Foundation of Computer Science Laboratory

Takafumi Hayashi Professor	Shuxue Ding Associate Professor	Wenlong Liu Visiting Researcher

The research and education activities in the laboratory focus on the theoretical foundations of computers and computations, including broad applications in science and engineering. Our work covers algorithms and computation, programming languages, discrete mathematics, statistical signal processing, neuro-computing, optimization, simulated acoustics and related topics.

Areas of our research interest include Combinatorics and its applications; Spread spectrum communication; Sparse representation and sparse component analysis; Content-Aware networking; Secure Cloud Computing; SOA, SaaS, IaaS, Daas, and Paas; Signal processing; Image analysis for measurement; Enterprise Integration and Messaging Network: Security Management; Networks; GRID as a Service Oriented Architecture Based System; Security and management of computer system for e-Government; Blind source separation and independent component analysis, and their applications in acoustic signals and vital signs; Neural computing and brain-style signal processing; Optimization and machine learning; Time-reversal wave propagation in ergodic environment and its applications in acoustics, ultrasonics and telecommunications; Information theory and algorithmic complexity.

Faculty of the FCS laboratory teach Computer Literacy, Programming I, Algorithms and Data Structures, Advanced Algorithms, Digital Signal Processing, Linear Systems, Information Security, SCCPs and other selective courses. Students join faculty research and also develop their own research themes. We participate in various research projects of JSPS, NIFS, RIKEN etc.

Refereed Journal Papers

[sding-01:2008]	T. Haneda and S. Ding. Pseudo Online Independent Component Analysis for Dynamical Mixing Using Gradient-Optimization. Journal of Advanced Computational Intelligence and Intelligent Informatics, 13(3):275–283, 2009.
	Many of the algorithms developed for independent component analysis (ICA) operate efficiently only in batch processing because they include ensemble expectation operations. The online ICA algorithm that we propose in this paper operates recursively on sequential finite lengthened input blocks for learning mixing parameters and for separating sources based on maximized non-Gaussianity of outputs. To enable the algorithm to work more efficiently in separating nonstationary sources and/or in dynamical mixing environments, we proposed an online estimation for the covariance matrix of input signals and an online optimization for the step size. The covariance matrix is used to calculate the whitening matrix and must be estimated appropriately for ICA processing to be efficient. Determining the step-size parameter in an online algorithm is critical to higher convergence and stability after convergence but is notoriously tiresome, especially if sources or/and the mixing environment are nonstationary. The online optimized step size we proposed is automatically optimized for suiting the powers in each block. Numerical experiments confirm that the online algorithm converges efficiently and separates sources appropriately.
[sding-02:2008]	W. Liu and S. Ding. An Efficient Method to Determine the Diagonal Loading Factor Using the Constant Modulus Feature. IEEE Transactions on Signal Processing, 56(12):6102–6106, 2008.
	The diagonal loading method is a simple and efficient method that improves the robustness of beamformers. However, determining an ideal diagonal loading factor (DLF) is not a trivial problem, one that still has not been adequately addressed. Although beamformers are widely used in radar, sonar, and many other applications, in this correspondence, we consider a beamformer used only for digital communication applications. In digital communications, user information is coded into a sequence with the constant modulus (CM) in the baseband. Obviously, if the beamformer can cancel interference sufficiently well, the outputs of the beamformer should satisfy the CM condition more precisely. Therefore, minimizing CM errors can act as a natural criterion for determining DLFs. In this correspondence, we present a cost function based on the criterion. We also propose a direct search algorithm for DLF determination by minimizing the cost function. Numerical experiments show the effectiveness of the proposed method.
[takafumi-01:2008]	Takafumi Hayashi. Zero-Correlation Zone Sequence Set Constructed from a Perfect Sequence. IEEE Signal Processing Letters, 16(2):331–334, 2009.
	In this letter, we present a new approach to the construction of a novel ternary ZCZ sequence set.
[takafumi-02:2008]	Takafumi Hayashi. A Novel Class of Zero-Correlation Zone Sequence Sets Constructed from a Perfect Sequence. IEICE Transaction of Fundamentals, E91-A(2n):1233–1237, 2008.
	In this letter, we present a new integrated scheme to construct ZCZ sequence sets.
[takafumi-03:2008]	Takafumi Hayashi. Zero-Correlation Zone Sequence Set Constructed from a Perfect Sequence and a Complementary Sequence Pair. IEICE Transaction of Fundamentals, E91-A(8):1676–1681, 2008.
	In this letter, we present a new approach to the construction of a new ZCZ sequences using even-perfect sequence and odd-perfect sequence pair

