Magnetic vortex core reversal by excitation with short bursts of an alternating field

The vortex state, characterized by a curling magnetization, is one of the equilibrium configurations of soft magnetic materials and occurs in thin ferromagnetic square and disk-shaped elements of micrometre size and below. The interplay between the magnetostatic and the exchange energy favours an in-plane, closed flux domain structure. This curling magnetization turns out of the plane at the centre of the vortex structure, in an area with a radius of about 10 nanometres--the vortex core. The vortex state has a specific excitation mode: the in-plane gyration of the vortex structure about its equilibrium position. The sense of gyration is determined by the vortex core polarization. Here we report on the controlled manipulation of the vortex core polarization by excitation with small bursts of an alternating magnetic field. The vortex motion was imaged by time-resolved scanning transmission X-ray microscopy. We demonstrate that the sense of gyration of the vortex structure can be reversed by applying short bursts of the sinusoidal excitation field with amplitude of about 1.5 mT. This reversal unambiguously indicates a switching of the out-of-plane core polarization. The observed switching mechanism, which can be understood in the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application in data storage.     

智能控制中的定性与定量综合集成方法的研究

定性与定量的综合集成是智能控制中所要解决的关键问题之一。本文利用面向对象的思想,研究了智能控制系统的广义知识模型,并以此为基础,提出了智能控制中定性与定量的综合集成方法及具体实施策略。应用结果验证了这种方法的可实施性和有效性,为智能控制系统中异构型知识基于系统的无缝集成提供了基础。     

三维全内反射荧光光谱法研究细胞色素C在银电极表面的吸附特性

利用现场三维全内反射荧光光谱法研究了细胞色素Ｃ在不同电极表面的吸附特性,发现与细胞色素Ｃ溶液的荧光峰峰位相比,吸附在裸露银电极表面的细胞色素Ｃ的荧光峰峰位发生蓝移,表明埋在细胞色素Ｃ多肽链内血红素的暴露面积减少,而使细胞色素Ｃ的电化学反应不可逆。当细胞色素Ｃ吸附在促进剂修饰的银电极表面时,其荧光峰峰位基本上不发生蓝移,表明血红素的暴露面积基本上不减少,而能观察到细胞色素Ｃ准可逆的电化学反应。     

230t钢包搅拌效果和去夹杂水模型研究

以某钢厂230 t钢包为研究对象,通过实验水模型对现场生产过程的模拟,研究底吹透气元件的布置方式和吹氩流量对搅拌效果和夹杂物去除率的影响.结果表明,双透气元件吹氩优于单透气元件吹氩搅拌效果,0.6R-γ双透气元件布置方式最佳,混匀时间随吹气量和透气元件夹角的增大而减少;夹杂物的去除率取决于吹氩量和吹氩时间,在0.2～0.8 L/min吹气量下,处理时间为0～4 min时夹杂物去除效果最好,5～8 min时可去除大部分夹杂物,24 min左右可去除所有夹杂物.     

Dynamics of phytoplankton and picoplankton over a tidal cycle in a subtropical lagoon

The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area. Results showed that the highest concentrations of picoplankton and phytoplankton were found in the middle and inner part of the lagoon, irrespective of the tides. The MDS result also revealed that phytoplankton communities, dominated by Ceratium furca, were similar among stations in the inner bay during both flood tides and ebb tides. The time series sampling results at the inlet-outlet channel revealed that almost the same amounts of phytoplankton and picoplankton were carried through the channel during flood and ebb tides, with no trend in nutrient fluctuations except for phosphate which had a net loss from the lagoon. The results showed that tidal cycles do not effectively flush away phytoplankton and picoplankton from the lagoon, and the blooming of phyto- and picoplankton is inevitable should the situation stay the same. Steps are needed to alleviate the eutrophication condition instead of depending on the natural process such as tidal cycle.     

A model for estimating the viscosity of blast furnace slags with optical basicity

Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental measurement, viscosity data are also limited, so a reasonable and accurate estimation model is required to provide the data for controlling and optimizing the blast furnace process. In the present study a viscosity model was proposed for blast furnace slags. In the model the activation energy was calculated by the optical basicity corrected for cations required for the charge compensation of AlO₄5-, and the temperature dependence was described by the Weymann-Frenkel equation. The estimated viscosity values of the CaO-Al₂O₃-SiO₂, CaO-Al₂O₃-SiO₂-MgO, and CaO-Al₂O₃-SiO₂-MgO-TiO₂ systems fit well with experiment data, with the mean deviation less than 25%.     

Combustion characteristics and kinetics of anthracite with added chlorine

The combustion process of Yangquan anthracite (YQ) with the addition of 0.045wt%, 0.211wt%, 1.026wt%, and 2.982wt% chlorine was investigated using a thermogravimetric method from an ambient temperature to 1173 K in an air atmosphere. Results show that the YQ combustion characteristics are not significantly affected by an increase in chlorine content. Data acquired for combustion conversion are then further processed for kinetic analysis. Average apparent activation energies determined using the model-free method (specifically the KAS method) are 103.025, 110.250, 99.906, and 110.641 kJ/mol, respectively, and the optimal kinetic model for describing the combustion process of chlorine-containing YQ is the nucleation kinetic model, as determined by the z(α) master plot method. The mechanism function of the nucleation kinetic model is then employed to estimate the pre-exponential factor, by making use of the compensation effect. The kinetic models to describe chlorine-containing YQ combustion are thus obtained through advanced determination of the optimal mechanism function, average apparent activation energy, and the pre-exponential factor.     

Topography,structure, and formation kinetic mechanism of carbon deposited onto nickel in the temperature range from 400 to 850℃

The carbon deposition behavior on nickel particles was observed within the temperature range from 400 to 800℃ in a pure methane atmosphere. The topography, properties, and molecular structure of the deposited carbon were investigated using field-emission scanning electron microscopy (FESEM), temperature-programmed oxidation (TPO) technology, X-ray diffraction (XRD), and Raman spectroscopy. The deposited carbon is present in the form of a film at 400-450℃, as fibers at 500-600℃, and as particles at 650-800℃. In addition, the structure of the deposited carbon becomes more ordered at higher temperatures because both the TPO peak temperature of deposited carbon and the Raman shift of the G band increase with the increase in experimental temperature, whereas the intensity ratio between the D bands and the G band decreases. An interesting observation is that the carbon deposition rate is suppressed in the medium-temperature range (M-T range) and the corresponding kinetic mechanism changes. Correspondingly, the FWHM of the G and D1 bands in the Raman spectrum reaches a maximum and the intensities of the D2, D3, and D4 bands decrease to low limits in the M-T range. These results indicate that carbon structure parameters exhibit two different tendencies with respect to varying temperature. Both of the two group parameters change dramatically as a peak function with increasing reaction temperature within the M-T range.     

三角模糊数的立方根及在模糊系统上的应用

以往的文献很少讨论模糊数的立方根表示和成员关系函数.模糊数的立方根能够用来解决模糊控制系统中的一些问题.本文新提出了一种三角模糊数的立方根代表值和隶属度函数.最后,作为一个数值示例,模糊数的立方根被应用到一个模糊系统例子中.