Hans Georg Schaathun

• dr.scient., PGCAP
• Professor at Norwegian University of Science and Technology, Ålesund, Norway

Diabetes management datasets are often compiled from various sensors and devices, including diabetes technology, activity trackers, and other health-related equipment, resulting in heterogeneous data formats. Despite the abundance of available data, inconsistencies in dataset formats and data-sharing practices limit the ability to build on prior wo...

Sfard og Leron (1996) observerte at studentar arbeider flittigare og oftare lukkast når dei programmerer enn dei gjer med analytisk matematikk, sjølv om programmeringsoppgåva løyser det same matematiske problemet i ein meir generell form. Her går me gjennom relevant litteratur og teori for å drøfta kvifor det kan vera slik. Dette reiser interessant...

Blood glucose prediction is an important component of biomedical technology for managing diabetes with automated insulin delivery systems. Machine learning and deep learning algorithms hold the potential to advance this technology. However, the lack of standardized methodologies impedes direct comparisons of emerging algorithms. This study addresse...

The divide between weak and strong lensing is of course artificial, in that both regimes are manifestations of the same physical phenomenon: gravity bending the path of light. Nevertheless, these two regimes have to a large extent been treated separately, with different methods. This review traces the development of methods combining weak-lensing a...

Gravitational lensing occurs as the path of light from distant celestial bodies is distorted due to gravitational attraction by other celestial bodies, whose mass is partly invisible, being so-called dark matter. When observed through a gravitational lens, distant galaxies appear distorted. A lot of research activity goes into mapping the dark matt...

In the field of blood glucose prediction, the literature is abounded with algorithms that demonstrate potential in glucose management. However, these propositions face an issue common to many machine learning algorithms: the repeated reuse of datasets (overfitting) and a tendency to develop algorithms in isolation, detached from practical scenarios...

Gravitational lensing refers to the deflection of light by the gravity of celestial bodies, often predominantly composed of dark matter. Seen through a gravitational lens, the images of distant galaxies appear distorted. A range of mathematical frameworks exist to model the lensing effect, but reconstructing the dark lens mass remains a difficult p...

In this paper, we examine the region- and layer-specific collagen fiber morphology via second harmonic generation (SHG) in combination with planar biaxial tension testing to suggest a structure-based constitutive model for the human meniscal tissue. Five lateral and four medial menisci were utilized, with samples excised across the thickness from t...

It is often difficult to teach mathematics for understanding. Many students seem to prefer to learn computational skills by rote, and seem to remember very little of the course contents the following semester. The reasons for this are surely manifold. This paper reviews the concept of understanding, looking particularly towards the meaning it has i...

Structure-function correlations are crucial for understanding meniscal tears, creating novel meniscal repair techniques, and predicting tissue behavior through computational models. A challenge for modelling structure-function correlations of the meniscus is the complex heterogeneous microstructure, which contributes to region and layer-specific ma...

Simon and Schön are commonly seen to represent two conflicting views on design method, but this interpretation has been challenged in recent years. In this paper we discuss their differences and agreements in more depth. Both of them agree on a rationality which is distinct from science and its reliance on universal truth. They depend on a practica...

The use of digital twins to represent a product or process digitally is trending in many engineering disciplines. This term has also been recently introduced in the medical field. In arthroscopic surgery education, the paradigm shift from apprenticeship to simulation training has driven the need for better simulators, and the current focus is on im...

Denne artikkelen tek for seg iterativ evaluering, revisjon og design over to år, for eit emne i grunnleggjande matematikk. Me har lagt vekt på tett dialog med studentane, mellom anna gjennom improvisert quiz i førelesingane. I denne tette kontakten vart me overraska av to observasjonar. For det fyrste var hovudutfordringa for studentane ikkje dei g...

Pandemien har i 2020 tvunge mange matematikkførelesarar til å bruka mappevurdering og heimeeksamen i staden for dei tradisjonelle skuleeksamenane med streng kontroll på hjelpemiddel. Dette er kontroverielt når eksamen skal testa rekneferdigheiter. I denne artikkelen vil me vri spørsmålet og sjå på kva matematikkompetansar me kan vurdera gjennom map...

