著者

Ken Umeno

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

Nonlinear Theory and Its Applications, IEICE (ISSN:21854106)

巻号頁・発行日

vol.7, no.1, pp.14-20, 2016 (Released:2016-01-01)

参考文献数

11

被引用文献数

2 13

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We consider a family of ergodic transformations on the real line R preserving Cauchy laws. A dualistic nature between the ergodic transformation and the associated transformation of the scale parameter of a Cauchy law is proven to be hold, which provides a systematic view of explicit mixing property with the ergodic transformation having the Cauchy law as the limiting distribution.

著者

Atsushi Iwasaki Ken Umeno

出版者

一般社団法人 日本応用数理学会

雑誌

JSIAM Letters (ISSN:18830609)

巻号頁・発行日

vol.9, pp.5-8, 2015 (Released:2017-02-18)

参考文献数

8

被引用文献数

2

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Permutation polynomials over a ring of modulo $2^w$ are well adopted to digital computers and digital signal processors, and so they are in particular expected to be useful for cryptography and pseudo random number generator{s}. For a longer period of the polynomial is demanded in general, we derive a necessary and sufficient condition that polynomials are permutating and their periods are the longest over the ring. We call polynomials which satisfy the condition ``one-stroke polynomials over the ring''.

著者

Atsushi Iwasaki Ken Umeno

出版者

一般社団法人 電子情報通信学会

雑誌

Nonlinear Theory and Its Applications, IEICE (ISSN:21854106)

巻号頁・発行日

vol.8, no.3, pp.215-223, 2017 (Released:2017-07-01)

参考文献数

13

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Vector Stream Cipher (VSC) is a stream cipher which consists of permutation polynomial over a ring of modulo 2w. The algorithm for generating key stream is very simple and the encryption is very fast. Some theoretical attacks for VSC have been reported so far since the invention of VSC in 2004. Then, the authors proposed some improvements and developed “Vector Stream Cipher 2.0 (VSC 2.0)” to be immune against the theoretical attacks. In this paper, we propose further improvement of VSC 2.0 to publish as a new chaos cipher “Vector Stream Cipher 2.1 (VSC2.1)”. VSC 2.1 is faster and more secure than VSC 2.0. Our result suggests that permutation polynomials over a ring of modulo 2w are useful for cryptography.

著者

Atsushi Iwasaki Ken Umeno

出版者

一般社団法人 電子情報通信学会

雑誌

Nonlinear Theory and Its Applications, IEICE (ISSN:21854106)

巻号頁・発行日

vol.7, no.1, pp.30-37, 2016 (Released:2016-01-01)

参考文献数

7

被引用文献数

6

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Vector Stream Cipher (VSC) is a stream cipher based on the chaos theory. The algorithm for generating stream keys is very simple and the encryption speed is very fast. Some theoretical attacks for VSC have been reported so far since the invention of VSC in 2004. In this paper, we improve the security of VSC and design a new cipher system “Vector Stream Cipher 2.0” so that the theoretical attacks cannot work. We show that the encryption speed of VSC 2.0 keeps more than 85% of that of VSC, and key-stream of VSC 2.0 has good randomness. The main result of this paper is that our proposed VSC 2.0 is shown to have provable security for attacks with linear masking. Because there is few cryptography based on the chaos theory which has proven security, VSC 2.0 is a rare example.

著者

Masaru Shintani Ken Umeno

出版者

The Japan Society for Industrial and Applied Mathematics

雑誌

JSIAM Letters (ISSN:18830609)

巻号頁・発行日

vol.14, pp.49-52, 2022 (Released:2022-04-06)

参考文献数

13

被引用文献数

1

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We propose a new dynamic pricing algorithm based on the universal exponential law of booking curves in services with reservations. The algorithm includes a parametric learning model which makes it possible to simulate the effect of changes in prices on quantity demanded from historical data continuously for practical use. Furthermore, we show an example, where some real data in a hotel applies for the learning model. Our proposed algorithm with the learning model, which can dynamically update the optimum parameters, is envisaged to be utilized as a practical dynamic pricing strategy.

