Hiroyasu Ando
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View article: Linear-inverse-modeling approach to estimating Liang-Kleeman information flow in a cyclostationary process under memoryless and persistent noise
Linear-inverse-modeling approach to estimating Liang-Kleeman information flow in a cyclostationary process under memoryless and persistent noise Open
The Liang-Kleeman (LK) information flow provides a powerful framework for quantifying causality among variables, while linear inverse modeling (LIM) offers an effective empirical approach to studying the dynamical evolution of system state…
View article: Nonlinear extensions of linear inverse models under memoryless or persistent random forcing
Nonlinear extensions of linear inverse models under memoryless or persistent random forcing Open
This study extends the linear inverse modeling (LIM) framework to nonlinear settings by presenting White-nLIM and Colored-nLIM, statistics-based empirical methods that construct approximate stochastic systems incorporating quadratic determ…
View article: On cyclostationary linear inverse models: a mathematical insight and implication
On cyclostationary linear inverse models: a mathematical insight and implication Open
Cyclostationary linear inverse models (CS-LIMs) are advanced data-driven techniques for extracting first-order time-dependent dynamics and random forcing information from cyclostationary observational data. This study focuses on the mathem…
View article: Colored linear inverse model: A data-driven method for studying dynamical systems with temporally correlated stochasticity
Colored linear inverse model: A data-driven method for studying dynamical systems with temporally correlated stochasticity Open
In real-world problems, environmental noise is often idealized as Gaussian white noise, despite potential temporal dependencies. The linear inverse model (LIM) is a class of data-driven methods that extract dynamic and stochastic informati…
View article: Mathematical analysis of the Wiener processes with time-delayed feedback
Mathematical analysis of the Wiener processes with time-delayed feedback Open
It is known that time delays generally make a system unstable. However, it is numerically observed that the diffusion coefficients of the Wiener processes with time-delayed feedback decrease while increasing the time delay τ. In particular…
View article: On the Cyclostationary Linear Inverse Models: A Mathematical Insight and Implication
On the Cyclostationary Linear Inverse Models: A Mathematical Insight and Implication Open
Cyclostationary linear inverse models (CS-LIMs), generalized versions of the classical (stationary) LIM, are advanced data-driven techniques for extracting the first-order time-dependent dynamics and random forcing relevant information fro…
View article: Reducing Total Trip Time and Vehicle Emission through Park-and-Ride -- methods and case-study
Reducing Total Trip Time and Vehicle Emission through Park-and-Ride -- methods and case-study Open
This study addresses important issues of traffic congestion and vehicle emissions in urban areas by developing a comprehensive mathematical framework to evaluate Park-and-Ride (PnR) systems. The proposed approach integrates queueing theory…
View article: Colored-LIM: A Data-Driven Method for Studying Dynamical Systems with Temporally Correlated Stochasticity
Colored-LIM: A Data-Driven Method for Studying Dynamical Systems with Temporally Correlated Stochasticity Open
In real-world problems, environmental noise is often idealized as Gaussian white noise, despite potential temporal dependencies. The Linear Inverse Model (LIM) is a class of data-driven methods that extract dynamic and stochastic informati…
View article: Two Long-period Giant Planets around Two Giant Stars: HD 112570 and HD 154391
Two Long-period Giant Planets around Two Giant Stars: HD 112570 and HD 154391 Open
We present the discoveries of two giant plants orbiting the red-giant-branch star HD 112570 and the red-clump star HD 154391, based on the radial-velocity (RV) measurements from the Xinglong station and Okayama Astrophysical Observatory. S…
View article: Computation harvesting from nature dynamics for predicting wind speed and direction
Computation harvesting from nature dynamics for predicting wind speed and direction Open
Natural phenomena generate complex dynamics because of nonlinear interactions among their components. The dynamics can be exploited as a kind of computational resource. For example, in the framework of natural computation, various natural …
View article: Two long-period giant planets around two giant stars: HD 112570 and HD 154391
Two long-period giant planets around two giant stars: HD 112570 and HD 154391 Open
We present the discoveries of two giant planets orbiting the red giant branch (RGB) star HD 112570 and the red clump (RC) star HD 154391, based on the radial velocity (RV) measurements from Xinglong station and Okayama Astrophysical Observ…
View article: Revisiting Planetary Systems in Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and multiplicity-metallicity trend around evolved stars
Revisiting Planetary Systems in Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and multiplicity-metallicity trend around evolved stars Open
In this study, we revisit 32 planetary systems around evolved stars observed within the framework of the Okayama Planet Search Program and its collaborative framework of the EAPS-Net to search for additional companions and investigate the …
View article: Functional improvement in <i>β</i> cell models of type 2 diabetes using on-demand feedback control
Functional improvement in <i>β</i> cell models of type 2 diabetes using on-demand feedback control Open
The bursting activity of pancreatic β cells is correlated with insulin secretion. Although normal pancreatic β cells show periodic bursting, the bursting activity becomes irregular in dysfunctional pancreatic β cells of type 2 diabetic pat…
