Joos Vandewalle

KU Leuven | ku leuven · Department of Electrical Engineering (ESAT)

Over the recent years the role of mathematics in innovations for Circuits, Systems and Signal processing has increased considerably. The talk will overview the dynamical forces and their impact on the research and education. Examples will be given of mathematical methodologies for signal and image classification, data fusion, biomedical diagnostics...

A new battery of positioning tests for Science and Engineering was broadly implemented in Flanders in the summer of 2013. The goal of the non-mandatory and non-binding positioning test is to allow future students, with a clear choice for engineering or science, to position themselves with respect to the required prior knowledge and skills and to st...

In higher education, exams with multiple choice questions (MPQ) are very common since they allow testing large groups while providing fast feedback. Although multiple choice exams are considered to be an objective way of assessing knowledge and competences of students, their use raises some concerns. One important concern is that a student can obta...

Abstract E-content revolution, technological advances, and ever-shrinking budgets oblige libraries to efficiently allocate their limited resources between collection and services. Unfortunately, resource allocation is a complex process due to the diversity of data sources and formats required to be analyzed prior to decision making, as well as the...

This article provides a comprehensive literature review and classification method for data mining techniques applied to academic libraries. To achieve this, forty-one practical contributions over the period 1998-2014 were identified and reviewed for their direct relevance. Each article was categorized according to the main data mining functions: cl...

It is acknowledged worldwide over the past several decades that the basic education of circuits and systems (CAS) is not in stable water. A first reason is that smart phones, iPads, the Internet and computers have created expectations of instant gratification among young people. This has reduced the attention span of students, so that they are not...

A new positioning test for BSc Engineering was broadly and uniformly implemented in Flanders in the summer of 2013. The non-mandatory test measures the ability of future engineering students to solve engineering problems and compares a student’s mathematical skills with the required previous knowledge. The positioning test was organized twice duri...

Services offered in a commercial context are expected to deliver certain levels of quality, typically contracted in a service level agreement (SLA) between the service provider and consumer. To prevent monetary penalties and loss of reputation by violating SLAs, it is important that the service provider can accurately estimate the Quality of Servic...

With the rapid increase in demand of new digital services, the high cost of information, and the dramatic economic slowdown, libraries have been pressured to improve their services at lower costs. To cope with these conditions, library managers must improve their knowledge and understanding of cost behaviour, as well as be aware of the different co...

The articles in this special issue focus on recent trends in circuits and systems engineering education, with particular emphasis on the principles of multiport communication theory; curriculum development; and biometric educational development.

Academic libraries have recently been subjected to continuous budget reductions, mainly due to the increasing costs of information and the global economic crisis. As the primary purpose of an academic library is to provide well-balanced collections and a wide range of services to support education and research, an efficient use and allocation of li...

Th is article provides a comprehensive literature review of Time-Driven Activity Based Costing (TDABC), a relatively new tool to improve the cost allocation to products and services. Aft er a brief overview of traditional costing and activity based costing systems (ABC), a detailed description of the TDABC model is given and a comparison made betwe...

In this paper, we introduce a visualization tool for inter-active and efficient exploration of high dimensional data using parallel coordinates. An algorithm is developed to find an optimal permutation of dimensions, which allows the data miner to immediately see the most important features or irregularities in the dataset. This is implemented as a...

It has been shown that kernel based regression (KBR) with a least squares loss has some undesirable properties from robustness point of view. KBR with more robust loss functions, e.g. Huber or Logistic losses, often give rise to more complicated computations. In classical statistics, robustness is improved by reweighting the original estimate. We s...

Basic Circuits and Systems CAS education is crucial in the first phase of any electrical engineering curriculum, but increasingly under threat. This situation is in many ways similar to that of mathematics education in engineering. Creative shortcuts for teaching mathematics have recently been advocated in the “streetfighting mathematics approach”....

In most machine learning applications the time series to predict is fixed and one has to learn a prediction model that causes the smallest error. In this paper choosing the time series to predict is part of the optimization problem. This time series has to be a linear combination of a priori given time series. The optimization problem that we have...

In this brief, we propose a new method to reduce the number of support vectors of support vector machine (SVM) classifiers. We formulate the approximation of an SVM solution as a classification problem that is separable in the feature space. Due to the separability, the hard-margin SVM can be used to solve it. This approach, which we call the separ...

Electronic devices may undergo attacks going beyond traditional cryptanalysis. Side-channel analysis (SCA) is an alternative attack that exploits information leaking from physical implementations of e.g. cryptographic devices to discover cryptographic keys or other secrets. This work comprehensively investigates the application of a machine learnin...

