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.     

Indexed Dendrograms on random Dissimilarities

This paper studies the random indexed dendograms produced by agglomerative hierarchical algorithms under the non-classifiability hypothesis of independent identically distributed (i.i.d.) dissimilarities. New tests for classifiability are deduced. The corresponding test statistics are random variables attached to the indexed dendrograms, such as the indices, the survival time of singletons, the value of the ultrametric between two given points, or the size of classes in the different levels of the dendogram. For an indexed dendogram produced by the Single Link method on i.i.d. dissimilarities, the distribution of these random variables is computed, thus leading to explicit tests. For the case of the Average and Complete Link methods, some asymptotic results are presented. The proofs rely essentially on the theory of random graphs.     

便携式分光光度法快速测定水中铅方法研究

对3种便携式分光光度计快速测定水中铅的方法进行了优化和比对研究.通过研究各仪器性能指标以及测定实际水质样品,对不同便携式分光光度计的优势进行了比较,为突发性环境污染事故应急监测选择合适的监测仪器提供了技术参考.结果表明:JH916检测仪快速测定水中铅的方法检出限(0.003 mg/L)低于ZZW-Ⅱ测试仪和PORS-15V光谱仪的方法检出限(分别为0.2 mg/L和0.4 mg/L),在突发性环境污染事故应急监测中,JH916检测仪具有相对较高的灵敏度.JH916检测仪和PORS-15V光谱仪快速测定水中铅的方法精密度相近,其测试结果相对标准偏差(RSD)均未超过7.5%,ZZW-Ⅱ测试仪的方法精密度稍差,其相对标准偏差(RSD)最大值为20%.3种便携式分光光度计测定实际样品时,加标回收率分别为84%~115%(ZZW-Ⅱ测试仪)、81%~118%(PORS-15V光谱仪)、90%~117%(JH916检测仪),表明3种便携式分光光度计均有相对较好的准确度.3种便携式分光光度计与实验室分析方法相比,测试结果相对偏差较大,最大相对偏差分别为22%(ZZW-Ⅱ测试仪)、11%(PORS-15V光谱仪)、-26%(JH916检测仪).     

固定床反应器基于改进混合模型的串级推断控制

提出了非绝热式固定床反应器基于改进混合模型的串级非线性推断控制策略。道德提出了邻二甲苯氧化非绝热式固定床反应器基于改进混合模型的推断估计器;然后设计了基于新型非线性自适应控制算法的副控制器和基于程序变增益ＰＩＤ的主控制器,同时设计了新型非线性滤波器以解决该反应器主回路比副回路响应快的问题;最后建立了该固定床反应器基于改进混合模型的串级非线性推断控制系统。仿真结果表明该推断估计器具有良好的静态、动态     

TENTATIVE ANALYSIS OF PHYSICAL EDUCATION SPECIALITY REFORMATION IN NORMAL UNIVERSITIES UNDER NEW CIRCUMSTANCES——From the entire people's physical movement's requirement for qualified physical personnel

高师体育教育专业,几十年来一贯实行单一的人才培养模式,重视对从事学校体育的能力培养,忽视对从事社会体育的能力培养．随着全民健身计划的启动与全面开展,使高师体育专业人才的培养与社会需求矛盾日显突出．笔者从社会发展的角度,分析供求关系,谈高师体育专业在新形势下的教育改革     

铜阳极膜导电性转型起因探讨

对在不同酸碱度和添加剂的电解液中,铜电极氧化膜呈现与块体铜氧化物不同的ｎ型半导体性质的实验结果进行了综合分析,指出铜阳极膜导电性转型应归因于隙间铜离子在膜中向溶液方向的迁移并形成浓度梯度,使邻近基底的氧化物层转呈ｎ型导电,并在可吸收到足够强度和能量的照射光时呈现阳极光电流响应。     

Supply China Production-distribution Cost Optimization under Grey Fuzzy Uncertainty

Most supply chain programming problems are restricted to the deterministic situations or stochastic environments. Considering twofold uncertainty combining grey and fuzzy factors, this paper proposes a hybrid uncertain programming model to optimize the supply chain production-distribution cost. The programming parameters of the material suppliers, manufacturer, distribution centers, and the customers are integrated into the presented model. On the basis of the chance measure and the credibility of grey fuzzy variable, the grey fuzzy simulation methodology was proposed to generate input-output data for the uncertain functions. The designed neural network can expedite the simulation process after trained from the generated input-output data. The improved Particle Swarm Optimization (PSO) algorithm based on the Differential Evolution (DE) algorithm can optimize the uncertain programming problems. A numerical example was presented to highlight the significance of the uncertain model and the feasibility of the solution strategy.