National Technical University Of Athens Research Articles

Annual Review 2004

I want to express sincere thanks to a number of people who contribute to the success of the Journal. First of all, let me thank all members of ASCE for their continuing support. Membership in ASCE is a mark of support for excellence in hydraulic engineering. Most active hydraulic engineers are members of ASCE and we are proud of their endorsement. I would also like to take the opportunity to thank all volunteers of the ASCE organization. The activities of our volunteers through numerous task committees are effectively the brain and blood of our organization. I want to congratulate and welcome those who joined ASCE this year. We are seeking to extend the membership privileges to a larger number of professionals nationwide and abroad. A comprehensive list of JHE reviewers is presented at the end of this issue. The list includes all those who reviewed articles during a 12-month period starting July 2003, and we hope we did not forget anyone. After 3 years as Editor, I really appreciate the time commitment and effort made by the reviewers of the Journal. The reputation of the journal depends largely on the highquality reviews that we receive. The importance of the peerreview system and the role of external reviewers in improving the readability of all manuscripts cannot be overstated. This year, we want to specifically thank the following reviewers for their outstanding reviews: Jim L. Best, University of Leeds; George Christodoulou, National Technical University of Athens; Kenneth B. Edwards, LMNO Engineering, Research, and Software, Ltd.; Randall W. Gentry, University of Tennessee; Nickitas Georgas, HydroQual, Inc.; Christine Lauchlan, HR Wallingford Ltd; A. M. Wasantha Lal, South Florida Water Management District; Foo-Hoat Lim, Angkasa Consulting Services SDN BHD; Timothy B. Maddux, Woods Hole Oceanographic Institution; Erik Mosselman, WL/Delft Hydraulics, and Ian Ruthven Wood, University of Canterbury. These individuals are recognized for providing particularly thorough and helpful reviews to the Editorial Board this year. The role of the Editorial Board in ensuring quality reviews for our articles is also important. I appreciate all the support and commitment of Associate Editors in handling timely reviews on a continuous basis. The significant amount of time they volunteer to seek the best possible articles for the Journal is paramount to our success. This year, the Editorial Board met the challenge of reviewing a large number of high-quality manuscripts. We are con-

Aeroelastic stability of wind turbines: the problem, the methods and the issues

AbstractAeroelastic stability is a key issue in the design process of wind turbines towards both enchanced stability and increased fatigue life. The theory and models behind the state‐of‐the‐art aeroelastic stability tools developed for the analysis of the complete wind turbine at the Centre for Renewable Energy Sources and the National Technical University of Athens are presented in this article. Application examples of stability calculations for a pitch, variable speed and a stall‐regulated wind turbine are also presented. Copyright © 2004 John Wiley & Sons, Ltd.

Athens-Pittsburgh Symposium in the History and Philosophy of Science and Technology

The four papers (Biener, Dupre, Kosman, and Psillos) published in this issue are a subset of those originally presented at the fourth meeting of the biennial Athens-Pittsburgh Symposium in the History and Philosophy of Science and Technology, a joint undertaking of the University of Athens, the National Technical University of Athens, the University of Pittsburgh Center for Philosophy of Science, and European Cultural Center of Delphi. The topic of the symposium, convened at the European Cultural Center of Delphi, was Forms of Proof and Demonstration in Philosophy and Science. These symposia are held every two years in Greece in recognition of Athens as the birthplace of Western philosophy (all of them supported by the University of Athens, the National Technical University of Athens, and the University of Pittsburgh Center for Philosophy of Science). The arst Athens-Pittsburgh Symposium, devoted to the Problem of Anthropomorphism in Science and Philosophy, also took place at the European Cultural Center of Delphi in 1996. The second focused on Greek Medical Traditions from Hippocrates to Harvey, and was held at the University of Athens in 1998. The third, a conference on Experience and Knowledge, met at Rethymnon on the island of Crete in 2000. For the arst three of these symposia, the Latsis Foundation has provided major funding, supplemented by funding from the Harvey and Leslie Wagner Endowment. The European Cultural Center of Delphi was major contributor to the fourth Symposium. The Athens-Pittsburgh Planning Committee consisted of Dionysios Anapolitanos (Athens), Michael Frede (Oxford), John Cooper (Princeton), James Lennox (Pittsburgh), Gerald Massey (Pittsburgh), John McDowell (Pittbsurgh), plus the two symposia co-chairs Baltas and Machamer.