When an artificial neural network (ANN) is trained to predict signals p steps ahead, the quality of the prediction typically decreases for large values of p. In this paper, we compare two methods for prediction with ANNs: the classical recursion of one-step ahead predictors and a new kind of chain structure. When applying both techniques to the pre...

The study of circuits and systems requires some basic reasoning with various equivalent interconnections of components like resistors, sources, ideal opamps, ideal transistors, short and open circuits.... Students should be able to handle a rich variety of such interconnections correctly and appropriately. Special components like nullators and nora...

In many applications, the sampling frequency is limited by the physical characteristics of the components: the pixel pitch, the rate of the A/D converter, etc. A low-pass filter is then often applied before the sampling operation to avoid aliasing. However, when multiple copies are available, it is possible to use the information that is inherently...

We discuss certain aspects of the state of core education in circuits, signals, and systems and list a few current problems and issues. The colleagues who have contributed to the two special sessions on education not only share their valuable experiences and innovations, but also express their opinions on how to address a number of salient problems...

Basic circuits and systems topics still are essential ingredients of electrical engineering education at most universities around the world. However these topics are under threat at many places in much the same way as the basic mathematics like linear algebra, differential equations, and analysis is threatened. This is caused by an urge for instant...

LS-SVMlab, a Software Toolbox for Least Squares Support Vector Machines

Observability analysis is a very important tool in state estimation. For a given set of measurements and their geographical location in the system, it determines whether the state of the whole system can be estimated. In this paper a numerical observability analysis, applicable to distribution systems is discussed and applied to the IEEE 34 bus tes...

It is the aim of this paper to discuss the various critical elements in the education of the mathematics of circuits and systems in the present context of a lean, efficient, and performant, but above all attractive electrical engineering education. The paper motivates the need for a solid mathematical basis, and strong concepts, that are more than...

The mathematics of circuits and systems requires some basic knowledge of linear algebra, differential equations, and transforms. Moreover many concepts and methods of basic circuits and systems courses can and should rely on sharp mathematical insight. Efficient and effective teaching of the basic mathematics and the basic circuits and systems cour...

This paper discusses a number of critical issues that occur in the teaching process of basic circuit and systems concepts and methods to electrical engineering students. Different role models are introduced and some views on alternative choices are made. It is felt that extensive discussion and debate is desirable in order to enhance the efficacy o...

We present a new class of methods for the global optimization of continuous variables based on simulated annealing (SA). The coupled SA (CSA) class is characterized by a set of parallel SA processes coupled by their acceptance probabilities. The coupling is performed by a term in the acceptance probability function, which is a function of the energ...

The experiences and views leading to further interactions and role models with the introduction and outline of the circuit and systems (CAS) education are presented. The basic circuits and systems courses are designed based on the courses in mathematics and physics, and digital signal processing and control theory. Engineers presently face increasi...

Synchronous behavior in networks of coupled oscillators is a commonly observed phenomenon attracting a growing interest in physics, biology, communication, and other fields of science and technology. Besides global synchronization, one can also observe splitting of the full network into several clusters of mutually synchronized oscillators. In this...

This paper describes a hardware implementation of an arithmetic processor which is efficient for bit-lengths suitable for both commonly used types of Public Key Cryptography, i.e., Elliptic Curve (EC) and RSA Cryptosystems. Montgomery modular multiplication in a systolic array architecture is used for modular multiplication. The processor consists...

Reservoir Computing is a novel method in the field of neural networks and machine learning, which combines the computational power of a nonlinear dynamic system with the ease of training of a linear classifier. The basic setup is as follows: a sufficiently complex network of nonlinear nodes (called the reservoir) is excited by an input signal, and...

A new form of cluster synchronization is explored in cellular arrays of chaotic oscillators. Previously, it was shown in the literature that symmetries of the coupling topology with uniform interaction weights lead to several coexisting clusters of synchronized cells. In this study a new phenomenon is presented where highly asymmetric interaction w...

In many applications, the sampling frequency is limited by the physical characteristics of the components: the pixel pitch, the rate of the analog-to-digital (AID) converter, etc. A low- pass filter is usually applied before the sampling operation to avoid aliasing. However, when multiple copies are available, it is possible to use the information...

It is the aim of reproducible research to provide mechanisms for objective comparison of methods, algorithms, software and procedures in various research topics. In this paper, we discuss the role of data sets, benchmarks and competitions in the fields of system identification, time series prediction, classification, and pattern recognition in view...

The dominant set of eigenvectors of the symmetrical kernel Gram matrix is used in many important kernel methods (like e.g. kernel Principal Component Analysis, feature approximation, denoising, compression, prediction) in the machine learning area. Yet in the case of dynamic and/or large-scale data, the batch calculation nature and computational de...

