Traditionally, recommender systems have been studied in domains that focus on harnessing distribu... more Traditionally, recommender systems have been studied in domains that focus on harnessing distributed information resources, collaborative filtering, information aggregation, social schemes for decision making and user interfaces. In this paper, we present recommender systems in a different context-primarily as systems that select (scientific) software appropriate to a user's needs. This application is motivated by the wide acceptance of problem solving environments (PSEs) which are high level environments for doing computational science. We give an overview of the domain, argue the need for recommender systems and describe our work in this area. The research issues in this discipline are also highlighted.
The purpose of this research study is twofold. First to evaluate and compare the innovativeness o... more The purpose of this research study is twofold. First to evaluate and compare the innovativeness of Greece relative to the European Union using indicators from the European innovation scoreboard and second to propose practices and techniques concerning the utilization of machine learning for modeling and analyzing innovation in general. Systematic analysis is conducted regarding the over-performance and the under-performance of Greece and the trends of these indicators over the years through statistical techniques and methods. Machine learning and advanced statistical methods are incorporated to ascertain the most important features that drive the variation of the summary innovation score of the European Union and Greece. Clusters and groups of correlated indicators are also specified. Our study provides preliminary explanations and evidence to help the country value its advantages and deal with its disadvantages. It also paves the way towards an analysis of innovation approach that has the potential to help us elucidate certain issues and deeply understand observations concerning Greece and beyond.
This n'porl, I!; a IIser's guide to ROWDLAS. a Row~orit'nt.l'(l Disl.ributt'd Liu('<'lf Alp;t,hra... more This n'porl, I!; a IIser's guide to ROWDLAS. a Row~orit'nt.l'(l Disl.ributt'd Liu('<'lf Alp;t,hra Subroutine lH\rka~l'. ROWDLAS ran hr llsrd to c1l'v(']op hip;l\l'f 11•\'t'lliup'H al,£';l'bra blnrks (lih' dirert, and iterativ(' solvrrs) on disLrihllt('d llllllt,ipro('t'ssor "'ysl,('m"', II. a[,;ll provid,>s pOfl.ahility arross sf'veral distributt'd-memory tlllliliproces:;ors amI pxeClitioll (,carinA: for moni\.orill,£'; LlIl' [H'rformaucl;' :1\\(1 for IIf'bugging purposes.
Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-... more Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-point boundary value problems with mixed boundary conditions. These methods determine quintic spline approximation to the solution of the boundary value problem. by forcing lhe approximating solution to satisfy the given operator equation, or a perturbed one at the nodes, the boundary conditions and auxiliary end conditions. The methods that are based on the initial operator equation produce not optimal approximation. as compared to lhe corresponding interpolation procedures. This paper derives appropriate perturbations of lhe initial differential equation, such. that the application of the collocation procedure leads 10 optimal approximating schemes. The theoretical behavior of the method has been verified numerically on a variety of benchmark problems found in !.he literature. L INTRODUCTION In !.his paper we consider a collocation of the solul..ion u of the second order two-point boWl...
An 0 (h~collocation method based on quintic splines is developed and analyzed for general fourth-... more An 0 (h~collocation method based on quintic splines is developed and analyzed for general fourth-order linear two-point boundary value problems. The method determines a quintic spline approximation to the solution by forcing it to satisfy a high order perturbation of the original boundary value problem at the nodal points of the spline. A variation of this method is formulated as a deferred correction method. The error analysis of the new method and its numerical behavior is presented.
Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-... more Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-point boundary value problems with mixed boundary conditions. These methods determine quintic spline approximation to the solution of the boundary value problem. by forcing lhe approximating solution to satisfy the given operator equation, or a perturbed one at the nodes, the boundary conditions and auxiliary end conditions. The methods that are based on the initial operator equation produce not optimal approximation. as compared to lhe corresponding interpolation procedures. This paper derives appropriate perturbations of lhe initial differential equation, such. that the application of the collocation procedure leads 10 optimal approximating schemes. The theoretical behavior of the method has been verified numerically on a variety of benchmark problems found in !.he literature. L INTRODUCTION In !.his paper we consider a collocation of the solul..ion u of the second order two-point boWl...