Computational energy analysis of an innovative isothermal chamber for testing of the special equipment used in the transport of perishable products

This paper describes an improved numerical simulation study of an isothermal chamber recently constructed at Zografou Campus of the National Technical University of Athens (NTUA) for the testing of special equipment used for transporting perishable foodstuffs in accordance with the United Nations ATP agreement. Using a transient finite difference model, a simulation is developed for a modern ATP test chamber and a typical specimen refrigerated vehicle to be tested. The simulation results are compared to experimental measurements taken under real conditions by a data acquisition system and a refrigerated semi-trailer as specimen. Proportional–integral control is employed for the regulation of the cooling and heating system. The impact of various parameters on the time required to reach the set-point temperature (tset) is investigated and the energy consumption is simulated for a period of 22 h. In particular, the impact of specimen insulation thickness and the thickness of the chamber insulation floor are considered in detail. The total energy consumption increases by approximately 16% when the concrete floor layer thickness is increased from 8 to 16 cm for typical initial conditions and desired chamber and specimen temperatures of 32.5 and 7.5°C, respectively. Using a floor insulation of 6 cm extruded heavy strain-resistant polystyrene reduces the energy consumption by at least 13%. Specimen insulation thickness increase from U-value of 0.35 W m−2 K to 0.75 W m−2 K result to an increase in energy consumption by a percentage of 28%. Thermal capacity, temperature of car body and specimen dimensions are also treated as variables that affect the total duration of an ATP test and its total energy consumption. Copyright © 2004 John Wiley & Sons, Ltd.

Role of boehmite/solution interface in boehmite precipitation from supersaturated sodium aluminate solutions

This work presents the developments made in the Laboratory of Metallurgy of the National Technical University of Athens in the field of boehmite precipitation from supersaturated sodium aluminate solutions under atmospheric conditions. Initially, the boehmite process is described by giving emphasis to kinetic problems that reduce the process efficiency and make it less attractive. Moreover, it is demonstrated that the physicochemical properties of the boehmite/solution interface are of great importance for the understanding of the boehmite precipitation mechanism. Therefore, the physicochemical properties of the boehmite/solution interface are theoretically determined giving emphasis to the surface speciation diagrams and the surface potential that are presented as a function of pH and the boehmite seed concentration in the solution. Finally, the theoretical data are correlated to the mechanism of boehmite precipitation and utilized for the understanding of alternative precipitation methods that improve the process efficiency.

An Educational Simulation Tool for Power System Control and Stability

This paper presents a Simulink-based educational tool developed for the purpose of illustrating power system control and stability notions as well as introducing students to realistic, though tractable in size, design problems. Relevant courses are taught to last-year undergraduate as well as graduate students at the University of Lie/spl grave/ge, Belgium, and the National Technical University of Athens, Greece. After a brief description of the corresponding curricula, the paper describes the simulation tool and gives examples of problems and assignments given to the students.

Using internet GIS technology for early warning, response and controlling the quality of the public health sector

Recent EU and Greek Government legislation highlights the need for the modernisation of the public health management system and the improvement of the overall health of EU citizens. In addition, the effusion of epidemics even in developed countries makes the need for the enhancement of public health services imperative. In order to best confront the above-described challenges, the National Technical University of Athens, in cooperation with the Greek Ministry of Health and Welfare and the European Commission (EC), designed and developed an integrated public health information network, named GEPIMI (Integrated Geographical System for EPIdemiological and other Medical Information), in the framework of a three-year pilot project. This pilot project, funded by Greek Ministry of Health and Welfare and the EC supported the Programme INTERREG II to establish an advanced and integrated web-based information system that can process and move information in real time, allowing public health authorities to monitor events at hundreds or thousands of public health facilities at once. The system is established among hospitals, primary healthcare authorities and health agents in Greece, Bulgaria, Albania, Fyrom, and Turkey. The project aims at demonstrating the best practices, prospects, applications and high potential of Telematics Healthcare Networks in Europe, with a view to promoting cooperation and interconnection between European communities in the field of Telematics Healthcare Applications. The GEPIMI System, implemented via an innovative web based system, constitutes a replication of a highly effective mechanism. It incorporates state-of-the-art technologies such as Geographic Information Systems (G.I.S.), web based databases, GPS, and Smart Card Technology and supports a variety of health-related web applications including early warning and response of epidemics, remote management of medical records, seamless healthcare coverage, comprehensive statistical analysis of data, decision-making procedures, inter-communication between international scientific fora and other.

