320 research outputs found
sj-docx-1-mdm-10.1177_0272989X231165985 – Supplemental material for Constructing Relative Effect Priors for Research Prioritization and Trial Design: A Meta-epidemiological Analysis
No full textSupplemental material, sj-docx-1-mdm-10.1177_0272989X231165985 for Constructing Relative Effect Priors for Research Prioritization and Trial Design: A Meta-epidemiological Analysis by David Glynn, Georgios Nikolaidis, Dina Jankovic and Nicky J. Welton in Medical Decision Making</p
Application of Fundamental Analysis and Computational Intelligence in Dry Cargo Freight Market
No full textData for the Heritage Journal Publication 1760103
No full textThe data found here are part of the publication HERITAGE 1760103
Phaedon Kyriakidis et al. (2022)
Virtual sea-driting experiments between the island of Cyprus and the surrounding mainland in the early prehistroric Eastern Mediterranean
Phaedon Kyriakidis, Theodora Moutsiou, Andreas Nikolaidis, Christian Reepmeyer, Georgios Leventis, Stella Demesticha, Evangelos Akylas, Vasiliki Kassianidou, Constantine Michailides, Zomenia Zomeni, Daniella E. Bar-Yosef Mayer, Yizhaq Makovsky, and Carole McCartney
Contents
Working (Start here)
--> Auxiliary data (coastlines, landmask, source regions, and archaeological sites), and Matlab code roms01_xxx.m through roms07_xxx.m where the numbering indicates the order of execution followed
2014_ROMS_DRIFT_OBJ42
2014_ROMS_DRIFT_OBJ42
--> csv files of leeway-simulated drifting trajectories, matlab versions of csv files and of data produced during the analysis of simulated trajectories, as well as associated figures
WAVES
--> Significant wave height data used to define successful trajectoriesThe data found here are part of the publication HERITAGE 1760103
Phaedon Kyriakidis et al. (2022)
Virtual sea-driting experiments between the island of Cyprus and the surrounding mainland in the early prehistroric Eastern Mediterranean
Phaedon Kyriakidis, Theodora Moutsiou, Andreas Nikolaidis, Christian Reepmeyer, Georgios Leventis, Stella Demesticha, Evangelos Akylas, Vasiliki Kassianidou, Constantine Michailides, Zomenia Zomeni, Daniella E. Bar-Yosef Mayer, Yizhaq Makovsky, and Carole McCartne
Hydrologic analysis of Keritis basin-Determination of hydraulic structure design flow
No full textΠερίληψη: Η διπλωματική αυτή εργασία πραγματεύεται την λεκάνη απορροής του Κερίτη-Θερίσου η οποία βρίσκεται στο νησί της Κρήτης και υπάγεται στο νομό Χανίων. Αποτελεί μια τυπική Μεσογειακή λεκάνη απορροής με σύνθετη υδρογεωλογία. Εκτείνεται σε επιφάνεια 210 km^2 και είναι μια από τις σπουδαιότερες υδρολογικές λεκάνες απορροής, καθώς φορτίζεται με μεγάλο όγκου νερού και τροφοδοτεί ένα μέρος του νομού Χανίων. Στο κυρίως μέρος της εργασίας, περιγράφονται οι βασικές αρχές των υδρολογικών μοντέλων και αναλύεται η δομή και ο τρόπος λειτουργίας του μοντέλου SWAT (Soil Water Assesment Tool) σε συνδυασμό με το καρστικό μοντέλο των δύο ταμιευτήρων (Nikolaidis et al.,2013). Τα προαναφερθείσα μοντέλα χρησιμοποιήθηκαν για την επικαιροποίηση των πηγών των Μεσκλών και της Αγυιάς (Καλαμιώνας, Πλάτανος, Κολύμπα), καθώς και για την επιμέρους μοντελοποίηση των πηγών αυτής (ειδικότερα του Καλαμιώνα και του Πλατάνου, Κολύμπας). Πιο συγκεκριμένα, για τα Μεσκλά υπάρχουν δεδομένα παροχής ύδατος για τα έτη 1978-2005, για το σύνολο των πηγών της Αγυιά υπάρχουν δεδομένα για τα έτη 1978-1985, για την πηγή του Καλαμιώνα υπάρχουν