Why isn’t urban development sustainable? An institutional approach to the case of Athens, Greece

Despite the rise to prominence of sustainable planning, the state of urgency and the pressure imposed by the extreme competition between metropolitan territories reduce sustainability to a market-oriented doctrine for deregulated urban development. The aim of this article is an exploration of the current Athenian urban crisis, by centring on sustainable urban development plans, territorial planning institutions, and urban policies. To this end, the phenomenon of urban crisis is explained as a derivative of the failure of sustainability reforms. By establishing a link between the institutional framework governing urban development and the success or failure of sustainability reforms, this article seeks to contribute to the discussion around the attainability, scope and impact of sustainable urban development plans. Through the hypothesis that as long as territorial planning is used as means towards speculative urban development, it will only be equivalent to that of a real estate facilitating mechanism, it is argued that the urban development model of Athens, as well as the role that institutions have in its shaping, is incompatible with any notion of sustainability. The main contribution of this article is to potentially help towards developing a critical reflection on how projects, plans, territories and sustainability should be approached

Normal forms, resonance and bifurcation analysis via the Carleman linearization

AbstractEquivalence between the normal form (NF) and the Carleman linearization of a nonlinear dynamic system is established. The near-identity nonlinear coordinate transformation which brings a system to its NF is shown to be the similarity transformation bringing a Carleman system to a Jordan canonical form. It is shown that the steady-state multiplicity is given by the nullity of the first Carleman matrix with noncomplete nullspace. The stability of the limit cycles at Hopf bifurcation is determined by the direction of the iω-generalized eigenvector of the first odd order Carleman matrix which has a noncomplete iω-eigenspace. The coefficients of the resonant terms that are retained in the NF are explicitly determined

Ο ρόλος του κόμβου συνδυασμένων μεταφορών της Πάτρας για την περιφερειακή ανάπτυξη

Εθνικό Μετσόβιο Πολυτεχνείο. Μεταπτυχιακή εργασία. Διεπιστημονικό - Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) "Αρχιτεκτονική - Σχεδιασμός του Χώρου : Πολεοδομία - Χωροταξία (Κατ. Β')

SatNOGS: Satellite Networked Open Ground Station

Abstract—The SatNOGS, or Satellite Network Open Ground Stations, project promotes and supports free and open space applications. It seeks to solve the problem of connecting many satellite users/observers to many ground station operators. Modern open software, web, and hardware techniques are used in implementing the Network, Database, Client, and Ground Station sub- projects. Modularity in all the systems promotes the dual-use of ground stations by not interfering with local operation while utilizing the great amount of time a civilian, non-commercial ground station would otherwise sit idle

Describing SmallSat Missions with MetaSat

Space mission metadata is not standardized and various mission outputs are typically disconnected. This situation makes it hard for different teams to share information, collaborate, or advise each other on best practices and lessons learned. The MetaSat team, made up of staff from both the Wolbach Library at the Center for Astrophysics (CfA) and the Libre Space Foundation (LSF), is addressing these issues by creating a metadata vocabulary and example JSON-LD schemas that can be used to describe small satellite missions. This work will help facilitate the ease of sharing information between missions and lower the barrier of entry into the field

The History of Public Relations in Greece from 1950 to 1980: Professionalization of the “art”

The early development of public relations in Greece is explored through a focus on the period between 1950 and 1980. Specifically, the article considers the origins and early developments, important actors, international influences, professional bodies and the field of practice. It found that Greek business public relations was greatly influenced by American practices and through influential practitioners’ contact with the International Public Relations Association (IPRA)

Use of CCD to Detect Terrestrial Cosmic Rays at Ground Level: Altitude vs. Underground Experiments, Modeling and Numerical Monte Carlo Simulation

International audienceIn this work, we used a commercial charge-coupled device (CCD) camera to detect and monitor terrestrial cosmic rays at ground level. Multi-site characterization has been performed at sea level (Marseille), underground (Modane Underground Laboratory) and at mountain altitude (Aiguille du Midi-Chamonix Mont-Blanc at +3,780 m of altitude) to separate the atmospheric and alpha particle emitter's contributions in the CCD response. An additional experiment at avionics altitude during a long-haul flight has been also conducted. Experiment results demonstrate the importance of the alpha contamination in the CCD response at ground level and its sensitivity to charged particles. Experimental data as a function of CCD orientation also suggests an anisotropy of the particle flux for which the device is sensitive. A complete computational modeling of the CCD imager has been conducted, based on a simplified 3D CCD architecture deduced from a reverse engineering study using electron microscopy and physico-chemical analysis. Monte Carlo simulations evidence the major contribution of low energy (below a few MeV) protons and muons in the CCD response. Comparison between experiments and simulation shows a good agreement at ground level, fully validated at avionics altitudes with a much higher particle flux and a different particle cocktail composition

