Inversion of Gamow's Formula and Inverse Scattering

We present a pedagogical description of the inversion of Gamow's tunnelling formula and we compare it with the corresponding classical problem. We also discuss the issue of uniqueness in the solution and the result is compared with that obtained by the method of Gel'fand and Levitan. We hope that the article will be a valuable source to students who have studied classical mechanics and have some familiarity with quantum mechanics.Comment: LaTeX, 6 figurs in eps format. New abstract; notation in last equation has been correcte

Regaining altitude: a case analysis of the JetBlue Airways Valentine's Day 2007 crisis

Valentine's Day 2007 changed the course of history for JetBlue Airways. The upstart low-fare airline - which had enjoyed unprecedented acclaim from customers and industry observers since its launch in 2000 - suddenly found itself in the midst of a major operational catastrophe. A winter storm that enveloped the New York metropolitan region and JetBlue's hub at John F. Kennedy International Airport left hundreds of the company's passengers stranded aboard planes on the tarmac, some for as many as ten hours. Hundreds more waited in vain in the terminal for flights that the airline would eventually cancel. The flight disruptions at JFK plunged JetBlue's entire operation into chaos, forcing the carrier to cancel more than one thousand flights over a six day period. This thesis project describes the corporate crisis communication measures implemented by JetBlue Airways to repair its reputation

A statistical model for the prediction of wind-speed probabilities in the atmospheric surface layer

Wind fields in the atmospheric surface layer (ASL) are highly three-dimensional and characterized by strong spatial and temporal variability. For various applications such as wind comfort assessments and structural design, an understanding of potentially hazardous wind extremes is important. Statistical models are designed to facilitate conclusions about the occurrence probability of wind speeds based on the knowledge of low-order flow statistics. Being particularly interested in the upper tail regions we show that the statistical behavior of near-surface wind speeds is adequately represented by the Beta distribution. By using the properties of the Beta probability density function in combination with a model for estimating extreme values based on readily available turbulence statistics, it is demonstrated that this novel modelling approach reliably predicts the upper margins of encountered wind speeds. The model’s basic parameter is derived from three substantially different calibrating datasets of flow in the ASL originating from boundary-layer wind-tunnel measurements and direct numerical simulation. Evaluating the model based on independent field observations of near-surface wind speeds showed a high level of agreement between the statistically modelled horizontal wind speeds and measurements. The results show that, based on the knowledge of only a few simple flow statistics (mean wind speed, wind speed fluctuations and integral time scales), the occurrence probability of velocity magnitudes at arbitrary flow locations in the ASL can be estimated with a high degree of confidence

The "new diverted bed" of the Sperchios river and the new National Road Athina-Lamia in the area of the "Alamana Bridge" and the impact to the environment to the coastal area of the Maliakos Gulf and the Delta (Fthiotida-Greece)

The purpose of this work is to depict and evaluate the alterations in the geomorphological characteristics and the hydro-geomorphological processes as well as the effects to the environment of the coastal area of the Maliakos gulf and the delta of the Sperchios river, as a result of the construction of the "new bed" of the new diverted bed of Sperchios river, the "New Alamana Bridge" and the construction of the long embankments which are constructed in order to facilitate the road works for the New National Road Athina-Lamia in the section Thermopylae - Lamia (Fthiotida-Greece)

MODELLING THE CONCENTRATION FLUCTUATION AND INDIVIDUAL EXPOSURE IN COMPLEX URBAN ENVIRONMENTS

The concentrations fluctuations of a dispersing hazardous gaseous pollutant in the atmospheric boundary layer, and the hazard associated with short-term concentration levels, demonstrate the necessity of estimating the magnitude of these fluctuations using predicting models. Moreover the computation of concentration fluctuations and individual exposure in case of dispersion in realistic situations, such as built-up areas or street canyons, is of special practical interest for hazard assessment purposes. In order to predict or/and estimate the maximum expected dosage and the exposure time within which the dosage exceeds certain health limits, the knowledge of the behaviour of concentration fluctuations at the point under consideration is needed. In this study the whole effort is based on the ‘Mock Urban Setting Test – MUST’, an extensive field test carried out on a test site of the US Army in the Great Basin Desert in 2001 (Biltoft, 2001; Yee, 2004). The experimental data that was used for the model evaluation concerned the dispersion of a passive gas between street canyons which have been created by 120 standard size shipping containers. The computational simulations have been performed using the laboratory CFD code ADREA, which has been developed for simulating the dispersion and exposure of pollutants over complex geometries. The ADREA model is evaluated by comparing the model’s predictions with the observations utilizing statistical metrics and scatter plots. The present study has been performed in the frame of the Action COST 732 “Quality Assurance and Improvement of Micro-Scale Meteorological Models”