Digitalisering er ei utfordring for oss alle. Forventingane er store til å gje betre tenester til lågare pris ved hjelp av ny teknologi. For skulane tyder digitalisering både eit press mot effektivisering og eit behov for å utvikla og formidla digital kompetanse. Digitale løysingar i klasserommet vert ofte kritiserte. Det er ikkje alltid lett å sjå...

ONSITE is a research project that builds knowledge on how to implement human-centred design processes within ship design. The project focuses specifically on a field study methodology and the transfer of knowledge between human-centred design and engineering disciplines.

Doing field studies on ships to support maritime design is both time-consuming and costly. It is therefore important to make sure field studies are both effective (they produce the desired results) and efficient (they use the minimum resources necessary to achieve those results). Increased use of digital tools may potentially improve field studies....

Digital fingerprinting has been much studied in the literature for more than 20 years, motivated by applications in copyright protection. A popular and practical approach is to use spread spectrum watermarking to embed fingerprints in multimedia objects. Solutions are normally only validated against known attacks in simulation. In this paper, we re...

In an accompanying paper submitted concurrently to this conference, we present our first complete version of a generic and modular software framework for intelligent computer-automated product design. The framework has been implemented with a client-server software architecture that automates the design of offshore cranes. The framework was demonst...

For many years, NTNU in Ålesund (formerly Aalesund University College) has maintained a close relationship with the maritime industrial cluster, centred in the surrounding geographical region, thus acting as a hub for both education, research, and innovation. Of many common relevant research topics, virtual prototyping is currently one of the most...

The Coordination Reform of 2012 requires Norwegian municipalities and regional health authorities to enter into legally binding service agreements. Although several research projects have been undertaken to analyse the implications of this reform, there is no central database where researches can be given access and analyse the service agreements....

Tug fleet optimisation algorithms can be designed to solve the problem of dynamically positioning a fleet of tugs in order to mitigate the risk of oil tanker drifting accidents. In this paper, we define the tug fleet optimisation problem and present the details of a receding horizon genetic algorithm for solving it. The algorithm can be configured...

Aktiv læring har vore ein viktig trend i utdanningssektoren i lang tid med både klassiske og moderne proponentar. I praksis skjer det likevel at aktiv læring vert sekundær til tradisjonelle førelesingar og annan passiv formidling. Då får studentane ansvaret for å aktivisera seg sjølve, og ikkje alle klarer det like bra. I samband med ny rammeplan...

Sammendrag Med utgangspunkt i en dypevaluering av et emne ved dataingeniørutdanningen ved Høgskolen i Ålesund, diskuterer vi i denne artikkelen hvordan samfunnsvitenskapelige, kvalitative metoder er egnet til å studere og evaluere studentenes laering på en helt annen måte enn de spørreskjemaene som vanligvis brukes ved emneevaluering. Artikkelen he...

Samandrag I emnet Diskret Matematikk har me brukt omvendt klasserom sidan hausten 2013. Førelesingane er tilgjengeleg som videoopptak på ei vevside. medan klasseromstida vert brukt til tovegskommunikasjon og aktiv laering i ein eller annan form. Det kan innebera spørsmål frå studentane, vegleiing, gruppearbeid, diskusjon rundt oppgåver, med meir. S...

This paper presents the framework of a virtual prototyping system for the design and simulation of maritime crane operations. By combining the rapid-prototyping approach with the concept of interchangeable interfaces, different demanding operation scenarios can be simulated including models of the corresponding physical systems, the vessel and the...

Pseudo-random number generation is a fundamental problem in computer programming. In the case of sequential processing the problem is very well researched, but parallel processing raises new problems whereof far too little is currently understood. Splittable pseudo-random generators (S-PRNG) have been proposed to meet the challenges of parallelism....

A fleet of tugs along the northern Norwegian coast must be dynamically positioned to minimise the risk of oil tanker drifting accidents. We have previously presented a receding horizon genetic algorithm (RHGA) for solving this tug fleet optimisation (TFO) problem. Here, we first present an overview of the TFO problem, the basics of the RHGA, and a...

In Norway, as well as in other northern European nations, public expenditure is in the range of 50% of the Gross Domestic Product (GDP). This shows clearly that the public sector plays a dominant role in the national economy. This sector is challenged by a rapid aging society, an increased globalization, and stagnation in the economy. These factors...