δεδομένα 1971-1979 ενώ για τον ποταμό Κερίτη υπάρχουν δεδομένα για τα έτη 2012-2014. Παράλληλα, δίνονται οι απαραίτητες πληροφορίες που αφορούν τα μετεωρολογικά, τα γεωλογικά και τα υδρογεωλογικά στοιχεία της περιοχής μελέτης. Στο στάδιο της μεθοδολογίας, αναφέρονται αναλυτικά τα βήματα που ήταν απαραίτητο να ακολουθηθούν για τη δόμηση του μοντέλου, για την προσομοίωση της παροχής ύδατος καθώς και για τον υπολογισμό των στατιστικών δεικτών αποτελεσματικότητας του μοντέλου. Οι δείκτες αυτοί τελικά, αποδεικνύουν ότι τα παραπάνω μοντέλα είναι αξιόπιστα για τη μοντελοποιήση της υδρολογίας της λεκάνης απορροής του Κερίτη. Τέλος, πραγματοποιείται η υδρολογική ανάλυση του έτους 2019 και με την βοήθεια στατιστικών μεθόδων Gumbel και Log Pearson υπολογίστηκε η παροχή ύδατος που αντιστοιχεί σε περίοδο επαναφοράς 50 ετών 291.9 m^3/s ενώ παράλληλα υπολογίστηκε και η μέγιστη ωριαία βροχόπτωση που αφορά το σχεδιασμό υδραυλικών έργων.Summarization: This dissertation is about Keritis-Therisos river basin which is located in the prefecture of Chania on the island of Crete. It is a typical Mediterranean river basin with complex hydrogeology. It has a surface area of 210 Km2 and it provides the drinking and irrigation water of the most populated area of the prefecture of Chania. The dissertation examines the basic principles of hydrological modeling as well as the structure of the SWAT model (Soil Water Assessment Tool) in combination with the karst model of two reservoir (Nikolaidis et.al. 2013). These models were used for the updating of the modeling of Meskla and Agyia (Kalamionas, Platanos, Kolympa) springs . Data are available for Meskla springs (1978-2005), Agyia (1978-1985) and for Kalamiona (1971-1979). In addition, there are data for 2012 and 2014 hydrologic years for Keritis river and 2019-2020 for Agia springs. These data were used for the fine tuning of the calibration of the model for the area. At the same time, the necessary information regarding the meteorological, geological and hydrological data of the study area also are available. Statistical indicators showed that the hydrologic modeling of Keritis river basin was acceptable. The hindcasting of the hydrological flows for the past 50 years allowed the use of statistical analysis (Gumbel and Log Pearson) for the determination of the 50 year return flood over a 24 hour period. Finally, the rainfall analysis of 2019 identified the relationship between peak hourly flow to flood average flow. This information was used to determine the design flood flow with 50 year return period and hourly duration for the design of hydraulic and flood retention structures ( 291.9 m3s )
Single inhaler with beclometasone, formoterol, and glycopyrronium versus triple therapies in adults with uncontrolled asthma: a systematic review and meta-analysis
No full textRecent literature has shown that triple therapy is more effective than dual therapy for individuals with uncontrolled asthma. However, the comparative efficacy between different triple therapies remains unclear. The objective of this study was to determine the comparative efficacy of extra-fine single-inhaler medium-dose (MD) or high-dose (HD) of beclometasone/formoterol/glycopyrronium bromide (BDP/FOR/GLY) compared to other triple therapies in patients whose asthma remains uncontrolled with MD or HD inhaled corticosteroids and long-acting β2-agonists. A systematic literature