was performed in 18 patients with surgically and pathologically proven HAE(n = 18). The iodine values in different scanning(arterial phase, portal venous phase and parenchymal phase) and different organizational structures(hydatid tissues, normal liver tissues, edge tissue of the lesion and normal liver) were recorded. Pathological examination and micro- vessel density(MVD) count were performed in these different tissues. The iodine results of different phases and different tissues were compared with Rank test. The correlation of iodine value and MVD were performed with Spearman method. Results: MVD median of hydatid tissues, regional tissues, edge tissue of the lesion and normal liver were 0.00, 25.00 and 4.00/HPF respectively. The median iodine value of hydatid tissues in arterial phase, portal venous phase and parenchymal phase were 0.300, 0.150 and 0.150 mg/ml(Z = 1.216, P > 0.05) respectively. The median iodine value of edge tissue of the lesion and normal liver in 3 phases were 0.350, 2.150 and 2.550 mg/ml respectively. The median iodine values of normal liver tissues in 3 phases were 0.100, 1.600 and 1.900 mg/ml(Z values were 28.800 and 31.886, P < 0.01) respectively. In the same phase of arterial phase, portal venous phase and parenchymal phase, the iodine values showed statistically significant difference(P < 0.05). The iodine values of edge tissue of the lesion and normal liver in 3 phases showed significant difference between the arterial phase and portal venous phase(P < 0.017). The portal venous phase. (authors)

[en] Highlights: • This paper examines the financing efficiency of Chinese ECEP firms. • Financing efficiency of firms in Western and Central regions has been improved. • Banks are overall a better provider of green finance. • The policies issued supporting ECEP firms in 2013 and 2019 are more effective. With the implementation of a series of policies related to the energy conservation and environmental protection (ECEP) industry, green finance has become a crucial approach to provide credits for the ECEP industry. Using data on Chinese-listed ECEP firms from 2010 to 2019, this work quantitatively identifies the financing efficiency of these firms and its determinants. The main results show that banks are still dominant in the Chinese financial market for providing credits, and firms listed on the second board show higher financing efficiency. The financing efficiency of firms located in the central and western regions improves significantly, especially after 2016, reflecting the interaction effect of green finance policies and economic policies supporting underdeveloped regions. Both country-level factors (e.g., formal institutions and financial supervision) and firm-level factors (e.g., firm size and debt ratio) have an impact on financing efficiency. These findings have important implications for policymakers who are carefully contemplating green finance policies to support ECEP firms through an effective financial market mechanism, which eventually helps to realize the transition of the energy sector.

[en] In this work, in order to improve the dispersion and reinforcement of waterborne polyurethane (WPU), nano-SiO₂ was modified with a amphiphilic polymeric surfactant poly(propylene glycol) phosphate (PPG Phosphate) and oleic acid for comparison, then incorporated into WPU through in situ polymerization. The results show that both of the PPG phosphate and oleic acid were successfully grafted onto nano-SiO₂ surface and significantly improved its hydrophobic property. Scanning electron microscopy (SEM) observation reveals that PPG phosphate modified SiO₂ nanoparticles had good compatibility with WPU and uniformly dispersed into WPU matrix. The results also show that the tensile strength, water resistance and thermal stability were all significantly improved by incorporation of nano-SiO₂, especially PPG phosphate modified SiO₂, which was attributed to its good dispersion in WPU and strong interface adhesion. (paper)