Stavros D. Nikolopoulos

Bio: Stavros D. Nikolopoulos is an academic researcher from University of Ioannina. The author has contributed to research in topics: Chordal graph & Indifference graph. The author has an hindex of 20, co-authored 148 publications receiving 1377 citations. Previous affiliations of Stavros D. Nikolopoulos include Pierre-and-Marie-Curie University & National and Kapodistrian University of Athens.

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones – Part 1

Abstract: . Ultra low frequency, kHz and MHz electromagnetic (EM) anomalies were recorded prior to the L'Aquila catastrophic earthquake that occurred on 6 April 2009. The main aims of this paper are threefold: (i) suggest a procedure for the designation of detected EM anomalies as seismogenic ones. We do not expect to be able to provide a succinct and solid definition of a pre-seismic EM emission. Instead, we aim, through a multidisciplinary analysis, to provide the elements of a definition. (ii) Link the detected MHz and kHz EM anomalies with equivalent last stages of the earthquake preparation process. (iii) Put forward physically meaningful arguments for quantifying the time to global failure and the identification of distinguishing features beyond which the evolution towards global failure becomes irreversible. We emphasize that we try to specify not only whether a single EM anomaly is pre-seismic in itself, but also whether a combination of kHz, MHz, and ULF EM anomalies can be characterized as pre-seismic. The entire procedure unfolds in two consecutive parts. Here in Part 1 we focus on the detected kHz EM anomaly, which play a crucial role in our approach to these challenges. We try to discriminate clearly this anomaly from background noise. For this purpose, we analyze the data successively in terms of various concepts of entropy and information theory including, Shannon n-block entropy, conditional entropy, entropy of the source, Kolmogorov-Sinai entropy, T-entropy, approximate entropy, fractal spectral analysis, R/S analysis and detrended fluctuation analysis. We argue that this analysis reliably distinguishes the candidate kHz EM precursor from the noise: the launch of anomalies from the normal state is combined by a simultaneous appearance of a significantly higher level of organization, and persistency. This finding indicates that the process in which the anomalies are rooted is governed by a positive feedback mechanism. This mechanism induces a non-equilibrium process, i.e., a catastrophic event. This conclusion is supported by the fact that the two crucial signatures included in the kHz EM precursor are also hidden in other quite different, complex catastrophic events as predicted by the theory of complex systems. However, our view is that such an analysis by itself cannot establish a kHz EM anomaly as a precursor. It likely offers necessary but not sufficient criteria in order to recognize an anomaly as pre-seismic. In Part 2 we aim to provide sufficient criteria: the fracture process is characterized by fundamental universally valid scaling relationships which should be reflected in a real fracto-electromagnetic activity. Moreover, we aim to answer the following two key questions: (i) How can we link an individual EM precursor with a distinctive stage of the EQ preparation process; and (ii) How can we identify precursory symptoms in EM observations that indicate that the occurrence of the EQ is unavoidable.

A graph-based model for malware detection and classification using system-call groups

Abstract: In this paper we present a graph-based model that, utilizing relations between groups of System-calls, detects whether an unknown software sample is malicious or benign, and classifies a malicious software to one of a set of known malware families. More precisely, we utilize the System-call Dependency Graphs (or, for short, ScD-graphs), obtained by traces captured through dynamic taint analysis. We design our model to be resistant against strong mutations applying our detection and classification techniques on a weighted directed graph, namely Group Relation Graph, or Gr-graph for short, resulting from ScD-graph after grouping disjoint subsets of its vertices. For the detection process, we propose the $$\Delta $$ -similarity metric, and for the process of classification, we propose the SaMe-similarity and NP-similarity metrics consisting the SaMe-NP similarity. Finally, we evaluate our model for malware detection and classification showing its potentials against malicious software measuring its detection rates and classification accuracy.

Preseismic electromagnetic signals in terms of complexity

Abstract: There is a recent thesis in the literature that an important organization of a physical system precedes a catastrophic event. In this context, one can search for signatures that imply the transition from a normal state to a main catastrophic event (e.g., earthquake). Experimental techniques are thus useful in corroborating theories from observed data. For example, recent results indicate that preseismic electromagnetic time series contain information characteristic of an ensuing earthquake event. Hereby, we attempt to demonstrate that an easily computable complexity measure, such as $T$-complexity or approximate entropy, gives evidence of state changes leading to the point of global instability. The appearance of a precatastrophic state is characterized by significant lower complexity in terms of $T$-complexity and approximate entropy. The present study confirms the conclusions of previous works based on an independent linear fractal spectral analysis. This convergence between nonlinear and linear analysis provides a more reliable detection concerning the emergence of the last phase of the earthquake preparation process. More precisely, we claim that our results suggest an important principle: significant complexity decrease and accession of persistency in electromagnetic (EM) time series can be confirmed at the tail of the preseismic EM emission, which could be used as diagnostic tools for the Earth's impending crust failure. Direct laboratory and field experimental data as well as theoretical arguments support the conclusions of the present analysis.

