Papers by Dimitris Papageorgiou
Πολλοί ειδικοί σε θέματα εξωτερικής πολιτικής στην Τουρκία θεωρούν ότι η εξωτερική πολιτική της Τ... more Πολλοί ειδικοί σε θέματα εξωτερικής πολιτικής στην Τουρκία θεωρούν ότι η εξωτερική πολιτική της Τουρκίας υπό το κυβερνητικό καθεστώς του κόμματος της Δικαιοσύνης και της Ανάπτυξης (ΑΚΡ) βρίσκεται σε πλήρη κρίση. Αυτοί θεωρούν ότι η Τουρκία τα τελευταία χρόνια έχει εγκαταλείψει την παραδοσιακή της εξωτερική πολιτική για χάριν μιας Ισλαμιστικής προσέγγισης και προοπτικής. Η Τουρκία φαίνεται να κάνει πολλά λάθη με βάσει αυτής της μονοδιάστατης προσέγγισης.
Οι ανεύθυνες πολιτικές της κυβέρνησης στο μεταναστευτικό οδήγησαν στην γεωπολιτική αναβάθμιση της... more Οι ανεύθυνες πολιτικές της κυβέρνησης στο μεταναστευτικό οδήγησαν στην γεωπολιτική αναβάθμιση της Τουρκίας στην περιοχή και την κατέστησαν πρωταγωνιστικό παράγοντα στις διεθνείς και ευρωπαϊκές εξελίξεις.
Other by Dimitris Papageorgiou
MRS Proceedings, 2004
ABSTRACT Eight syntheses of mortars used for restoration interventions in historic masonry were p... more ABSTRACT Eight syntheses of mortars used for restoration interventions in historic masonry were produced using the traditional materials of aerial lime and artificial pozzolanic additives. The mortars were aged over a 15-month period and then tested for properties related to chemical and mechanical stabilization using the following four analytical techniques: ultrasonic velocity propagation and the mortars' dynamic modulus of elasticity (Ed), mercury intrusion porosimetry for evaluation of microstructural characteristics (percentage open porosity, bulk density, average pore radius, total cumulative volume, and specific surface area), water capillary rise tests for the determination of total cumulative volume accessible to water and capillary rise coefficients of the mortars, and conventional mechanical tests for the determination of the mortars' flexural and compressive strength. Performance is correlated to the mortars' chemical composition, microstructural characteristics (as measure by average pore radius) and mechanical characteristics as measured by dynamic modulus of elasticity (Ed) and flexural and compressive strength (Fc).
International Journal of Criminology and Sociological Theory, Jan 10, 2013
The proliferation of Information and Communication Technologies (ICT) and their interaction with ... more The proliferation of Information and Communication Technologies (ICT) and their interaction with certain social systems, led to the emergence of the phenomenon of globalization. Globalization lays on a technological infrastructure that makes it possible, by minimizing the time needed for communication and inter-systemic interactions. This also, has led to a strong support of the global financial system to the ICT industry, so that the latter can provide faster applications at any level of networking, thus putting both globalization ...
Applied Surface Science, 2000
Using molecular dynamics and a rigid ion potential, we studied the vibrational and structural pro... more Using molecular dynamics and a rigid ion potential, we studied the vibrational and structural properties of the NiO(001) surface with and without cationic adatoms. We found that the bulk phonon density of states (DOS) is altered by the presence of the surface and that the adatom introduces new frequency modes. From the relaxed positions of the surface ions, it came
Applied Surface Science, 2003
We present Molecular Dynamics simulation results concerning the structural properties of Cu and A... more We present Molecular Dynamics simulation results concerning the structural properties of Cu and Au 2D adlayers on the Cu3Au(110) surface. We found that at low coverage the Cu adatoms occupy mainly dumbbell positions forming “pairs” with the Cu surface atoms, giving an incommensurate 1 × 4 aspect in the surface layer. It appears that this “pairing” stabilizes the surface preventing
CESifo Economic Studies, 2013
Τεχνολογικά Χαρακτηριστικά και Εργαλεία της Διαδικτυακής Παρουσίας των Τμημάτων της Τριτοβάθμιας ... more Τεχνολογικά Χαρακτηριστικά και Εργαλεία της Διαδικτυακής Παρουσίας των Τμημάτων της Τριτοβάθμιας Εκπαίδευσης στην Ελλάδα
Chemical Engineering Science, 1994
of the original continuous-time system. In contrast to conventional explicit diacretization metho... more of the original continuous-time system. In contrast to conventional explicit diacretization methods, the proposed Carleman discretization does not deteriorate rapidly as the sampling period increases. Examples of open-loop and deadbeat closed-loop resuonses of an isothermal continuous stirred tank reactor reveal the advantages of the proposed discret&& scheme.
