514 research outputs found
Superposition of DC voltage and submicrosecond impulses for energization of electrostatic precipitators
No full textThis paper discusses the development of an impulsive microelectrostatic precipitation technology, which uses superposition of submicrosecond high-field pulses and dc electric field. Short impulses allow the application of higher voltages to the ionization electrodes of a precipitation system without the initiation of breakdown. These higher levels of electric field generate higher ionic concentrations, resulting in more efficient charging of the airborne particles, and can potentially improve precipitation efficiency. This work is focused on the analysis of the behavior of impulsive positive corona discharges in a coaxial reactor designed for precipitation studies. The efficiency of precipitation of coarse and fine particles has been investigated using different dc and impulse voltage levels in order to establish optimal energization modes
The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios Stageirites (Τίτλος περίληψης)
No full textσ. [281]-290Κείμενο στα ελληνικά με περίληψη στα αγγλικά με τον τίτλο: The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios StageiritesThe article first examines the close relationship between the publication “Δρομοδείχτης της Ελλάδος” [1824] and the publication “Ηπειρωτικά” (1819) by Athanasios Stageirites and then suggests that Athanasios Stageirites is the likeliest author of the “Δρομοδείχτης της Ελλάδος”.Δωδώνη: Τεύχος Πρώτο: επιστημονική επετηρίδα του Τμήματος Ιστορίας και Αρχαιολογίας της Φιλοσοφικής Σχολής του Πανεπιστημίου Ιωαννίνων; Τόμ. 43-44 (2014-2015
Micro-electrostatic precipitation for air treatment
No full textParticulate matter suspended in the atmosphere is a major contaminant and is prevalent in urban environs, reducing the quality of air in the places that the majority of humans reside. Medical research has labelled PM2.5 as a potential risk to human health. To combat this issue, new legislation regarding PM2.5 has been passed. Electrostatic precipitators exhibit a drop in efficiency at ~(0.1-1) μm PM diameter. Therefore, the present work is focused on an investigation of microelectrostatic precipitation technology, for improvement of indoor air quality.;Initial work included investigation of impulsive positive energisation, in a specially designed single stage, coaxial reactor, utilizing 250 ns impulses superimposed on dc voltage. Precipitation efficiency for coarse and fine powders has been investigated for various levels of superimposed impulsive and dc energisation in order to identify optimal energisation conditions.;Further steps were taken to decouple charging from collection stages in order to optimize the air cleaning process to a greater extent. Precipitation experiments were conducted using ambient air and cigarette smoke. Maximum precipitation efficiency was achieved when both stages were energised, under impulsive and dc energisation in each stage respectively. Analytical work regarding PM charging has also been conducted.;Lastly, the coaxial precipitator reactor was scaled-up for possible indoor air cleaning applications. Similarly, impulsive energisation combined with dc voltage at the different stages has been used and proved to increase precipitation efficiency. Test fluids used were beeswax candle fumes and ambient air. Simulations have also been conducted to optimize the ESP process.;In conclusion, it has been shown that impulsive energisation of ESPs is highly efficient,100% for particles greater than 250 nm, for PM2.5 in concentrations found in indoor environments. This could potentially help in increasing indoor air quality, with all the corresponding health, working efficiency and ultimately state economic benefits it could achieve.Particulate matter suspended in the atmosphere is a major contaminant and is prevalent in urban environs, reducing the quality of air in the places that the majority of humans reside. Medical research has labelled PM2.5 as a potential risk to human health. To combat this issue, new legislation regarding PM2.5 has been passed. Electrostatic precipitators exhibit a drop in efficiency at ~(0.1-1) μm PM diameter. Therefore, the present work is focused on an investigation of microelectrostatic precipitation technology, for improvement of indoor air quality.;Initial work included investigation of impulsive positive energisation, in a specially designed single stage, coaxial reactor, utilizing 250 ns impulses superimposed on dc voltage. Precipitation efficiency for coarse and fine powders has been investigated for various levels of superimposed impulsive and dc energisation in order to identify optimal energisation conditions.;Further steps were taken to decouple charging from collection stages in order to optimize the air cleaning process to a greater extent. Precipitation experiments were conducted using ambient air and cigarette smoke. Maximum precipitation efficiency was achieved when both stages were energised, under impulsive and dc energisation in each stage respectively. Analytical work regarding PM charging has also been conducted.;Lastly, the coaxial precipitator reactor was scaled-up for possible indoor air cleaning applications. Similarly, impulsive energisation combined with dc voltage at the different stages has been used and proved to increase precipitation efficiency. Test fluids used were beeswax candle fumes and ambient air. Simulations have also been conducted to optimize the ESP process.;In conclusion, it has been shown that impulsive energisation of ESPs is highly efficient,100% for particles greater than 250 nm, for PM2.5 in concentrations found in indoor environments. This could potentially help in increasing indoor air quality, with all the corresponding health, working efficiency and ultimately state economic benefits it could achieve
Dataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment'
No full textDataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment' Appendix D - Resistance data and Appendix C - Stability data.