On the Integrability of the Bukhvostov-Lipatov Model

The integrability of the Bukhvostov-Lipatov four-fermion model is investigated. It is shown that the classical model possesses a current of Lorentz spin 3, conserved both in the bulk and on the half-line for specific types of boundary actions. It is then established that the conservation law is spoiled at the quantum level -- a fact that might indicate that the quantum Bukhvostov-Lipatov model is not integrable, contrary to what was previously believed.Comment: 11 pages, 1 figure, LaTeX2e, AMS; new references adde

Marine geology data accessibility in the European Framework: The I.G.M.E. participation in the GEO-SEAS project.

Το Ινστιτούτο Γεωλογικών και Μεταλλευτικών Ερευνών, κατά τη διάρκεια περισσοτέρων από 30 χρόνων συμμετοχής σε διάφορα έργα και ερευνητικά προγράμματα, έχει σημαντική δράση στον τομέα της Υποθαλάσσιας Γεωλογίας, με αποτέλεσμα τη συλλογή ενός τεράστιου αριθμού δεδομένων. Για να καταστούν τα δεδομένα αυτά διαθέσιμα στην διεθνή επιστημονική κοινότητα ήταν επιτακτική η ανάγκη τυποποίησης και εναρμόνισής τους. Για το σκοπό αυτό το ΙΓΜΕ, μαζί με 25 ακόμη κέντρα, από 17 χώρες, που διαθέτουν γεωλογικά και γεωφυσικά δεδομένα από τον θαλάσσιο χώρο, συμμετείχε στο έργο GEO  -SEAS    που αφορούσε στη δημιουργία μιας ηλεκτρονικής υποδομής. Οι δράσεις του έργου στόχευαν στο να έχουν οι τελικοί χρήστες τη δυνατότητα αναζήτησης και πρόσβασης σε πανευρωπαϊκά, εναρμονισμένα και σύμφωνα με τα διεθνή πρότυπα δεδομένα υποθαλάσσιας γεωλογίας, μέσω μίας ενιαίας διαδικτυακής πύλης. Όλα τα διαθέσιμα δεδομένα του ΙΓΜΕ εναρμονίστηκαν με βάση τους κανόνες και τα πρότυπα που ορίστηκαν στα πλαίσια του έργου GEO  -SEAS. Παράχθηκαν λεπτομερή  αρχεία μεταδεδομένων που συνοδεύονται από τα αντίστοιχα αρχεία δεδομένων. Η τυποποίηση, εναρμόνιση και διάθεση των δεδομένων, όπως καθορίστηκε μέσα από το έργο    GEO  -SEAS   , είναι σε πλήρη συμφωνία με τις Οδηγίες της Ευρωπαϊκής Ένωσης καθώς και τα πρότυπα που χρησιμοποιούνται σε άλλα προγράμματα διάθεσης δεδομένων σε Ευρωπαϊκές και διεθνής κλίμακες.During more than 30 years of activity and participation in numerous research projects, the Institute of Geology and Mineral Exploration of Greece has carried out extensive work in marine geology and a vast amount of data has been collected. In order for those data to be available and used by the international scientific community, a need for standardization and harmonization was imminent. Towards this scope IGME, along with 25 other marine geological and geophysical data centres, located in 17 European maritime countries, participated in the GEO-SEAS project: the implementation of an e-infrastructure. The aim of the project was to enable users to identify, locate and access pan-European, harmonised and federated marine geological and geophysical datasets and derived data products held by the data centres through a single common data portal. All available data have been harmonized according to the GEO-SEAS guidelines and standards. Detailed metadata files were created, accompanied by the corresponding data and additional information files. The standardization, harmonization and provision of data and metadata, carried out through the GEO-SEAS project, are aligned with European directives and recent large-scale framework programs on global and European scales.