This paper examines functional aspects of the internet Web Sites that (re)present Greek Higher Ed... more This paper examines functional aspects of the internet Web Sites that (re)present Greek Higher Educational Departments and Institutes and focuses on the promotion and dissemination of their educational and scientific results. The study conforms to the theoretical guidelines of a systemic approach that produces an overview of the consistencies and the asymmetries that define the impact of a Web Site as a communicative system. Web Sites representing Greek Higher Educational Departments and Institutes are evaluated as communicative systems that promote certain distinctions (that suggest meanings) in the context of the World Wide Web (WWW). The relevant evaluation includes five hundred and one (501) Web Sites and was based on eight (8) criteria. The results of this study hopefully will account for (Greek) Departments' Web Sites to be efficient, interactive and provide their readers with appropriate services.
Computational Materials Science, 2003
An important step in the design of alloys and intermetallic compounds using semi-empirical potent... more An important step in the design of alloys and intermetallic compounds using semi-empirical potentials is to determine the appropriate parameters, which best describe experimental and/or quantum mechanical ab initio results. This task is quite difficult as the data are not always consistent and complete and furthermore, they contain errors. To facilitate the modelling we use the optimization environment of MERLIN ERLIN http://merlin.cs.uoi.gr/. This was applied to study a particular class of intermetallic compounds and alloys, which are very interesting, the so-called superalloys, such as Ni-Al. We have fitted the properties of such intermetallic alloys and compounds utilizing a semiempirical tight-binding potential in the second moment approximation. The potentials, which were produced in this way, were tested for properties at various temperatures, including segregation to surfaces and interfaces, and also for dynamical properties like the phonon density of states and mean-square displacements. We find a very good agreement to known experimental results and also a wealth of interesting information has revealed. Therefore the produced interatomic potentials present a realistic way to test scenarios which appear in the materials design.
Computer Aided Geometric Design, 1997
Reflection characteristics of surfaces, as visualized by highlight lines, are important design ob... more Reflection characteristics of surfaces, as visualized by highlight lines, are important design objectives in automotive styling. A method is presented that allows the direct modification of a highlight line on a NURBS surface. The algorithm presented will automatically adjust the control points of the NURBS surface resulting in a modified surface shape that produces the desired highlight line. A system of nonlinear equations is developed that expresses the relationship between NURBS control points and reference points on the highlight line. The inverse problem is solved through linearization by a first-order Taylor expansion. In addition, a shape control mechanism is introduced that distributes control point changes over the surface in a coherent and predictable way. With this mechanism, the user is able to interactively control the locality, or extent, of the surface modification while maintaining the desirable highlight line modification. © 1997 Elsevier Science B.V.
Computer Physics Communications, 1989
Merlin 2.0 is a new version of the recently published optimization package MERLIN-1.0. Apart from... more Merlin 2.0 is a new version of the recently published optimization package MERLIN-1.0. Apart from several minor improvements and extensions, this new version offers a very important feature: Programmability. A high level language has been developed, that enables the user to easily write programs that control the new MERLIN-2.0 at run time.
Computer Physics Communications, 1990
ABSTRACT
Economic Modelling, 2014
ABSTRACT This paper focuses on the performance of the Greek economy during the period 1979-2001. ... more ABSTRACT This paper focuses on the performance of the Greek economy during the period 1979-2001. Following the work of Cole and Ohanian (1999) and Kehoe and Prescott (2002, 2007) this twenty year episode can be characterized as a great depression. We use this methodology and ask whether, given the observed exogenous path of total factor productivity (TFP), the neoclassical growth model can generate an equilibrium behavior that has growth accounting characteristics similar to those in the data. The answer is affirmative: Changes in TFP are crucial in accounting for the Greek great depression. Our model economy predicts a big decline of economic activity during the 80s and until the mid-90s and a strong recovery for the period 1995-2001. This is exactly what happened in Greece. Moreover, the model successfully mimics the actual data with respect to the timing of peaks and troughs and the time paths of most key macroeconomic variables. However, puzzles between theory's predictions and the observed data are not missing. For instance, things are (not surprisingly for the neoclassical growth model) less successful when it comes to the labor factor.
Journal of Macroeconomics, 2012
ABSTRACT This paper quantifies the macroeconomic and welfare implications of (i) changes in the t... more ABSTRACT This paper quantifies the macroeconomic and welfare implications of (i) changes in the tax-spending mix and (ii) debt consolidation policies. The setup is a neoclassical growth model augmented with a relatively rich public sector. The model is calibrated to the Greek economy. The results suggest that, if the goal of fiscal policy is to stimulate the economy and increase welfare by changing the tax mix, then it should decrease the tax rate on labour income and increase the consumption tax rate. While higher public investment spending is good for the economy, it is lower public consumption spending that is found to be expansionary. The results also suggest that both tax- and expenditure-based debt consolidation policies lead to worse economic activity in the short run, but they have strong beneficial effects in the medium and long run when the consolidation period finishes.