著者

Masaru Shintani Ken Umeno

出版者

The Japan Society for Industrial and Applied Mathematics

雑誌

JSIAM Letters (ISSN:18830609)

巻号頁・発行日

vol.14, pp.45-48, 2022 (Released:2022-04-06)

参考文献数

12

被引用文献数

2

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The exponential law has been discovered in various systems around the world. In this study, we introduce two existing and one proposed analytical method for exponential decay time-series predictions. The proposed method is given by a linear regression that is based on rescaling the time axis in terms of exponential decay laws. We confirm that the proposed method has a higher prediction accuracy than existing methods by performance evaluation using random numbers and verification using actual data. The proposed method can be used for analyzing real data modeled with exponential functions, which are ubiquitous in the world.

著者

Masataka Motoyama Ken Umeno

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Electronics Express (ISSN:13492543)

巻号頁・発行日

pp.18.20210011, (Released:2021-02-10)

参考文献数

32

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This letter aims to demonstrate the concept of wireless power coloring (WPC), i.e., frequency division multiplexing of wireless power transfer (WPT). Currently, to obtain significant received power in WPT, the power is generated from a single transmission source. Herein, we propose a method of transmitting wireless power through more than one (N ≧ 2) multiplexed coloring source. To achieve this, we use power transmitting sources with different resonance frequencies in magnetic resonance-type WPT to selectively send power to a designated receiver.

著者

Isao Nakazawa Ken Umeno

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.6, no.12, pp.673-678, 2017 (Released:2017-12-01)

参考文献数

5

被引用文献数

2

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In this paper, we investigate the almost periodic frequency arrangement (APFA) asynchronous system for super-multi-access radio systems, and APFA configuration procedure on a frequency domain multiplex scheme by using almost periodic function (APF). We report on the relationship between the total number of prime numbers, the number of sub-carriers, and the normalized frequency standard deviation for a system with up to one million users. By using computer simulations, we show the multi-carrier modulation and asynchronous demodulation based on APFA, in which ICI interference by nonlinear elements is improved compared with the orthogonal frequency-division multiplexing (OFDM).

著者

Ryo TAKAHASHI Ken UMENO

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences (ISSN:09168508)

巻号頁・発行日

vol.E97-A, no.7, pp.1619-1622, 2014-07-01

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In this study, a performance of a synchronous code division multiple access (CDMA) using the chaotic spreading sequences with constant power is estimated in indoor power line fading channels. It is found that, in the fading channels, as the number of simultaneous users increases, the chaotic spreading sequences realize better performance than the Walsh-Hadamard sequences in the synchronous CDMA.

著者

梅野 健 Ken UMENO

出版者

総合研究大学院大学教育研究交流センター

雑誌

新分野開拓記

巻号頁・発行日

pp.91-100, 2004-06 (Released:2012-01-23)

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自然現象と計算論との整合性 梅野 健[独立行政法人 情報通信研究機構/株式会社 カオスウエア]*所属は当時のものを記載

著者

梅野 健 Ken UMENO

出版者

総合研究大学院大学教育研究交流センター

雑誌

新分野開拓記

巻号頁・発行日

pp.91-100, 2004-06

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自然現象と計算論との整合性

著者

Ryo Takahashi Etsushi Nameda Ken Umeno

出版者

The Japan Society for Industrial and Applied Mathematics

雑誌

JSIAM Letters (ISSN:18830609)

巻号頁・発行日

vol.2, pp.9-12, 2010 (Released:2010-03-09)

参考文献数

9

被引用文献数

2 1

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Inner angle of triangle made of consecutive three points on unit circle is investigated. We use two methods to plot points. One is plotting random numbers whose distribution is uniform. Another is plotting consecutive numbers obtained by a map which generates complex chaotic sequences with constant power. We focus on an inner angle at the middle point in consecutive three points. An angle for chaotic sequence is found to be different from one for uniform random sequence.