review identified randomized control trials on adult patients with uncontrolled asthma. Two separate networks were constructed according to patients’ previous inhaled-corticosteroid dosage. Network meta-analyses evaluated severe and moderate-to-severe exacerbations, pre-dose forced expiratory volume, and asthma control questionnaire responses at 52 (± 3) weeks. Among single-inhaler triple therapies, MD BDP/FOR/GLY significantly reduced the risk of severe exacerbations (RR [95% CrI] compared to MD fluticasone/umeclidinium/vilanterol: 0.65 [0.49, 0.89]), while HD BDP/FOR/GLY demonstrated an improved trend in reducing severe and moderate-to-severe exacerbations versus HD indacaterol acetate/glycopyrronium bromide/mometasone, fluticasone/umeclidinium/vilanterol, and salmeterol/fluticasone + tiotropium. HD BDP/FOR/GLY and HD BDP/FOR + tiotropium did not differ significantly. Compared to relevant single-inhaler triple therapies, MD and HD BDP/FOR/GLY are associated with a significant benefit or trend for improvement in terms of reducing the rate of severe and moderate-to-severe exacerbations
On a conjecture about generalized integration operators on Hardy spaces
No full textA conjecture posed by Chalmoukis in 2020 states that if is bounded, then must be in . In
this article, we provide a positive answer to the aforementioned conjecture. We
also consider the compactness of .Comment: This paper was finished and submitted to manuscripta mathematica on
April 24, 2024. In May 24, we found that Nikolaos Chalmoukis and Georgios
Nikolaidis have also independently proven this conjecture on arXiv. See
arXiv:2405.13920. arXiv admin note: substantial text overlap with
arXiv:2405.1627
On the boundedness of generalized integration operators on Hardy spaces
No full textWe study the boundedness and compactness properties of the generalized
integration operator when it acts between distinct Hardy spaces in
the unit disc of the complex plane. This operator has been introduced by the
first author in connection to a theorem of Cohn about factorization of higher
order derivatives of functions in Hardy spaces. We answer in the affirmative a
conjecture stated in the same work, therefore giving a complete
characterization of the class of symbols for which the operator is bounded
from the Hardy space to Comment: 19 page
Assessment of spatial and temporal distribution of rainfall in Crete using neural networks
No full textΠερίληψη: Στην παρούσα διπλωματική εργασία εξετάζεται η χρήση και εκπαίδευση τεχνητών νευρωνικών δικτύων, με σκοπό την προσομοίωση της βροχόπτωσης στην ευρύτερη περιοχή της Κρήτης. Η Κρήτη βρίσκεται στο νότιο άκρο του Αιγαίου πελάγους και καλύπτει μια περιοχή 8.336 km², με τους μετεωρολογικούς σταθμούς παρατήρησης να καλύπτουν ολόκληρη την έκταση της.
Τα νευρωνικά δίκτυα χρησιμοποιούνται με στόχο να προσομοιώσουν τα δεδομένα βροχόπτωσης, που έχουν συλλεχθεί από τους μετεωρολογικούς σταθμούς. Αρχικά, απαραίτητη ήταν η επεξεργασία των δεδομένων, καθώς απαιτούνταν η δημιουργία τόσο ενός πίνακα εισόδου, όσο και ενός διανύσματος στόχου στο νευρωνικό δίκτυο. Ο πίνακας εισόδου αποτελούνταν από τις συντεταγμένες των υδρολογικών σταθμών, την ταχύτητα του ανέμου και την ημερομηνία. Το διάνυσμα στόχου περιέχει τις πραγματικές τιμές βροχόπτωσης. Αξίζει να σημειωθεί, ότι τα δεδομένα προήλθαν από 46 υδρολογικούς σταθμούς και αφορούν τη χρονική περίοδο από 1/2/2006 μέχρι και 30/6/2021.
