In this thesis, we study routing problems on ring networks. The ring is a popular topology for communication networks and has attracted much research attention. A communication application on a ring network can be regarded as a set of connection requests, each of which is represented by a set of nodes to be connected in the ring network. To implement a communication application, we need to deve...

We give an approximation algorithm for non-uniform sparsest cut with the following guarantee: For any ε, δ ∈ (0, 1), given cost and demand graphs with edge weights C,D : ( V 2 ) → R+ respectively, we can find a set T ⊆ V with C(T,V \T ) D(T,V \T ) at most 1+ε δ times the optimal non-uniform sparsest cut value, in time 2 poly(n) provided λr ≥ Φ∗/(1 − δ). Here λr is the r’th smallest generalized ...

Sentence-level writing errors seem immune to many of the feedback forms devised over the years, apart from the slow accumulation of examples from the environment itself, which second language (L2) learners gradually notice and use to varying degrees. A computer corpus and concordance could provide these examples in less time and more noticeable form, but until now the use of this technology has...

The development of bulk, three-dimensional (3D), macroporous polymers with high permeability, large surface area and large volume is highly desirable for a range of applications in the biomedical, biotechnological and environmental areas. The experimental techniques currently used are limited to the production of small size and volume cryogel material. In this work we propose a novel, versatile...

The basic models of price dispersion due to Butters (1977) and Varian (1980), further developed by Narasimhan (1988), have been applied to a broad range of issues in industrial organization and marketing. Much of the previous research assumes that the captive and switcher segments are exogenously symmetric or asymmetric. We embed the Varian (1980) model in a broader setting that considers how c...

In this paper, we propose a data-embedding pen, which adds an ink-dot sequence along a handwritten pattern during writing. The ink-dot sequence represents some meta-information, such as writer’s name, date of writing, and URL. The meta-information can be extracted from the handwritten pattern by image processing techniques and a stroke recovery technique. Consequently, we can augment the handwr...

We study the topological entropy of chaotic repellers formed by those points in a given chaotic attractor that never visit some small forbidden hole-region in the phase space. The hole is a set of points in the phase space that have a sequence α = (α0α1 . . . αl−1) as the first l letters in their itineraries. We point out that the difference between the topological entropies of the attractor an...

SUMMARY A NURBS Enhanced eXtended Finite Element Approach is proposed for the unfitted simulation of structures defined by means of CAD parametric surfaces. In contrast to classical X-FEM that uses levelsets to define the geometry of the computational domain, exact CAD description is considered here. Following the ideas developed in the context of the NURBS-Enhanced Finite Element Method, NURBS...

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located i...