# Pekka NeittaanmäkiUniversity of Jyväskylä | JYU · Department of Mathematical Information Technology

Pekka Neittaanmäki

Prof.

## About

420

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5,246

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Citations since 2017

## Publications

Publications (420)

This paper is devoted to techniques in bifurcation analysis for continuous mechanical systems, concentrating on polynomial equations and implicitly given functions. These are often encountered in problems of mechanics and especially in stability analysis. Taking a classical approach, we summarize the relevant features of the cubic polynomial equati...

This book deals with theoretical aspects of modelling the mechanical behaviour of manufacturing, processing, transportation or other systems in which the processed or supporting material is travelling through the system. Examples of such applications include paper making, transmission cables, band saws, printing presses, manufacturing of plastic fi...

In this paper, we consider the static stability problems of axially moving or- thotropic membranes and plates. The study is motivated by paper production processes, as paper has a fiber structure which can be described as orthotropic on the macroscopic level. The moving web is modelled as an axially moving orthotropic plate. The original dynamic pl...

The out-of-plane instability of a moving plate, travelling between two rollers with constant velocity, is studied, taking into account the mutual interaction between the buckled plate and the surrounding, axially flowing ideal fluid. Transverse displacement of the buckled plate (assumed cylindrical), is described by an integro-differential equation...

Problems of stability of an axially moving elastic band travelling at constant velocity between two supports and experiencing small transverse vibrations are considered in a 2D formulation. The model of a thin elastic plate subjected to bending and tension is used to describe the bending moment and the distribution of membrane forces. The stability...

We deduce a posteriori error estimates of functional type for the stationary Stokes problem with slip and leak boundary conditions. The derived error majorants do not contain mesh dependent constants and are valid for a wide class of energy admissible approximations that satisfy the Dirichlet boundary condition on a part of the boundary. Different...

This book discusses the stability of axially moving materials, which are encountered in process industry applications such as papermaking. A special emphasis is given to analytical and semianalytical approaches. As preliminaries, we consider a variety of problems across mechanics involving bifurcations, allowing to introduce the techniques in a sim...

This book treats Modelling of CFD problems, Numerical tools for PDE, and Scientific Computing and Systems of ODE for Epidemiology, topics that are closely related to the scientific activities and interests of Prof. William Fitzgibbon, Prof. Yuri Kuznetsov, and Prof. O. Pironneau, whose outstanding achievements are recognised in this volume.
It cont...

We consider an infinite continuous elastic beam that interacts with linearly elastic foundation and is under compression. The problem of the beam buckling is formulated and analyzed. Then the optimisation of beam against buckling is investigated. As a design variable (control function) we take the parameters of cross-section distribution of the bea...

Spectral imaging (SI) refers to the acquisition of the three-dimensional (3D) spectral cube of spatial and spectral data of a source
object at a limited number of wavelengths in a given wavelength range. Snapshot spectral imaging (SSI) refers to the instantaneous
acquisition (in a single shot) of the spectral cube, a process suitable for fast chang...

In our study we have considered problems of stability of a moving orthotropic web traveling between a system of rollers at a constant velocity. The plate is subjected to combined thermo-mechanical loading, including pure mechanical in-plane tension and centripetal forces. Thermal in-plane strains corresponding to thermal and mechanical tension and...

In this paper, local cubic quasi-interpolating splines on non-uniform grids are described. The splines are designed by fast computational algorithms that utilize the relation between splines and cubic interpolation polynomials. These splines provide an efficient tool for real-time signal processing. As an input, the splines use either clean or nois...

The harnessing of untapped resources has become essential for inclusive growth in digital economies particularly as developed economies continue to age demographically. The harnessing of women's potential is an urgent subject in this context, and successive initiatives have been flourishing in many countries.
However, given the institutional comple...

The specific objective of this study was to better understand Nigerian university students’ perceptions and readiness towards mobile learning. Recently, the influence of mobile technology is seen to have infiltrated everyday life and the learning institutions. It is thus crucial for learning institutions to assess and understand the factors advanci...

Problems of defining the optimal (against buckling) cross section area distribution for beams interacting with elastic foundation are considered. The stability of limited pinned beams and infinite continuous beams is analyzed. For all beams under consideration, the stability analysis is performed as for constant as for variable distributions of str...