A fleet of tugs along the northern Norwegian coast must be dynamically positioned to minimise the risk of oil tanker drifting accidents. We have previously presented a receding horizon genetic algorithm (RHGA) for solving this tug fleet optimisation (TFO) problem. In this paper, we begin by presenting an overview of the TFO problem and the details...

The main threat against fingerprinting systems is collusion attacks. The attack most commonly assumed in the literature is a combination of averaging the collusion fingerprints and additive noise. In this correspondence, we demonstrate that the recently proposed fingerprinting scheme of Kuribayashi's is very vulnerable to certain nonlinear collusio...

People with dementia or other kinds of cognitive failure are at risk of getting lost when they are out walking. Depending on weather conditions, this is potentially a life-threatening risk. Electronic tracking is proposed as a tool to allow safe walking, and a help for the caregivers to locate a missing care recipient in the event of getting lost....

This paper introduces a flexible and general control system architecture that allows for modelling, simulation and control of different models of maritime cranes and, more generally, robotic arms by using the same universal input device regardless of their differences in size, kinematic structure, degrees of freedom, body morphology, constraints an...

Increasing offshore activity result in new, demanding marine operations. Risks increase as loads get heavier, installations move subsea, and activities move further North. Detailed planning is required, but current techniques make little use of information technology, with paper-based plan-work easily filling multiple binders. Information overload...

Offshore activity is developing and resulting in new demanding high-risk operations. Operation complexity increases with factors like heavier loads, subsea installations, and arctic waters; operational planning requirements increase as well. Demanding offshore operations are usually planned in detail, where plans may fill several binders, leading t...

Steganography is the art of communicating a secret message, hiding the very existence of a secret message. This is typically done by hiding the message within a non-sensitive document. Steganalysis is the art and science of detecting such hidden messages. The task in steganalysis is to take an object (communication) and classify it as either a steg...

Early Histogram Analysis Notation Additive Independent Noise Multi-dimensional Histograms Experiment and Comparison

Visual Steganalysis Autocorrelation Features Binary Similarity Measures Evaluation and Comparison

Bayesian Classifiers Estimating Probability Distributions Multivariate Regression Analysis Unsupervised Learning Summary

JPEG Compression Histogram Analysis Blockiness Markov Model-based Features Conditional Probabilities Experiment and Comparison

Overfitting and Underfitting Scalar Feature Selection Feature Subset Selection Selection Using Information Theory Boosting Feature Selection Applications in Steganalysis

Image Forensics Conclusions and Notes

The Difference Matrix Image Quality Measures Colour Images Experiment and Comparison

Linear Classifiers The Kernel Function í-SVM Multi-class Methods One-class Methods Summary

Cryptography versus Steganography Steganography Steganalysis Summary and Notes

Different Use Cases Images and Training Sets Composite Classifier Systems Summary

A Visual View The Wavelet Domain Farid's Features HCF in the Wavelet Domain Denoising and the WAM Features Experiment and Comparison

Estimation and Simulation Scalar Measures The Receiver Operating Curve Experimental Methodology Comparison and Hypothesis Testing Summary

Calibrated Features JPEG Calibration Calibration by Downsampling Calibration in General Progressive Randomisation

We formalize a new attack model for collusion secure codes, incorporating attacks on the underlying watermarking scheme as well as cut-and-paste attacks traditionally considered for collusion secure codes. We use this model to analyze the collusion resistance of two versions of the Tardos code, both for binary and nonbinary alphabets. The model all...

Samandrag Steganografi er teknikkar for hemmeleg kommunikasjon, der sjølve eksisten-sen av den hemmelege meldinga må haldast løynd. Steganalyse dreier seg om teknikkar for å påvisa slike meldingar. Ei rekkje moderne steganografiteknik-kar finst for å modulera digital informasjon i digitale bilete. Dei mest lovande steganalyseteknikkane byggjer på m...

The Deletion-Insertion Correcting Code construction proposed by Davey and MacKay consists of an inner code that recovers synchronization and an outer code that provides substitution error protection. The inner code uses low-weight codewords which are added (modulo two) to a pilot sequence. The receiver is able to synchronise on the pilot sequence i...

We introduce a new attack model for collusion-secure codes, called the combined digit model, which represents signal processing attacks against the underlying watermarking level better than existing models. In this paper, we analyze the performance of two variants of the Tardos code and show that both variants can accommodate the new model and resi...