GEOLOGICAL CONTROLS ON INTACT ROCK STRENGTH. THE EFFECT OF ANISOTROPY

The factors that influence the strength and deformation of the intact rock are the mineral composition, the fabric, the grain size and the degree of alteration and weathering. Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists). The current paper deals with the pronounced effect of the fabric of anisotropic rocks on the strength and deformation characteristics of intact rocks. It is part of ongoing research in the Department of Geotechnical Engineering, National Technical University of Athens. Testing was used to establish the anisotropic behaviour of selected metamorphic rocks. The effect of anisotropy on various mechanical properties (strength, deformation) and dynamic properties (wave velocity) was examined. The degree of strength anisotropy of these rocks can be indirectly estimated, by wave propagation through the rock, and thus they can be classified by means of geological and geotechnical indexes.

Radiological characteristics and investigation of the radioactive equilibrium in the ashes produced in lignite-fired power plants

Coal- and lignite-fired power plants produce significant amounts of ashes, which are quite often being used as additives in cement and other building materials. In many cases, coal and lignite present high concentrations of naturally occurring radionuclides, such as 238U, 226Ra, 210Pb, 232Th and 40K. During the combustion process, the produced ashes are enriched in the above radionuclides. The different enrichment of the various radionuclides within a radioactive series, such as that of 238U, results in the disturbance of radioactive secular equilibrium. An extensive research project for the determination of the natural radioactivity of lignite and ashes from Greek lignite-fired power plants is in progress in the Nuclear Engineering Department of the National Technical University of Athens (NED-NTUA) since 1983. This paper presents detailed results for the natural radioactivity, the secular radioactive equilibrium disturbance and the radon exhalation rate of the fly-ash collected at the different stages along the emission control system of a lignite-fired power plant as well as of the bottom-ash. From the results obtained so far, it may be concluded that 226Ra radioactivity of fly-ash in some cases exceeds 1 kBq kg −1, which is much higher than the mean 226Ra radioactivity of surface soils in Greece (25 Bq kg −1). Furthermore, the radioactivity of 210Pb in fly-ash may reach 4 kBq kg −1. These results are interpreted in relation to the physical properties of the investigated nuclides, the temperature in the flue-gas pathway, as well as the fly-ash grain size distribution. It is concluded that towards the coldest parts of the emission control system of the power plant, the radioactivity of some natural nuclides is gradually enhanced, secular radioactive equilibrium is significantly disturbed and the radon exhalation rate tends to increase.

Industrial pollution and control measures for a foundry in Cyprus

Over the last decades improvements have been achieved in industry regarding several major polluting substances and gradually the environmental impact has shifted towards the so-called diffuse sources of pollution. Nevertheless, industrial processes still account for a considerable share of the overall pollution in Europe and it is very important to further reduce their contribution to ‘unsustainability’. The European Union (EU) has a set of common rules on permitting of industrial installations. These rules are set out in the so-called Integrated Pollution Prevention and Control Directive of 1996 (IPPC). Cyprus is one of the accession countries to become a full member of the EU and is currently in the implementation process, in order to fulfill all the obligations that apply to the 15 Member States. A large number of these obligations derive from the IPPC Directive, which aims at the protection of the environment as a whole and the public health as well. In this framework, the National Technical University of Athens, after thorough examination of a large number of documents relevant to the Best Available Technologies, developed guidelines for the application of BATs for 14 categories of the industry of Cyprus. This paper concerns the developed guidelines for foundries.

Research and Development Activities of the Electric Energy Systems Laboratory of the National Technical University of Athens in the Field of Wind Energy

Research and Development Activities of the Electric Energy Systems Laboratory of the National Technical University of Athens in the Field of Wind Energy

Study of using JP-8 aviation fuel and biodiesel in CI engines

The first jet fuels were aviation gasoline (avgas), and the characteristics of subsequent jet fuels have evolved from this original choice, the available supply infrastructure, and the refiners’ capabilities. Earlier on, it was evident that avgas would have to be altered to operate satisfactorily in jet powered aircraft. The present contribution outlines the various requirements that led to development of various operational jet fuels, including United States Jet A (European Jet A-1), JP-4 (NATO code, F-40), JP-5 (NATO code, F-44), JP-7 (US only), JP-8 (F-34), JP-TS (US only), and JP-8+100. To reduce this fuel logistic burden, the NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate Diesel fuel in many applications. In order to make this type of fuel compatible with direct injection compression engines, the Fuels and Lubricants Laboratory of the National Technical University of Athens, used a stationary Diesel engine fueled with fuel blends containing two different types of biodiesel, at proportions up to 50%. In this paper, fuel consumption and exhaust emission measurements from a single cylinder, stationary, Diesel engine are described. The two types of biodiesel appeared to have equal performance, and irrespective of the raw material used for their production, their addition to the JP-8 aviation fuel improved the particulate matter emissions.

