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[en] The authors have constructed and tested a supersonic beam machine. The vacuum system of this machine consists of three vacuum chambers, three diffusion pumps, three mechanical pumps and one turbo molecular pump. The detecting system of the machine includes a time-of-flight mass spectrometer, a high-speed lens system with a monochromator and a quadrupole mass spectrometer. The machine is equipped with a two-stage Haensch dye laser pumped by an excimer pulsed laser and controlled by a PDP 11/73 computer through CAMAC. Nozzles and skimmers are the crucial elements of the beam machine. The authors have tested different types of pulsed nozzles and skimmers. Both theory and experimental results are presented. By modifying a General Valve solenoid pulsed nozzle, Xe clusters with size up to n = 15 have been detected. Some problems of pulsed nozzles are discussed. The development of the time-of-flight mass spectrometer was a major part of the experiment, and is discussed in detail from simplest design to double-field with an ion reflector. Xenon cluster ions up to n = 15 can be clearly distinguished with a very short drift tube (about 20cm). The authors also suggest a new design-a double-reflector time-of-flight mass spectrometer. With the beam machine, the authors have measured the excitation spectra of Xe dimers formed in the supersonic beams by two-photon resonant, three-photon photoionization in the vicinity of Xe* 6p[1/2]0, 6p[3/2]2, and 6p[5/2]2, similar to the work by Dehmer et al., and Lipson et al. [Dehmer et al., J. Chem, Phys. 85, 13 (1986); Lipson et al., J. Chem. Phys. 90, 9 (1989)]. Simultaneously, fluorescence was measured in the infrared. Similar techniques are applied to small Xe clusters (n = 3, 4, 5). Some preliminary spectra are reported
[en] In this study, a new polymeric ionic liquid-based adsorbent was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE) of three organic acid preservatives, namely, p-hydroxybenzoic acid, sorbic acid and cinnamic acid. The adsorbent was synthesized by the copolymerization of 1-ally-3-vinylimidazolium chloride (AV) and divinylbenzene (DVB) in the presence of a porogen solvent containing 1-propanol and 1,4-butanediol. The effect of the content of monomer and the porogen solvent in the polymerization mixture on the extraction performance was investigated thoroughly. The adsorbent was characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. To obtain the optimal extraction conditions of SCSE/AVDVB for target analytes, key parameters including desorption solvent, adsorption and desorption time, ionic strength and pH value in sample matrix were studied in detail. The results showed that under the optimized conditions, the SCSE/AVDVB could extract the preservatives effectively through multiply interactions. At the same time, a simple and sensitive method by combining SCSE/AVDVB and high-performance liquid chromatography with diode array detection was developed for the simultaneous analysis of the target preservatives in orange juices and tea drinks. Low limits of detection (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target analytes were achieved within the range of 0.012–0.23 μg/L and 0.039–0.42 μg/L, respectively. The precision of the proposed method was evaluated in terms of intra- and inter-assay variability calculated as relative standard deviation (RSD), and it was found that the values were all below 10%. Finally, the proposed method was used to detect preservatives in different orange juice and tea drink samples successfully. The recoveries were in the range of 71.9–116%, and the RSDs were below 10% in the all cases. - Highlights: • A new polymeric ionic liquid-based adsorbent was prepared. • The adsorbent was used as the extractive medium of SCSE. • The multiply interactions involved the extraction of preservatives. • Method of determination of preservatives in juice and tea drinks was developed.
[en] Air ingress, one of the beyond design basis accidents for high temperature gas-cooled reactors, receives high attention during the design of the 250 MW pebble-bed modular high temperature gas-cooled reactor (HTR-PM), because it may result in severe consequence including the corrosion of the fuel element and graphite reflector. The diffusion process and the set-up time of the stable natural convection after the double-ended guillotine break of the hot-gas duct are studied in the paper. On the basis of the preliminary design of the HTR-PM and its DLOCA analysis results, the diffusion process, as well as the influence of the core temperature distribution and the length of the hot-gas duct, is studied with the DIFFLOW code, which adopts a one-dimension variable cross-section diffusion model with fixed wall temperature. To preliminarily estimate the influence of chemical reaction between oxygen and graphite, which will change the gas component of the mixture, the diffusion processes between the He/N2, He/O2, He/CO and He/CO2 are calculated, respectively. Furthermore, the code has been improved and the varying wall temperature can be simulated. The more accurate analysis is carried out with the changing temperature distribution from the DLOCA calculation. The analysis shows that there is enough time to adopt appropriate mitigation measures to stop the air ingress and the severe consequence of fuel element damage and large release of fission product can be avoided
[en] White-light scanning interferometry (WLSI) is a useful technique to measure surface profile when a test object contains discontinuous structures or microstructures. A black and white CCD camera is usually utilized to capture interferograms, and a series of corresponding algorithms is used to achieve the profile measurement. However, the color information in the interferograms is lost. A novel profile measurement method that uses phase information in different color channels (red-green-blue) of an interferogram obtained using a three-chip color CCD in WLSI is proposed. The phase values are extracted by a windowed Fourier transform algorithm. Simulation and experimental results are presented to demonstrate the validity of the proposed method.
