托卡马克中带电粒子的直接损失问题研究

首次发现了托卡马克中存在迥异于通行粒子和香蕉粒子的第三种粒子, 这种粒子会由于漂移运动而摆脱磁场的约束. 研究了该类粒子在其速度空间上的类磁镜损失锥, 给出了这一损失锥的数学表达式, 分析了存在这一类粒子的物理成因, 模拟与数学分析的结果基本一致. 研究还发现, 回旋半径在二阶条件下带电粒子的轨道损失高于零阶情况, 且与装置参数密切相关.     

Nonlinear analysis of a rub-impact rotor supported by turbulent couple stress fluid film journal bearings under quadratic damping

This work reports a numerical study undertaken to investigate the dynamic response of a rotor supported by two turbulent flow model journal bearings with nonlinear suspension and lubricated with couple stress fluid under quadratic damping. This may be the first time that analysis of rotor-bearing system considered the quadratic damping effect. The dynamic response of the rotor center and bearing center are studied. The analysis methods employed in this study are inclusive of the dynamic trajectories of the rotor center and bearing center, power spectra, Poincaré maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The modeling results provide some useful insights into the design and development of rotor-bearing system for rotating machinery that operates at highly rotational speed and highly nonlinear regimes.     

Non-linear dynamic analysis of a HSFD mounted gear-bearing system

An investigation is carried out on the systematic analysis of the dynamic behavior of the hybrid squeeze-film damper (HSFD) mounted a gear-bearing system with strongly non-linear oil-film force and gear meshing force in the present study. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless unbalance coefficient, damping coefficient and the dimensionless rotating speed ratio as control parameters. The non-dimensional equations of the gear-bearing system are solved using the fourth order Runge-Kutta method. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, bifurcation diagrams, maximum Lyapunov exponents and fractal dimension of the gear-bearing system. The results presented in this study provide some useful insights into the design and development of a gear-bearing system for rotating machinery that operates in highly rotating speed and highly non-linear regimes.     

In-situ Raman Studies on the Oxide Species of Cathode in MCFC

In MCFC the mechanism of cathode reaction is more complex than that of anode reaction. It is very important to clarify the reaction mechanism of cathode in order to direct the selection of cathode materials. The oxide species present in molten carbonate is the key to understand the mechanism of cathode reaction. Although there have been many papers to discuss the oxide species formed at cathode, no general conclusions have been reached so far, some results even contradicted. Appleby and Nicholson stated that peroxide ion appears to be the predominant species in the Li/K eutectic, but some other researchers concluded that the dominant species is superoxide ion in this melt.     

AFM Study on the Surface of Reinforcing Steel in Simulated Concrete Pore Solution

Atomic Force Microscopy (AFM) is a powerful technique to study corrosion processes in the μm- and nm- range because it is able to provide real space images of the surface with high spatial resolution while the operation is simple and fast and the sample is free from exposure to high vacuum atmosphere in which some properties may deviate from those under common pressure. Microscopic study on the topography of the surface layer of passivated metal is of great importance to abstaining better understanding of localized corrosion, especially the early stage of this process. In this paper a systematic AFM study on steel in simulated concrete pore solution (SPS) was carried out in order to illustrate the relationship between the stability of passive film at the surface of the steel and aggressive species in the solution and evaluate the effect of several inhibitors on corrosion resistance of reinforcing steel.     