This dataset is focused on two appendices:
Appendix D - Resistance data. D.1 Resistance data produced by the author via MAXSURF Resistance for this thesis.
Appendix C - Stability data
C1. Stability data – STIX and ISO criteria, produced by the author via MAXSURF Stability software for his thesis
This research was funded by Southampton Marine and Maritime Institute (SMMI), Vice-Chancellor's Scholarship, Greek Archaeological Committee UK (GACUK)
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Peak power reduction algorithms in asymmetric digital subscriber line modems
No full textThesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaves 94-96).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.This thesis investigates peak-to-average ratio (PAR) reduction techniques for multicarrier modulation systems, such as discrete multitone (DMT) modems and orthogonal frequency-division multiplexed (OFDM) terrestrial broadcast transmitters. Through simulation and test implementation on a state-of-the-art programmable ADSL development platform, this thesis pursues a suitable solution for minimizing PAR given the resources of a programmable platform. This solution is integrated as a prototype implementation into a fully-functional ADSL modem and optimized for maximum PAR reduction performance within modem complexity constraints.by Athanasios Dimitri Dousis.M.Eng
Homophobic Statements, a Bishop, and the Limits of Freedom of Expression. An In-Depth Commentary on ECtHR 31.08.2023, Amvrosios-Athanasios Lenis v. Greece, no. 47833/20
No full textDichiarazioni omofobe, un vescovo e i limiti della libertà di espressione. Un commento approfondito su CEDU 31.08.2023, Amvrosios-Athanasios Lenis v. Greece, no. 47833/20.
ABSTRACT: The decision of the ECtHR of 31.08.2023, Amvrosios-Athanasios Lenis v. Greece (no. 47833/20), is a further step toward an increasingly dense jurisprudence on “hate speech” and the limits of freedom of expression. The public proclamation of religious doctrines that are in conflict with the values of the contracting States enshrined in the ECHR is protected to a certain extent by the fundamental right of freedom of religion and belief. However, the qualification of a statement as religious does not justify “hate speech.” The AUTHOR shows the tension between freedom of religion, freedom of expression, and protection against discrimination, and analyzes the decision against the backdrop of Article 17 of the ECHR (prohibition of abuse of rights).
SOMMARIO: 1. Preliminary Remarks - 2. The Concept of Hate Speech - 3. The Facts of the Case - 4. The Procedure and Reasoning of the Court - 4.1 The ECtHR’s Preliminary Considerations on Fundamental Rights - 4.2 Legal assessment - 4.3 Some Remarks on (the Non-Invoked) Article 9 of the ECHR - 5. Concluding Remarks
Investigation of high altitude/tropospheric correction factors for electric aircraft applications
No full textWith rising fuel costs and CO2 emissions, the aviation industry is moving rapidly toward increased electrification of aircraft, and power demand for propulsion and safety critical systems necessitates a move to on-board distribution voltages in excess of 1 kV. The increased stress experienced by cable insulation, connectors and other equipment, combined with extreme and dynamic environmental conditions experienced in flight, presents a number of technical challenges.
