Search results for "021108 energy"
showing 10 items of 80 documents
Investigation on partial discharges in HVDC cables after polarity reversal events
2020
Due to the accumulation of space charge inside the insulating layer of HVDC cables, the electric field under load conditions may be altered compared to what is established in HVAC cables. For example, a high thermal gradient leads to the inversion of the electric field pattern until the maximum value is reached in proximity of the dielectric-semicon interfaces. These maximum values can be further increased due to transient overvoltages and polarity reversal events until reaching electric field values higher than the rated ones. The main goal of this research is to investigate the possibility that, during these transient phenomena, conditions are created that favor the occurrence of partial …
Comparison between Deep-Drawing and Incremental Forming Processes from an Environmental Point of View
2019
Deep-drawing is an industrial forming process which allows the user to process large batches of sheet metals parts. One of the major drawbacks of this process is the complexity and the high cost of dies. In comparison incremental forming is a flexible process, allowing the user to obtain sheet metal parts without the need of using a die. The present paper aims to present a comparative study of the two forming processes by presenting the main advantages and drawbacks of each one. The comparative study, aimed on the industrial implementation of the incremental forming process requires a comparison of the two processes regarding the environmental impact. Thus, the results of the study will jus…
Damage identification of a jacket support structure for offshore wind turbines
2020
Offshore jacket structures are regarded as a suitable type of support structure for offshore wind turbines in immediate water depths. Because of the welded tubular members used and environmental conditions, offshore jackets are often subjected to fatigue damages during their service life. Underwater sensors can provide measurements of the structural vibration signals and provide an efficient way to detect damages at early stages. In this work, simplified forms of the damages are assumed, random damages are imposed on the jacket structure, and damaged indicators are established from combination of modal shapes. Then, a response surface is constructed mapping the damage indicators and damages…
Schatten über der Schwarzarbeit
2008
Die Diskussion uber Messung, Grosenordnung und Konsequenzen der Schwarzarbeit steht bereits deshalb unter einem Schatten, der den Blick dafur truben kann, weil Enste und Schneider trotz jahrelanger Befassung mit dem Thema Schwarzarbeit und Schattenwirtschaft nicht systematisch zu unterscheiden vermogen. Ihre Schatzungen fur die Dimension des Phanomens beruhen zudem generell auf wissenschaftlich nicht haltbaren Vorgehensweisen, die sie gleichwohl repetitiv anwenden. Die unterstellten Einnahmenverluste beim Staat ergeben sich im Ubrigen lediglich bei Vernachlassigung mikrookonomisch bedeutsamer Budgetrestriktionen sowie durch Auserachtlassung zwingender makrookonomischer Kreislaufzusammenhang…
Die volkswirtschaftliche Bedeutung von Schwarzarbeit
2007
Die Schwarzarbeit wird in der finanzpolitischen Diskussion in Deutschland als volkswirtschaftlich gewichtig angesehen, und es werden ihr erhebliche Einnahmenverluste des Staates zugeschrieben. Die vorliegende Arbeit hinterfragt diese Behauptungen. Nach einer Definition der Schwarzarbeit und ihrer Abgrenzung gegenuber ahnlichen Sachverhalten wird die unterstellte volkswirtschaftliche Bedeutung zuruckgewiesen. Auserdem lasst sich im Rahmen einer konsistenten okonomischen Analyse zeigen, dass dem Staat durch Schwarzarbeit keinerlei Einnahmeausfalle entstehen. Nach allem ist das Ausmas der Schwarzarbeit in Deutschland gering, wobei gleichwohl allokative Wirkungen der Schwarzarbeit nicht auszusc…
From electric mobility to hydrogen mobility: current state and possible future expansions
2020
The expansion of electric vehicles in Italy, has already started a few years ago, but some aspects prevent its expansion. Currently users prefer hybrid technology, mainly due to socio-economic factors related to initial investment and anxiety about autonomy. The aim of the document is to understand if the adoption of Fuel Cell technology can be a solution to overcome the problems of environmental pollution. The possibility to be able to use fuel cells to store electricity is very advantageous, especially on charging times that are significantly reduced. Based on the current situation and analyzing the available data, this work reports the current state of electric mobility in Italy and trie…
Experimental alteration of granitic rocks: Implications for the evolution of geothermal brines in the Upper Rhine Graben, Germany
2020
Abstract Geothermal energy exploitation in the Upper Rhine Graben (URG) chiefly has targeted faults and fractures within or connected with the crystalline basement, where hot fluids of c. 200 °C circulate at depths of c. 5 km. Formation fluids of the crystalline basement are highly saline, NaCl-dominated brines, whereas shallow crystalline basement water ( The trace element concentrations of the leachates are hereby related to the composition and stability of minerals in the rocks and can be directly linked to the proposed and observed dissolution processes at the different temperatures. In experiments with pure water at 70 °C, representing the recharge or infiltration conditions, water-roc…
Monitoring results and analysis of thermal comfort conditions in experimental buildings for different heating systems and ventilation regimes during …
2017
This paper focuses on the long-term monitoring of thermal comfort and discomfort parameters in five small test buildings equipped with different heating and cooling systems. Calculations of predicted percentage of dissatisfied people (PPD) index and discomfort factors are provided for the room in winter season running three different heating systems – electric heater, air-air heat pump and air-water heat pump, as well as for the summer cooling with split type air conditioning systems. It is shown that the type of heating/cooling system and its working regime has an important impact on thermal comfort conditions in observed room. Recommendations for the optimal operating regimes and choice o…
Mean Radiant Temperature Measurements through Small Black Globes under Forced Convection Conditions
2021
One of the most critical variables in the field of thermal comfort measurements is the mean radiant temperature which is typically measured with a standard 150 mm black globe thermometer. This is also the reference instrument required for the assessment of heat stress conditions by means of the well-known Wet Bulb Globe Temperature index (WBGT). However, one of the limitations of this method is represented by the relatively long response time. This is why in recent years there has been a more and more pressing need of smart sensors for controlling Heating Ventilation and Air Conditioning (HVAC) systems, and for pocket heat stress meters (e.g., WBGT meters provided with table tennis balls). …
Assessing the electricity consumption of outdoor lighting systems in the presence of automatic control: The OL-BAC factors method
2020
Abstract Building automation systems are able to influence significantly buildings’ energy performance. The BAC factors method, presented for the first time by the International Standard EN 15232, is the most used and simple instrument for evaluating the impact of such systems in terms of reduction of the electrical and thermal energy consumption of buildings services. Nevertheless, Standard EN 15232 does not take into consideration the automation of lighting systems serving buildings’ external areas like passages, gardens, entrance walkways, etc. In some cases, such areas can be very extended and, as a consequence, responsible for a not negligible percentage of the overall electricity cons…