Showing papers by "University of Piraeus published in 2003"

The Dynamic Berth Allocation Problem for a Container Port

Abstract: This paper addresses the problem of determining a dynamic berth assignment to ships in the public berth system. While the public berth system may not be suitable for most container ports in major countries, it is desired for higher cost-effectiveness in Japan's ports. The berth allocation to calling ships is a key factor for efficient public berthing. However, it is not calculated in polynomially-bounded time. To obtain a good solution with considerably small computational effort, we developed a heuristic procedure based on the Lagrangian relaxation of the original problem. We conducted a large amount of computational experiments which showed that the proposed algorithm is adaptable to real world applications.

Berth allocation with service priority

Abstract: Over the past several years, port related charges in Japanese ports have been substantially higher than those charged in other major international hub ports. All major container ports in Japan feature so-called Dedicated Terminals in which cost-effectiveness is justified by huge container volume to be handled. One of the reasons cited for high port charges is a relative decrease in handling volume compared to the terminal capacity, resulting in inefficient use of the existing capacity. The use of the Multi-User Container Terminal (MUT) concept employed in some of the major container hub ports such as Hong Kong, Pusan, Hamburg and Rotterdam reduces redundant terminal space and results in substantial cost savings in cargo handling costs and therefore is desired for ports in Japan as well. One of the key issues in the MUT operation is the berth allocation to calling vessels. In a recent study, an allocation problem for the MUT was examined, in which each vessel was treated equally. However, as some vessel operators desire high priority services, the goal of this paper is to modify the existing formulation of the berth allocation problem in order to treat calling vessels at various service priorities by developing a genetic algorithm based heuristic for the resulting non-linear problem.

Macroeconomic determinants of outward foreign direct investment

Abstract: The aim of this paper is to test the hypothesis that the outward foreign direct investment (FDI) position of countries may be considered as a function of country specific characteristics, such as income, exchange rate, technology, human capital and openness of the economy. The model developed identifies the main determinants of outward FDI using time series data for five European Union members and four non‐European Union countries. The model indicates that real gross national product is proved the most important determinant of outward FDI. Developed European countries specialise in human capital intensive FDI, while non‐European Union countries in technology intensive. Overall, the results verify that the outward FDI position of countries is influenced by national characteristics and that the same type of endowments have different significance for different countries.

The Greek Implied Volatility Index: Construction and Properties

Abstract: There is a growing literature on implied volatility indices in developed markets. However, no research has been conducted in the context of emerging markets. In this paper, an implied volatility index (GVIX) is constructed for the fast developing Greek derivatives market. Next, the properties of GVIX are explored. In line with earlier results, GVIX can be interpreted as a gauge of the investor's sentiment. In addition, we find that the underlying market can forecast the future movements of GVIX. However, the reverse relationship does not hold. Finally, a contemporaneous spillover between GVIX, and the US volatility indices VXO and VXN is detected.

Empirical Modelling of Money Demand in Periods of Structural Change: The Case of Greece

Abstract: This paper examines the behaviour of the demand for money in Greece during 1976Q1 to 2000Q4, a period that witnessed many of the influences that cause money‐demand instability. Two empirical methodologies, vector error correction (VEC) modelling and second‐generation random coefficient (RC) modelling, are used to estimate the demand for money. The coefficients of both the VEC and RC procedures support the hypothesis that the demand for money becomes more responsive to both the own rate of return on money balances and the opportunity cost of holding money because of financial deregulation. In general, both procedures also support the hypothesis that the income elasticity of money demand declines over time as a result of technological improvements in the payments system and the development of money substitutes, which lead to economies of scale in holding money.

Towards Secure and Practical E-Elections in the New Era

Abstract: We overview the main e-voting schemes currently proposed in the literature and assess their security and practicality. We also analyze the security risks and discuss methods to minimize them.