Development of guidelines on best practices for the slaughter of animals in Cyprus

Cyprus is one of the candidate countries to become a full member of the European Union. In order to access formally to the EU, Cyprus has to follow an implementation process and take into account all the obligations that the fifteen Member States have to respect. A large number of obligations derive from the European Integrated Pollution Prevention and Control (IPPC) Directive 96/61/EC, which intends to result in the protection of the environment as a whole and the public health as well. This will be the outcome of determining ways of pollution prevention and control for several industrial sectors, which are covered by the IPPC Directive and then taking action so that all operators act according to the Directive's demands. In this framework, the National Technical University of Athens, after thorough examination of a large number of documents relevant to the Best Available Techniques (BATs), developed guidelines for the application of BATs for 14 categories of the industry of Cyprus. This paper concerns the developed guidelines for slaughterhouses.

A quality assurance and quality control (QA QC) procedure of the monitored drift tubes (MDT) for the BIS-chambers of the ATLAS muon spectrometer

The ATLAS detector for the Large Hadron Collider at CERN of which construction has recently started, will study the products of proton collisions at energies of up to 14 TeV. One of its subdetectors is a high-resolution Muon Spectrometer designed to exploit the physics potentials of the collisions. It consists of 1206 Monitored Drift Tube (MDT) chambers, which will be built in 13 institutes of the ATLAS collaboration. Three Greek Universities (University of Athens, National Technical University and University of Thessaloniki) have undertaken the responsibility to construct 30 000 drift tubes of 1.67 length, to test them and to finally to build 128 BIS (Barrel Inner Small) chambers. Dedicated setups have been developed and automated at the National Technical University of Athens for the Quality Assurance and Quality Control (QA QC) procedures of the drift tubes. The QA QC tests include anode wire tension measurement, high voltage dark current measurement, anode wire displacement measurement and gas leak-rate measurement of the end-plugs and the cylinder. Up to now about 10 000 drift tubes have been tested.

Stockholm Agreement—Past, Present, Future (Part 1)

April 1, 2001 marked the fourth anniversary of the Stockholm Agreement (SA), a period during which almost 80% of the roll-on/roll-off (Ro-Ro) fleet in North West Europe have been subjected to calculations, model testing and numerical simulations in the struggle to meet these demanding new requirements. The experience gained has been invaluable in understanding better the problem at hand and is being utilized to shape new developments likely to lead to more meaningful requirements. The North-South divide, however, continues to cause unrest, particularly at the European level. Efforts to assess the status quo in North West Europe, and to use the information amassed so far as a means to predict the potential impact of introducing the SA in the South, led to a dedicated call by the Commission and to a contract being awarded to two closely collaborating teams, one at the Ship Stability Research Centre of the University of Strathclyde under the leadership of Professor Vassalos and one at the Ship Design Laboratory of the National Technical University of Athens, under the leadership of Professor Papanikolaou, representing the North and South of Europe, respectively. This background provided the incentive for an introspective look at the SA, with a view to ascertaining its status before embarking into future projections. This forms Part 1 of the SA related research with Part 2 aiming to cover the results of the Commission study itself.

A novel concept for the manufacture of individual sapphire-metallic hip joint endoprostheses

During the last decade, hip joint endoprostheses have been ever more widely carried out in orthopaedic practice in the world; more than 400 000 operations are performed every year and more than 100 types of endoprosthetic construction have been designed [1, 2]. The best known are those of Biomet, Zimmer (USA), and Aesculap (Germany), in which metallic and polymer or ceramic and polymer joints are used. Analysis of the results of endoprosthetic operations on joints show that in 7–12% of cases 2–3 years later, and in 25–30% of cases 5–7 years later, complications arise that are generally deleterious to the health of the recipient [3]. The most frequent and dangerous complication is an aseptic shattered condition of the endoprosthesis in the bone tissue, which leads to the necessity of recurrent operations. One of the negative factors leading to this condition is friction in the hinge of the artificial joint, releasing nanoparticles produced from the endoprosthetic material. Furthermore, different loads in the hinge of the endoprosthesis during walking cause friction in the components of the joint and it wears out (see Fig. 1). A novel concept for the manufacture of individual sapphire-metallic hip joint endoprostheses A.G. Mamalis, J.J. Ramsden, A.I. Grabchenko, L.A. Lytvynov, V.A. Filipenko and S.N. Lavrynenko 1 Laboratory of Manufacturing Technology, National Technical University of Athens, Greece 2 Advanced Materials Department, Cranfield University, UK 3 Department of Integrated Technologies in Mechanical Engineering, National Technical University Kh. P. I., Kharkov, Ukraine 4 Institute for Single Crystals, National Academy of Science of Ukraine, Kharkov, Ukraine 5 Sytenko Institute of Spine and Joint Pathology, Ukrainian Academy of Medical Sciences, Kharkov, Ukraine