The publicly-available F5 software (F5Software) implementation takes a possibly compressed cover image, decompresses it if necessary, and embeds the hidden message during a second compression process. This procedure introduces a risk that the stego image goes through ‘double compression’. While this is not a problem from the embedding and extractio...

Several open questions in coding theory relate to non- existence or construction of certain optimal codes. Many previous problems of this kind have been solved by studying possible weight enumerators. A couple of authors in this decade have proposed using higher weights (generalised Hamming weights) to a similar effect. In this paper we suggest one...

Digital fingerprinting is one of many proposed approaches to combat unauthorised copying. The idea is to make every sold copy unique, so that an unauthorised copy can be traced back to a guilty user. One of the major challenges of such a system is attacks made by a collusion of several users. Possessing multiple copies, a collusion can compare them...

The Davey-MacKay construction is a deletion-insertion correcting code scheme consisting of an inner code that functions as a pilot sequence to which the receiver seeks to synchronize, and an outer code that provides error protection. We analyse the performance of the inner code in isolation, arguing that these codes provide unequal protection, and...

We introduce a new attack model for collusion secure codes, and analyze the collusion resistance of two version of the Tardos code in this model, both for binary and non-binary alphabets. The model allows to consider signal processing and averaging attacks via a set of symbol detection error rates. The false positive rate is represented as a single...

In this paper, we analyse and extend the steganalysis technique employed by Shi et al. (2006), where they used a first-order Markov model to generate second order statistics from the JPEG 2-D array. They have suggested that a second order Markov model should improve the performance, but did not proceed with the implementation due to its computation...

Inspired by works on the Markov process based steganalysis, we propose a new steganalysis technique based on the conditional probability statistics. Specifically we focus on its performance against the F5 software. In our experiment, we prove that the proposed technique works as well or better than the Markov process based technique in terms of cla...

In this paper, we study the wavelet decomposition based steganalysis technique due to Lyu and Farid. Specifically we focus on its performance with JSteg steganograpy. It has been claimed that the Lyu-Farid technique can defeat JSteg; we confirm this using different images for the training and test sets of the SVM classifier. We also show that the t...

In this paper we consider the use of q-ary turbo codes on abstract q-ary channels. Simulations show that our 16-ary codes perform well on the q-ary symmetric channel. This validates their suitability as outer codes in non-binary applications. We also compare with the performance of same codes on conventional PSK and QAM modulation, and demonstrate...

With a digital fingerprinting scheme, a vendor of digital copies of copyrighted material marks each individual copy with a unique fingerprint. If an illegal copy appears, it can be traced back to one or more guilty pirates due to this fingerprint. A coalition of pirates may combine their copies to produce an unauthorized copy with a false, hybrid f...

ABSTRACT We present a key-recovery attack on a watermarking scheme for authentication and localisation due to Li and Yuan. The attack exploits a lack of diusion,in the system. Each bit of the key aects,only a small region of the watermarked image. Even though a brute-force attack is intractible, an exhaustive search is possible by considering one r...

Digital fingerprinting has been suggested for copyright protection. Using a watermarking scheme, a fingerprint identifying the buyer is embedded in every copy sold. If an illegal copy appears, it can be traced back to the guilty user. By using collusion-secure codes, the fingerprinting system is made secure against cut-and-paste attacks. In this pa...

The Davey-MacKay construction is a Deletion-Insertion Correcting Code scheme consisting of all inner code that functions as a pilot sequence to which the receiver seeks to synchronize, and an outer code that provides error protection. We analyse the performance of the inner code in isolation, arguing that these codes provide unequal protection, and...

Spread-spectrum watermarking is generally considered to be robust against collusion attacks, and thereby suitable for digital fingerprinting. We have previously introduced the minority extreme attack (IWDW '07), and showed that it is effective against orthogonal fingerprints. In this paper, we show that it is also effective against random Gaussian...

We introduce two novel collusion attacks against digital fingerprinting using additive spread-spectrum watermarks. These attacks demonstrate that the He-Wu fingerprinting system is considerably less secure against collusive attacks than suggested by the original paper. In addition to causing error rates above 85% at the decoder with as few as 8 col...