This research project proposes to quantify the effect of atmospheric conditions on partial discharge thresholds in uprated aircraft electrical systems, and to derive atmospheric correction factors appropriate to in-service operating conditions to assist the aircraft electrical design engineer in the insulation coordination of modern aviation systems.
The development of a controlled atmospheric test facility for the precise replication of in-flight conditions is outlined, and an initial visual assessment of partial discharge activity in an ex-service wire harness at a range of pressures is presented. We also present plans for the ongoing development of the facility and test capabilities
Plasma closing switches
No full textThe 19900 Individual MSc project is a direct continuation of the EE928 Case study, thus objectives are already set and most theoretical parts of the work conducted has been already discussed. However, it was deemed necessary to include some of these chapters, in much more detail thought, as a way to justify the course taken in the experimental work and also as an introduction to the project report, so as not to have as prerequisite the study of the case study report. As a consequence, the first two chapters, namely 3 and 4 , placed after a brief introduction and the contents page, make a detailed description about pulsed power in general, both from historical and application perspective, and explain some basic physical processes occurring in plasma switches, namely the corona effect and the spark discharge. In the 5th chapter a description of the experiments conducted, the topologies under test, together with the experimental results are presented in detail. Important information extracted from the experiments is combined in the 6th chapter in order to propose an analytical model, based on which the design of corona stabilised plasma closing switches can be performed. Finally, in the conclusions and discussion section, the main project points and some important experimental results are summarised, and some possible future continuation of the work done is presented. The report ends with the bibliography section in ISO 690 format
La tomba III di Haghios Athanasios e il valore semantico dell'incarnato
No full textThe tomb III at Haghios Athanasios stands out among the Macedonian tombs for the exceptional painted decoration of the temple-like façade. Excavated in the '90s by M. Tsimbidou-Avloniti it has been published by the scholar in full detail and the iconographic program of the monument has been the object of many publications. This article re-examines the different ways of reproducing the skin color (το ανδρείκελον) in the figures of the miniature frieze and in the megalographic figures beside the door. The realistic rendering of the megalographic figures of armed men in Macedonian attire, showing their sorrow for the lost of an etairos, is contrasting with the pale color of the participants to the symposion in the frieze above the door, a scene whose illusionistic overtone has been yet perceived by the critics. This symposion is articulated in three scenes and it can be interpeted as a necrodeipnon, but in the same time as a celebration of the Macedonian banquet style, centered on the royal court. The author suggests that the first figure on the right of the frieze, related to the group of armed men looking towards the banqueters feasting in the center of the frieze, can be read as the dead himself, for the particular rendering of his ανδρείκελον, showing the typical ochròtes or necròdes face color, according to the contemporary medical lexicon. The pathetic stance assumed by the same figure, the sole in the group which is not bearing arms, seems to confirm his role in the context of the scene
Partial Discharge Inception Voltage of Pigtail Samples with Type II Insulation and Sinusoidal vs Switched Voltage
No full textPartial discharge inception voltage (PDIV) under sinusoidal voltage and switched voltage with dV/dt of 20 V/ns have been investigated for pigtail samples with type II insulation consisting of Litz wire as conductor and mica-Kapton tape as groundwall insulation. Voltage was increased in steps of 100 V peak with duration of 60 s for both sinusoidal and switched voltage with switching frequency of 45 Hz until PDs were observed. No significant difference in the PDIV for sinusoidal and switched voltage was found. Further, sinusoidal voltage was applied until breakdown. No correlation between breakdown voltage and PDIV was found, but very large PDs (∼ 100 nC) consequently initiated 4-5 kV below breakdown voltage. Dissection of the tested pigtails showed multiple voids in the wedge between Litz wire strands and the inner insulation layer, suspected to cause the main portion of the PDs. Such voids with only a thin varnish covering the electrode surfaces would get less significant space charge build-up. Therefore, a low field enhancement from space charges is expected during the fast voltage change of switched voltage.Partial Discharge Inception Voltage of Pigtail Samples with Type II Insulation and Sinusoidal vs Switched VoltageacceptedVersio
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