Deciphering the effects of agglomeration economies on firms’ productive efficiency

The present work assess the effects of MAR and Jacob’s type agglomeration economies on a sample of firms in the machineries and textiles industries in Greece for the periods 1989-91 and 1999-01. The analysis employs a stochastic production frontier function and allows agglomeration economies to enter as inputs and/or as factors reducing inefficiency. Results re-confirm that the effects of agglomeration economies are industry specific. In our study, the machineries industry benefits from MAR type agglomeration economies and the textiles industry benefits from Jacob’s type agglomeration economies. Agglomeration economies may exercise a twin effect on firms’ productive efficiency. First, as in the case of the machineries industry in our study, MAR agglomeration economies may act as a new input and affect the kernel of the production frontier. Second, agglomeration economies may act as a factor reducing technical inefficiency with non-neutral effects with labour and capital as in the case of both the machineries and the textiles industries in our study. Finally, it is indicated that agglomeration economies establish a type of “path dependence†for firms. Firms that make significant use of agglomeration economies survive to the next period at higher percentages in comparison to other firms in the same industry. At the same time, entrants are favoured by MAR type agglomeration economies while incumbents are favoured by Jacob’s type agglomeration economies.

The experimentation-accountability trade-off in innovation and industrial policy: are learning networks the solution?

The exact nature of industrial/innovation (I/I) policy challenges and the best way to address them are unknown ex ante. This requires a degree of experimentation, which can be problematic in the context of an accountable public administration and leaves the question of how to reconcile the experimental nature of I/I policy with the need for public accountability, a crucial but unresolved issue. The trade-off between experimentation and accountability requires a governance model that will allow continuous feedback loops among the various stakeholders and ongoing evaluation of and adjustments to activities as programmes are implemented. We propose an ‘action learning’ approach, incorporating the governance mechanism of ‘learning networks’ to handle the problems of implementing experimental governance of new and untried I/I policies. We resolve the issue of accountability by drawing on the literature on network governance in public policy. By integrating control and learning dimensions of accountability, this approach enables us to resolve conceptually and empirically trade-offs between the need for experimentation and accountability in I/I policy

Δείκτες Ενεργειακής Απόδοσης Πλοίου στο Πλαίσιο του ΙΜΟ

140 σ.Στο πλαίσιο της παρούσας διπλωματικής εργασίας, μελετώνται οι Δείκτες Ενεργειακής Απόδοσης, που έχουν προταθεί από τον IMO (International Maritime Organization) και αφορούν στην Σχεδίαση και Λειτουργία των Πλοίων, εστιάζοντας στην απεικόνιση της ενεργειακής απόδοσης των ηλεκτρικών συστημάτων ενέργειας και στα ζητήματα που προκύπτουν γενικότερα κατά την εφαρμογή των δεικτών αυτών. Συγκεκριμένα για τον Δείκτη Ενεργειακής Απόδοσης που αφορά στην Σχεδίαση Νέων Πλοίων (EEDI), τα ζητήματα αφορούν: α) την περιορισμένη δυνατότητα του να εκφράσει την ενεργειακή απόδοση του πλοίου για περισσότερες από μία καταστάσεις λειτουργίας, β) την έλλειψη εξαγωγής συγκρίσιμων αποτελεσμάτων κατά την εφαρμογή του σε ορισμένες κατηγορίες πλοίων (Επιβατηγά), γ) την ακαταλληλότητα του για πλοία με μη συμβατικά συστήματα πρόωσης (Δηζελοηλεκτρική Πρόωση) και δ) την εξαγωγή πλασματικών αποτελεσμάτων που στην πράξη οδηγούν στην σχεδίαση λιγότερο ενεργειακά αποδοτικών νέων πλοίων. Επιπροσθέτως, ε) η έλλειψη σαφούς ορισμού του Δείκτη Ενεργειακής Απόδοσης για την Λειτουργία των Πλοίων (EEOI) και στ) η απουσία ενός Δείκτη που να απεικονίζει με μεγαλύτερη ακρίβεια τα ενεργειακά οφέλη από την εγκατάσταση νέων τεχνολογιών, ειδικότερα για την παραγωγή ηλεκτρικής ενέργειας, καθώς και από την εφαρμογή βέλτιστων σεναρίων λειτουργίας, είναι μερικά μόνο από τα ζητήματα που επιζητούν λύση. Για τον λόγο αυτό, προτείνεται η εφαρμογή ενός εναλλακτικού δείκτη VENEFI (Vessel Energy Efficiency Index) για την συνολική λειτουργία του πλοίου που προκύπτει από την σύνθεση επιμέρους δεικτών που περιγράφουν την ενεργειακή απόδοση σε κάθε κατάσταση λειτουργίας. Οι επιμέρους δείκτες δύναται να περιγράψουν με μεγαλύτερη ακρίβεια την ενεργειακή απόδοση του πλοίου σε κάθε κατάσταση ξεχωριστά, τόσο κατά την λειτουργία του όσο και κατά την σχεδίαση ενός νέου πλοίου. Επιπλέον, προτείνονται επιμέρους δείκτες που αξιολογούν την ενεργειακή απόδοση του συστήματος πρόωσης και του ηλεκτρικού συστήματος παραγωγής. Όλοι οι δείκτες συνδέονται μεταξύ τους μέσω κατάλληλων σχέσεων ενώ είναι συγκρίσιμοι υπό προϋποθέσεις και με τους υφιστάμενους δείκτες EEDI & EEOI. Για την περεταίρω διερεύνηση, αναπτύχθηκε ένα φύλλο υπολογισμού των δεικτών και χρησιμοποιήθηκαν στοιχεία από υφιστάμενα πλοία για την πραγματοποίηση υπολογισμών και την εξαγωγή αποτελεσμάτων. Στο Κεφάλαιο 4 παρουσιάζεται αναλυτικά ο υπολογισμός του δείκτη VENEFI για το πλοίο “BS1” ενώ στο Παράρτημα 3 παρουσιάζονται επιπλέον υπολογισμοί καθώς και η διερεύνηση βέλτιστου σεναρίου συνολικής λειτουργίας με χρήση ή μη αξονικής γεννήτριας. Τα αποτελέσματα που προέκυψαν έδειξαν ότι μέσω του δείκτη VENEFI είναι εφικτή η διερεύνηση βέλτιστων σεναρίων λειτουργίας αλλά και η διερεύνηση του μέτρου της ενεργειακής απόδοσης με την εφαρμογή μιας νέας τεχνολογίας, ειδικότερα όσον αφορά την ηλεκτρική ενέργεια, ενώ παράλληλα επιλύθηκαν και τα υπόλοιπα προαναφερθέντα ζητήματα εφαρμογής των Δεικτών.This dissertation analyzes the proposed by the IMO (International Maritime Organization) Energy Efficiency Indices for the Design and Operation of Ships (EEDI & EEOI respectively), focusing on energy efficiency of electric power systems and the arising implementation issues of these indices. More specifically, the issues considering the Energy Efficiency Design Index (EEDI) are: a) its limited ability to express the energy efficiency of the ship for more than one operating condition, b) the failure to produce comparable results when applied to certain ship categories (Passenger Vessels), c) it is not applicable to ships with non-conventional propulsion systems (Diesel-Electric Propulsion) and d) it produces misleading results driving practically to the design of less energy efficient ships. Additionally: e) the definition of Energy Efficiency Operation Index (EEOI) which is not precise and f) the absence of an index that reflects more accurately the benefits of: i) installing new energy efficient technologies onboard vessels, particularly for electrical power generation and ii) the implementation of optimal operating scenarios; are some of the issues seeking a solution. Therefore, it is proposed an alternative index VENEFI (Vessel Energy Efficiency Index) for the complete operation of the vessel, as a resultant of individual indices that describe the energy efficiency in each operation mode of the vessel. Individual indices may describe more accurately the energy efficiency of the ship in every activity mode during operation and at design stage for new vessels. In addition, there are proposed specific indices of energy efficiency for the propulsion and the auxiliary power system, individually. All indices are linked through appropriate formulas, while under conditions are comparable with existing indices EEDI & EEOI. For further investigation on VENEFI, there was developed a spreadsheet for calculating the proposed indices using data from existing ships, performing the calculations and exporting the results. Chapter 4 presents in detail the sample calculation of VENEFI on the ship "BS1", while in Annex 3 are presented additional calculations and an investigation on the effect of the use of shaft generator on VENEFI. The results showed that through the index VENEFI is possible to investigate optimal operating scenarios and account the benefits of energy efficiency by implementing new technologies, particularly for electric power systems, while the rest of the issues considering indices implementation were resolved.Νικόλαος Κ. Τσεκούρα