Applying life cycle inventory to reverse supply chains: a case study of lead recovery from batteries

Abstract: The increasing demand for efficient management of used products after the end of their life cycle stems from the increasing awareness of modern society about possible threats against the environment. Used starter or lead–acid batteries contain lead up to 65%, which is also valuable after the end of their life cycle. Recycling of lead gives rise to some environmental problems associated with its collection, processing and recycling and, finally, entering the main (forward) supply chain. In this paper, the lead recovery from old batteries is examined using life cycle inventory analysis (LCIA). The reverse supply chain of used starter or lead–acid batteries is outlined and analyzed. A model for this product system is formulated, which is used to identify the lead emissions as well as all the environmental exchanges through materials balance. The proposed model formulation, which is appropriately adapted to the needs of the reverse supply chain, is used as a tool in a LCIA in order to identify those stages in the battery life cycle that give rise to the greatest environmental burdens. A similar analysis is also made for the case of disposal. The model may be used in order to assess all the associated impacts in an in-depth life cycle analysis (LCA). A preliminary comparison between the two end-of-life scenarios in terms of their environmental inputs and outputs is also attempted. Thus, based on several assumptions, an inventory analysis referring to the above chains has been conducted whose results have been summarized in an Inventory table, which produces comprehensive information about each life stage of the examined end-of-life scenarios.

Beyond stakeholder satisfaction: Aiming for a new frontier of sustainable stakeholder trust

Abstract: We live in a period in which management's efforts to satisfy an organization's stakeholders, i.e. customers, employees, shareholders, etc may not be enough for survival or to achieve high performance in the long run. Despite worldwide recognition for excellence, as defined by the markets and/or models for assessing business excellence, several organizations today suffer from the lack of trust and what future revelations will bring. There have been simply too many instances of well-known companies, even as widely rewarded and innovative as Xerox, that could not enjoy the unquestionable support of their stakeholders, because something critical was missing, and that was their previously taken for granted trust. In this paper we examine ways that an organization can achieve the level of trust needed for sustainable excellence. The proposed approach involves the simultaneous improvement of exploring the space of navigating the future and setting a vision and supporting strategic goals, the building of sound re...

Ten Benchmark Database Queries for Location-based Services

Abstract: Location-based services (l-services for short) comprise an emerging application involving spatiotemporal databases. In this paper, we discuss this type of application in terms of database requirements and provide a set of ten benchmark database queries (plus two operations for loading and updating data). The list includes selection queries on stationary and moving reference objects, join queries and unary operations on trajectories of moving objects. We also survey recent work in query processing for those query types, with an emphasis on indexing moving objects, and suggest candidates for efficiently supporting databases for l-services.

Analysis and design of a web-based authoring tool generating intelligent tutoring systems

Abstract: Authoring tools for intelligent tutoring systems (ITSs) are meant to provide environments where instructors may author their own ITSs in varying domains. In this way, painful constructions of ITSs, which are not reusable, may be avoided. However, the construction of an authoring tool is associated with many problems, such as the generality of the techniques incorporated, domain-independence, effectiveness for the prospective authors (instructors), and effectiveness for the students who will use the resulting ITSs. In this paper we will report on an empirical study that we conducted in order to design and develop WEAR, an ITS authoring tool for Algebra-related domains. In the study we investigated several aspects concerning the attitude and behaviour of both students and instructors. The study revealed important issues and was then used for the specification of the design of WEAR. A brief description of the developed system is also included in the paper so that the way that the design specifications were put into practice may be shown. However, a lot of the authoring tool's requirements that came to light could be applicable to other authoring tools as well. The most important requirement of this kind was the need for an instructor modelling component so that adaptivity could be provided to human instructors (authors). The provision of such facility is a novelty in the area of ITS authoring tools.

Specifying Workflow Process Requirements for an Emergency Medical Service

Abstract: Recent trends in healthcare delivery have led to a gradual shift in the conceptualisation of healthcare information systems towards supporting healthcare processes in a more direct way. The move towards integrated and managed care, which requires designing healthcare processes around patient needs and incorporating efficiency considerations, has led to an increased interest in process-oriented healthcare information systems based on workflow technology. This means to actively deliver the tasks to be performed to the right persons at the right time with the necessary information and the application functions needed. Moreover, workflow technology promotes a component-oriented development whereby the process logic is separated from application logic. This paper presents an approach to capturing process logic requirements for healthcare workflow systems with a view to design a system that is easily adjustable to process changes and to evolving organizational structures at a reasonable cost.

