Magnetic susceptibility of a composite medium with variable parameters that consists of arbitrarily oriented anisotropic ferrite particles

The dynamic high-frequency tensor susceptibility of a composite medium consisting of independent chaotically oriented uniaxially anisotropic ferrite spheres is calculated by averaging over directions under the conditions of an orientation transition. It is established that the tensor magnetic susceptibility has all nine components, among which the maximum components are those responsible for oscillations of the magnetization vector in the directions perpendicular to the constant magnetic field. It is shown that these peculiarities of the tensor make it possible to analyze waves in the medium with the help of the methods known in the electromagnetics of gyrotropic media.     

Deposition mechanism of fine glass particles and high-rate production of fibre preforms in the VAD process

In order to achieve the high-rate production of fibre preforms, the deposition mechanism in the VAD process has been investigated. The particle deposition rate was found to depend on the Reynolds number of the flame stream. The high-rate preform production of 4.5 g/min was attained by applying this result to the preform fabrication technique.     

面向对象方法在可编程逻辑部件分析技术研究中的应用

在黑箱辩识方法论的基础上,已经完成了对加密可编程逻辑器件的无损伤破译,所提出的局部穷举法理论,成功解决了在微机环境下大数据量的快速采集和处理问题。该文沿着面向对象方法的新发展趋势,从面向对象分析与设计的角度出发,提出对加密可编程逻辑器件的无损伤破译的一种改进方法。     

扫描探针显微镜在胶原纤维精细结构研究中的应用

作为一种新型的微区分析仪器，扫描探针显微镜已迅速普及和应用到了各门学科，而在生物领域的应用则相对比较落后。本文简要介绍了扫描探针显微镜这一新型表面测试技术在猪皮胶原精细结构研究中的应用方法，并将所得结果与透射电镜结果进行了比较分析。     

A novel harmless trimming for micro-device with defects and particles in arbitrary geometry by fine milling of focused ion beam

A novel method combining focused ion beam (FIB) milling and image processing for fine trimming of micro-device is introduced in detail in this paper. By using small beam spot size and beam current, selective milling can be realized according to requirement in terms of the difference of gray scale color intensity between defects and useful areas of the FIB images. A magnetoresistive head and ink jet spray head of color printer trimming were described as examples. Trimming result shows that the method is practical and suitable for the fine trimming of micro-device by the selective milling.     

Automatic tracking of individual fluorescence particles: application to the study of chromosome dynamics.

We present a new, robust, computational procedure for tracking fluorescent markers in time-lapse microscopy. The algorithm is optimized for finding the time-trajectory of single particles in very noisy dynamic (two- or three-dimensional) image sequences. It proceeds in three steps. First, the images are aligned to compensate for the movement of the biological structure under investigation. Second, the particle's signature is enhanced by applying a Mexican hat filter, which we show to be the optimal detector of a Gaussian-like spot in 1/omega2 noise. Finally, the optimal trajectory of the particle is extracted by applying a dynamic programming optimization procedure. We have used this software, which is implemented as a Java plug-in for the public-domain ImageJ software, to track the movement of chromosomal loci within nuclei of budding yeast cells. Besides reducing trajectory analysis time by several 100-fold, we achieve high reproducibility and accuracy of tracking. The application of the method to yeast chromatin dynamics reveals different classes of constraints on mobility of telomeres, reflecting differences in nuclear envelope association. The generic nature of the software allows application to a variety of similar biological imaging tasks that require the extraction and quantitation of a moving particle's trajectory.     

Statistics of deformations in histology and application to improved alignment with MRI

An exact registration of magnetic resonance images (MRI) with histological sections is impeded by local deformations resulting from histological preparation procedures. Therefore, it is desirable to know the probability density function of spatial deformations in order to estimate optimal global least-square transformation parameters from suitable landmarks. For this reason, the statistics of deformations is investigated. It is shown analytically that the frequency of occurrence of the absolute geometrical differences (deformations) are Rayleigh-Bessel distributed for anisotropic histological preparation procedures and Rayleigh distributed in the case of isotropic procedures. The probabilistic analysis is given in conjunction with an iterative optimization technique in order to ensure that the probability density function is within a threshold required for the application to experimental data. The application of the analytical model is investigated with real data. It is shown with this data that the extent of deformations varies with the size of the histological section. An individual threshold can be selected on the basis of a Rayleigh-function restricting local corrections to small parts of the image. Thus, global misalignment in each section can be avoided, resulting in an improved 3-D reconstruction of the volume, i.e., the transitions from one section to the next are more continuous.     