Με την ολοκλήρωση της επεξεργασίας των δεδομένων, ξεκίνησε η εκπαίδευση των νευρωνικών δικτύων με τα εργαλεία Neural Fitting tool (nftool) και Neural Network tool (nntool). Επίσης χρησιμοποιήθηκαν δύο διαφορετικοί αλγόριθμοι εκπαίδευσης, Bayesian-Regularization και Levenberg-Marquardt. Ακολούθως πραγματοποιήθηκε η εκπαίδευση των νευρωνικών δικτύων, διαφοροποιώντας με κάθε επανάληψη τα χρησιμοποιούμενα εργαλεία, τον αριθμό των κόμβων σε κάθε κρυφό επίπεδο ή/και τους αλγόριθμους εκπαίδευσης.
Κατά την διαδικασία εκπαίδευσης των τεχνητών νευρωνικών δικτύων, η προσπάθεια εστιάζεται στην εύρεση του μοντέλου και των παραμέτρων του που προσφέρει τα βέλτιστα αποτελέσματα. Τα κριτήρια επιλογής του μοντέλου περιλαμβάνουν το μέσο τετραγωνικό σφάλμα, τον συντελεστή συσχέτισης και τον συντελεστή αποδοτικότητας Nash –Sutcliffe model efficiency coefficient (NSE). Η εκπαίδευση των τεχνητών νευρωνικών δικτύων συμπεριέλαβε το σύνολο των διαθέσιμων υδρολογικών σταθμών.
Συμπερασματικά, μετά το πέρας της εκπαίδευσης των τεχνητών νευρωνικών δικτύων, επιτεύχθηκε το βέλτιστο αποτέλεσμα με τη χρήση του αλγόριθμου εκπαίδευσης Bayesian Regularization και μέσω της χρήσης του εργαλείου nntool για το σύνολο των μετεωρολογικών σταθμών και των ετών παρατήρησης.Summarization: The objective of the current thesis is using and training neural networks, in order to simulate rainfall in the region of Crete. Crete is located at the southernmost tip of the Aegean Sea and covers an area of 8 336 km², with hydrological observation stations covering its entire area.
Neural networks are used to simulate rainfall data collected from hydrological stations. Initially, data processing was necessary, as it required the creation of both an input table and a target vector in the neural network. The input table consisted of the coordinates of the hydrological stations, the wind speed and the date. The target vector contains the actual rainfall values. It is worth noting that the data came from 46 hydrological stations and relate to the period from 1/2/2006 to 30/6/2021.
With the completion of the data processing, the training of the neural networks with the Neural Fitting tool (nftool) and the Neural Network tool (nntool) began. Two different training algorithms were also used Bayesian-Regularization and Levenberg-Marquardt. The training of the neural networks was then carried out, differentiating with each iteration the parameters in terms of the tools used, the hidden nodes and the training algorithms.
During the process of training artificial neural networks, the effort is focused on finding the model and its parameters that offer the best results. Model selection criteria include mean square error, correlation coefficient and Nash – Sutcliffe model efficiency coefficient (NSE). The training of artificial neural networks included all available hydrological stations.
In conclusion, after the completion of the training of artificial neural networks, the best accuracy was achieved by using the Bayesian Regularization training algorithm and by using the Neural Network tool (nntool) to refer to the total number of stations and years of observation
Implications of military aircraft’s mission optimal performance on gas turbine engine life expectancy
No full textDevaiah, Nalianda - Associate SupervisorGas turbine engines have a crucial role in evaluating military aircraft performance.
Operating in a range of missions and environmental conditions, they are
subjected to an excessively demanding usage often reaching their operating
limits. The impact prediction on engine components degradation of this adverse
usage requires a multi-disciplinary approach to best capture its effects.