A new collocation method based on quadratic splines is presented for second order two point boun·... more A new collocation method based on quadratic splines is presented for second order two point boun· dary value problems. First, O(h) approximations to the first and second derivative of a fwlclion are derived using a quadratic spline interpolant of u. Then these approximations are used to define an 0 (h 4) perturbation of the given boundary value problem. Second, the perturbed problem is used to define a collocation approximation at inLerval midpoints for which an oplimal 0 (h ~i) global estimate for the j til derivative of the error is derived. Further, 0 (h4-i ) error bounds for the j th derivative are obtained for certain superconvergence points. It should be observed that standard collocation at midpoints gives O(h2-i ) bounds. ResullS from numerical experiments are reported that verify the theoretical behavior of the method. (i') This research was SIIpportcd by ARO granl DAA929-83-K-Q026 and AFOSR granr. 84-0385. (U) This lCSurcll WILl supported by I.K.Y. (NauQoBl FclIQwship ...
Most places of interest (University campus, town center) are within a walking distance. In additi... more Most places of interest (University campus, town center) are within a walking distance. In addition, Karsruhe has an efficient public transport system: tramways on the main lines, connecting busses on the less important im. Summer 1991 was dry and hot in Karlsruhe (the local newspaper said it was the driest August since 1876). The weather in the end of September in Karlsruhe is frequently still warm and friendly. Street cafis are still open in the pedestrian zone. However, the evenings may be cool and there may be some rain. Summertime (daylight savings time) ends on Saturday night, September 28. Credit cards are by far not as common in Germany as in e.g. France or the United States. Most smaller shops and restaurants accept only cash or eurocheque, no foreign currency. You should exchange some money, e.g. at Frankfurt airport. English is more or less understood by many Germans. But apart from airports, there are nearly no signs or other information in English. Opening hours of shops and banks are regulated by law. Only shops in railway stations, airports, and gas stations are allowed to be open after regular shopping hours open on ... Mon-Wed&Fri [ Thu Sat Sun
Problem oriented. very high level languages represent a first step toward the modernization of sc... more Problem oriented. very high level languages represent a first step toward the modernization of scientific mathematical software. An example of such a system is XELLPACK, an environment for solving elliptic partial differential equations (PDEs).
In today's networked world, virtual mobility for know-how exchange and enrichment of informationa... more In today's networked world, virtual mobility for know-how exchange and enrichment of informational resources is as commonplace as physical mobility. Professionals typically resort to a lingua franca, such as English, French, or German, for efficient communication in the world of work. This is a result from the need for accurate understanding to ensure the elimination of misconceptions, effective business processes, the development of trusting business relations, and even safety. Training programs exist that aim to build basic competencies for communicating on everyday life and professional activities in a foreign tongue. However, most of the mainstream approaches for foreign language learning, including the learning of vehicular languages, focus on developing knowledge of the use of the language in the country of origin. Most widely accessible language learning approaches fail to integrate the diverging use of a lingua franca by non-native speakers. For example, a professional who uses English as a vehicular language for basic and professional communication in different regions, e.g. Germany, Spain, France, Italy, or Scandinavia will be faced with widely varying pronunciations that are affected by native languages as well as additional so called "transfer effects": influences on syntax, choice of words and expressions, and more. In addition, communication with peers is more effective if an individual is well versed into cultural information and practices to help establish a good relationship as well as to avoid pitfalls, such as in-avertedly insulting a business peer; for example, common practices on initiating a business conversation, on introducing themselves, on continuing and closing the communication. Lately, the perceptions about language learning are evolving: instead of forcing all individuals to speak with one particular accent and one particular way, there is a shift towards embracing the richness of European cultures as this is manifested in the diverging uses of vehicular languages. In this respect, situated language learning can be advantageous by enabling the design of learning activities that familiarize an individual with specific work-related situations in varying cultures. This paper presents siLang, a serious gaming approach that is based on the Brown et al [1] model for situated cognition. siLang exposes learners to the use of English language by native as well as nonnative speakers aiming at providing opportunities for enculturation and role playing within a real-life context. Serious-gaming technology, virtual microworlds and innovative learning content are being used to promote interaction, conversation and verbal communication tasks.Validation activities will take place in Greece, Norway, Italy, Portugal, and Estonia involving undergraduate students, professionals and workers. This work is funded with the support of the Life Long Learning Programme of the European Commission and specifically KA2: Languages and runs from 2012 to 2014.
GENCRAY is a code translator that translates a Lisp-like language to FORTRAN 77. TIlls manual des... more GENCRAY is a code translator that translates a Lisp-like language to FORTRAN 77. TIlls manual describes the input language of GENCRAY. The GENCRAY input language is very similar to Common LISP, but contains extensions designed to accomoda.te the needs of FOH.,'l'HAN. We describe each construct by providing its input form and then explaining what FORTRAN output is produced. Several examples axc provided at the end of this docllrnenl to give a cohesive view of the language.
