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In a wide range of applications, the stochastic properties of the observed time series change over time. The changes often occur gradually rather than abruptly: the properties are (approximately) constant for some time and then slowly start…

Methodology · Statistics 2015-04-03 Michael Vogt , Holger Dette

In this research, we propose a novel technique for visualizing nonstationarity in geostatistics, particularly when confronted with a single realization of data at irregularly spaced locations. Our method hinges on formulating a statistic…

Methodology · Statistics 2023-08-29 ShengLi Tzeng , Bo-Yu Chen , Hsin-Cheng Huang

In biomedical imaging reliable segmentation of objects (e.g. from small cells up to large organs) is of fundamental importance for automated medical diagnosis. New approaches for multi-scale segmentation can considerably improve performance…

Numerical Analysis · Mathematics 2016-10-04 Leonie Zeune , Guus van Dalum , Leon W. M. M. Terstappen , S. A. van Gils , Christoph Brune

In this paper, we propose a level set regularization approach combined with a split strategy for the simultaneous identification of piecewise constant diffusion and absorption coefficients from a finite set of optical tomography data…

Numerical Analysis · Mathematics 2020-12-23 J. P. Agnelli , A. De Cezaro , A. Leitao , M. Marques Alves

In this paper we propose a novel machine-learning method for anomaly detection applicable to data with periodic characteristics where randomly varying period lengths are explicitly allowed. A multi-dimensional time series analysis is…

Signal Processing · Electrical Eng. & Systems 2019-05-22 Lia Ahrens , Julian Ahrens , Hans D. Schotten

This paper studies high-dimensional trend inference for piecewise smooth signals under nonstationary noise and asynchronous structural breaks by first detecting asynchronous changes without assuming stationarity and then further exploiting…

Methodology · Statistics 2026-04-27 Lujia Bai , David Veitch , Weichi Wu , Wenyang Zhang , Zhou Zhou

This paper studies the unsupervised change point detection problem in time series of networks using the Separable Temporal Exponential-family Random Graph Model (STERGM). Inherently, dynamic network patterns are complex due to dyadic and…

Methodology · Statistics 2025-09-01 Yik Lun Kei , Hangjian Li , Yanzhen Chen , Oscar Hernan Madrid Padilla

An inverse problem of identifying inhomogeneity or crack in the workpiece made of nonlinear magnetic material is investigated. To recover the shape from the local measurements, a piecewise constant level set algorithm is proposed. By means…

Mathematical Physics · Physics 2012-12-04 Xiangyin Kong , Zhengfang Zhang , Zhengda Huang

We develop a new method to find the number of volatility regimes in a nonstationary financial time series by applying unsupervised learning to its volatility structure. We use change point detection to partition a time series into locally…

Statistical Finance · Quantitative Finance 2022-11-15 Arjun Prakash , Nick James , Max Menzies , Gilad Francis

We propose a new class of univariate nonstationary time series models, using the framework of modulated time series, which is appropriate for the analysis of rapidly-evolving time series as well as time series observations with missing…

In this paper we develop a generalized likelihood ratio scan method (GLRSM) for multiple change-points inference in piecewise stationary time series, which estimates the number and positions of change-points and provides a confidence…

Statistics Theory · Mathematics 2017-03-03 Wai Leong Ng , Shenyi Pan , Chun Yip Yau

Time-series analysis is critical for a diversity of applications in science and engineering. By leveraging the strengths of modern gradient descent algorithms, the Fourier transform, multi-resolution analysis, and Bayesian spectral…

Signal Processing · Electrical Eng. & Systems 2021-06-23 Daniel E. Shea , Rajiv Giridharagopal , David S. Ginger , Steven L. Brunton , J. Nathan Kutz

A sequential piecewise linear programming method is presented where bounded domains of non-convex functions are successively contracted about the solution of a piecewise linear program at each iteration of the algorithm. Although…

Optimization and Control · Mathematics 2020-04-21 James P. L. Tan

While a substantial literature on structural break change point analysis exists for univariate time series, research on large panel data models has not been as extensive. In this paper, a novel method for estimating panel models with…

Econometrics · Economics 2021-09-24 Oualid Bada , Alois Kneip , Dominik Liebl , Tim Mensinger , James Gualtieri , Robin C. Sickles

This article proposes an online bootstrap scheme for nonparametric level estimation in nonstationary time series. Our approach applies to a broad class of level estimators expressible as weighted sample averages over time windows, including…

Methodology · Statistics 2026-03-02 Thomas Nagler , Tobias Brock , Nicolai Palm

The synchrosqueezing transform (SST) was developed recently to separate the components of non-stationary multicomponent signals. The continuous wavelet transform-based SST (WSST) reassigns the scale variable of the continuous wavelet…

Signal Processing · Electrical Eng. & Systems 2020-08-26 Jian Lu , Qingtang Jiang , Lin Li

Most data processing techniques, applied to biomedical and sociological time series, are only valid for random fluctuations that are stationary in time. Unfortunately, these data are often non stationary and the use of techniques of…

Data Analysis, Statistics and Probability · Physics 2009-11-10 M. Ignaccolo , P. Allegrini , P. Grigolini , P. Hamilton , B. J. West

In this paper we propose a wavelet-based methodology for estimation and variable selection in partially linear models. The inference is conducted in the wavelet domain, which provides a sparse and localized decomposition appropriate for…

Methodology · Statistics 2016-09-26 Norbert Remenyi

The problem of time-series clustering is considered in the case where each data-point is a sample generated by a piecewise stationary ergodic process. Stationary processes are perhaps the most general class of processes considered in…

Machine Learning · Statistics 2019-06-27 Azadeh Khaleghi , Daniil Ryabko

Given a heterogeneous time-series sample, the objective is to find points in time (called change points) where the probability distribution generating the data has changed. The data are assumed to have been generated by arbitrary unknown…

Machine Learning · Statistics 2015-05-13 Azadeh Khaleghi , Daniil Ryabko