Problems of defining of optimal (against buckling) cross section area distribution for beams interacting with elastic foundation are considered. The stability of limited pinned beams and infinite continuous beams is analyzed. For all beams under consideration, the stability analysis is performed as for constant as for variable distributions of stre...

While digitization of music, particularly streaming services, has gained increasing popularity, it has also led to a steady decline in the revenues of recorded music industry. This is causing strong concern regarding a potential collapse of the music industry comparable to other print media industries such as newspaper and book publishing.

Based on a powerful notion that the quality of higher education is crucial for innovation in digital economy and that such quality is subject to a conception of trust in teachers to deliver good education and advancement of information and communication technology (ICT), the dynamism of co-evolution between them was analyzed. Using a unique dataset...

In the present work the lock-in range of PLL-based circuits with proportionally-integrating filter and sinusoidal phase-detector characteristics are studied. Considered circuits have sinusoidal phase detector characteristics. Analytical approach based on the methods of phase plane analysis is applied to estimate the lock-in ranges of the circuits u...

Many in the industry see the ride-sharing company Uber as the significant advancement through information and communication technology (ICT) particularly of the digital service platform and sharing economy. Uber has been exploring the new frontier of the ICT-driven disruptive business model (IDBM) and succeeded in its global expansion to over 479 c...

In light of the increasing significance of trust-based higher education towards digitally-rich learning environments, co-evolution dynamism between trust in teachers and higher education enabled by ICT advancement was analyzed. Using the rate of trust in teachers for good education in the Global Teacher Status Index, together with statistics on hig...

A basic operation of spectr is filterin. In this introductory chapter, processing of one- and two-dimensional signals by digital filters and filter banks is outlined. A polyphase implementation of multirate filtering is described. The application of filtering with IIR filters, whose transfer functions are rational, is described. Bases and frames in...

This chapter describes how to design families of biorthogonal wavelet transforms of signals and respective biorthogonal Wavelet bases in the signal space using spline-based prediction filters. Although the designed Wavelets originate from splines, they are not splines themselves. The design and implementation of the biorthogonal Wavelet transforms...

In this chapter, we outline the essentials of the splines theory. By themselves, they are of interest for signal processing research. We use the Zak transform to derive an integral representation of polynomial splines on uniform grids. The integral representation facilitated design of different generators of spline spaces and their duals. It provid...

In this chapter we introduce the mixed continuous–discrete and discrete–discrete convolutions. Important special cases of such convolutions are the polynomial and discrete splines, respectively. The Zak transforms, which are introduced in the chapter, provide integral representation of signals, which, in the following chapters, serves as a tool for...

This chapter describes wavelet analysis in the spaces of discrete splines whose spans are powers of 2. This wavelet analysis is similar to wavelet analysis in the polynomial-spline spaces. The transforms are based on relations between exponential discrete splines from different resolution scales. Generators of discrete-spline wavelet spaces are des...

This chapter presents wavelets in the spaces of polynomial splines. The wavelets’ design is based on the Zak transform, which provides an integral representation of spline-wavelets. The exponential wavelets which participate in the integral representation are counterparts of the exponential splines that were introduced in Chap. 4. Fast algorithms f...

Wavelets in the polynomial and discrete spline spaces were introduced in Chaps. 8 and 10, respectively. In both cases, the wavelets’ design and implementation of the transforms were associated with perfect reconstruction (PR) filter banks. In this chapter, those associations are discussed in more detail. Biorthogonal wavelet bases generated by PR f...

This introductory chapter contains some definitions and facts concerning one- and two-dimensional signals and their Fourier and \(z\)-transforms.

Uber used a disruptive business model driven by digital technology to trigger a ride-sharing revolution. The institutional sources of the company's platform ecosystem architecture were analyzed to explain this revolutionary change.Both an empirical analysis of a co-existing development trajectory with taxis and institutional enablers that helped to...

Problems of stability and deformation of a moving web, traveling between a system of rollers at a constant velocity are considered. The plate is subjected to a combined thermomechanical loading, including pure mechanical in-plane tension and also centripetal forces. Thermal strains corresponding to thermal tension and bending of the plate are accou...