电铸超细晶Cu超高速变形机理的TEM研究

电铸材料由于具有独特的显微组织结构和晶粒生长方向的可控性而广泛地应用于工业及军事等领域。本文应用电铸法制备超细晶粒金属Ｃｕ ,对电铸工艺参数与形成的材料的微观组织的关系进行了探讨。运用扫描电子显微镜 (ＳＥＭ )、透射电子显微镜(ＴＥＭ)和ＥＰＳＤ等实验手段 ,对电铸Ｃｕ的显微组织及晶粒的生长方向进行了系统的研究 ,对超高速塑性变形机理进行了初步探讨。实验方法电铸法加工是在芯模上电沉积一定厚度的连续金属后再与之分离得到金属薄壳零件的成形技术 ,它是利用电解原理的相反过程来进行的[1] 。本研究采用不锈钢芯模作为阴…     

复杂场景下面向时空模糊性的人体动作检测方案研究

与严格受控环境下传统的人体动作检测不同,进行复杂场景下的动作检测时由于背景带有噪声、人体遮挡和跟踪不全导致空间和时间边界存在时空模糊性。现有的动作检测方案无法有效解决这一问题,为此,首先采用运动历史图像特征和外观特征对人体运动进行区分,然后将一个动作的候选区域看成是一个实例包,提出模拟退火多实例学习支持向量机(SMILE-SVM)算法实现人体动作检测。仿真结果表明,该算法在公共的CMU运动数据集上的性能优于现有算法。另外,还提出了一种超市客户意图检测系统,可检测拥挤的超市中客户是否有意从货架上取货,对于商家研究客户兴趣具有重大价值。     

LED活化竹红菌素光动力治疗卵巢癌的实验研究

目的:观察LED活化竹红菌素介导的光动力作用对人卵巢癌细胞生长的抑制作用.方法:采用倒置显微镜观察和MTF法检测LED活化HB光动力作用后人卵巢癌细胞株H08910细胞的乍长状况.结果:LED活化HB介导的光动力作用显著抑制人卵巢癌细胞H08910细胞的乍长,在一定浓度的HB条件下,细胞生长抑制作用和LED能量密度间呈...     

双波长激光传输特性的室内模拟实验研究

为了研究大气信道在特定条件下对光束的影响,建立基于双波长同信道传输的室内模拟大气实验系统,对不同浓度的雾气和粉尘分别进行了模拟传输实验。结果表明,空气水蒸气密度与衰减系数近似满足线性关系,且衰减系数随波长变大而减小,当雾气浓度达到一定时趋于一致;根据测量数据拟合出粉尘浓度与透射率满足指数关系,符合比尔-郎伯定律;实验测试数据结果与大气散射理论相符合。该实验结果和实验方法对研究大气对光的作用具有一定的参考价值。     

HPL-2000CO2激光器工作气体的试验研究

针对横流HPL-2000 CO2激光器工作气体进行了试验研究，用LSQD35型冷水机组与HPL-2000激光器组成系统，能够在无氮工作气体的条件下稳定运行，使激光器运行成本大为降低。     

High robustness of correlation-based alignment with Penrose patterns to marker damage in electron beam lithography

Correlation-based alignment is an alternative alignment method for electron beam lithography. Using complex marker patterns, such as Penrose patterns, which contain more positional information, greater alignment accuracy can be achieved. Correlation-based alignment with Penrose patterns is less susceptible to marker edge defects, such as rat bites, roughness and flagging, since many more edges contribute to determining the marker position. There are however other defects associated with fabricating markers and this paper investigates how defects that result in parts of the pattern being omitted or obscured affect the correlation process when using Penrose pattern markers. We show that in both cases severely damaged markers can be used successfully and demonstrate fabricated structures with sub-5 nm alignment using markers with up to 80% of the marker pattern missing.     

