Table of Contents


Fall 2018

Unless stated otherwise, the seminar takes place on Mondays, starting at 13:30 in Seminar Room 406, Faculty of Engineering Integrated Research Building (No. 53 on this map).
The person in charge of the seminar is Naveed Ahmed Azam from the Discrete Mathematics Laboratory.

Important: The ICT-Innovations 2019 will be held on February 20, 2019.
The deadline for registering a presentation title is November 16 extended to November 19, 2018.
Note, the registration link is only accessible from the University's network.

October 15

The first meeting of the semester.
Let us gather, greet new members to the Department, and set a plan for the semester before us.
We can play some warm-up board games to get to know each other, and hear some information on the ICT-Innovations event from experience participants.

October 22

Speaker: Naveed Ahmed Azam

Discrete Mathematics Research Group,
Topic: Enumerating All Pairwise Compatibility Graphs with a Given Number of Vertices Based on Linear Programming
Pairwise compatibility graphs (PCGs) are widely used in the fi eld of bioinformatics in the study of evolutionary theory. In this paper, we propose an efficient technique for the enumeration of all PCGs with a given number of vertices. The proposed method uses a linear program to get a weight assignment on some tree if the graph is PCG, while for a non-PCG it uses duality to get a proof that no such witness tree and weight assignment exist. We have used our technique on graphs with eight vertices and discovered that there are exactly seven graphs on eight vertices that are not PCGs, fi ve of which are shown for the first time with this work.

October 29

Speaker: Tankaria Hardik

System Optimization Research Group,
Topic: Modified Regularized Limited Memory BFGS (RL-BFGS) method for Unconstrained Optimization
The regularized limited memory BFGS method is a popular method for solving large-scale unconstrained minimization problems. In this talk, we propose a modified version of the regularized limited memory BFGS method (RL-BFGS), which combines the regularized limited memory BFGS and the idea of adaptive trust region method. We have used one more parameter along with the regularized parameter to update the L-BFGS direction. Once we update the regularized parameter and ratio of adaptive trust region, we use line search with Wolfe's condition, so that there will be a better improvement in step length by following parameter of adaptive trust region method. We will explain that the proposed method is more efficient than the regularized limited memory BFGS method.

November 12

Speaker: Hirofumi Tsuda

Physical Statistics Research Group,
Topic: Optimal Sequence and SINR for Desired User in Asynchronous CDMA System
We consider asynchronous CDMA systems in no-fading environments and focus on a certain user. This certain user is called a desired user in this presentation. In such a situation, an optimal sequence, maximum Signal-to-Interference Noise Ratio (SINR) and the maximum capacity for a desired user are derived with other spreading sequences being given and fixed. In addition, the optimal sequence and SINR for a desired user are written in terms of the minimum eigenvalue and the corresponding eigenvector of a matrix, respectively. Since it is not straightforward to obtain an explicit form of the maximum SINR, we evaluate SINR and obtain the lower and upper bounds of the maximum SINR. From these bounds, the maximum SINR may get larger as the quantities written in terms of quadratic forms of other spreading sequences decreases.

November 19

Speaker 1: Hafez Sarkawi

Control System Theory Research Group,
Topic: On the DC-DC Zeta Converter Hybrid Control: Discontinuous Conduction Mode Operation
n this presentation, we propose a hybrid control algorithm for the dc-dc zeta converter operating in discontinuous conduction mode (DCM). We derive a switching control law to stabilize the dc-dc zeta converter in DCM. We find mathematical models instrumental in limiting the arbitrary fast steady-state switching frequency thus guaranteeing the DCM operation. The effectiveness of the proposed method is illustrated with simulation results.

Speaker 2: Shogo Yamanaka

Dynamical Systems Research Group,
Topic: Existence of transverse heteroclinic orbits and nonintegrability in two-degree-of-freedom Hamiltonian systems with saddle-centers
We consider a class of two-degree-of-freedom Hamiltonian systems with saddle-centers connected by heteroclinic orbits. We show that if the sufficient conditions for real-meromorphic nonintegrability hold, then the stable and unstable manifolds of the periodic orbits intersect transversely, are quadratically tangent or do not intersect in general, and they do not intersect when the Hessian matrix of the Hamiltonian has a different number of positive eigenvalues at the associated saddle-centers. Our theory is illustrated for a system with quartic single-well potential.

December 17

Speaker: Man Zheng

Control System Theory Research Group,
Topic: Convex input design problems for the frequency response in Bayesian system identification
Recently, the research of identification input for Bayesian methods has been considered. However, the problem formulation in previous researches suffers a non-convex issue which may lead to optimization difficulty. In this contribution, a new minimum power input design problem formulation is organized via viewing the input as a stochastic process. The stochastic consideration facilitates the input design problem be presented as convex optimization problems. We obtain the finite autocorrelation coefficients of the desired stochastic input signal by solving the proposed problems and then realize the input stochastic process by the maximum entropy extension of finite autocorrelation coefficients. Simulations results demonstrate the effectivity of the proposed algorithm. The further research for the confidence region is considered.

January 21

Speaker: Tomoyuki Mao

Physical Statistics Research Group,
Investigation of the Difference Between Chaos Degree and Lyapunov Exponent
Lyapunov Exponent is commonly used as a measure of chaos in nonlinear dynamical systems. On the other hand, Chaos Degree is proposed as another measure of chaos based on information theory. Chaos Degree is calculable from data, but there is the difference between Chaos Degree and Lyapunov Exponent. We researched the difference between them on asymmetric tent map and found that the difference can be interpreted as the average of some kind of information.

January 28

ICT Poster Checking

Let us meet and check the poster of each other for ICT innovation 2019.

Past seminars