Open data and models are becoming increasingly available, but there are not yet good methods and platforms to turn those into systematic evidence-based decision support. Unicorn will produce such an environment based on existing theoretical and practical knowledge about decision support and models. This consortium possesses the necessary models,...

With the understanding that current ICT-driven global development depends on a trend shifting from traditional co-evolution of computer-initiated ICT, captured GDP, and economic functionality to new co-evolution of the Internet, un-captured GDP, and supra-functionality beyond economic value, the following hypothetical view was postulated:. The disp...

The chapter describes an algorithm that compresses two-dimensional data arrays, which are piece-wise smooth in one direction and have oscillating events in the other direction. Seismic, hyper-spectral and fingerprints data, for example, have such a mixed structure. The transform part of the compression process is an algorithm that combines wavelet...

In this chapter, two types of local cubic splines on non-uniform grids are described: 1. The simplest variation-diminishing splines and 2. The quasi-interpolating splines. The splines are computed by a simple fast computational algorithms that utilizes a relation between the splines and cubic interpolation polynomials. Those splines can serve as an...

In this chapter, local quasi-interpolating and smoothing splines are described. Although approximation properties of local spline are similar to properties of the global interpolating and smoothing splines, their design does not require the IIR filtering of the whole data array. The computation of a local spline value at some point utilizes only a...

In this chapter, fast stable algorithms are presented, which compute splines’ values at dyadic and triadic rational points starting from their samples at integer grid points. The algorithms are implemented by the causal-anticausal recursive filtering of initial data samples, which is followed by iterated application of FIR filters. Extension of the...

It was indicated in Sect. 2. 2 that oversampled perfect reconstruction (PR) filter banks
generate specific types of frames in the signal space. In this chapter, a family of tight and semi-tight frames is presented. The three- and four-channel filter banks that generate the framed originate from polynomial and discrete splines. Those frames have pro...

In this paper, we analyze the stability and bifurcation of elastic systems using a general scheme developed for problems with implicitly given functionals. An asymptotic property for the behaviour of the natural frequency curves in the small vicinity of each bifurcation point is obtained for the considered class of systems. Two examples are given....

This book presents various contributions of splines to signal and image processing from a unified perspective that is based on the Zak transform (ZT). It expands the methodology from periodic splines, which were presented in the first volume, to non-periodic splines. Together, these books provide a universal toolbox accompanied by MATLAB software f...

In the present work the pull-in range of the classical PLL with impulse signals is studied. Numerical experiments in MatLab Simulink are presented and two analytical approaches are discussed.

In the present work the pull-in range of PLL-based circuits with proportionallyintegrating filter is studied. Two approaches based on the methods of phase plane analysisand Lyapunov functions are discussed.

This volume contains selected papers in three closely related areas: mathematical modeling in mechanics, numerical analysis, and optimization methods. The papers are based upon talks presented on the International Conference for Mathematical Modeling and Optimization in Mechanics, held in Jyväskylä, Finland, March 6-7, 2014 dedicated to Prof. N. Ba...

Transportation planning is central activity in logistic network design. In this study, we examine the deployment of optimization methodology to transportation planning. More specifically, we examine the adoption of system solving the well-known combinatorial optimization problem, the vehicle routing problem (VRP). Its application has resulted in ef...

The majority of countries with advanced information and communication technology (ICT) infrastructure have been experiencing extended stagnation due to an “embedded” trap in ICT advancement. However, certain countries have been able to sustain a high level of ICT- driven global competitiveness. This suggests that in these contexts there is resilien...

A posteriori error estimation methods are usually developed in the
context of upper and lower bounds of errors. In this paper, we are concerned with a posteriori analysis in terms of identities, i.e., we deduce error relations, which holds as equalities. We discuss a general form of error identities for a wide class of convex variational problems....

We present a design scheme that generates tight and semi-tight frames in discrete-time periodic signals space originated from four-channel perfect reconstruction periodic filter banks. Filter banks are derived from interpolating and quasi-interpolating polynomial and discrete splines. Each filter bank comprises one linear phase low-pass filter (in...