Referred Proceeding Papers

[sding-03:2008]	Z. Tang, W. Liu, and S. Ding. An Invariant Pattern Recognition System Using the Bayesian Inference on Hierarchical Sequences with Pre-Processing. In Proc. Japan-China Joint Workshop on Frontier of Computer Science & Technology (FCST 2008), pages 208–213. Japan-China Joint Workshop on Frontier of Computer Science & Technology (FCST 2008), IEEE, 2008.
	The human being can understand real-world objects based on some kinds of invariable characteristics. Recently, a mathematical model for this has been proposed that is based on the Bayesian inference on hierarchical sequences [1]. It assumed that human brain cortex solves the invariance problem in a manner that is using a multihierarchical structure. When we applied the model to a line Drawing Recognition System (DRS), however, the performance was not as good as we had expected. This is especially the case when the hand input character is too small or too big. In this paper, wepropose a method for improving this. Our method is based on a fact that human eyes are able to automatically focus on the object by its position, size, and lightness. That is, before the recognition, we perform a piece of pre-processing so that it can adjust the position, size and the lightness to make them most suitable for the recognition followed.
[sding-04:2008]	T. Haneda and S. Ding. A Robust Gradient-Descent Algorithm for On- Line Independent Component Analysis Based on Negentropy Maximization. In Proc. Joint 4th International Conference on Soft Computing and Intelligent Systems and 9th International Symposium on advanced Intelligent Systems (SCIS & ISIS 2008), pages 870–875. Joint 4th International Conference on Soft Computing and Intelligent Systems and 9th International Symposium on advanced Intelligent Systems (SCIS & ISIS 2008), 2008.
	This paper addresses the problem of on-line Independent Component Analysis (ICA). This area has been explosively investigated, and nowadays, there have already been a great many algorithms. However, a serious problem is that most of the existing algorithms can only work as batch processing, since they usually include some ensemble expectation operations. In this paper, we propose an on-line ICA algorithm that is a recursive processing, on a sequential finite lengthened input blocks, for learning the mixing parameters and separating the sources based on the maximization of non-Gaussianity of the outputs. Numerical experiments show that the proposed algorithm can work efficiently and can separate appropriate sources.
[sding-05:2008]	W. Liu and S. Ding. A ‘Decision and Re-solving’ Beamformer for the PAM Communication System. In Proc. International Conference on Innovative Computing, Information and Control 2008 (ICICIC-08), pages 352–355. International Conference on Innovative Computing, Information and Control 2008 (ICICIC-08), IEEE, 2008.
	Minimum variance distortionless response (MVDR) beamforming is known to degrade due to effects of imprecise knowledge about the steering vector and finite sample size. However, the theoretical reasons for these have not been well investigated yet. In this paper, we propose a new mathematical model about beamforming. In the new model, beamforming is posed as ill-conditioned linear equations. The new model can clearly explain why the MVDR method suffers significant performance degradation when the knowledge about the steering vector is imprecise and the sample size is finite. Using the new model, we also propose a new beamformer for the PAM communication, which is termed as ‘Decision and Re-solving Beamformer’. Numerical experiments have shown the robustness of the proposed beamformer against imprecise knowledge on the steering vector and/or against the finite signal length effect.
[takafumi-04:2008]	Junya Terazono, Noriaki Asada, Hirohide Demura, Naru Hirata, Kazuto Saiki, Akira Iwasaki, Ryuichi Oka, Takafumi Hayashi, Taro Suzuki, and Hideaki Miyamoto. Web-GIS based Collaboration Environment Using Scientific Data of the Moon. In Proc. The XXI Congress of The International Society for Photogrammetry and Remote Sensing, 2008., 2008.
	An WEB-GIS based collaboration environment is constructed for scientifc research of the moon.
[takafumi-05:2008]	H. Fukuhara, K. Kawauchi, I. Koseda, R. Fujita, T. Miyazaki, S. Saito, A. Kara, and T. Hayashi. Integration of Sensor Networks with Information Systems using the Messaging Network. In Proc. of SICE 2008. SICE, 2008.
	We prposed an new approach to integrate various sensor networks using messaging networking.
[takafumi-06:2008]	T. Hayashi, Y. Takahashi, and S. Kanemoto. Novel optimal zerocorrelation zone sequence set and its application to ultrasonic imaging. In Proc. of SICE 2008. SICE Computer Society, 2008.
	We prposed a new scheme to generate ZCZ sequence set.
[takafumi-07:2008]	T. Hayashi, Y. Takahashi, and S. Kanemoto. Novel optimal zerocorrelation zone sequence set and its application to ultrasonic imaging. In Proc. of SICE 2008. SICE Computer Society, 2008.
	We prposed a new scheme to generate an optimal ZCZ sequence set and its application to ultrasonic imaging.

