217 research outputs found
Crises and perceptions in enduring rivalries
The thesis assesses the impact of tense international crises on leadership perceptions, across enduring rival and non-rival dyads. Associated in the relevant literature with escalation and conflict, interstate militarized crises are systematically explored in order to ascertain their impact on perceptions. Cognitive theories of decision making suggest that rationality is compromised in crises, as emotional stress, time constraints and pervasive uncertainty intensify cognitive rigidities among policy makers. A strong possibility, therefore, exists that leaders will be oblivious to crucial information, which will either be neglected or erroneously interpreted. In that sense, crises are viewed with apprehension by analysts, fearing misperception and miscalculation that may lead to unintended war. Through a detailed assessment of severe crisis case studies (The Greco-Turkish Aegean Sea crisis of 1996, the Russo-Georgian War of 2008 and the Cypriot S-300 missile crisis of 1998), this thesis suggests that crises may, contrary to expectations, shed light on long-running trends which were ignored or misinterpreted by decision makers, thereby “forcing” an accurate re-assessment of enemy and third party intentions and capabilities. Therefore, by posing a clarifying (shock) effect on leadership perceptions, cognitive mechanisms in crises could actually act supportively in drawing accurate inferences, bolstering objectivity
Impact of Degradation on the Operational Behaviour of a Stationary Gas Turbine and in Detail on the Associated Compressor
LectureDegradation of stationary gas turbines is a quite often observed burden and can impact financial revenues of end-users significantly. In addition to the well-known occurrence of increased pressure losses in the intake filter systems due to clogging (filter loaded with deposits), the compressor has been shown to be one of the main contributors to this change in gas turbine performance. In case of compressor blading and flow path degradation, additionally to a compressor efficiency reduction, the inlet mass flow can be significantly reduced as well. As a consequence also the gas turbine pressure ratio is decreasing. Therefore, compressor degradation acts detrimentally twice on the overall gas turbine power.
Degradation of a compressor in the context of this paper is understood as the behavior of a stationary gas turbine, where intake filter systems are getting clogged and/or dirt deposits on the compressor blading surface, which impact the aerodynamics, and therefore the overall gas turbine performance.
The paper focuses on compressor and gas turbine performance parameters for degraded engines with varying ambient conditions. Furthermore the internal aerodynamic loading distribution and possible operational limitations (e.g. surge) for certain degradation rates and gas turbine operating conditions are assessed. For this purpose a simplified CFD model is applied, capable to simulate certain degradation rates for every individual compressor blade row. In addition a simplified gas turbine model is applied, to study the compressor degradation impact with its overall consequences.
Two basic case studies are shown. The 1st one is addressing filter clogging. The 2nd one takes compressor blading degradation into consideration while assessing the impact of different fouling distribution rates. The case studies are substantiated and supported by field measurements. Finally recommendations are given for possible activities to be taken by the end-users to ensure efficient and safe gas turbine operation
Impact of Degradation on the Operational Behaviour of a Stationary Gas Turbine and in Detail on the Associated Compressor
LectureDegradation of stationary gas turbines is a quite often observed burden and can impact financial revenues of end-users significantly. In addition to the well-known occurrence of increased pressure losses in the intake filter systems due to clogging (filter loaded with deposits), the compressor has been shown to be one of the main contributors to this change in gas turbine performance. In case of compressor blading and flow path degradation, additionally to a compressor efficiency reduction, the inlet mass flow can be significantly reduced as well. As a consequence also the gas turbine pressure ratio is decreasing. Therefore, compressor degradation acts detrimentally twice on the overall gas turbine power.
Degradation of a compressor in the context of this paper is understood as the behavior of a stationary gas turbine, where intake filter systems are getting clogged and/or dirt deposits on the compressor blading surface, which impact the aerodynamics, and therefore the overall gas turbine performance.
The paper focuses on compressor and gas turbine performance parameters for degraded engines with varying ambient conditions. Furthermore the internal aerodynamic loading distribution and possible operational limitations (e.g. surge) for certain degradation rates and gas turbine operating conditions are assessed. For this purpose a simplified CFD model is applied, capable to simulate certain degradation rates for every individual compressor blade row. In addition a simplified gas turbine model is applied, to study the compressor degradation impact with its overall consequences.
