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[en] A new rectangular pulse trigger generator has been developed which can generate two 10 kV pulses with a risetime less than 1 ns, a jitter of 0.2 ns and a width of about 10 ns and 40 ns, respectively. This generator uses two polymer-foil switches and 25 ohm Blumlein transmission lines composed of two-parallel standard coaxial cables discharging into two 50 ohm output cables. The pulse width and the delay between two pulses can be adjusted by changing the length of the cables
[en] Highlights: • The significant electrocatalytic effects of imidazolium salts are due to a strong ion-pairing. • DFT calculation predicts the ion pair [BMIM"+][CO_2"."−] conformation. • The extent of ion-pairing decreases with increasing the size of the alkyl substituent. - Abstract: The roles of ion pairing on CO_2 electroreduction involving imidazolium-based salts are explored on an Ag electrode in a DMF solution. The electroreductive behaviours of CO_2 and the IR results establish the dominant role of the cation of imidazolium-based salts in CO_2 electrocatalytic reduction process. Density functional theory (DFT) calculations predict that the ion pair formation is mainly driven by the attraction of the four nearby and positively charged hydrogen atoms which are at the C2, N1 and N3-positions of an imidazolium cation for the negatively charged oxygen atoms in the CO_2"."− species. The electrostatic interaction between an imidazolium cation and the CO_2"."− species decreases with increasing the size of the alkyl substituent at the N1-position of that imidazolium cation
[en] This article describes the working principle of scintillation detector for measuring radon, presents the application of new materials and techniques to achieve the technical performance. Through the test application and measurement result comparison, the instrument is proven feasible in design and reliable in performance. (authors)
[en] This paper calculates the conservative radioactive source term released to the containment based on the assumptions specified in NUREG-1465 and IAEA-TECDOC-1127, using some of the available information of Fukushima Dai-ichi NPP. A series of environmental release source terms is obtained with the consideration of the parameters such as the cumulative amount of the radioactive material and the de- contamination factor in suppression pool. Moreover, this paper calculates the equivalent dose after accident using the models and parameters in some related technical documents. The containment radioactive releases and the resultant doses, which are based on two assumptions mentioned above, are analyzed and compared. In conclusion, this paper does make sense for the quick establishment of the severe accident source term and the accident consequences estimation in nuclear power plant. (authors)
[en] A 20 kV, 1 ns risetime pulsed electron beam source was developed using an extremely small gap (0.1 mm) diode driven by a sub-nanosecond risetime, 10 kV rectangular pulse generator. A beam current of 5 A was detected by using a fast response Faraday cup at a distance of 2 cm away from a grid anode. The shot to shot variation of the electron beam pulse was less than 10%
[en] Conservative source term of radioactive release to the environment is calculated after the accident at Fukushima Daiichi nuclear power station based on updated informational materials and the assumptions made in NUREG-1465 by U.S. Nuclear Regulatory Commission (U.S. NRC), with the consideration of the various uncertainties. And a series of atmospheric dispersion factors are obtained from U.S. NRC Regulatory Guide 1.4 (RG 1.4). Finally,this paper provides calculation of the accidental dose, which is analyzed and assessed specifically, using the models and parameters in ICRP Publication 71, FGR 12 and so on. (authors)
[en] A tunable surface plasmon resonance based on polarization beam splitter (PBS) is proposed by using a dual-core photonic crystal fiber with magnetic fluid. Propagation characteristics of the PBS are analyzed by finite element method. The resonance wavelength which satisfied the phase matching condition shifts when change external magnetic field. Simulation results show that incident light wavelengths with a wide range of 1.45–m can be split, the minimum bandwidth of 168 nm and the extinction ratio can reach to − 128 dB when external magnetic field range 400–760 Oe at the same structure.These properties make the splitter we proposed a competitive candidate for fiber beam splitter.
[en] In this study, a combustion study of tire pyrolytic carbon black (CBp), gas coal (GC), and their blends was carried out by thermogravimetric analysis with four heating rates under air atmosphere. And the structure characteristics of CBp and GC were studied using particle size distribution, scanning electron microscope, X-ray diffraction, Raman spectra followed by peak deconvolution and data analysis. The results demonstrated that the structural differences between CBp and GC directly affected their thermal behavior trends. GC with low graphitization degree had more combustibility reactivity than that of CBp, while the mean reaction rate and maximum reaction rate of CBp were larger than GC due to its bigger specific surface area and higher porosity. For blends, the combustibility reactivity could be improved by blending with GC, and there was obviously synergetic effect for the co-combustion of CBp and GC. The combustion reaction mechanisms and kinetic parameters were carried out using three non-isothermal kinetic models: random nucleation nuclei growth model (RNGM), volume reaction model, and unreacted core model. The kinetic analysis demonstrated that the RNGM model had a better performance than other models for describing the thermal behavior of the selected samples. In addition, the synergetic effect between CBp and GC was observed from the kinetics data calculated by RNGM. The activation energies of CBp and GC calculated by RNGM model were 119.6 kJ mol−1 and 126.4 kJ mol−1, respectively, whereas the lowest activation energy for their blends was 104.3 kJ mol−1 when CBp ratio was 40%.
[en] A quasi-D-shaped photonic crystal fiber plasmonic sensor with a rectangular lattice is proposed by using Au as a plasmonic layer and graphene to enhance the sensing performance. By moving the core to the edge of the fiber, a shorter polishing depth is achieved, which makes the fiber proposed have a greater mechanical strength than other common D-shaped fibers. Benefiting from the natural advantage of the rectangular lattice, the dual sensing channels make the proposed sensor show a maximum wavelength interrogation sensitivity of 3877 nm/RIU with the dynamic refractive index range from 1.33 to 1.42 and a maximum amplitude sensitivity of 1236 RIU−1 with the analyte RI = 1.41 in the visible region. The corresponding resolutions are 2.58 × 10−5 and 8.1 × 10−6 with the methods of the wavelength interrogation method and amplitude- or phase-based method. These advantages make the proposed sensor a competitive candidate for biosensing in the field of refractive index detection, such as water quality analysis, clinical medicine detection, and pharmaceutical testing. (paper)
[en] The catalytic activity of Mo-based catalysts prepared from (NH_4)_6Mo_7O_2_4 and (NH_4)_2MoS_4 was compared in the sulfur resistant methanation process. The catalyst using oxide precursor had relatively higher activity than the catalyst using sulfide precursor, and the presulfidation procedure almost had no effect on the catalytic performance of the catalyst using oxide precursor. In view of the characterization results, it could be supposed that the amorphous MoS_2 was more active for sulfur-resistant methanation than the crystalline MoS_2. The molybdenum sulfides and oxides with lower valence states (Mo"4"+, Mo"5"+) could be responsible for the catalytic activity and make a possible contribution to the carbon monoxide methanation in the reaction condition