Addressing network survivability issues by finding the K-best paths through a trellis graph

Abstract: Due to the increasing reliance of society on the timely and reliable transfer of large quantities of information (such as voice, data, and video) across high speed communication networks, it is becoming important for a network to offer survivability, or at least graceful degradation, in the event of network failure. In this paper we aim to offer a solution in the selection of the K-best disjoint paths through a network by using graph theoretic techniques. The basic approach is to map an arbitrary network graph into a trellis graph which allows the application of computationally efficient methods to find disjoint paths. Use of the knowledge of the K-best disjoint paths for improving the survivability of ATM networks at the virtual path and virtual circuit level is discussed.

教学模式 = Models of Teaching

Abstract: Dedication Preface Foreword PART I: FRAME OF REFERENCE We begin with the idea of giving students the tools that increase their capacity for learning. The primary role of education is to increase student capacity for personal growth, social growth, and academic learning. Models of Teaching is an avenue to liberate student learning capacity and, by doing so, to help teachers take charge of their lives as teachers. CHAPTER 1: BEGINNING THE INQUIRY Creating Communities of Expert Learners On the whole, students are in schools and classes within those schools. Both need to be developed into learning communities and provided with the models of learning that enable them to become expert learners. We study how to build those learning communities. CHAPTER 2: WHERE MODELS OF TEACHING COME FROM Multiple Ways of Constructing Knowledge The history of teacher researchers comes to us in the form of models of teaching that enable us to construct vital environments for our students. Models have come from the ages and from teacher-researchers who have invented new ways of teaching. Some of these are submitted to research and development and how teachers can learn to use them. Those are the models that are included in this book. CHAPTER 3: STUDYING THE SLOWLY-GROWING KNOWLEDGE BASE IN EDUCATION A Basic Guide Through the Rhetorical Thickets We draw on descriptive studies, experimental studies, and experience to give us a fine beginning to what will eventually become a research-based profession. Here we examine what we have learned about how to design good instruction and effective curriculums. And, we learn how to avoid some destructive practices. CHAPTER 4: MODELS OF TEACHING AND TEACHING STYLES Three Sides of Teaching--Styles, Models, and Diversity We are people and our personalities greatly affect the environments that our students experience. And, as we use various models of teaching our selves -- our natural styles -- color how those models work in the thousands of classrooms in our society. Moreover, those models and our styles affect the achievement of the diverse students in our classes and schools. PART II: THE INFORMATION-PROCESSING FAMILYOF MODELS How can we and our students best acquire information, organize it, and explain it? For thousands of years philosophers, educators, psychologists, and artists have developed ways to gather and process information. Here are several live ones. CHAPTER 5: LEARNING TO THINK INDUCTIVELY Forming Concepts by Collecting and Organizing Information Human beings are born to build concepts. The vast intake of information is sifted and organized and the conceptual structures that guide our lives are developed. The inductive model builds on and enhances the inborn capacity of our students. CHAPTER 6: ATTAINING CONCEPTS Sharpening Basic Thinking Skills Students can develop concepts. They also can learn concepts developed by others. Concept attainment teaches students how to learn and use concepts and develop and test hypotheses. CHAPTER 7: THE PICTURE-WORD INDUCTIVE MODEL Developing Literacy across the Curriculum Built on the language experience approach, the picture-word inductive model enables beginning readers to develop sight vocabularies, learn to inquire into the structure of words and sentences, write sentences and paragraphs, and, thus, to be powerful language learners. In Chapter 19 the outstanding results from primary curriculums and curriculums for older struggling readers are displayed. CHAPTER 8: SCIENTIFIC INQUIRY AND INQUIRY TRAINING The Art of Making Inferences From the time of Aristotle, we have had educators who taught science-in-the-making rather than teaching a few facts and hoping for the best. We introduce you to a model of teaching that is science on the hoof, so to speak. This model has had effects, among other things, on improving the capacity of students to learn. We concentrate on the Biological Sciences Study Group, where for 40 years science teachers have shared information and generated new ideas. And, Inquiry training is a "best yet" model for teaching basic inquiry skills. CHAPTER 9: MEMORIZATION Getting the Facts Straight Memorization has had something of a bad name, mostly because of deadly drills. Contemporary research and innovative teachers have created methods that not only improve our efficiency in memorization, but also make the process delightful. CHAPTER 10: SYNECTICS The Arts of Enhancing Creative Thought Creative thought has often been thought of as the province of a special few, and something that the rest of us cannot aspire to. Not so. Synectics brings to all students the development of metaphoric thinking -- the foundation of creative thought. The model continues to improve. CHAPTER 