HCT晶体上电化学阳极化膜的AES研究

对Ｈｇ１－ｘＤｄｘＴｅ（ＨＣＴ）晶体表面上由电化学阳极化生长的氧化膜进行了俄歇电子能谱分析，并经Ａｒ＾＋离子蚀刻，研究了薄膜及其与底晶的界面层的深度元素分布和化学计量，估计了可能生成的化合物，阐述了阳极化过程中电流密度，糟电压及电解质溶液浓度对阳极化膜的ＡＥＳ的影响。     

SPECT研制及其影像研究

对单光子发射型计算机断层（ＳＰＥＣＴ）方面的研制和开展ＳＰＥＣＴ影像研究进行了描述，介绍了ＳＰＥＣＴ的基本组成，性能指标和临床软件，为提高ＳＰＥＣＴ影像的质量，提出了ＳＰＥＣＴ分辨率和灵敏度方面所作改进的建议和计算机仿真在ＳＰＥＣＴ中的应用。     

光学CT技术在大坝位移自动检测中的应用研究（一）

介绍采用光学ＣＴ和ＣＣＤ技术的大坝移位自动检测系统，建立适合本课题特点的光学ＣＴ数学模型，在数字信号处理上结合实际，采用了利用信号自卷积的信息提取方法，对这一 在各种情况下对信号处理的结果进行详细分析。     

基于Wigner-Ville分布的宽带回波到达时刻估计方法

研究了基于 Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布的宽带回波到达时刻的估计方法。通过回波信号与参考信号Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布的时频相关，完成对回波到达时刻的估计。在此基础上，本文提出了瞬时频域相关和ＸＷＶＤ峰值估计两种改进方法。通过仿真研究，发现这两种改进估计方法在低信噪比（０ｄＢ）下具有很好的估计性能，估计均方误差可以达到克拉美－罗界，并且运算量也大大降低，有利于工程实时应用。最后，本文讨论了线性调频信号时宽和带宽对估计性能的影响。     

正交频分复用在水声通信中频率同步的研究

正交频分复用（OFDM）通信系统对频率偏移比较敏感，容易导致系统性能急剧下降。水声通信中存在着严重的多普勒频率偏移，限制了OFDM技术在水下的应用。本文仿真分析了频率偏移对OFDM系统的性能影响，提出了一种适用于水声通信的频率同步方法。本方法不仅可以对固定的频率偏移进行估计，也可以对连续变化的频率偏移进行估计。仿真表明，本方法具有较高的频偏估计精度和大的频偏估计范围。湖试结果也表明，采用这种方法可有效地进行频偏估计。     

压差式矢量水听器方位估计中的干扰抵消

矢量水听器由于能获取声场中标量（声压）和矢量（振速）信息，因此单个的矢量水听器就可实现目标方位估计。单个矢量水听器是利用信号的声压和质点振速之间相关性进行信号方位估计，但是当存在干扰，并且干扰和信号之间相关时，如果对运用能量流进行方位估计的方法不加改进，则会出现很大的误差，甚至出现错误的估计。本文提出一种存在已知噪声干扰情况下的干扰抵消方法，并针对该方法进行了仿真试验，最后运用湖试数据进行了验证。结果表明，该方法能有效地减弱相千千柑对信号的影响，实现对信号的方位估计。     

光学CT图象重建的数值模拟研究─Kosenbrock坐标轮换法

时间分辨光学 ＣＴ技术因其对生物组织体的无损性，在生物成象领域引起了广泛的兴趣和研究，已提出许多方案，意在克服由于生物组织体中的多光散射效应所造成的成象障碍．本文简述了基于扩散方程近似的光学ＣＴ正向问题有限元解法，提出采用直接搜索优化算法一Ｒｏｓｅｎｂｒｏｃｋ坐标轮换法求解时间分辨光学 ＣＴ中的图象重建问题，给出了基于积分光强和光子平均飞行时间及其加权组合的二维图象重建问题的数值模拟结果，证实了该方法的可行性．     