Parallel Coupling of Symmetric and Asymmetric Exclusion Processes

A system consisting of two parallel coupled channels where particles in one of them follow the rules of totally asymmetric exclusion processes (TASEP) and in another one move as in symmetric simple exclusion processes (SSEP) is investigated theoretically. Particles interact with each other via hard-core exclusion potential, and in the asymmetric channel they can only hop in one direction, while on the symmetric lattice particles jump in both directions with equal probabilities. Inter-channel transitions are also allowed at every site of both lattices. Stationary state properties of the system are solved exactly in the limit of strong couplings between the channels. It is shown that strong symmetric couplings between totally asymmetric and symmetric channels lead to an effective partially asymmetric simple exclusion process (PASEP) and properties of both channels become almost identical. However, strong asymmetric couplings between symmetric and asymmetric channels yield an effective TASEP with nonzero particle flux in the asymmetric channel and zero flux on the symmetric lattice. For intermediate strength of couplings between the lattices a vertical cluster mean-field method is developed. This approximate approach treats exactly particle dynamics during the vertical transitions between the channels and it neglects the correlations along the channels. Our calculations show that in all cases there are three stationary phases defined by particle dynamics at entrances, at exits or in the bulk of the system, while phase boundaries depend on the strength and symmetry of couplings between the channels. Extensive Monte Carlo computer simulations strongly support our theoretical predictions.Comment: 16 page

R&D collaborations: Is diversity enhancing innovation performance?

We develop a theoretical framework which builds on the existence of a feedback loop relationship between internal innovation efforts and the diversity of types of R&D collaborations. Such a feedback loop allows for decomposing the total effects of both internal and external knowledge sources on innovation performance in direct and indirect effects. We argue that such feedback loop lies in the heart of the interplay between the benefits and costs associated with generating knowledge internally and accessing knowledge from diverse external knowledge sources. In particular we argue that anticipated benefits from accessing knowledge from diverse external knowledge sources may be outweighed by (i) costs associated with accessing increasingly diverse knowledge through collaboration and (ii) a negative network effect on firms' internal innovation efforts. We employ Structural Equation Modelling on a bespoke dataset of Greek R&D active manufacturing firms; empirical results confirm the existence of an idiosyncratic feedback loop relationship and show that internal innovation efforts positively influence firm innovation performance. On the other hand, diversity in external collaborations has a negative impact on internal innovation efforts, elevating the importance of the optimal balance between internal R&D investments and the diversity of R&D collaborations. The same picture emerges when examining the corresponding direct and indirect effects of internal and external knowledge sources on innovation performance