11: LEARNING FROM PRESENTATIONS Advance Organizers Learning from presentations has almost as bad a name as learning by memorization. Ausubel developed a system for creating lectures and other presentations that will increase learner activity and, subsequently, learning. PART III: THE SOCIAL FAMILY OF MODELS Working together might just enhance all of us. The social family expands what we can do together and generates the creation of democracy in our society in venues large and small. In addition, the creation of learning communities can enhance the learning of all students dramatically. CHAPTER 12: PARTNERS IN LEARNING From Dyads to Group Investigation Can two students who are paired in learning increase their learning? Can students organized into a democratic learning community apply scientific methods to their learning? You bet they can. Group Investigation can be used to redesign schools, increase personal, social, and academic learning among all students, and -- is very satisfying to teach. CHAPTER 13: THE STUDY OF VALUES Role Playing and Public Policy Education Values provide the center of our behavior, helping us get direction and understand other directions. Policy issues involve the understanding of values and the costs and benefits of selecting some solutions rather than others. In these models, values are central. Think for a moment about the issues that face our society right now -- research on cells, international peace, including our roles in Iraq and the rest of the Middle East, the battle against AIDS, poverty, and who controls the decisions about pregnancy and abortion. Not to mention just getting along together. PART IV: THE PERSONAL FAMILY OF MODELS The learner always does the learning. His or her personality is what interacts with the learning environment. How do we give the learner centrality when we are trying to get that same person to grow and respond to tasks we believe will enhance growth? CHAPTER 14: NONDIRECTIVE TEACHING The Learner at the Center How do we think about ourselves as learners? As people? How can we organize schooling so that the personalities and emotions of students are taken into account? Let us inquire into the person who is the center of the education process. CHAPTER 15: DEVELOPING POSITIVE SELF-CONCEPTS The Inner Person of Boys and Girls, Men and Women If you feel great about yourself, you are likely to become a better learner. But you begin where you are. Enhancing self concept is a likely avenue. The wonderful work by the SIMs group in Kansas (see Chapter 3) has demonstrated how much can be accomplished. PART V: THE BEHAVIORAL SYSTEMS FAMILY OF MODELS We are what we do. So how do we learn to practice more productive behaviors? Let's explore some of the possibilities. CHAPTER 16: LEARNING TO LEARN FROM MASTERY LEARNING Bit by bit, block by block, we climb our way up a ladder to mastery. CHAPTER 17: DIRECT INSTRUCTION Why beat around the bush when you can just deal with things directly? Let's go for it! However, finesse is required, and that is what this chapter is all about. CHAPTER 18: LEARNING FROM SIMULATIONS Training and Self-Training How much can we learn from quasi-realities? The answer is, a good deal. Simulations enable us to learn from virtual realities where we can experience environments and problems beyond our present environment. Presently, they range all the way to space travel, thanks to NASA and affiliated developers. PART VI: INDIVIDUAL DIFFERENCES, DIVERSITY, AND CURRICULUM The rich countryside of humanity makes up the population of our schools. The evidence suggests that diversity enhances the energy of schools and classrooms. However, some forms of teaching make it difficult for individual differences to flourish. We emphasize the curriculums and models of teaching that enable individual differences to thrive. CHAPTER 19: LEARNING STYLES AND MODELS OF TEACHING Making Discomfort Productive By definition, learning requires knowing, thinking, or doing things we couldn't do before the learning took place. Curriculums and teaching need to be shaped to take us where we haven't been. The trick is to develop an optimal mismatch in which we are pushed but the distance is manageable. CHAPTER 20: EQUITY Gender, Ethnicity, and Socioeconomic Background The task here is to enable differences to become an advantage. The best curriculums and models of teaching do just that. In other words, if differences are disadvantages, it is because of how we teach. CHAPTER 21: CREATING AND TESTING CURRICULUMS The Conditions of Learning Robert Gagne's framework for building curriculums is discussed and illustrated. This content is not simple, but it is powerful. CHAPTER 22: TWO WORDS ON THE FUTURE The Promise of Distance Learning and Using Models of Teaching to Ensure that No Child is Left Behind. Afterword APPENDIX PEER COACHING GUIDES Related Literature and References Index

Discrete Applied Mathematics

Abstract: : Significant progress has been made with solution of location problems and in preprocessing and decomposition for discrete optimization. There has also been research on the application of techniques from combinational optimization to nonlinear problems.

Introduction to Nonlinear Science

Abstract: Preface 1. Nonlinear behavior in the physical sciences and biology: some typical examples 2. Quantitative formulation 3. Dynamical systems with a finite number of degrees of freedom 4. Linear stability analysis of fixed points 5. Nonlinear behavior around fixed points: bifurcation analysis 6. Spatially distributed systems, broken symmetries, pattern formation 7. Chaotic dynamics Appendices References Index.