An Updated Overview of the Satellite Networked Open Ground Stations (SatNOGS) Project

An overview of the SatNOGS project, a network of satellite ground stations around the world, optimized for modularity, built from readily available and affordable tools and resources. The rate of Low Earth Orbit (LEO) satellite launches increases with the participation of old and new entities. In this growing environment, SatNOGS provides a scalable and modular solution to track, identify, receive telemetry from, monitor, and assist operators in command/control of satellites. The SatNOGS global community, dedicated to its free and open-source values, develops hardware ground station designs (antennas, rotators, electronics), software for SDR-based communications, satellite scheduling and mission monitoring platforms. SatNOGS continuously develops and improves its infrastructure to allow observers to use this networked ground segment and remotely operate SatNOGS ground stations around the world. It also provides an easy way to store, access and view increasingly received satellites data, by supporting VHF, UHF, L and S bands

Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments : Evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation

The gas-phase reaction of isoprene with the nitrate radical (NO3) was investigated in experiments in the outdoor SAPHIR chamber under atmospherically relevant conditions specifically with respect to the chemical lifetime and fate of nitrato-organic peroxy radicals (RO2). Observations of organic products were compared to concentrations expected from different chemical mechanisms: (1) the Master Chemical Mechanism, which simplifies the NO3 isoprene chemistry by only considering one RO2 isomer; (2) the chemical mechanism derived from experiments in the Caltech chamber, which considers different RO2 isomers; and (3) the FZJ-NO3 isoprene mechanism derived from quantum chemical calculations, which in addition to the Caltech mechanism includes equilibrium reactions of RO2 isomers, unimolecular reactions of nitrate RO2 radicals and epoxidation reactions of nitrate alkoxy radicals. Measurements using mass spectrometer instruments give evidence that the new reactions pathways predicted by quantum chemical calculations play a role in the NO3 oxidation of isoprene. Hydroperoxy aldehyde (HPALD) species, which are specific to unimolecular reactions of nitrate RO2, were detected even in the presence of an OH scavenger, excluding the possibility that concurrent oxidation by hydroxyl radicals (OH) is responsible for their formation. In addition, ion signals at masses that can be attributed to epoxy compounds, which are specific to the epoxidation reaction of nitrate alkoxy radicals, were detected. Measurements of methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations confirm that the decomposition of nitrate alkoxy radicals implemented in the Caltech mechanism cannot compete with the ring-closure reactions predicted by quantum chemical calculations. The validity of the FZJ-NO3 isoprene mechanism is further supported by a good agreement between measured and simulated hydroxyl radical (OH) reactivity. Nevertheless, the FZJ-NO3 isoprene mechanism needs further investigations with respect to the absolute importance of unimolecular reactions of nitrate RO2 and epoxidation reactions of nitrate alkoxy radicals. Absolute concentrations of specific organic nitrates such as nitrate hydroperoxides would be required to experimentally determine product yields and branching ratios of reactions but could not be measured in the chamber experiments due to the lack of calibration standards for these compounds. The temporal evolution of mass traces attributed to product species such as nitrate hydroperoxides, nitrate carbonyl and nitrate alcohols as well as hydroperoxy aldehydes observed by the mass spectrometer instruments demonstrates that further oxidation by the nitrate radical and ozone at atmospheric concentrations is small on the timescale of one night (12gh) for typical oxidant concentrations. However, oxidation by hydroxyl radicals present at night and potentially also produced from the decomposition of nitrate alkoxy radicals can contribute to their nocturnal chemical loss

A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry

Abstract Oxidation of isoprene by nitrate radicals (NO3) or by hydroxyl radicals (OH) under high NOx conditions forms a substantial amount of organonitrates (ONs). ONs impact NOx concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula C4H7NO5 are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe. From chamber experiments we found that C4H7NO5 isomers contribute 5%?17% of all measured ONs formed during nighttime and constitute more than 40% of the measured ONs after further daytime oxidation. In ambient measurements C4H7NO5 isomers usually dominate both nighttime and daytime, implying a long residence time compared to C5 ONs which are removed more rapidly. We propose potential nighttime sources and secondary formation pathways, and test them using a box model with an updated isoprene oxidation scheme