MULTIPLE PERIODIC SOLUTIONS OF ASYMPTOTICALLY LINEAR HAMILTONIAN SYSTEMS VIA CONLEY INDEX THEORY

In this paper we study the existence of periodic solutions of asymptotically linear Hamiltonian systems which may not satisfy the Palais-Smale condition. By using the Conley index theory and the Galerkin approximation methods, we establish the existence of at least two nontrivial periodic solutions for the corresponding systems.

基于重叠分块的FM-index性能研究与分析

FM-index压缩查询方法结合压缩技术和索引技术,其最大优势是能够在不解开压缩文件的情况下对源文件进行查询。该文通过理论分析和详细的测试数据研究重叠分块对FM-index压缩查询性能的改善。对改进后的FM-index和压缩软件Winrar在压缩时间和文件占用空间上进行分析和比较,进一步证明了重叠分块对FM-index压缩查询性能的改善。

FM-index分块并行算法及其实现

查询海量数据有压缩和索引两种方法来提高速度,该文结合这两种方法提出了压缩查询的方法.FM-index是一种自索引的全文查询算法,存在内存占用过大的问题,对于复杂的查询效率也不理想.该文提出分块FM-index算法,在分块的基础上采用MPI对算法进行并行化,解决了内存占用过多的问题,达到了较好的并行效率.

semantic oriented ontology cohesion metrics for ontology-based systems

Ontologies play a core role to provide shared knowledge models to semantic-driven applications targeted by Semantic Web. Ontology metrics become an important area because they can help ontology engineers to assess ontology and better control project management and development of ontology based systems, and therefore reduce the risk of project failures. In this paper, we propose a set of ontology cohesion metrics which focuses on measuring (possibly inconsistent) ontologies in the context of dynamic and changing Web. They are: Number of Ontology Partitions (NOP), Number of Minimally Inconsistent Subsets (NMIS) and Average Value of Axiom Inconsistencies (AVAI). These ontology metrics are used to measure ontological semantics rather than ontological structure. They are theoretically validated for ensuring their theoretical soundness, and further empirically validated by a standard test set of debugging ontologies. The related algorithms to compute these ontology metrics also are discussed. These metrics proposed in this paper can be used as a very useful complementarity of existing ontology cohesion metrics.

the tilt cursor: enhancing stimulus-response compatibility by providing 3d orientation cue of pen

In order to improve stimulus-response compatibility of touchpad in pen-based user interface, we present the tilt cursor, i.e. a cursor dynamically reshapes itself to providing the 3D orientation cue of pen. We also present two experiments that evaluate the tilt cursor’s performance in circular menu selection and specific marking menu selection tasks. Results show that in a specific marking menu selection task, the tilt cursor significantly outperforms the shape-fixed arrow cursor and the live cursor [4]. In addition, results show that by using the tilt cursor, the response latencies for adjusting drawing directions are smaller than that by using the other two kinds of cursors.

Trapping of low-refractive-index particles with azimuthally polarized beam

Azimuthally polarized beams, focused by a high-numerical-aperture (NA) objective lens, form a hollow intensity distribution near the focus, which is appropriate for trapping low-refractive-index particles, in contrast to common linearly polarized or radially polarized beams. In this paper, the field distribution of the azimuthally polarized beam focused by a high-NA objective is described by the vectorial diffraction integral, and then the radiation forces on spherical particles with different parameters such as radius and refractive index are calculated by the T-matrix method. Numerical results show that the azimuthally polarized beam not only can steadily trap low-refractive-index particles at the focus center but also can trap multiple high-refractive-index particles around the focus center by virtue of the hollow-ring configuration. The range of the sizes of low-refractive-index particles that can be trapped steadily are presented, corresponding to different parameters such as the NA of the objective and the relative refractive index, based on which the NA of the objective can be selected to trap the appropriate size of particles. (C) 2009 Optical Society of America

Spectral relationship of photoinduced refractive index and absorption changes in fulgide films

Fulgides are one kind of organic photochromic compound, which are famous for their thermal irreversibility. In this report, from the difference spectra of the absorption A() of one kind of pyrrylfulgide, the spectral refractive index change n() was calculated by the Kramers-Kronig relation (KKR), and a good correlation of theoretically derived values and the experimental values of the n measured by a modified Michelson interferometer was found. Further, it is demonstrated that it was possible to calculate the spectral dependence of diffraction efficiency from the easily accessible absorption changes. This method will be a useful tool for the characterization and optimization of fulgide films. The results show that the diffraction efficiency is high at 488 and 750 nm, where the absorption is very small, so we can realize non-destructive reconstruction.