Two basic case studies are shown. The 1st one is addressing filter clogging. The 2nd one takes compressor blading degradation into consideration while assessing the impact of different fouling distribution rates. The case studies are substantiated and supported by field measurements. Finally recommendations are given for possible activities to be taken by the end-users to ensure efficient and safe gas turbine operation
The Bear Learns to Swim: Russia's Re-emergence in the Mediterranean
The article explores the recent surge of Russian military presence in the Eastern Mediterranean and evaluates the implications of Moscow’s decision to challenge the regional status quo. In November 2015, the downing of a Russian fighter jet over Syrian airspace turned analysts’ attention to the increasing involvement of Russia in the Syrian battlefield. Moscow’s entanglement in the Syrian civil war was only the latest episode in its historically persistent effort to establish a permanent presence in Mediterranean waters. Developments in recent years, however, point to a more ambitious approach. This article argues that Moscow’s unfolding strategy entails the gradual assertion of Russian air superiority over critical parts of the Eastern Mediterranean, a Russian aspiration that has been elusive even during the peak of the Cold War rivalry. Moscow’s grand strategy, in this regard, signals a renewed effort to disrupt NATO's south-eastern flank. Under this prism, the deployment of long-range S-400 and S-300 Surface-to-Air Missiles (SAMs), S-300 equipped ships and advanced fighter jets across regional flashpoints may prove to be a game changing initiative. The implications of Russia’s contemporary strategy could be important for the future of the Eastern Mediterranean, as Moscow’s approach appears to be upsetting the regional balance of power. Israel’s unchallenged dominance of the skies over Syria and Lebanon is compromised for the first time since 1970, when Russian air-defence forces were deployed to Egypt. The Turkish armed forces, moreover, will struggle to compensate for the Russian game plan, which complicates Ankara’s ability to project power over Syria, Iraq and the Aegean Sea. These dispersed airpower “webs” could, finally, restrict NATO’s capacity to deploy assets in the region and nullify the credibility of the alliance’s anti-ballistic shield. Overall, contemporary developments may enable Russia to challenge American control of a geopolitically vital area that has been in essence uncontested since the end of World War II
Practical shape optimization for turbine and compressor blades
The shape optimization of blades is a crucial step within the design cycle of a whole turbomachine. This paper is a report on a joint project between academia and industry leading to an efficient solution software for this problem to be used in the daily work of concerned engineers. The problem description and solution method, characterized as a partially reduced SQP method, as well as numerical results are presented
What Role for Media in Security Crises?
The chapter examines the impact of media on public opinion and leadership decision-making during security crises. Leaders pay particular attention to media outlets during crises in an effort to collect as much information as possible from open sources. While intelligence from state services and allies plays a crucial role in reaching decisions, the impact of electronic and social media in shaping leadership perceptions is increasingly hard to ignore. The fact that governments have access to “accurate” intelligence should mitigate, in principle, the danger of misperception arising from erroneous media reports. Nevertheless, we have no way of limiting the potential “contamination” of leadership perceptions by inaccurate media information. Intelligence, after all, may be inconclusive, and intelligence assessments could themselves be affected by factors such as hostile images of the “other” engineered by the media. But the media’s independence is being gradually compromised, with the post-Cold War trend being particularly revealing. From the “CNN effect” of the 1990s to the “War on Terror” campaign in the 2000s and the Hybrid Warfare doctrines of the 2010, it becomes increasingly evident that governments aspire to “weaponise” information so as to achieve their military objectives. Maintaining, therefore, accurate perceptions in an environment where disinformation, fake news, and propaganda are pervasive is a demanding task. As a result, governments will have to exercise effective oversight across media outlets in the future in order to ensure that public opinion and leadership perceptions are unaffected by disinformation and propaganda campaigns. With more governments engaging into the “weaponisation” of media, however, it is up to media professionals and journalists to defend their field and ensure that global audiences have access to impartial coverage of security crises
THE RISE OF A STRATEGIC SPOILER: RUSSIA’S EUROPEAN SECURITY STRATEGY