Brillouin light scattering study of the spin dynamics in nanoscale permalloy stripes: Theory and experiment

The spin-wave modes in nanoscale permalloy stripes are studied using Brillouin light scattering for the case where an external magnetic field is applied transversely to the length of the stripes. By adjusting the magnitude of this external field, the overall magnetization may be varied between the approximately transverse and longitudinal orientations. The observed spin-wave frequencies are analysed using a recently developed microscopic dipole-exchange theory that is particularly appropriate when the magnetization displays strong spatial inhomogeneity. Comparison between theory and experiment for the two sizes of stripes studied gives fairly good agreement, allowing the magnetic parameters of permalloy to be deduced. A small magnetic anisotropy of the easy-plane type is shown to play an important role.     

Activation annealing of ultra-low-energy implanted boron in silicon: a study combining experiment and process modeling

We present our investigations on the clustering, diffusion and electrical activation of ultra-low-energy (<1 keV) implanted boron in crystalline silicon during annealing in the temperature range between 900 and 1200°C. We show that during the initial stage of the annealing, boron is bound to non-diffusing clusters. The formation and the dissolution in dependence of temperature are analyzed. We determine a dissolution time constant with an average activation energy of 2.3 eV. The depth-dependent electrical activation as measured by spreading resistance profiling was used to determine the fraction of electrically active boron. From the analysis of the time dependence of the electrically active fraction, a time constant was determined which is faster compared with the boron cluster dissolution time constant in the investigated temperature range. We have simulated the annealing process to demonstrate the influence of the boron clustering on the broadening of the boron profile.     

Use of gas cluster ion source depth profiling to study the oxidation of fullerene thin films by XPS

The analysis of organic materials such as phenyl-C61-butyric acid methyl ester (PC₆₁BM) by depth profiling is typically fraught with difficulty due to the fragile nature of the sample. In this work we utilise a gas cluster ion source for the controlled depth profiling of organic materials that would historically have been too fragile to analyse and obtain quantitative compositional data through the whole thickness of the film. In particular we examine the oxygen diffusion and photo-oxidation kinetics of one of the most commonly used electron acceptor materials for many organic optoelectronic applications, namely PC₆₁BM, in both neat films and in blends with polystyrene. Exposure to AM1.5G light and air under ambient conditions, results in a higher level of surface oxidation of blended PC₆₁BM:polystyrene than is observed for either pure control film. Gas cluster ion source depth profiling further confirms that this oxidation is strongest at the extreme surface, but that over time elevated oxygen levels associated with oxidised organic species are observed to penetrate through the whole blended film. The results presented herein provide further insights on the environmental stability of fullerene based organic optoelectronic devices.     

Calculation of the flow capacity of a gas channel in the sources of beams of fast neutral particles by means of the Monte-Carlo method

This paper describes the model based on the Monte-Carlo method and presents the results of the mathematical simulation of the flow capacity of the exit aperture for an ion source with a ribbon-shaped beam and for the same source equipped with the system for ion beam neutralization and the electrostatic deflection system. For the designs mentioned above distributions of the normalized pressure and the collision thickness of gas along the channel axis are given. The results obtained are indicative of the fairly strong effect of these design elements on the flow capacity and, consequently, on the operating conditions of the ion source. The results of simulation can be used for correcting the value of the gas flow rate in the source for the purpose of maintaining invariant conditions of discharge glow, as well as for evaluating the effectiveness of the process of ion charge exchange in the source channel.     

磁场对氮化物抛物量子阱中束缚极化子的影响

采用改进的Lee-Low-Pines中间耦合方法研究了在外磁场作用下纤锌矿氮化物抛物量子阱中极化子能级,给出不同磁场下极化子基态能量、结合能随阱宽L的变化关系以及能量随磁场强度B变化的函数关系。在计算抛物量子阱材料中考虑了纤锌矿GaN和Al0.3Ga0.7N构成的抛物量子阱中材料中准LO和准TO声子模的各向异性以及外磁场对极化子能量的影响。结果表明:纤锌矿氮化物抛物量子阱材料中电子-声子相互作用和外磁场对极化子能级有明显的影响。极化子基态能量、结合能随阱宽的增加而减小,随磁场的增加而增大,电子-声子相互作用使极化子能量降低,并且GaN/Al0.3Ga0.7N抛物量子阱对极化子的束缚程度比GaAs/Al0.3Ga0.7As抛物量子阱强,因此,在GaN/Al0.3Ga0.7N抛物量子阱中束缚于杂质中心处的电子比在GaAs/Al0.3Ga0.7As抛物量子阱中束缚于杂质中心处的电子稳定。