斜坡海底波导中随机声源的信道盲解卷积

该文研究了在斜坡海底环境中，通过基于射线的盲解卷积(RBD)方法，利用随机声源发出的信号来估计信道响应(CIR)的有效性，并讨论了不同信噪比和海底坡度情况下，RBD估计到的CIR与CIR理论值的相关性，对2016年美国圣巴巴拉海峡实验进行了仿真验证。RBD方法通过宽带波束形成估计随机声源的相位，以得到声源和接收阵之间的CIR。仿真结果表明，斜坡海底情况下RBD方法仍能较为准确地估计信道的CIR，噪声和海底坡度的变化均会对RBD估计到的CIR的精确度产生一定的影响。在具有一定粗糙度的斜坡海底波导或存在海底山丘的波导中，RBD仍然可以对CIR进行有效估计。     

时延估计的高分辨方法

目前，时延估计方法的研究热点集中在自适应解卷积方面，但解卷积方法的分辨率下限是数据的采样间隔，在短数据情况下无法获得足够的分辨率。本文首先指出了常用时延估计方法的局限性，然后提出了两种时延估计的高分辨方法：时延频率估计和特征结构法。这两种方法的最小分辨率都可以突破数据采样间隔。本文详细论述了它们的估计原理及性能特点，并给出了计算机仿真结果。最后，列表比较了多种时延估计方法的性能．     

基于Wigner-Ville分布的宽带回波瞬时多普勒估计方法

研究了基于 Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布的宽带回波瞬时多普勒估计方法。利用时频分析特有的时、频特征分离的特点，通过信号Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布的时频相关，进行回波信号瞬时多普勒的估计，并通过理论证明其等价与传统的多普勒估计方法；在此基础上，本文提出了一种基于互 Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布峰值估计的瞬时多普勒估计方法。通过仿真研究，发现基于互 Ｗｉｇｎｅｒ－Ｖｉｌｌｅ分布峰值估计的方法具有更低的估计信噪比门限，大大降低了运算量，有利于工程实时应用。     

惠更斯次波法在遥感图像去云和云影中的应用

针对在遥感图像中有云和云影的区域无法获取信息的情况，提出一种对遥感图像局域增强的新方法，即采用惠更斯次波法寻找遥感图像中有云覆盖的区域和有云阴影的区域，进而采用邻域平均法，将有云覆盖的区域和云阴影区域与大尺寸的平滑卷积核进行卷积得到具有较宽的渐变边缘，再对原图像中有云覆盖的区域和云阴影区域的亮度进行补偿，从而获得原图中被云覆盖的区域和云阴影区域的信息。这种半自动提取地物的方法，对在有云和有云影的遥感图像中提取地物信息具有辅助作用。     

Collaborate,compete and share

We introduce and study a model of an interacting population of agents who collaborate in groups which compete for limited resources. Groups are formed by random matching agents and their worth is determined by the sum of the efforts deployed by agents in group formation. Agents, on their side, have to share their effort between contributing to their group’s chances to outcompete other groups and resource sharing among partners, when the group is successful. A simple implementation of this strategic interaction gives rise to static and evolutionary properties with a very rich phenomenology. A robust emerging feature is the separation of the population between agents who invest mainly in the success of their group and agents who concentrate in getting the largest share of their group’s profits.     

折射率连续周期分布一维光子晶体的带隙分析

微分传输矩阵法(DTMM)可以解析求解一维非均匀介质中的波动方程。用该方法,对几种折射率连续且周期分布的一维光子晶体进行了带隙分析。结果表明,折射率连续变化的一维周期结构也具有明显的带隙特征,折射率变化越平缓,光带隙的宽度越小。对于折射率正弦变化的一维光子晶体,其折射率变化得越剧烈,光子晶体的中心频率越小,带隙越宽;同时,折射率的平均值越大,中心频率越小,带隙越窄。由于材料的物理特性都是连续变化的,同样可以把结构推广到一维周期性功能梯度材料。     