Lab on a Chip, 2010
We demonstrate a mass-production-amenable technology for fabrication, surface modification and mu... more We demonstrate a mass-production-amenable technology for fabrication, surface modification and multifunction integration in polymeric microfluidic devices, namely direct lithography on the polymeric substrate followed by polymer plasma etching, and selective plasma deposition. We apply the plasma processing technology to fabricate polymeric microfluidics in poly(methyl methacrylate) (PMMA) and poly(ether ether ketone) (PEEK). First, deep anisotropic O(2) plasma etching is utilized to pattern the polymer via an in situ, highly etch-resistant, thin, Si-containing photoresist, or via a thick organic photoresist. Absolute control of surface roughness (from smooth to very rough), and the production of stable-in-time (slowly ageing) superhydrophilic microchannels are demonstrated. Second, we demonstrate the spontaneous capillary pumping through such rough, superhydrophilic plasma-etched microchannels in contrast to smooth ones, even 5 weeks after fabrication. Third, by using C(4)F(8) fluorocarbon plasma deposition through a stencil mask, we produce superhydrophobic patches inside the microchannels, and use them as passive valves. Our approach proposes "smart" multifunctional microfluidics fabricated by a plasma technology toolbox.
Sensors and Actuators B: Chemical, 2012
Plasma processing is demonstrated as a generic technology not only to fabricate, roughen, and con... more Plasma processing is demonstrated as a generic technology not only to fabricate, roughen, and control the wetting properties of microfluidic devices but also to control the protein adsorption in microfluidic channels intended for bio-analysis. After lithography on poly(methyl methacrylate) (PMMA) substrates, deep anisotropic O2 plasma etching was utilized to pattern microchannels, at conditions where very rough bottom walls were obtained.
Surface Science, 2002
We present molecular dynamics results concerning the transport and the structural properties of t... more We present molecular dynamics results concerning the transport and the structural properties of the Cu 3 Au and Ni 3 Al(1 1 0) surfaces in presence of adatoms and vacancies. In the Cu 3 Au case we found that below 500 K the Cu adatom occupies preferably the so-called ''dumb-bell'' position, while the Au adatom penetrates into the second pure Cu layer via an exchange type mechanism inducing thereby local disorder. At higher temperatures the Cu adatom resides almost exclusively at fourfold positions, while spontaneous creation of adatom-vacancy pairs is also present. Vacancy diffusion processes induce surface disorder that starts by as much as 150 K below the bulk order-disorder temperature. In the case of Ni 3 Al(1 1 0) surface, we found a new Al adatom position situated between two Ni surface atoms. It came out that this position plays an important role in the adatom's diffusive behavior. Above 800 K adatomvacancy pairs are spontaneously created and in conjunction with exchange type diffusion mechanisms they affect seriously the surface order. In addition, we found that the Ni adatoms are more active than the Al adatoms, this difference in the adatom diffusivity being accentuated by exchange events, leading very quickly the surface in a disordered state. In conclusion, it comes out that the Cu 3 Au and Ni 3 Al(1 1 0) surfaces disorder well below the bulk transition temperature (663 K, Cu 3 Au) and the melting point (1663 K, Ni 3 Al) via diffusion processes of the adatoms and/or vacancies.
Surface Science, 2003
Using an effective potential model in analogy to the tight-binding scheme in the second-moment ap... more Using an effective potential model in analogy to the tight-binding scheme in the second-moment approximation, we investigated the transport processes and the structural properties of the Cu 3 Au and Ni 3 Al(1 1 1) surfaces by molecular dynamics simulations. We found that in the case of the Cu 3 Au(1 1 1) surface both Cu and Au adatoms are unstable and penetrating into the bulk (already at room temperature) induce local surface disorder that is propagating into the substrate. It is interesting to note that the interlayer diffusion takes place exclusively via Cu atoms and therefore, only Au adatoms stimulate local disorder through this process. Unlike, in the Ni 3 Al(1 1 1) surface the adatoms are stable, they diffuse via a multitude of hopping mechanisms, the Ni being more active than Al adatom. Below T s ¼ 900 K exchange mechanisms are lacking for both adatoms, while above this temperature exchange diffusion of the Al adatom with Ni surface atoms is present inducing local disorder in the surface layer. Interestingly, no exchange events were detected for the Ni adatom. Consequently, below T s the presence of adatoms on this surface does not affect the surface order, in agreement with the available experimental observations referring to Ni 3 Al. In addition, contrary to the behaviour found in the cases of the (0 0 1) and (1 1 0) surfaces, the presence of surface vacancies has no serious effect on the surface order in either of the alloys. This is essentially attributed to the structural difference of this surface, the second layer (Au or Al) atoms appearing to be an effective restraining element of any surface vacancy hopping mechanism.
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Papers by Dimitris Papageorgiou
Other by Dimitris Papageorgiou