Russia’s annexation of Crimea in March 2014 was the latest step in Moscow’s steadfast rejection of the post-Cold War security order in Europe. Nevertheless, analysts and scholars remain puzzled as to what exactly constitutes Russia’s long-term game plan vis-à -vis Europe. This chapter suggests that, far from following a concrete, well-planned blueprint at the operational and tactical levels, Russia’s grand strategic objectives enable Moscow to adopt a fluid, adaptive posture aiming at achieving two interconnected goals: to maintain, or even improve, the continental military balance of power through the deployment of strategic weapons and at the same time acquire the capabilities to disrupt NATO’s air and naval superiority in critical flashpoints, an aspiration that had been elusive even at the peak of the Cold War rivalry. The implications of Russia’s grand strategic doctrine are thus crucial for Europe’s security outlook; Moscow’s approach implies that Russian deterrence at the highest levels will be robust, while low-level, disruptive tactics in areas where Russia maintains an operational advantage could challenge the European security status quo. Contemporary developments, therefore, may enable Russia to undermine NATO’s supremacy in the Euro-Atlantic geopolitical space, altering the post-Cold War order
Influence of Apple stem grooving virus on Malus sieboldii-derived apple proliferation resistant rootstocks
Apple stem grooving virus (ASGV, Capillovirus) is widely spread in apple growing regions. As it causes no symptoms on most cultivated apple varieties and rootstocks it is considered latent in Malus x domestica. In Asia, however, ASGV has been found associated with topworking disease of apple rootstocks originating from Malus sieboldii. Recently, M. sieboldii and its hybrids have gained new interest in Europe as they confer resistance to apple proliferation (AP) disease. A new breeding program aiming to develop AP-resistant rootstocks of agronomic value for modern apple culture, reported unexpected tree decline which was to be associated with ASGV. As little information is available on the variability of ASGV isolates in Germany, the complete genome of a German isolate of ASGV associated with tree decline was cloned and sequenced. Sequence comparisons with available ASGV isolates revealed two regions of high variability in the genome. The genetic variability of additional isolates from Germany and other countries were collected and the variable areas characterised. In addition ASGV was successfully maintained in micropropagated apple trees and could be transmitted by in vitro grafting to various genotypes, making it possible to study in vitro the effect of the virus and virus/phytoplama combination on M. sieboldii-derived genotypes. Keywords: Latent apple viruses, Candidatus Phytoplasma mali, micropropagation, in vitro grafting, genetic variabilit
More health-supporting substances and taste in the storage organ of vegetables by colored foils
Die Wirkung von Veränderungen der Lichtspektren hinsichtlich des Rot-Blau-Verhältnisses und der Anteile an Dunkelrot (700 nm ± 30) auf die Bildung des Speicherorgans von GemĂĽse wurde in mehreren wissenschaftlichen Arbeiten bestätigt. Diese Wirkung kann mit der Erhöhung des Gehaltes an Antioxidantien im Speicherorgan begleitet sein. In den vom IASP 2015 durchgefĂĽhrten Feldversuchen mit Kohlrabi und Radies wurden unterschiedliche Lichtspektren mit Hilfe von Farbfolien (rot, grĂĽn, gelb und farblos) erzeugt. Dabei wurden diese Lichtspektren nur temporär zu bestimmten Entwicklungsstadien der Pflanzen eingesetzt. In den Versuchen zeigte sich, dass der Impuls durch veränderte Lichtspektren vor allem einen Einfluss auf den Gehalt der Antioxidantien und des Zuckers der Speicherorgane hat. Auswirkungen auf die Größe der Speicherorgane (Knolle bei Kohlrabi, Wurzel bei Radies) waren relativ gering.Deutlich wurde, dass eine Ă„nderung des LichtspekÂtrums nur in einigen Entwicklungsstadien der Pflanzen sinnvoll ist. Gleichzeitig wurde festgestellt, dass die Farbfolien bei den zwei untersuchten Kulturen unterschiedÂliche Wirkung auf die jeweiligen Gehalte der Antioxidantien haben, z.B. wurde der Riboflavin-Gehalt im Versuch mit Kohlrabi durch die grĂĽne Folie positiv beeinflusst. Er betrug das 5-fache der Konzentration, die in der Kontrolle zu finden war. Bei Radies wurde mehr Riboflavin unter der roten Folie gebildet und betrug 48% mehr als in der Kontrolle. DOI: 10.5073/JfK.2016.08.02, https://doi.org/10.5073/JfK.2016.08.02The effect from changing of the light spectra concerning the red-blue relation and the percentage in dark red (700 nm ± 30) on the building of the storage organ of vegetables were confirmed in several scientific works. This effect can be accompanied by an increased antioxidant concentration in the storage organ. In the field tests carried out by the IASP 2015 with kohlrabi and radish different light spectra were generated by transparent coloured foils (red, green, yellow and colourless). These light spectra were applied temporary only during certain development stages of the plants to induce plant reactions. The experiments revealed that this light impulse has above all an influence on the content of the antioxidants and the sugar concentration of the storage organs. Effects on the size of the organs (bulb of kohlrabi, root of radish) were insignificant.It became apparent that a change of the light spectrum makes sense in some development stages of the plants only. At the same time it was found that the coloured foils have different effects on the content of the antioxidants in the examined cultures. For example, the riboflavin content in the kohlrabi under the green foil was positively influenced. It was five times as much as in the control. In radish more riboflavin was synthesized under the red foil, it was 48% more than in the control. DOI: 10.5073/JfK.2016.08.02, https://doi.org/10.5073/JfK.2016.08.0
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