The State of the Theory of Vacuum Arc Cathodes

The physics of vacuum arc cathodes, the advances in their interpretation and the still unsolved problems are summarized. Starting from the experimental experiences the theories of stationary arc spots are described, with their assumptions and variants, their successes and deficiencies. It is shown that an extension of these models by inclusion of non-stationary processes is inevitable. Such processes are suggested and their importance in a theory of the dynamic arc spot is investigated. Finally the role of surfacecontaminations is discussed, and the general applicability of the vacuum arc models to all kinds of arc electrodes is emphasized.     

三类硬磁畴的形成及静态特性

本文提出畴壁中含有大量VBL的石榴石磁泡材料的三类硬磁畴的分类标准,描述了它们的形成方法和静态特性,并示出典型照片。从形成条件可以合理地推论,畴壁中VBL数目的增加导致硬磁畴静态特性的质的变化。 关键词：     

Impact and Prevention of Voice Problems in the Teaching Profession: Embracing the Consumers'' View

Teachers are vulnerable to developing voice problems due to their specific occupational demands during teaching. Information on how the teaching profession is impacted by voice problems and what the profession perceives to be useful information for preventing voice problems is important for health care service providers. A total of 122 subjects from the teaching profession (55 practicing teachers and 67 prospective teachers) were therefore surveyed to ascertain their perception of their voice condition and the impact of voice problems on their communication, social life, personal emotions, and occupation. The results showed that the practicing teachers perceived their voice to be significantly worse than the prospective teachers. In addition, the teachers also faced significantly more difficulties in their daily communication than the prospective teachers. These two groups of subjects believed that information on breathing exercises and specific vocal hygiene strategies would help them prevent voice problems.     

并联线圈的等效自感和电流分配问题的讨论

首先讨论了并联(顺接)线圈的等效自感,给出了并联线圈的等效自感随耦合系数及两线圈自身自感的变化关系.然后从理论上详细讨论了并联线圈的电流分配问题,指出在耦合系数较大,互感大于其中一个自感时,电路在接通的暂态过程中,会出现两线圈电流反向的现象,且冲击电流会大于稳态的电流值.最后通过实验测试验证了理论分析的正确性.     

Reply to: “Comment on: ‘Efficient high-capacity quantum secret sharing with two-photon entanglement’ [Phys. Lett. A 372 (2008) 1957]” [Phys. Lett. A 373 (2009) 396]

A corresponding Comment, raised by Yang and Wen, claimed that (i) our scheme cannot complete the task of secret sharing well even if the agents obtain the information about their measuring bases; (ii) they give a feasible improvement of our protocol. In this Reply, we show that their first judgment is wrong and their improvement is insecure.     

Lattice vibration of amorphous and disordered crystalline silicon

The disappearance of low-energy tunneling states in an amorphous solid discovered recently has shown that the amorphous structure is not their primary cause, as had previously been widely accepted. We have also found that the same tunneling states can be generated in crystalline silicon as the crystal structure is gradually disordered by Si⁺ and B⁺ ion implantation. Most strikingly, their number densities saturate at their characteristic level regardless whether the crystal amorphizes or not. It is concluded that the nature of the tunneling states, and the cause for their saturation density, should be explored in disordered crystals.     

Beyond butterflies—the diversity of biological photonic crystals

When biological photonic crystals are discussed, butterfly photonic crystals are often cited as representative; in fact, numerous diverse biological photonic crystals exist and butterfly photonic crystals have several quirks when compared with others, with the consequence that considering them typical is in many ways unhelpful. In this paper, we give an overview of biological photonic crystals and discuss their typical features, specifically with regard to their periodicities, geometries, chemical compositions, the wavelengths they reflect and their band gaps. The low refractive index contrast and low mean refractive index: a universal feature of biological photonic crystals compared with artificial ones is highlighted and attention is drawn to their comparatively complex band diagrams.