View article: Recovering Arrhythmic EEG Transients from Their Stochastic Interference
Recovering Arrhythmic EEG Transients from Their Stochastic Interference Open
Traditionally, the neuronal dynamics underlying electroencephalograms (EEG) have been understood as arising from \textit{rhythmic oscillators with varying degrees of synchronization}. This dominant metaphor employs frequency domain EEG ana…
View article: Predicting traffic breakdown on expressways using linear combination of vehicle detector data
Predicting traffic breakdown on expressways using linear combination of vehicle detector data Open
Traffic congestion is closely associated with various social issues that must be solved urgently. With the recent advancement of machine learning technologies, diverse methods for predicting traffic congestion have been developed. Specific…
View article: A Close-in Planet Orbiting Giant Star HD 167768
A Close-in Planet Orbiting Giant Star HD 167768 Open
We report the detection of a giant planet orbiting a G-type giant star HD 167768 from radial velocity measurements using HIgh Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory (OAO). HD 167768 has a mass of $1.08…
View article: A trio of giant planets orbiting evolved star HD 184010
A trio of giant planets orbiting evolved star HD 184010 Open
We report the discovery of a triple-giant-planet system around an evolved star HD 184010 (HR 7421, HIP 96016). This discovery is based on observations from Okayama Planet Search Program, a precise radial velocity survey, undertaken at Okay…
View article: Regular Radial Velocity Variations in Nine G- and K-type Giant Stars: Eight Planets and One Planet Candidate
Regular Radial Velocity Variations in Nine G- and K-type Giant Stars: Eight Planets and One Planet Candidate Open
We report the detection of radial velocity variations in nine evolved G- and K-type giant stars. The observations were conducted at Okayama Astrophysical Observatory. Planets or planet candidates can best explain these regular variations. …
View article: Regular radial velocity variations in nine G- and K-type giant stars: Eight planets and one planet candidate
Regular radial velocity variations in nine G- and K-type giant stars: Eight planets and one planet candidate Open
We report the detection of radial velocity (RV) variations in nine evolved G- and K-type giant stars. The observations were conducted at Okayama Astrophysical Observatory. Planets or planet candidates can best explain these regular variati…
View article: Mathematical analysis of the effect of portal vein cells on biliary epithelial cell differentiation through the Delta-Notch signaling pathway
Mathematical analysis of the effect of portal vein cells on biliary epithelial cell differentiation through the Delta-Notch signaling pathway Open
Objective The Delta-Notch signaling pathway induces fine-grained patterns of differentiation from initially homogeneous progenitor cells in many biological contexts, including Drosophila bristle formation, where mathematical modeling repor…
View article: Decentralized Learning with Virtual Patients for Medical Diagnosis of Diabetes
Decentralized Learning with Virtual Patients for Medical Diagnosis of Diabetes Open
Machine learning, applied to medical data, can uncover new knowledge and support medical practices. However, analyzing medical data by machine learning methods presents a trade-off between accuracy and privacy. To overcome the trade-off, w…
View article: Mathematical analysis of the effect of portal vein cells on biliary epithelial cell differentiation through the Delta-Notch signaling pathway
Mathematical analysis of the effect of portal vein cells on biliary epithelial cell differentiation through the Delta-Notch signaling pathway Open
Objective: The Delta-Notch signaling pathway induces the differentiation of initially homogeneous progenitor cells in many biological contexts. A mathematical modeling of this signaling pathway on Drosophila wing vein differentiation sugge…
View article: A model of computing with road traffic dynamics
A model of computing with road traffic dynamics Open
Reservoir computing derived from recurrent neural networks is more applicable to real world systems than deep learning because of its low computational cost and potential for physical implementation.Specifically, physical reservoir computi…
View article: Multiple transition of synchronization by interaction of external and internal forces in bursting oscillator networks
Multiple transition of synchronization by interaction of external and internal forces in bursting oscillator networks Open
A bursting oscillator network is a typical model of a biological system, and analyzing its dynamics is important for understanding biological phenomena and their functions. In this study, we investigate the interaction of the dynamics of n…
View article: Decentralized algorithms for consensus-based power packet distribution
Decentralized algorithms for consensus-based power packet distribution Open
Power packets are proposed as a transmission unit that can deliver power and information simultaneously. They are transferred using the store-and-forward method of power routers. A system that achieves power supply/demand in this manner is…
View article: Special section on computation with nonlinear dynamics
Special section on computation with nonlinear dynamics Open
Special section on computation with nonlinear dynamicsThis special section is organized for transmitting recent research results related to computation with nonlinear dynamics.The topics of the special section gathered attention from the a…
View article: Computation harvesting in road traffic dynamics
Computation harvesting in road traffic dynamics Open
Owing to recent advances in artificial intelligence and internet of things (IoT) technologies, collected big data facilitates high computational performance, while its computational resources and energy cost are large. Moreover, data are o…