研究発表

公開件数: 5 件
No. 会議種別 タイトル 会議名 開催年月日 URL 概要
1 口頭発表(招待・特別)
Islay– An educational programming tool based on state diagrams
International Conference on Advances in Electrical, Electronic and System Engineering (ICAEESE 2016)
2016/11


2 口頭発表(招待・特別)
Cardinal splines in piecewise constant tension
5th International Conference on Computational Harmonic Analysis
2014/05/22

The cubic spline gives the smoothest interpolation of data in the sense that it minimizes the integral of its squared second derivative. The linear spline gives the shortest polygonal interpolation. The spline in tension was devised as a generalization of those two splines. It minimizes the integral of a weighted sum of the squared first and second derivatives. The weight on the first derivative is called tension because its increase makes the spline in tension approach the shortest linear spline while retaining smoothness like the cubic spline. The tension has been fixed as a single constant over the entire domain since its first appearance in 1966.

In this talk, we shall look at the spline in tension as the output of a linear dynamical system model with a series of delta functions input. In exchange of restricting the sampling points to be uniform, we can place a different tension in each sampling interval because the control theory allows for time-varying dynamics. Solving the dead beat control problem of the system, we will eventu- ally have a locally supported basis for the space of cardinal splines in piecewise constant tension.
An application is an adaptive image interpolation algorithm made up of the univariate spline interpolations in the horizontal and vertical directions. Varying the tension in proportion to an index of sharp change in brightness, we obtain image interpolation results with less ringing artifacts compared to those by the cubic spline interpolation.

We will also discuss a similar model for bivariate splines in piecewise constant tension which may generalize the bicubic spline interpolation.
3 口頭発表(招待・特別)
Beat-Rest Pulsing for Impulse Radio Communications
Second International Conference on Computer and Communications Engineering
2008/05/13

Keynote speech: A practical approach is presented for fast impulse-radio ultra-wide-bandwidth communications. It employs a train of overlapping time-limited pulses that are orthogonal to one another. For the sake of practicability, we assume that each pulse is shaped through a common bandpass filter excited by a staircase function. Instead of sending the pulses at the maximum rate, we transmit them every other clock interval, i.e., in the beat-and-rest rhythm. This relaxing rhythm halves the transmission rate but brings in the properties of being time-limited and orthogonal, which are crucial for real-time and robust detection of the received pulses, respectively. We obtain an example pulse which complies with the FCC regulation for indoor ultra-wide-bandwidth radio communications. This talk is based on the speaker's joint work with Semih Özlem and Hiromasa Habuchi.
4 口頭発表(招待・特別)
Locally supported splines in variable tension
Second International Conference on Optimization and Optimal Control
2007/07/17


5 口頭発表(招待・特別)
On the Optimality of Splines for Expressing the Hand-Writing Process
The X European Signal Processing Conference
2000/09