Achieving long-term sustainable development requires international initiatives for the preservati... more Achieving long-term sustainable development requires international initiatives for the preservation of the environment as well as an environmentally-aware next generation. The development of active future citizens taking a responsible stance on natural resources management at the personal as well as civic level calls for environmental skill building starting early, at the primary school level. Recognizing the importance of environmental education, most European national level curricula include high level objectives on the development of related skills. However, teachers in the field point to lack of supporting educational material and guidelines for classroom deployment, including fully developed learning activities as well as tools, especially in digital form. As a result, environmental education in primary schools currently mostly involves off-line activities such as recycling at the school grounds, site visits, and story-telling projects presented to classmates. The EnvKids proje...
I nformal learning is a research area not fully explored yet [1], but interest in out of classroo... more I nformal learning is a research area not fully explored yet [1], but interest in out of classroom learning methods and settings is currently increasing [2], [3]. In parallel to that, the advent of Internet, which allows for a plethora of educational content to be widely shared, seems to be promoting self-directed learning for all ages. Furthermore the rapid technological advancement makes obvious the need to identify opportune times and methods for technology and computer education, starting probably from the very early ages [3] and [4].
Enabling Technologies for Computational Science assesses future application computing needs, iden... more Enabling Technologies for Computational Science assesses future application computing needs, identifies research directions in problem-solving environments (PSEs), addresses multi-disciplinary environments operating on the Web, proposes methodologies and software architectures for building adaptive and human-centered PSEs, and describes the role of symbolic computing in scientific and engineering PSEs. The book also includes an extensive bibliography of over 400 references.&amp;amp;amp;amp;amp;lt; br&amp;amp;amp;amp;amp;gt; Enabling Technologies for ...
Journal of Mathematical Analysis and Applications, 1978
A collocation method based on piecewise polynomials is applied to boundary value problems for mth... more A collocation method based on piecewise polynomials is applied to boundary value problems for mth order systems of nonlinear ordinary differential equations. Optimal a priori estimates are obtained for the error of approximation in the maximum norm and superconvergence is verified at particular points.
Traditionally, recommender systems have been studied in domains that focus on harnessing distribu... more Traditionally, recommender systems have been studied in domains that focus on harnessing distributed information resources, collaborative filtering, information aggregation, social schemes for decision making and user interfaces. In this paper, we present recommender systems in a different context-primarily as systems that select (scientific) software appropriate to a user's needs. This application is motivated by the wide acceptance of problem solving environments (PSEs) which are high level environments for doing computational science. We give an overview of the domain, argue the need for recommender systems and describe our work in this area. The research issues in this discipline are also highlighted.
The purpose of this research study is twofold. First to evaluate and compare the innovativeness o... more The purpose of this research study is twofold. First to evaluate and compare the innovativeness of Greece relative to the European Union using indicators from the European innovation scoreboard and second to propose practices and techniques concerning the utilization of machine learning for modeling and analyzing innovation in general. Systematic analysis is conducted regarding the over-performance and the under-performance of Greece and the trends of these indicators over the years through statistical techniques and methods. Machine learning and advanced statistical methods are incorporated to ascertain the most important features that drive the variation of the summary innovation score of the European Union and Greece. Clusters and groups of correlated indicators are also specified. Our study provides preliminary explanations and evidence to help the country value its advantages and deal with its disadvantages. It also paves the way towards an analysis of innovation approach that has the potential to help us elucidate certain issues and deeply understand observations concerning Greece and beyond.
This n'porl, I!; a IIser's guide to ROWDLAS. a Row~orit'nt.l'(l Disl.ributt'd Liu('<'lf Alp;t,hra... more This n'porl, I!; a IIser's guide to ROWDLAS. a Row~orit'nt.l'(l Disl.ributt'd Liu('<'lf Alp;t,hra Subroutine lH\rka~l'. ROWDLAS ran hr llsrd to c1l'v(']op hip;l\l'f 11•\'t'lliup'H al,£';l'bra blnrks (lih' dirert, and iterativ(' solvrrs) on disLrihllt('d llllllt,ipro('t'ssor "'ysl,('m"', II. a[,;ll provid,>s pOfl.ahility arross sf'veral distributt'd-memory tlllliliproces:;ors amI pxeClitioll (,carinA: for moni\.orill,£'; LlIl' [H'rformaucl;' :1\\(1 for IIf'bugging purposes.
Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-... more Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-point boundary value problems with mixed boundary conditions. These methods determine quintic spline approximation to the solution of the boundary value problem. by forcing lhe approximating solution to satisfy the given operator equation, or a perturbed one at the nodes, the boundary conditions and auxiliary end conditions. The methods that are based on the initial operator equation produce not optimal approximation. as compared to lhe corresponding interpolation procedures. This paper derives appropriate perturbations of lhe initial differential equation, such. that the application of the collocation procedure leads 10 optimal approximating schemes. The theoretical behavior of the method has been verified numerically on a variety of benchmark problems found in !.he literature. L INTRODUCTION In !.his paper we consider a collocation of the solul..ion u of the second order two-point boWl...
An 0 (h~collocation method based on quintic splines is developed and analyzed for general fourth-... more An 0 (h~collocation method based on quintic splines is developed and analyzed for general fourth-order linear two-point boundary value problems. The method determines a quintic spline approximation to the solution by forcing it to satisfy a high order perturbation of the original boundary value problem at the nodal points of the spline. A variation of this method is formulated as a deferred correction method. The error analysis of the new method and its numerical behavior is presented.
Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-... more Collocation methods based on quintic splines are fonnulated and analyzed for the secondorder two-point boundary value problems with mixed boundary conditions. These methods determine quintic spline approximation to the solution of the boundary value problem. by forcing lhe approximating solution to satisfy the given operator equation, or a perturbed one at the nodes, the boundary conditions and auxiliary end conditions. The methods that are based on the initial operator equation produce not optimal approximation. as compared to lhe corresponding interpolation procedures. This paper derives appropriate perturbations of lhe initial differential equation, such. that the application of the collocation procedure leads 10 optimal approximating schemes. The theoretical behavior of the method has been verified numerically on a variety of benchmark problems found in !.he literature. L INTRODUCTION In !.his paper we consider a collocation of the solul..ion u of the second order two-point boWl...
A new collocation method based on quadratic splines is presented for second order two point boun·... more A new collocation method based on quadratic splines is presented for second order two point boun· dary value problems. First, O(h) approximations to the first and second derivative of a fwlclion are derived using a quadratic spline interpolant of u. Then these approximations are used to define an 0 (h 4) perturbation of the given boundary value problem. Second, the perturbed problem is used to define a collocation approximation at inLerval midpoints for which an oplimal 0 (h ~i) global estimate for the j til derivative of the error is derived. Further, 0 (h4-i ) error bounds for the j th derivative are obtained for certain superconvergence points. It should be observed that standard collocation at midpoints gives O(h2-i ) bounds. ResullS from numerical experiments are reported that verify the theoretical behavior of the method. (i') This research was SIIpportcd by ARO granl DAA929-83-K-Q026 and AFOSR granr. 84-0385. (U) This lCSurcll WILl supported by I.K.Y. (NauQoBl FclIQwship ...
Most places of interest (University campus, town center) are within a walking distance. In additi... more Most places of interest (University campus, town center) are within a walking distance. In addition, Karsruhe has an efficient public transport system: tramways on the main lines, connecting busses on the less important im. Summer 1991 was dry and hot in Karlsruhe (the local newspaper said it was the driest August since 1876). The weather in the end of September in Karlsruhe is frequently still warm and friendly. Street cafis are still open in the pedestrian zone. However, the evenings may be cool and there may be some rain. Summertime (daylight savings time) ends on Saturday night, September 28. Credit cards are by far not as common in Germany as in e.g. France or the United States. Most smaller shops and restaurants accept only cash or eurocheque, no foreign currency. You should exchange some money, e.g. at Frankfurt airport. English is more or less understood by many Germans. But apart from airports, there are nearly no signs or other information in English. Opening hours of shops and banks are regulated by law. Only shops in railway stations, airports, and gas stations are allowed to be open after regular shopping hours open on ... Mon-Wed&Fri [ Thu Sat Sun
Problem oriented. very high level languages represent a first step toward the modernization of sc... more Problem oriented. very high level languages represent a first step toward the modernization of scientific mathematical software. An example of such a system is XELLPACK, an environment for solving elliptic partial differential equations (PDEs).
