The minimum k-enclosing ball problem seeks the ball with smallest radius that contains at least k of m given points in a general n-dimensional Euclidean space. This problem is NP-hard. We present a branch-and-bound algorithm on the tree of the subsets of k points to solve this problem. The nodes on the tree are ordered in a suitable way, which, complemented with a last-in-first-out search strat...

We propose a fast algorithm for image denoising, which is based on a dual formulation of a recent denoising model involving the total variation minimization of the tangential vector field under the incompressibility condition stating that the tangential vector field should be divergence free. The model turns noisy images into smooth and visually pleasant ones and preserves the edges quite well....

Given a nonlinear It^ o equation dx(t)=f(x(t);t)dt+ug(x(t);t)dw(t), suppose that the equation is almost surely exponentially stable provided the noise intensity u is large enough. We show that if u is replaced by u= R t 0 jr(s)x(s)j p ds, then the equation stabilizes itself in the sense that R 1 0 jr(t)x(t)j p dt<1 a.s. Moreover, if u is replaced by u=sup 0t jr(s)x(s)j, then the equation stabil...

A time-dependent system modeling the interaction between a Stokes fluid and an elastic structure is studied. A divergence-free weak formulation is introduced which does not involve the fluid pressure field. The existence and uniqueness of a weak solution is proved. Strong energy estimates are derived under additional assumptions on the data. The existence of an L2 integrable pressure field is e...

REI-HENG CHENG, CHANG WU YU AND TUNG-KUANG WU Department of Information Management Hsuan Chuang University Hsinchu, 300 Taiwan E-mail: [email protected] Department of Computer Science and Information Engineering Chung Hua University Hsinchu, 300 Taiwan E-mail: [email protected] Department of Information Management Ming Hsin University of Science and Technology Hsinchu, 304 Taiwan E-mail: [email protected]...

For wireless local area networks based on OFDM we study the sum rate of time and frequency division multiple access (TDMA, OFDMA) as well as superimposed transmission (SUP). In the analysis traffic-imposed constraints on the maximum exploitable user rates apply. For a large number of subcarriers the effective sum rate is low with TDMA but much higher with OFDMA and SUP. The spatial properties o...

We report evidence on the profitability and statistical significance among 2,127 technical trading rules. The best rules are found to be significantly profitable based on standard tests. We then employ White’s (2000) Reality Check to evaluate these rules and find that data-snooping biases do not change the basic conclusions for the full sample. A sub-sample analysis indicates that the data-snoo...