Trusted Computing is a special branch of computer security. One branch of computer security involves protection of systems against external attacks. In that branch we include all methods that are used by system owners against external attackers, for example Firewalls, IDS, IPS etc. In all those cases the system owner installs software that uses its...

FOREWORD
The CM3 event is the first ECCOMAS Thematic Conference organized by University of
Jyväskylä, Finland in the context of activities proposed by the new Industrial Interest Group
(IIG) of ECCOMAS.
Efficient European transport remains an important factor of economic growth to be considered
in view of environmental and societal challenges. It...

Chapter 2 exposes a mathematical model of a waveguide with several cylindrical ends going to infinity, basic notions and mathematical results (with complete proofs) needed in successive chapters: waves, continuous spectrum eigenfunctions, intrinsic radiation principle, and scattering matrices.KeywordsSmooth FunctionCompact SupportContinuous Spectru...

Chapter 7 presents an asymptotic and numerical studies of resonant tunneling in a two-dimensional waveguide with two-narrows in magnetic field. It is supposed that the electron energy is between the first and the second thresholds.

Chapter 3 is devoted to various properties of a waveguide scattering matrix, which is a matrix function on the waveguide continuous spectrum. There is a sequence of threshold values of the spectral parameter where the scattering matrix changes its size; the thresholds accumulate at infinity. In particular, both two-sided limits of the scattering ma...

Chapter 10 presents an asymptotic theory of resonant tunneling for electrons of high energy in a three dimensional waveguide with two narrows.

Chapter 11 presents examples of electronics devices based on quantum waveguides with narrows: transistors controlled by external electric field and magnetic field sensors controlled by external magnetic field. Moreover, an electron flow switch is also described for quantum nets. Unlike the transistors and sensors, the switch has no relation to the...

Chapter 4 presents statement and justification of a method for approximate computing a waveguide scattering matrix. As an approximation to a row of such a matrix, a minimizer of a quadratic functional is suggested. To construct the functional, one has to solve a boundary value problem in a bounded domain obtained by cutting off the cylindrical ends...

Chapter 6 exposes an asymptotic theory of resonant tunneling in a three-dimensional waveguide with two narrows for electrons with energy between the first and the second thresholds.

Chapter 5 is devoted to asymptotic studies of electron resonant tunneling in a two-dimensional waveguide with two narrows. The narrow diameter plays the role of a small parameter. The asymptotics of basic characteristics of resonant tunneling are presented for electrons with energy between the first and the second thresholds. Moreover, the asymptot...

Chapter 9 is devoted to numerical simulation of resonant tunneling in a two-dimensional waveguide with two narrows for electrons with energy between the first and the fifth thresholds.

This paper is devoted to a bifurcation problems, based on some models, described by algebraic (cubic) equations with real coefficients. Bifurcation analysis, parametric representation of solutions and their asymptotic analysis and expressions are described in the frame of analytical approaches. The results, presented in the paper, can be used to he...

A new non-invasive method for delineation of lentigo maligna and lentigo maligna melanoma is demonstrated. The method is based on the analysis of the hyperspectral images taken in vivo before surgical excision of the lesions. For this, the characteristic features of the spectral signatures of diseased pixels and healthy pixels are extracted, which...

This paper is devoted to a dynamic stability analysis of an axially moving elastic web, modelled as a panel (a plate undergoing cylindrical deformation). The results are directly applicable also to the travelling beam. In accordance with the dynamic approach of stability analysis, the problem of harmonic vibrations is investigated via the study of...

Nowadays simplified mathematical models and numerical simulation are widely used for the analysis of QPSK Costas loop. In the work it is shown that the use of simplified mathematical models and the application of non-rigorous methods of analysis may lead to wrong conclusions concerning the operability of real model of QPSK Costas loop.

In this paper a new approach to the analysis of implicitly given functionals is developed in the frame of elastic stability theory. The approach gives an effective procedure to analyse stability behaviour, and to determine the bifurcation points. Examples of application of the proposed approach for analysis of stability are presented, more precisel...

In this chapter, our focus is to analyse the behaviour of moving panels using viscoelastic materials. As the reader will have noticed, all the models discussed in previous chapters have concerned the case of a purely elastic material. The deformation of an elastic material depends only on the applied forces; it has no explicit time dependence. Pape...