[en] Adherent Cu films were electrodeposited onto polycrystalline W foils from purged solutions of 0.05 M CuSO4 in H2SO4 supporting electrolyte and 0.025 M CuCO3Cu(OH)2 in 0.32 M H3BO3 and corresponding HBF4 supporting electrolyte, both at pH 1. Films were deposited under constant potential conditions at voltages between -0.6 V and -0.2 V vs. Ag/AgCl. All films produced by pulses of 10 s duration were visible to the eye; copper colored, and survived the Scotch tape test. Characterization by scanning electron microscopy (SEM)/energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of metallic Cu, with apparent dendritic growth. No sulfur impurity was observable by XPS or EDX. Kinetics measurements indicate that the Cu nucleation process in the sulfuric bath is slower than in the borate bath. In both baths, nucleation kinetics does not correspond to either instantaneous or progressive nucleation. Films deposited from 0.05 M CuSO4/H2SO4 solution at pH>1 at -0.2 V exhibited poor adhesion and decreased Cu reduction current. In both borate and sulfate baths, small Cu nuclei are observable by SEM upon deposition at higher negative overpotentials, while only large nuclei (approx. 1 μm or larger) are observed upon deposition at less negative potentials
[en] The thermal shock performances of ITER-like high purity tungsten were examined by an electron beam heat load test and finite element code simulation. Experiments under ITER-like plasma major disruption instability happening condition with test sample background temperature at room temperature were simulated by an electron beam facility EMS-60 newly constructed. Recrystallization, cracking and melting behaviors of test sample after irradiation tests were observed by a scanning electron microscopy (SEM) and their formation mechanisms have been discussed. Finite element simulation has been carried out by ANSYS code and the result shows that the cracking threshold of ITER grade tungsten is about 1.5 MJ·m"-"2 for 5 ms pulse loading, which is in accordance with experimental results. (authors)
[en] Experiments about stability operation region (SOR) on HT-7 and high plasma parameters in Ohmic discharge are performed. Two boundaries of low density limit and Murakami density limit are scanned out through about 80 shots. The Murakami limit Mmax=2.96x1019 m-2/T and Hugill number H=9.5x1019 m-2/T are obtained. On the Murakami boundary, the radiation characters are specially analyzed. Coupling of m=1 and m=2 modes leads impurities from boundary to core, then line radiation of those impurities causes energy quenching inside and near q=1 surface and finally disruption occurs. This kind of disruption restricts Murakami density limit. (author)
[en] Stress intensity factor is one of the most important parameters in fracture mechanics. Both the stress field distribution and the crack propagation are closely related to these parameters. Due to the complexity of actual engineering problems, it is difficult to calculate the stress intensity factor by theoretical formulation, so photoelasticity method is a good choice. In this paper, modified two parameter method is employed to calculate stress intensity factor for opening mode by using data from more than one photoelastic fringe loop. For getting accurate experiment results, the initial fringes are doubled and sharpened by digital image programs from the fringe patterns obtained by a CCD camera. Photoelastic results are compared with those obtained by the use of empirical equation and FEM. Good agreement shows that the methods utilized in experiments are considerably reliable. The photoelastic experiment can be used for bench mark in theoretical study and other experiments
[en] Highlights: • SAPG with concentrating and non-concentrating collectors has been compared. • Non-concentrating collectors could be superior to concentrating collectors in SAPG. • Using non-concentrating collectors is more effective in low latitude. - Abstract: The preheating of the feedwater in a Regenerative Rankine Cycle power plant with solar thermal energy, termed Solar Aided Power Generation, is an efficient method to use low to medium temperature solar thermal energy. Here, we compared the use of medium temperature (200–300 °C) energy from concentrating solar collectors (e.g. parabolic trough collectors) to displace the extraction steam to high temperature/pressure feedwater heaters with that from low temperature (100–200 °C) non-concentrating solar collectors (e.g. evacuated tube collectors) to displace the extraction steam to low temperature/pressure feedwater heaters of the power plant. In this paper, the in terms of net land based solar to power efficiency and annual solar power output per collector capital cost of a Solar Aided Power Generation using concentrating and non-concentrating solar collectors has been comparted using the annual hourly solar radiation data in three locations (Singapore; Multan, Pakistan and St. Petersburg, Russia). It was found that such a power system using non-concentrating solar collectors is superior to concentrating collectors in terms of net land based solar to power efficiency. In some low latitude locations e.g. Singapore, using non-concentrating solar collectors even have advantages of lower solar power output per collector capital cost over using the concentrating solar collectors in an SAPG plant.
[en] In this manuscript, porous Co3O4 nanorods are prepared through a two-step approach which is composed of hydrothermal process and heating treatment as high performance anode for lithium-ion battery. Benefiting from the porous structure and 1-dimensional features, the product becomes robust and exhibits high reversible capability, good cycling performance, and excellent rate performance. - Graphical abstract: 1D porous Co3O4 nanostructure as anode for lithium-ion battery with excellent electrochemical performance. - Highlights: • A two-step route has been applied to prepare 1D porous Co3O4 nanostructure. • Its porous feature facilitates the fast transport of electron and lithium ion. • Its porous structure endows it with capacities higher than its theoretical capacity. • 1D nanostructure can tolerate volume changes during lithation/delithiation cycles. • It exhibits high capacity, good cyclability and excellent rate performance