This master thesis investigates the implications of optimal mission performance
on the degradation of military gas turbine engines. The research focuses on the
degradation of first stage of the high-pressure turbine caused by the failure
mechanisms of creep, low cycle fatigue and high cycle fatigue, each acting
independently on the turbine blades.
By exploring the implications of mission performance on engine degradation, this
study provides valuable insights for optimizing mission execution strategies and
improving operational efficiency in military aviation.
Through a comprehensive analysis, several key findings have been identified. It
was observed that as the turbine entry temperature (TET) decreases, the
stresses on the turbine blade have a disproportionately greater effect on the
overall damage. This suggests that maintaining optimal TET levels is crucial for
mitigating engine degradation, as an increase of 0.005% in blade temperature
can lead to 40% more thrust, 100% more fuel consumption but can reduce life by
18% in Creep, 15% in LCF and 14% in HCF.
In addition, the study reveals that the use of afterburner though having similar
thermo-mechanical stresses upon the blades with the maximum dry setting, the
extensive usage in a mission can significantly impact the life consumption. A
mission with 40% less overall duration can present an up to 40% reduced life
expectancy.
Lastly, the investigation highlights the significant differences in life consumption
during several optimal climb paths. A time optimized profile is found to be the
most damage inflicting having 3 times less lifespan than noise and IR optimized
paths. A life expectancy of only 80 flight hours is predicted for the usage applied
on this profile resulting from the impact of low cycle fatigue contribution.
This research contributes to the field of military-related costs by shedding light on
the operational availability of gas turbine engines.MSc by Research in Aerospac
Using Data Interpolating Empirical Orthogonal Functions (DINEOF) Algorithm for filling missing data of AVHHR satellite images
No full textUsing Data INterpolating Empirical Orthogonal Functions (DINEOF) Algorithm for filling the missing data of AVHHR satellite images. Andreas Nikolaidis(*,a,b), Stavros Stylianou(b,Georgios Georgiou(b), Diofantos Hajimitsis(a) and Evangelos Akylas(a) a. Department of Civil Engineering and Geomatics, Cyprus University of Technology, 30 Archbishop Kyprianou Str., 3036, Limassol, Cyprus b. University of Cyprus, PO BOX 20537, 1678, Nicosia, Cyprus, Oceanography Centre KEY WORDS: Remote Sensing, Cyprus, Mediterranean, DINEOF, ArcGIS, data reconstruction. During the last decade, Rixen (2005) and Alvera-Azkarate (2010) presented the DINEOF (Data Interpolating Empirical Orthogonal Functions) method, a EOF-based technique to reconstruct missing data in satellite images. The application of DINEOF method, proved to provide relative success in various experimental trials (Wang and Liu, 2013; Nikolaidis et al., 2013;2014), and tends to be an effective and computationally affordable solution, on the problem of data reconstruction, for missing data from geophysical fields, such as chlorophyll-a, sea surface temperatures or salinities and geophysical fields derived from satellite data. Implementation of this method in a GIS system will provide with a more complete, integrated approach, permitting the expansion of the applicability over various aspects. This may be especially useful in studies where various data of different kind, have to be examined. For this purpose, in this study we have implemented and present a new GIS toolbox that aims to automate the usage of the algorithm, incorporating the DINEOF codes provided by GHER (GeoHydrodynamics and Environment Research Group of University of Liege) into the ArcGIS®. ArcGIS® is a well known standard on Geographical Information Systems, used over the years for various remote sensing procedures, in sea and land environment alike. A case-study of filling the chlorophyll-a missing data in the Mediterranean Sea area, for a 18-day period is analyzed, as an example for the effectiveness and simplicity of the usage of this toolbox. The specific study focuses to chlorophyll-a MODIS satellite data collected by CNR-ISAC (Italian National Research Council, Institute of Atmospheric Sciences and Climate), from the respective products of MyOcean2® organization, that provides free online access to Level 3, with 1 km resolution. In particular, all the daily products with an initial level of only 27% data coverage were successfully reconstructed
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