Application and analysis of rt-level software-based self-testing for embedded processor cores

Abstract: Embedded processor testing techniques based on the execution of self-test routines, have been recently proposed as an effective alternative to classical hardware Built-In Self Test. Software-based self-testing provides atspeed testing capability and does not add hardware or performance penalties. It efficiently partitions the testing task between external testers and internal processor resources. In this paper we analyze the application of a softwarebased self-testing methodology to different implementations of a complex embedded processor architecture. We demonstrate that such a methodology provides high test quality in different processor implementations with low test development and low test application costs.

Easily Testable Cellular Carry Lookahead Adders

Abstract: Cellular Carry Lookahead (CLA) adders are systematically implemented in arithmetic units due to their regular, well-balanced structure. In terms of testability and with respect to the classical Cell Fault Model (CFM), cellular CLA adders have poor testability by construction. Design-for-testability (DFT) modifications for cellular CLA adders have been proposed in the literature providing complete CFM testability making the adders either level-testable or C-testable. These designs impose significant area and performance overheads. In this paper, we propose DFT modifications for cellular CLA adders to achieve complete CFM testability with special emphasis on the minimum impact in terms of area and performance. Complete CFM testability is achieved without adding any extra inputs to the adder, with very small area and performance overheads, thus providing a practical solution. The proposed DFT scheme requires only 1 extra output and it is not necessary to put the circuit in a special test mode, while the earlier schemes require the addition of 2 extra inputs to set the circuit in test mode. A rigorous proof of the linear-testability of the adder is given and a sufficient linear-sized test set is provided that guarantees 100% CFM fault coverage. Surprisingly, the size of the proposed linear-sized test set is, in most practical cases, comparable or even smaller than a logarithmic-sized test set proposed in the literature.

The pursuit of sustainable business excellence: Guiding transformation for effective organizational change

Abstract: Like normal people living a typical life, human organizations generally operate in such a way that they alternate between periods of stability and periods of significant change in their environment. In periods of a dramatic change, brought about by advances in technology, the deregulation of their industry, or large social and economic restructuring, the objective of survival in the presence of a threatening challenge takes precedence over the improvement of performance based on best practices or other methods applicable in periods of stability. The first step in addressing such a challenge is to become aware of what is known as a strategic inflection point. This signals a big change in the environmental conditions and the emergence of new rules and priorities for becoming and staying successful. It marks the end of a previously successful mindset and of strategies that are no longer effective. The next step requires close attention to a set of key attributes that are essential to develop organizational r...

Emergency healthcare process automation using workflow technology and web services.

Abstract: Emergency healthcare delivery involves a variety of interrelated activities performed from the time of a call to the ambulance service until the time of patient's exit from the emergency department of a hospital. As these activities can be viewed as parts of inter-organizational healthcare processes that involve at least two organizations (e.g. an ambulance service and a hospital), there is a need to provide the appropriate technological infrastructure for automating and managing these processes even in cases where the organizations involved use heterogeneous systems to support their internal services. Web-based workflow systems in conjunction with web services present a new way for service-oriented integration (SOI) of disparate systems and for developing distributed applications within and between organizations. Thus, process automation with the use of web services can provide an appropriate infrastructure for the integration of pre-hospital and in-hospital emergency healthcare. A prototype development of such a system is presented in this paper.

On the distribution of the total number of run lengths

Abstract: In the present paper, we study the distribution of a statistic utilizing the runs length of “reasonably long” series of alike elements (success runs) in a sequence of binary trials. More specifically, we are looking at the sum of exact lengths of subsequences (strings) consisting ofk or more consecutive successes (k is a given positive integer). The investigation of the statistic of interest is accomplished by exploiting an appropriate generalization of the Markov chain embedding technique introduced by Fu and Koutras (1994,J. Amer. Statist. Assoc.,89, 1050–1058) and Koutras and Alexandrou (1995,Ann. Inst. Statist. Math.,47, 743–766). In addition, we explore the conditional distribution of the same statistic, given the number of successes and establish statistical tests for the detection of the null hypothesis of randomness versus the alternative hypothesis of systematic clustering of successes in a sequence of binary outcomes.

Low-Cost Software-Based Self-Testing of RISC Processor Cores

Abstract: Software self-testing of embedded processor cores which effectively partitions the testing effort between low-speed external equipment and internal processor resources, has been recently proposed as an alternative to classical hardware built-in self-lest techniques over which it provides significant advantages. In this paper we present a low-cost software-based self-testing methodology for processor cores with the aim of producing compact test code sequences developed with a limited engineering effort and achieving a high fault coverage for the processor core. The objective of small test code sequences is directly related to the utilization of low-speed external testers since test time is primarily determined by the time required to download the lest code to the processor memory at the tester's low frequency. Successful application of the methodology to a RISC processor core architecture with a 3-stage pipeline is demonstrated.