In today's networked world, virtual mobility for know-how exchange and enrichment of informationa... more In today's networked world, virtual mobility for know-how exchange and enrichment of informational resources is as commonplace as physical mobility. Professionals typically resort to a lingua franca, such as English, French, or German, for efficient communication in the world of work. This is a result from the need for accurate understanding to ensure the elimination of misconceptions, effective business processes, the development of trusting business relations, and even safety. Training programs exist that aim to build basic competencies for communicating on everyday life and professional activities in a foreign tongue. However, most of the mainstream approaches for foreign language learning, including the learning of vehicular languages, focus on developing knowledge of the use of the language in the country of origin. Most widely accessible language learning approaches fail to integrate the diverging use of a lingua franca by non-native speakers. For example, a professional who uses English as a vehicular language for basic and professional communication in different regions, e.g. Germany, Spain, France, Italy, or Scandinavia will be faced with widely varying pronunciations that are affected by native languages as well as additional so called "transfer effects": influences on syntax, choice of words and expressions, and more. In addition, communication with peers is more effective if an individual is well versed into cultural information and practices to help establish a good relationship as well as to avoid pitfalls, such as in-avertedly insulting a business peer; for example, common practices on initiating a business conversation, on introducing themselves, on continuing and closing the communication. Lately, the perceptions about language learning are evolving: instead of forcing all individuals to speak with one particular accent and one particular way, there is a shift towards embracing the richness of European cultures as this is manifested in the diverging uses of vehicular languages. In this respect, situated language learning can be advantageous by enabling the design of learning activities that familiarize an individual with specific work-related situations in varying cultures. This paper presents siLang, a serious gaming approach that is based on the Brown et al [1] model for situated cognition. siLang exposes learners to the use of English language by native as well as nonnative speakers aiming at providing opportunities for enculturation and role playing within a real-life context. Serious-gaming technology, virtual microworlds and innovative learning content are being used to promote interaction, conversation and verbal communication tasks.Validation activities will take place in Greece, Norway, Italy, Portugal, and Estonia involving undergraduate students, professionals and workers. This work is funded with the support of the Life Long Learning Programme of the European Commission and specifically KA2: Languages and runs from 2012 to 2014.
GENCRAY is a code translator that translates a Lisp-like language to FORTRAN 77. TIlls manual des... more GENCRAY is a code translator that translates a Lisp-like language to FORTRAN 77. TIlls manual describes the input language of GENCRAY. The GENCRAY input language is very similar to Common LISP, but contains extensions designed to accomoda.te the needs of FOH.,'l'HAN. We describe each construct by providing its input form and then explaining what FORTRAN output is produced. Several examples axc provided at the end of this docllrnenl to give a cohesive view of the language.
Achieving long-term sustainable development requires international initiatives for the preservati... more Achieving long-term sustainable development requires international initiatives for the preservation of the environment as well as an environmentally-aware next generation. The development of active future citizens taking a responsible stance on natural resources management at the personal as well as civic level calls for environmental skill building starting early, at the primary school level. Recognizing the importance of environmental education, most European national level curricula include high level objectives on the development of related skills. However, teachers in the field point to lack of supporting educational material and guidelines for classroom deployment, including fully developed learning activities as well as tools, especially in digital form. As a result, environmental education in primary schools currently mostly involves off-line activities such as recycling at the school grounds, site visits, and story-telling projects presented to classmates. The EnvKids proje...
I nformal learning is a research area not fully explored yet [1], but interest in out of classroo... more I nformal learning is a research area not fully explored yet [1], but interest in out of classroom learning methods and settings is currently increasing [2], [3]. In parallel to that, the advent of Internet, which allows for a plethora of educational content to be widely shared, seems to be promoting self-directed learning for all ages. Furthermore the rapid technological advancement makes obvious the need to identify opportune times and methods for technology and computer education, starting probably from the very early ages [3] and [4].
Enabling Technologies for Computational Science assesses future application computing needs, iden... more Enabling Technologies for Computational Science assesses future application computing needs, identifies research directions in problem-solving environments (PSEs), addresses multi-disciplinary environments operating on the Web, proposes methodologies and software architectures for building adaptive and human-centered PSEs, and describes the role of symbolic computing in scientific and engineering PSEs. The book also includes an extensive bibliography of over 400 references.&amp;amp;amp;amp;amp;lt; br&amp;amp;amp;amp;amp;gt; Enabling Technologies for ...
Journal of Mathematical Analysis and Applications, 1978
A collocation method based on piecewise polynomials is applied to boundary value problems for mth... more A collocation method based on piecewise polynomials is applied to boundary value problems for mth order systems of nonlinear ordinary differential equations. Optimal a priori estimates are obtained for the error of approximation in the maximum norm and superconvergence is verified at particular points.
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Papers by elias houstis