Experimental investigation of the earthquake response of a model of a marble classical column

AbstractExperimental results concerning the earthquake response of a marble model of a classical column are reported herein. The model was a 1: 3 scale replica of a column of the Parthenon on the Acropolis of Athens, made from the same material as the original. Several earthquake motions, scaled appropriately in order to cause significant rocking but no collapse of the column, were used as the excitation. The base motion was applied in plane (in one horizontal and the vertical direction) or in space (in two horizontal and the vertical direction), using the shaking table facility at the Laboratory for Earthquake Engineering of the National Technical University of Athens. It was found that the column might undergo large deformations during the shaking, which are not necessarily reflected by the residual displacements at the end of it. For planar excitations, significant out‐of‐plane displacements can happen, triggered by the inevitable imperfections of the specimen. It was also verified that the response is very sensitive, even to small changes of the geometry or the input motion parameters. For this reason, the experiments were not repeatable and ‘identical’ experiments produced different results. Copyright © 2002 John Wiley & Sons, Ltd.

Cities and energy: The sustainability (r)evolution

The author graduated as an engineer from the National Technical University of Athens, and completed her DEA at the National Geographical Institute in Paris. She continued with a DEA at the French Institute of City Planning where she also obtained her Ph.D. Her post-doctorate studies include research on Regional Policy at Oxford Brookes University and Environmental Economics at Harvard University. She started her career as Special Adviser to the Greek Ministry of Transport and Communications, and the European Union. She has been an official of the European Union and Research Manager at the European Foundation for the Improvement of Living and Working Conditions. She has co-written 25 EU publications, and has published nearly 100 articles on sustainable development, urban dynamics, regional capital, city and spatial policy and cultural value-added. She worked as a consultant on issues of sustainable development at the Directorate for Science, Technology and Industry of the Organisation for Economic Co-operation and Development (OECD). She is now Scientific Officer at the Directorate General for Research, European Commission, Brussels, where her main duties are on energy research. The text that follows is a slightly edited and revised version of a paper presented at the World Society for Ekistics Symposion"Defining Success of the City in the 21st Century," Berlin, 24-28 October, 2001.

Cities and energy: The sustainability (r)evolution

The author graduated as an engineer from the National Technical University of Athens, and completed her DEA at the National Geographical Institute in Paris. She continued with a DEA at the French Institute of City Planning where she also obtained her Ph.D. Her post-doctorate studies include research on Regional Policy at Oxford Brookes University and Environmental Economics at Harvard University. She started her career as Special Adviser to the Greek Ministry of Transport and Communications, and the European Union. She has been an official of the European Union and Research Manager at the European Foundation for the Improvement of Living and Working Conditions. She has co-written 25 EU publications, and has published nearly 100 articles on sustainable development, urban dynamics, regional capital, city and spatial policy and cultural value-added. She worked as a consultant on issues of sustainable development at the Directorate for Science, Technology and Industry of the Organisation for Economic Co-operation and Development (OECD). She is now Scientific Officer at the Directorate General for Research, European Commission, Brussels, where her main duties are on energy research. The text that follows is a slightly edited and revised version of a paper presented at the World Society for Ekistics SymposionDefining Success of the City in the 21st Century, Berlin, 24-28 October, 2001.

Non-Destructive Techniques for the Characterization of Structural Materials: Materials Science & Engineering Curriculum for the Education of an Innovative Model

ABSTRACTIn this paper, the example of the Materials Science and Engineering (MSE) Curriculum that exists as a scientific direction in the undergraduate programme of the Chemical Engineering School, in the National Technical University of Athens (NTUA), in Greece, is presented. The course content includes several tools, such as theoretical lessons, laboratory modules - nondestructive testing (NDT) and instrumental techniques - semi industrial scale devices, fieldworks and a dissertation thesis. The presented curriculum can be regarded as an innovative educational model for chemical engineering students that choose to become involved in the field of MSE.