Collusion-secure codes are used for digital fingerprinting and for traitor tracing. In both cases, the goal is to prevent unauthorized copying of copyrighted material, by tracing at least one guilty user when illegal copies appear. The most well-known collusion-secure code is due to Boneh and Shaw (1995/98). In this paper we improve the decoding al...

Digital fingerprinting has been suggested for copyright protection. Using a watermarking scheme, a fingerprint identifying the buyer is embedded in every copy sold. If an illegal copy appears, it can be traced back to the guilty user. By using collusion-secure codes, the fingerprinting system is made secure against cut-and-paste attacks. In this pa...

Collusion-secure codes are used for digital fingerprinting and for traitor tracing. In both cases, the goal is to prevent unauthorized copying of copyrighted material, by tracing at least one guilty user when illegal copies appear. The most well-known collusion-secure code is due to Boneh and Shaw (1995/98). In this paper we improve the decoding al...

Digital fingerprinting is a forensic method against illegal copying. The distributor marks each individual copy with a unique fingerprint. If an illegal copy appears, it can be traced back to one or more guilty pirates due to this fingerprint. To work against a coalition of several pirates, the fingerprinting scheme must be based on a collusion-sec...

Dirty paper coding are relevant for wireless networks, multiuser channels, and digital watermarking. We show that the problem of dirty paper is essentially equivalent to some classes of constrained memories, and we explore the binary so-called nested codes, which are used for efficient coding and error-correction on such channels and memories.

We explore some links between higher weights of binary codes based on entropy/length profiles and the asymptotic rate of (2,1)-separating codes. These codes find applications in digital fingerprinting and broadcast encryption for example. We conjecture some bounds on the higher weights, whose proof would considerably strengthen the upper bound on t...

We compute the second support weight distribution of the Kasami codes.

Separating codes find applications in many fields including automata theory and digital fingerprinting. It is known that the Kerdock code of sufficient order is (2,1)- and (2,2)-separating, but the separating weight is only known by a lower bound due to Sagalovich. In this correspondence, we prove that the lower bound on the (2,1)-separating weight...

Collusion-secure codes are used for digital fingerprinting and for traitor tracing. In both cases, the goal is to prevent unauthorised copying of copyrighted material, by tracing at least one guilty user when illegal copies appear. The most well-known collusion-secure code is due to Boneh and Shaw (1995/98). In this paper we improve the decoding al...

Collusion-secure codes are used in digital fingerprinting and traitor tracing. Scattering codes were recently introduced by Sebe and Domingo-Ferrer (2002), and used to contstruct a family of codes allegedly collusion-secure against three pirates. We prove that their codes are insecure against optimal pirate strategies, and we present a new secure c...

The combinatorial concept of separating systems has numerous applications, such as automata theory, digital fingerprinting, group testing, and hashing. In this correspondence, we derive upper bounds on the size of codes with various separating properties.

We show how to compute the support weight distribution A_i^r for r≥k-d₂^⊥+3, where d₂^⊥ is the second minimum support weight of a code, provided the weight enumerator of the dual code is known.

Separating codes, initially introduced to test automaton, have revived lately in the study of fingerprinting codes, which are used for copyright protection. Separating codes play their role in making the fingerprinting scheme secure against coalitions of pirates. We provide here better bounds, constructions and generalizations for these codes.

A greedy 1-subcode is a one-dimensional subcode of minimum (support) weight. A greedy r-subcode is an r-dimensional subcode with minimum support weight under the constraint that it contain a greedy (r - 1)-subcode. The r-th greedy weight e r is the support weight of a greedy r-subcode. The greedy weights are related to the weight hierarchy. We use...

Separating codes have recently been applied in the construction of collusion secure fingerprinting schemes. They are related to other combinatorial concepts like intersecting codes, superimposed codes, hashing families, and group testing. In this paper we study some good, binary asymptotic constructions of such codes.

The complexity status of the stable set problem in the class of P5-free graphs is unknown. In the present paper we study an approach to the problem based on finding augmenting graphs. The main result is that the stable set problem in ...

Separating codes (or systems) are known from combinatorics, and they enjoy increasing attention due to applications in digital fingerprinting.

Let Γ be a code of length n. Then x is called a descendant of the coalition of codewords a,b,…,e if xi∈{ai,bi,…,ei} for i=1,…,n. We study codes with the following property: any two non-intersecting coalitions of a limited size have no common descendant.We present constructions based on linear intersecting codes.