The control of the synthesis section of a urea plant is a challenge due to delays, recirculation flows and large residence times. This paper presents the results of applying MPC control techniches for controlling the synthesis section of a urea process. The control system stabilizes the syntehsis section while maximizing the throughput of the synth...

We present a software implementation of arithmetic operations in a finite field GF(2n), based on an alternative representation of the field elements. An important application is in elliptic curve crypto-systems. Whereas previously reported implementations of elliptic curve cryptosystems use a standard basis or an optimal normal basis to perform fie...

This paper considers the universal coding problem for stationary ergodic sources with countably infinite alphabets. We propose modified versions of LZ77 and LZ78 codes for sources with countably infinite alphabets. Then, we show that for any source μ ...

A method is presented that unifies previous approaches with the aim of learning new templates with the ability to tune cellular nonlinear network (CNN) templates to individual chip instances in a global optimization framework. The proposed method is built on earlier approaches extending them in three main aspects. First, hardware parameters of the...

An algorithm for fast and robust face tracking with the CNN universal machine is proposed in this paper. It is applied to a driving mechanism for a wheelchair with an on-chip implementation. A novel object tracking CNN visual algorithm is introduced and employed in the tracking of multiple face features. The speed and robustness of this method are...

In this paper, Stochastic Coupled Local Minimizers (SCLMs) are presented for global optimization of smooth cost functions. This extends the deterministic coupled local minim-izers (CLMs) whose best performing elements impose their dy-namics to others by means of master–slave synchronization. The elements of the CLM network are excited by Gaussian w...

In this demonstration we will present an application of a fast and robust face tracking algorithm implemented with a CNN Universal Machine chip. The application is the driving of a wheelchair according to predefined movements of the user's head. A D model of a wheelchair is used in order to demonstrate the driving mechanism.

In this paper, a geometrically inspired algorithm is derived for identification of state space models for multivariable linear time-invariant systems using noisy input-output measurements. The algorithm contains two conceptual steps which allow a robust implementation using SVD techniques: 1. Using canonical correlation, first a state vector sequ...

In this paper, a survey is presented of some recently obtained results in the problem of identifying linear relations from noisy data. Starting from a geometrically inspired definition of noise and linear relations, the mathematical problem is formulated. Existing identification techniques, such as (total) linear least squares, factor analysis and...

Human electrogastric signals can be detected by properly locating electrodes on the abdominal skin. The detailed waveform analysis for medical researches or clinical use is, however, hindered by its poor quality. A modified adaptive enhancing technique is described in the paper for eliminating noise and interference while keeping the modification o...

System theory is a discipline which applies mathematical methods in order to provide a unified approach for many application areas. Such a unification is not only useful for communication between experts, but also in order to be able to carry over concepts, methods and software between areas. Also intellectually such a unified approach is mandatory...

The goal of this paper is to present results of a feasibility study for multivariable realization algorithms. The realization algorithms are of the Markov Block Hankel (MBH) type. A Singular Value Decomposition (SVD) variant, and a Gauss Elimination (GE) based pick-out variant were tested on a representative set of test Markov Sequences. Much atten...

In this paper we present an algorithm ASVD for the computation of the singular value decomposition (SVD). The method presented is a power method for calculating the largest triplets of the SVD of a matrix A when multiplication is "cheap". The method used bears a lot of similitude with the power method for finding the eigenvalues of a symmetric matr...

In this paper the problem of learning spatiotemporal behaviour with cellular neural networks is analysed and a novel method is proposed to approach the problem. The basis for this method is found in trajectory learning with recurrent neural networks. Despite of similarities, the two learning problems have underling differences which make non-trivia...

In this paper Josephson junctions are used in order to generate n-scroll and n-scroll hypercube attractors. We propose to use of the Josephson junction in a general Jerk circuit in such a way that there is no need for synthesizing the nonlinearity towards n-scroll and n-scroll hypercube attractors. The results are illustrated with computer simulati...

In this paper we describe the use of cou-pling to interconnect different Simulated Annealing (SA) processes. The objective is to allow cooperative behav-ior among the processes in order to improve performance. Coupled Simulated Annealing (CSA) permits a high de-gree of parallelization while delivering much better results than a typical Parallel SA...

In many applications, the sampling frequency is limited by the physical characteristics of the components: the pixel pitch, the rate of the A/D converter, etc. A low-pass filter is then often applied before the sampling operation to avoid aliasing. However, when multiple copies are available, it is possible to use the information that is inherently...