Modelling the student to individualise tutoring in a web-based ICALL

Abstract: In this paper we describe the techniques used for student modelling in an adaptive web-based intelligent computer assisted language learning (ICALL) system. The system teaches the domain of the passive voice of the English language and is called Web Passive Voice Tutor (Web-PVT). It dynamically models a student's progress in learning and is able to provide individualised tutoring and advice, tailored to a student's knowledge level and individual weaknesses. The initialisation of the student model is based on a multidimensional stereotype approach. However, after the individual student has interacted with the system sufficiently, the initial values provided by the stereotype are overwritten to reflect the individual student. This allows the system to adapt to each particular student.

The Impact of Globalization on the Equity Cost of Capital

Abstract: The advent of the single currency within the European Union provides a natural experiment to measure how the cost of equity changes as globalization takes place. This is because the launch of the single currency has led to the elimination of currency-related restrictions on the composition of institutional investors' portfolios and, hence, to increased risk sharing among EU investors. We focus not only on the impact of globalization on the level of the cost of equity, but also on the cross-country and cross-sectoral dispersion in the cost of capital. Over the 1990s it is shown that the cost of equity within EU sectors falls by between 0.5 and 3 percentage points. There is strong evidence of convergence in the cost of equity across different countries in the same sector. Convergence across different sectors is small. An implication for portfolio management is that country effects are becoming smaller and sector effects larger.

IGARCH models and structural breaks

Abstract: Using Monte Carlo simulations, it is shown that fitting a mis-specified GARCH model to a true MS-GARCH process tends to produce IGARCH parameter estimates. In other words, the presence of structural breaks can result in spuriously high estimates of the degree of persistence of shocks to the conditional variance.

Port Reorganisations and the Worlds of Production Theory

Abstract: Taking into account the new dimensions of port production that have become evident during the recent past, this paper tackles the issue of port reorganisation. In the light of the changes in the world economy and the new competitive environment, the paper focuses on the new structures of the port industry and the characteristics of the contemporary port product within a more general analytical framework of ‘Worlds of Production’. This conceptualisation suggests that neither the industrial model of mass production, nor any other model alone, can determine a single effective pattern of organisation of port production. Within the new reality, modern ports must provide a greater variety of services to port users than in the past. The diversity and complexity of the contemporary port product demand the application of multiple organisational transformations incorporating elements of different possible action frameworks. In this vein, the introduction of intra-port competition, the development of strategic or regional networks, and the reconsideration of the role of port authority turn to critical parameters of the essential restructuring.

A decision support system for the promotion of security in shipping

Abstract: Shows transportation appears to be a target and/or means of achieving the illegal pursuits of organised crime and terrorism. Among transportation modes, shipping presents the highest security risk since, on the one hand, it is the main facilitator of international trade (within this context it inevitably serves the illegal transportation of people, drugs and arms) and, on the other hand, a terrorism‐targeted ship, whether a passenger or cargo carrier, poses a major threat in terms of loss of human life and property, as well as the threat of damage to the environment. Despite efforts to address the issues of maritime security, the shipping industry still presents a sizeable deficit in implementing security measures. Furthermore, when global events, such as the Athens 2004 Summer Olympics, are organised in coastal locations where extensive shipping activity is concentrated, maritime security becomes a particularly critical issue. The development of a decision support system (DSS) for the promotion of security in shipping is proposed and presented. The DSS is basically a security management tool utilising the capabilities of information and communication technologies, in order to provide support towards the general implementation of the International Ship and Port Security (ISPS) Code, and the development as well as maintenance of the associated security plans.

Synthetic and Real Spatiotemporal Datasets.

Abstract: In the context of a spatiotemporal research environment, it is very important to be able to systematically generate data with predictable characteristics. For instance, it allows one to use the same datasets, or others similarly characterized, for benchmarking access structures or mining techniques. This paper presents a survey of existing generators of synthetic spatiotemporal data. It also covers a few real datasets, which are (at the time of this writing) publicly available for research use.