The focus of this chapter is the stability analysis of axially moving materials. There are many similarities with classical stability analysis of structures, like the buckling of beams and plates. However, the axial motion introduces the effects of inertia, bringing out many challenges that are discussed in this chapter. The chapter is divided as f...

In this chapter, problems of fracture and stability of a moving plate, travelling in a system of rollers at a constant velocity, are studied. It is known that in the manufacturing process, there may occur many kinds of defects in the paper web, such as
edge cracks and blister and fiber cuts. Our aim is to tackle this problem and analyse theoretical...

In this chapter, the problems of safety analysis and optimization of a moving elastic plate travelling between two rollers at a constant axial velocity are considered. We will use a model of a thin elastic plate subjected to bending and in-plane tension (distributed membrane forces). We will study transverse buckling (divergence) of the plate and i...

This chapter is devoted to the analysis of the travelling panel, submerged in axially flowing fluid. In order to accurately model the dynamics and stability of a lightweight moving material, the interaction between the material and the surrounding air must be taken into account somehow. The light weight of the material leads to the inertial contrib...

In this chapter, we will look at the influence of a skewed tension profile on the divergence instability of a travelling, thin elastic plate. The travelling plate is subjected to axial tension at the supports, but the tension distribution along the supports is not uniform. For the nonuniformity, we will use a linear distribution. First, we will per...

The heat conduction problems for anisotropic bodies are studied taking into account the uncertainties
in the material orientation. The best estimations of the upper and lower bounds of the considered
energy dissipation functional are based on developing new approach consisting in solution of some
optimization problems and finding the extremal inter...

In the paper, we discuss error estimation methods for optimal control problems with distributed control functions entering the right-hand side of the corresponding elliptic state equations. Our analysis is based on a posteriori error estimates of the functional type, which were derived in the last decade for many boundary value problems. They provi...

Anomaly detection is a central task in high-dimensional data analysis. It can be performed by using dimensionality reduction methods to obtain a low-dimensional representation of the data, which reveals the geometry and the patterns that exist and govern it. Usually, anomaly detection methods classify high-dimensional vectors that represent data po...

In this paper, we present a unified approach to error indication for elliptic boundary value problems. We introduce two different definitions of the accuracy (weak and strong) and show that various indicators result from one principal relation. In particular, this relation generates all the main types of error indicators, which have already gained...

We consider an infinite two-dimensional waveguide that, far from the coordinate origin, coincides with a strip. The waveguide has two narrows of diameter ϵ. The narrows play the role of effective potential barriers for the longitudinal electron motion. The part of the waveguide between the narrows becomes a ‘resonator’, and there can arise conditio...

There are many mathematical models of drilling systems Despite, huge efforts in constructing models that would allow for precise analysis, drilling systems, still experience breakdowns. Due to complexity of systems, engineers mostly use numerical analysis, which may lead to unreliable results. Nowadays, advances in computer engineering allow for si...

In this chapter, we will introduce in a general manner some of the most common models for axially travelling materials, which will be used in the rest of the book. We will introduce the linear models of travelling strings, panels, and plates. It will be assumed that the material is thin, i.e. its planar dimensions are much larger than its thickness...

In this chapter, we discuss foundations of new error control methods developed during the last 10–12 years. First, we consider the simplest boundary value problems generated by ordinary differential equations and show that proper transformations of the corresponding integral identity yield a guaranteed bound of the difference between the exact solu...

In Chap. 3, we discussed the main ideas of fully reliable error control methods and the corresponding numerical algorithms with the paradigm of simple elliptic type problems. This chapter is intended to show a deep connection between a posteriori estimates of the functional type and physical relations generating the problem. Also, the goal of this...

In this chapter, we study effects caused by incompletely known data. In practice, the data are never known exactly, therefore the results generated by a mathematical model also have a limited accuracy. Then, the whole subject of error analysis should be treated in a different manner, and accuracy of numerical solutions should be considered within a...

Error indicators play an important role in mesh-adaptive numerical algorithms, which currently dominate in mathematical and numerical modeling of various models in physics, chemistry, biology, economics, and other sciences. Their goal is to present a comparative measure of errors related to different parts of the computational domain, which could s...