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[en] Highlights: • A LES-VOF model is conducted to simulate atomization of coaxial swirling jets. • Structure and flow field of coaxial swirling jets are investigated. • Merging process occurs at the nozzle exit and generates additional perturbation. • The Rayleigh mode instability dominates the breakup of ligaments. - Abstract: Spray atomization process of a liquid-liquid coaxial swirl injector in bipropellant thruster has been investigated using volume of fluid (VOF) method coupled with large eddy simulation methodology. With fine grid resolution, detailed flow field of interacted liquid sheet has been captured and analyzed. For coaxial swirling jet, static pressure drop in the region between the liquid sheets makes two liquid sheets to approach each other and merge. A strong pressure, velocity and turbulent fluctuations are calculated near the contact position of two coaxial jets. Simulation results indicate that additional perturbations are generated due to strong radial and axial shear effects between coaxial jets. Observation of droplet formation process reveals that the Rayleigh mode instability dominates the breakup of the ligament. Droplet diameter and distribution have been investigated quantitatively. The mean diameter of the coaxial jets is between that of the inner and the outer jets. Compared with the individual swirling jets, wider size distributions of droplets are produced in the coaxial jets.
[en] Highlights: • Questions about the applicability, technical status, and future of MSW incineration in China are answered. • Comparison involves China, EU, U.S., Japan, South Korea, and Taiwan area. • MSW incineration is not out of date around the world. • The structure of MSW incineration technologies is changing in China. • Perspectives and suggestions are given for the compliance with the emission standard. - Abstract: With the rapid expansion of municipal solid waste (MSW) incineration, the applicability, technical status, and future improvement of MSW incineration attract much attention in China. This paper aims to be a sensible response, with the aid of a comparison between China and some representative developed regions including the EU, the U.S., Japan, South Korea, and Taiwan area. A large number of up-to-date data and information are collected to quantitatively and impartially support the comparison, which covers a wider range of key points including spatial distribution, temporal evolution, technologies, emissions, and perspectives. Analysis results show that MSW incineration is not an outdated choice; however, policy making should prevent the potentially insufficient utilization of MSW incinerators. The structure of MSW incineration technologies is changing in China. The ratio of plants using fluidized bed is decreasing due to various realistic reasons. Decision-makers would select suitable combustion technologies by comprehensive assessments, rather than just by costs. Air pollution control systems are improved with the implementation of China’s new emission standard. However, MSW incineration in China is currently blamed for substandard emissions. The reasons include the particular elemental compositions of Chinese MSW, the lack of operating experience, deficient fund for compliance with the emission standard, and the lack of reliable supervisory measures. Some perspectives and suggestions from both technical and managerial aspects are given for the compliance with the emission standard. This paper can provide strategic enlightenments for MSW management in China and other developing countries.
[en] A 600 kV Marx generator accompanied with a water compression line, an output switch and a diode component is designed to generate the X ray with low energy level and low dose rate. The diode parameters are follows: gap space of anode and cathode is 3∼5 mm; cathode with ring structure is a graphite electrode which diameter is 40 mm; the anode is a tantalum target with a thickness of l.5 mm and a diameter of 200 mm. The study results show that: when the output voltage of Marx generator reaches to 550 kV, the voltage drop of the diode is 196 kV. And a low energy level, small dose rate X ray can be obtained in front of the anode. The X ray at the distance of 30 mm before the anode surface has a half width of 20 ns. The total energy dose of the X ray on the center of anode surface is 8 rad and dose rate is 4 × lO"8 rad/s, which have been measured by the method of thermoluminescence dosimetry. (authors)
[en] In Deng et al. (Eur. Phys. J. C 70:113, 2010), we have dealt with the production of the two color-singlet S-wave (c anti b) -quarkonium states Bc(vertical stroke (c anti b)1[1S0] right angle) and B*c(vertical stroke (c anti b)1[3S1] right angle) through the Z 0 boson decays. As an important sequential work, we make a further discussion on the production of the more complicated P-wave excited (c anti b) -quarkonium states, i.e. vertical stroke (c anti b)1[1P1] right angle and vertical stroke (c anti b)1[3PJ] right angle (with J=(1,2,3)). More over, we also calculate the channel with the two color-octet quarkonium states vertical stroke (c anti b)8[1S0]g right angle and (c anti b)8[3S1]g right angle, whose contributions to the decay width maybe at the same order of magnitude as that of the color-singlet P-wave states according to the naive nonrelativistic quantum chromodynamics scaling rules. The P-wave states shall provide sizable contributions to the Bc production, whose decay width is about 20% of the total decay width ΓZ0→Bc. After summing up all the mentioned (c anti b) -quarkonium states' contributions, we obtain ΓZ0→Bc=235.9+352.8-122.0 KeV, where the errors are caused by the main sources of uncertainty. (orig.)