In recent years it was discovered that cellu-lar neural networks with local and space-invariant connec-tions are able to generate a wide range of two-dimensional spatiotemporal behavior. Many of these dynamics can be directly mapped into natural phenomena occurring in physics, chemistry, and biology. These mappings make cel-lular neural network a s...

In this chapter, we present a comprehensive description of the use of piecewise-linear methods in modeling, analysis, and structural properties of nonlinear circuits. The main advantages of piecewise linear circuits are fourfold. (1) Piecewise-linear circuits are the easiest in the class of nonlinear circuits to analyze exactly, because many method...

Often, in engineering education there is much emphasis on theoretical issues, especially during the first years. Still, students should be exposed to more than just theoretical knowledge. This paper describes a project-oriented approach to undergraduate teaching in the field of electrical power engineering applied in the Department of Electrical En...

Pattern formation occurring on the ACE (analogic cellular engine)16k CNN (cellular neural network) chip is presented. The CNN chip can be programmed with a cloning template in order to generate spiral waves and autowaves. The waves diffract from the internal sources which cannot be relocated on the network. However, by using initial and/or input im...

In this paper, we derive a prewhitening-induced lowerbound on the Frobenius norm of the difference between the true mixing matrix and its estimate in independent component analysis. This bound applies to all algorithms that employ a prewhitening. Our analysis allows one to assess the contribution to the overall error of the partial estimation error...

Kernel based methods suffer from exceeding time and memory requirements when applied on large datasets since the involved optimization problems typically scale polynomially in the number of data samples. As a remedy, some least squares meth-ods on one hand only reduce the number of parameters (for fast training), on the other hand only work on a re...

The (extended) propagation criterion was defined in cryptography in order to analyze the security of cryptographic components with respect to differential cryptanalysis. In this paper, we obtain the spectral characterization of functions satisfying the (extended) propagation criterion of degree l and order k. This important problem was left open si...

Introduction -- Cellular neural/nonlinear networks -- Multi-scroll chaotic and hyperchaotic attractors -- Synchronization of chaotic Lur'e systems -- Engineering applications -- General conclusions and future work.

Least Squares Support Vector Machines (LS-SVM) is aproven method for classification and function approximation. In comparison to the standard Support Vector Machines (SVM) it only requires solving a linear system, but it lacks sparseness in the number of solution terms. Pruning can therefore be applied. Standard ways of pruning the LS-SVM consist o...

In this paper we review a multilinear generalization of the singular value decomposition and the best rank-(R1,R2,…,RN) approximation of higher-order tensors. We show that they are important tools for dimensionality reduction in higher-order signal processing. We discuss applications in independent component analysis, simultaneous matrix diagonaliz...

In this paper a new approach to fragile watermarking technique is introduced. This problem is particularly interesting in the field of modern multimedia applications, when image and video authentication are required. The approach exploits the cellular automata suitability to work as pseudorandom pattern generators and extends the related algorithms...

We show that the best rank-(R 1,R 2,...,R N ) approximation in multilinear algebra is a powerful tool for dimensionality reduction in ICA schemes without prewhitening. We consider the application to different classes of ICA algorithms.

We derive a Grassmann-Rayleigh Quotient Iteration for the computation of the best rank-(R 1, R 2, R 3) approximation of higher-order tensors. We present some variants that allow for a very efficient estimation of the signal subspace in ICA schemes without prewhitening.

In this chapter a systematic overview is given of methods for chaotic systems synchronization in the case of Lure systems. For autonomous schemes the link with absolute stability theory is emphasized and robust synchronization is discussed. For non-autonomous schemes nonlinear H synchronization is explained. Criteria for schemes with time delay are...

Kernel based methods suffer from exceeding time and memory requirements when applied on large datasets since the involved optimization problems typically scale polynomially in the number of data samples. As a remedy we propose both working on a reduced set (for fast evaluation) and at the same time keeping the number of model parameters small (for...

In this paper, a novel true random bit generator (TRBG) based on a double-scroll attractor is proposed. The double-scroll attractor is obtained from a simple model which is qualitatively similar to Chua's circuit. In order to face the challenge of using the proposed TRBG in cryptography, the proposed TRBG is subjected to statistical tests which are...

This paper presents a dedicated known-plaintext attack on up to four rounds of the IDEA cipher, that trades-off a small number of known data blocks (114) for a larger time complexity (2114). This attack is also applied to up to 2.5-round MESH block ciphers, but are not more effective than previously known attacks. An advantage of this attack compar...

In signal processing systems, aliasing is normally treated as a disturbing signal. That motivates the need for effective analog, optical and digital anti-aliasing filters. However, aliasing also conveys valuable information on the signal above the Nyquist frequency. Hence, an effective processing of the samples, based on a model of the input signal...