Grants

[sding-06:2008]	S. Ding. Blind source separation using sparse frame representation for multi source signals and its applications, 2008-2010.
	Scientific Research C, No. 20500209, 2008 Grants-In-Aid for Scientific Research, Ministry of Education, Culture, Sports, Science and Technology
[takafumi-09:2008]	Takafumi Hayashi. Study of of ternary sequence set having zerocorrelation zone for periodic and Aperiodic correlation functions, 2007-2009.
	Grants-In-Aid for Scientific Research, JSPS Japan.
[takafumi-10:2008]	Takafumi Hayashi, Toshiaki Miayzaki, and Senro Saito. Messaging Network for surviving info-plosion, 2007-2008.
	Grants-In-Aid for Scientific Research, Ministry of Education, Culture, Sports, Science and Technology
[takafumi-11:2008]	Takafumi Hayashi. A Knowledge Information Infrastructure using Messaging Metworking - Sapience Networking -, Fukushima Prefectural Foundation, 2008.

Academic Activities

[sding-07:2008]	S. Ding, 2008. The Acoustical Society of America (ASA), Membership
[sding-08:2008]	S. Ding, 2008. Program committee member of The Third International Conference on Innovative Computing, Information and Control (ICICIC 2008)
[sding-09:2008]	S. Ding, 2008. Institute of Electrical and Electronics Engineers (IEEE), Membership.
[sding-10:2008]	S. Ding, 2007. IEEE Signal Processing Society, Membership. Reviewers for the IEEE Transactions on Signal Processing and IEEE Signal Processing Letters
[sding-11:2008]	S. Ding, 2008. Program Committee Member of 2008 IEEE International Conference on Computer and Information Technology (CIT 2008)
[sding-12:2008]	S. Ding, 2008. Program Committee Member of The Fifth International Symposium on Neural Networks (ISNN 2008)
[sding-13:2008]	S. Ding, 2008. IEICE, Membership
[sding-14:2008]	S. Ding, 2008. The Association for Computing Machinery (ACM), Membership
[sding-15:2008]	S. Ding, 2008. Review committee member candidate for Grants-In-Aid for Scientific Research projects, JSPS
[sding-16:2008]	S. Ding, 2008. Reviewer for Signal Processing, Elsevier
[takafumi-12:2008]	Takafumi Hayashi, 2008. Reviewer of IEEE Signal Processing Letters
[takafumi-13:2008]	Takafumi Hayashi, 2008. Reviewer of IEEE Communication Letters
[takafumi-14:2008]	Takafumi Hayashi, 2008. Reviewer of ICC, IEEE
[takafumi-15:2008]	Takafumi Hayashi, 2008. Reviewer of IEICE Transactions
[takafumi-16:2008]	Takafumi Hayashi, 2008. Reviewer of OE Magazine

Patents

[takafumi-17:2008]

Takafumi Hayashi, Ltd. Fukushima Information Processing Center Co., Ltd. Fukushimaken Chuo Keisan Center Co., and Ltd. FSK Co. Onetime-password authentication system, Patent Pending 2008-000351, Japan, 2008., March 2008.

Ph.D. and Other Theses

[sding-17:2008]	Kiminobu Nagao. Graduation Thesis: Improving Online Independent Component Analysis Based on Fast Fixed-Point Algorithm, University of Aizu, 2008. Thesis Advisor: Ding, S.
[sding-18:2008]	Masahito Shinkai. Graduation Thesis: Improving Simulation for Wave Convergence in Time-Reversal Acoustics, University of Aizu, 2008. Thesis Advisor: Ding, S.
[sding-19:2008]	Yuuki Nakayama. Graduation Thesis: Solving Permutation Switching Problem of Online Independent Component Analysis Using Cross-Correlations of Outputs, University of Aizu, 2008. Thesis Advisor: Ding, S.
[sding-20:2008]	Daichi Tanaka. Graduation Thesis: Independent Component Analysis via Negentropy Approximation with Two Non-linear Functions, University of Aizu, 2008. Thesis Advisor: Ding, S.
[sding-21:2008]	Zunyi Tang. Master Thesis: An Invariant Pattern Recognition System Using the Bayesian Networks for Hierarchical Sequences with Data Pre- Processing, University of Aizu, 2008. Thesis Advisor: Ding, S.
[takafumi-18:2008]	Kazunori Suzuki. Graduation Thesis: Joint Outsourcing Using IDC for Local e-Governments, University of Aizu, March 2008. Thesis Advisor: Takafumi Hayashi
[takafumi-19:2008]	Toshiaki Nihei. Graduation Thesis: Reference Management for an Efficient Data Storage System, University of Aizu, March 2008. Thesis Advisor: Takafumi Hayashi
[takafumi-20:2008]	Takuto Yamada. Graduation Thesis: An Efficient Web contents Rediscovery Using Tag History, University of Aizu, March 2008. Thesis Advisor: Takafumi Hayashi
[takafumi-21:2008]	Kenji Oota. Graduation Thesis: Contents Management Integration Using Folksonomy, University of Aizu, March 2008. Thesis Advisor: Takafumi Hayashi
[takafumi-22:2008]	Makoto Sato. Graduation Thesis: A Novel Mailing System Using a Messaging Network, University of Aizu, March 2008. Thesis Advisor: Takafumi Hayashi

2010 THE UNIVERSITY OF AIZU ALL RIGHTS RESERVED