[en] Two kinds of self-breakdown water switches with different configurations for Qiangguang-I accelerator were described. The electrical model of the water switch was built. By estimation and Pspice calculation, the parameters of the switches were determined. The acquired breakdown characteristics of the two different switches by experiments were described by two different breakdown models. The critical field of the transfer switch could be calculated by J.C. Martin empirical expression about water breakdown with a mostly uniform field. The critical field of the output switch could be calculated by J.C. Martin expression about divergent field of point-plane electrodes. The experimental data of breakdown of water switch show that the above-mentioned methods for breakdown field calculation are reliable. (authors)
[en] Borate waste is the main waste from nuclear power plants. Glass is an acceptable waste form because of its ability to accept a wide range of components into its network structure. Vitrification of borate waste from nuclear power plants is an attractive approach from the viewpoint of environment and safety. Fly ash is a headache waste generated from the coal combustion power stations. Fly ash contains high contents of SiO2 and Al2O3, which are also the most important glass structure formers. This project takes fly ash as a main additive to vitrify borate waste. Na2O, the only non-waste additive was added, in order to decrease the melting temperature. The experimental results indicate that glasses with ∼ 60 wt% of fly ash, ∼ 30 wt% of borate waste, and ∼ 10 wt% of Na2O have good chemical durability and good processability. This approach not only obtained the minimum cost, but also find a treatment method for the industrial waste
[en] As the fundament of wire array Z pinch experiment, the design of the load is very important. In this paper, the slug model is introduced. On the basis of analyzing the principle of the model, the wire array experiment results on Saturn generator are used to test the model and the program. The calculation results prove the program is of better reliability and practicality. After analyzing Qiangguang I generator's circuit and getting the electric parameters of the generator, the wire array experiments on the Qiangguang I are simulated by the slug model. The calculated load current results well agree with the experiment results and the errors are within 5%. This indicates that the slug model will be helpful to the design and the experiments on Qiangguang I generator
[en] A dualband terahertz (THz) absorber including periodically distributed cross-shaped graphene arrays and a gold layer spaced by a thin dielectric layer is investigated. Numerical results reveal that the THz absorber displays two perfect absorption peaks. To elucidate the resonant behavior, the LC model is introduced to fit the spectra. Moreover, the strength and linewidth of the absorption peak can be effectively tuned with structural parameters and the relaxation time of graphene. Owing to its rotational symmetry, this THz absorber exhibits polarization insensitivity. Our designed absorber is a promising candidate in applications of tunable optical sensors and optical filters. (paper)
[en] In this work, plasmon-induced transparency has been realized with graphene metamaterial consisting of double asymmetric L strips. Due to the weak hybridization between this two L strip resonator, a clear transparency window on the transmission spectrum of the originally opaque frequency range can be realized. With a Lorentz coupled oscillator model, our theoretical results of the transmission spectra agree well with the numerical calculations. Moreover, the transparency window can be dynamically modulated via regulating the Fermi energy and carrier mobility. The reflection and absorption spectrum has also been analyzed concretely, and its absorption rate approaches as high as 50%, which provides a solid application in terahertz absorbers. According to the effective medium theory, the sensitivity of the transparency window as a function of the surrounding medium embodies a linear relationship. As for its dispersion behavior, the group index of the structure can reach up to 1125. This work shadows a fascinating application in the area of highly integrated sensor devices, filters or absorbers. (paper)
[en] Because of incongruent melting, phase separation occurs when CsLiLaBr:Ce (CLLB:Ce) is grown from a melt using stoichiometric raw materials. In this study, raw materials with different amounts of excess LiBr are used to grow CLLB:Ce crystals. It is found that enough excess of LiBr is beneficial to the crystal growth of CLLB:Ce. A transparent 1 × 2‐in. CLLB:Ce single crystal is successfully grown by the vertical Bridgman method. The differential scanning calorimeter‐thermogravimetric analysis (DSC‐TG), X‐ray diffraction, and inductively coupled plasma mass spectrometry results are used to understand the crystallization behavior at different stages of the crystal growth process. The luminescence and related scintillation properties of the CLLB:Ce single crystal are investigated. The relative light output of the CLLB:Ce single crystal is about 48 000 ph MeV, which is 80% that of the LaBr:Ce crystal. The energy resolution of the CLLB:Ce single crystal is 4.0% at Cs 662 keV. (© 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)