Memory effect on the pressure-temperature condition and induction time of gas hydrate nucleation

The focus of this study is to investigate the influence of memory effect and the relation of its existence with the dissociation temperature, using gas hydrate formation and dissociation experiments. This is beneficial because memory effect is considered as an effective approach to promote the thermodynamic and dynamic conditions of gas hydrate nucleation. Seven experimental systems (twenty tests in total) were performed in a 1 L pressure cell. Three types of hydrate morphology, namely massive, whiskery and jelly crystals were present in the experiments. The pressures and temperatures at the time when visual hydrate crystals appeared were measured. Furthermore, the influence of memory effect was quantified in terms of pressure-temperature-time (p-T-t) relations. The results revealed that memory effect could promote the thermodynamic conditions and shorten the induction time when the dissociation temperature was not higher than 25 ℃. In this study, the nucleation superpressure and induction time decrease gradually with time of tests, when the earlier and the later tests are compared. It is assumed that the residual structure of hydrate dissociation, as the source of the memory effect, provides a site for mass transfer between host and guest molecules. Therefore, a driving force is created between the residual structures and its surrounding bulk phase to promote the hydrate nucleation. However, when the dissociation temperature was higher than 25 ℃, the memory effect vanished. These findings provide references for the application of memory effect in hydrate-based technology.     

ITER馈线系统CTB盒冷屏多层绝热结构传热性能的实验研究

线圈终端盒(CTB)是保证ITER装置可靠运行的关键部件之一,为磁体系统与低温车间、电源大厅、数据采集系统和低温控制元件提供4.5K的超低温工作环境。线圈终端盒(CTB)内部设有80K冷屏,以吸收室温环境对其内部工作空间带来的辐射热负荷,在杜瓦和冷屏中间,设有30mm的真空多层绝热夹层。首先采用量热法和称重法,对多层绝热试件进行了热性能测试,然后分别与理论分析和CTB原型件系统实验结果进行对比,得出了CTB盒中多层绝热结构的热性能参数,为下一步大规模生产提供了有力的技术支持。     

基于重模多项式矩阵理论的分组密码算法

运用重模多项式理论,设计了密钥控制下的重模多项式矩阵环上的可逆矩阵加密新算法,算法具备很好的抵抗现有攻击的性能,有很好的应用前景.     

基于分形维数的Ni-Co电刷镀层表面形貌分析研究

采用电刷镀技术获得了Ni-Co合金电刷镀层,借助于扫描电子显微镱观察得到了镀层的表面形貌图.通过改变镀液中Co离子含量的比例,使镀层中Co元素含量发生变化,从而使镀层表面形貌发生变化.利用盒维数的计算方法,计算出了不同Co元素含量的表面形貌分形维数.以分形维数作为衡量指标,研究了镀液中Co元素比例对镀层表面形貌的影响.     

多脉冲序列飞秒钛宝石激光的啁啾脉冲放大

在数太瓦钛宝石啁啾脉冲放大系统中（极光Ⅱ升级装置）,对多脉冲序列的放大过程进行了详细的实验研究,获得了多脉冲序列的放大输出.每一个放大脉冲串中包含有19个独立的飞秒单脉冲,其相邻间隔为14.8 ns,对应的重复频率为67.5 MHz.脉冲串的总能量约为122 mJ,各单脉冲能量从20 mJ指数衰减至0.5 mJ,脉宽约为60fs,对应的峰值功率约为10¹¹—10¹⁰W.这种脉冲序列在产生长寿命激光等离子体、激光微加工等方面有重要应用前景.     

基于PXI总线的温控盒自动测试系统设计

温控盒作为飞机温度调节系统中的核心部件,在飞机运行安全中起着举足轻重的作用,需要对温控盒的各项参数进行详细测试。传统的温控盒测试设备普遍存在测试数据不精确、扩展性差以及测试人员操作繁琐、工作量大等缺点。提出了基于PXI总线的温控盒自动测试技术,阐述了其基本的测试原理以及具体软硬件实现方法,重点介绍了阻值动态分段逼近闭环设计及脉冲输出的低延时处理算法,完成了测试过程的一键自动化,拥有通用性、扩展性强、功能全面、智能化程序高等特点。     

On <Emphasis Type="Italic">p</Emphasis>-variation of bifractional Brownian motion

In this paper we study p-variation of bifractional Brownian motion. As an application, we introduce a class of estimators of the parameters of a bifractional Brownian motion and prove that both of them are strongly consistent; as another application, we investigate fractal nature related to the box dimension of the graph of bifractional Brownian motion.     

区域法立体匹配的实时性问题研究

立体匹配的一个关键问题是计算量大，实时性难以保证，作者从两个方面着手对立体匹配算法进行优化，首先是在算法结构上，应用盒滤波技术消除了冗余计算；其次在实现上，针对Intel Pentium4处理器的特性，从存储器组织和高速缓存的利用，SSE2多媒体扩展指令的应用以及基于超线程技术的并行处理等三个方面进行优化实现。实验结果表明，所提出的算法在实时性上有了很大的提高。     

Sierpinski锥及其Hausdorff维数与Hausdorff测度

首先给出了 Sierpinski锥的概念及构造过程 ,然后求出其计盒维数、Hausdorff维数和 Hausdorff测度 .