Electrochemical Processing of Reaction-bonded Ceramic Composite Coatings

Ceramic matrix composite coatings are currently of much interest for application in high-temperature and highly corrosive environments. Formation of ceramic coatings by electrochemical processing is a relatively new mean^[1-2]. It presents several advantages over alternative coating techniques, the thickness and morphology of the deposit can be controlled by the electrochemical parameters, relatively uniform deposits are obtainable on complex shapes, the deposition rate is higher than that using most other methods and the equipment required is of low cost Recently we developed a novel fabrication technique for the production of ceramic/ceramic and ceramic/metal composite coatings by electrochemical processing^[3]. The technique combined two electrochemical deposition methods, electrophoretic deposition (EPD) and electrolytic deposition (ELD), which can produce uniform composite layers of closely controlled thickness on both metallic and ceramic substrates at ambient temperature with inexpensive equipment. However, the main problem associated with electrochemical processing is the difficulty in sintering of the coatings. First, high temperature is required for sintering of the coatings. Secondly, the volume shrinkage of the coatings during sintering leads to the formation of cracks in coatings bonded to metal substrates. So a reaction forming technique, reaction bonding process, also has been developed to produce near net-shape ceramic coatings, which overcome problems caused by the shrinkage of ceramics during sintering.     

Investigation of odd-parity Rydberg states of Eu I with autoionization detection

Isolated-core-excitation (ICE) scheme and autoionization detection are employed to study the bound Rydberg states of europium atom. The high-lying states with odd parity have been measured using the autoionization detection method with three different excitation paths via 4f⁷6s6p[ ⁸P_5/2], 4f⁷6s6p[ ⁸P_7/2] and 4f⁷6s6p[ ⁸P_9/2] intermediate states, respectively. In this paper the spectra of bound Rydberg states of Eu atom are reported, which cover the energy regions from 36000~cm^-1 to 38250~cm^-1 and from 38900~cm^-1 to 39500 cm^-1. The study provides the information about level energy, the possible J values and relative line intensity as well as the effective principal quantum number n^* for these states. This work not only confirms the previous results of many states, but also discovers 11 new Rydberg states of Eu atom.     

Spin-Polarized States of Nuclear Matter

The equations of state of spin-polarized nuclear matter and pure neutron matter are studied in theframework of the Brueckner-Hartree-Fock theory including a three-body force. The energy per nucleon E A (δ) calculatedin the full range of spin polarization δ = (ρ↑ - ρ↓)/ρ for symmetric nuclear matter and pure neutron matter fulfills aparabolic law. In both the cases the spin-symmetry energy is calculated as a function of the baryonic density alongwith the related quantities such as the magnetic susceptibility and the Landau parameter Go. The main effect of thethree-body force is to strongly reduce the degenerate Fermi gas magnetic susceptibility even more than the value withonly two-body force. The equation of state is monotonically increasing with the density for all spin-aligned configurationsstudied here so that no any signature is found for a spontaneous transition to a ferromagnetic state.     

D-氨基葡萄糖Schiff碱及其金属配合物的抗菌活性

The effects of D-glucosamine schiff base and its metal complexes on the growth of Aerobacter aerogenes were investigated by the microcalorimetry. Among the substances tested. Zn-SG was shown to be the most bacteriostasic, followed by Zn-o-VG and SG (with the Ic50 of 242, 287 and 320 μg•mL-1, respectively). Cu(Ⅱ)-SG showed less inhibitory effect on Aerobacter aerogenes over the concentration rang of 50~300μg•mL-1.     

钛醇盐电化学合成的研究

采用钛金属为“牺牲”阳极,首次在无隔膜电解槽中,电化学一步法制备了纳米TiO~2前驱体钛醇盐Ti(OEt)~4,Ti(OPr-i)~4,Ti(OBu)~4。产物通过元素分析、红外光谱(FT-IR)、拉曼光谱进行表征。电化学一步法直接制备纳米材料前驱体钛醇盐,克服了传统化学方法合成金属醇盐步骤多、产率低、纯度达不到要求及后续分离繁琐等缺点。本文同时讨论了影响电合成钛醇盐的关键因素及可能的反应机理,实验表明钛在醇溶液中呈点蚀行为,钛醇盐卤化物Ti(Ⅲ)(OR)~nBr~m在阳极形成,然后被氧化为Ti(Ⅳ)(OR)~nBr~m,这种物质在阴极上ROH参与下被还原生成钛醇盐Ti(OR)~4,钛阳极表面拉曼光谱证实了上述观点。防止阳极钝化,温度控制在50～60℃之间,彩有机胺溴化物为导电盐,可以提高电合成收率。