12,386 research outputs found
Improved system operations with high penetration of wind power : a dialog between academia and industry - Ireland
No full textPanel session submission for the IEEE Power and Energy Society (PES) 2010 General Meeting, July 25-29 2010, Minneapolis, MinnesotaThis is a submission to a panel session at the 2010
IEEE PES General Meeting. It discusses effective collaboration
between academia and industry.Science Foundation IrelandConference websitehttp://ewh.ieee.org/conf/pesgm10/Charles Parsons Energy Research AwardsCharles Parso
Letter from M.J. Browne to Hagan
No full textHolograph letter from M.J. Browne, St. Patrick’s College, Maynooth (County Kildare), to Hagan. Stating their satisfaction that Patten seems to be accepted by Liverpool diocese. Then observing that the country 'if properly tapped would sweep the gang from power'; Fianna Fail is the only party holding meetings at present and they are gathering strength apace. (The Archbishop of) Tuam would approve of the party were they to go in the Dáil; Browne disagreeing sees the power an extra-parliamentary group can have, emphasising their objective. Then asking for information on Fr. Ellis whom he is to meet this week. Also asking for copy programmes of the chief universities for comparison. Adding he said nothing of Kildare
Kinetic energy harvesting
No full textThis paper reviews kinetic energy harvesting as a potential localised power supply for wireless applications. Harvesting devices are typically implemented as resonant devices of which the power output depends upon the size of the inertial mass, the frequency and amplitude of the driving vibrations, the maximum available mass displacement and the damping. Three transduction mechanisms are currently primarily employed to convert mechanical into electrical energy: electromagnetic, piezoelectric and electrostatic. Piezoelectric and electrostatic mechanisms are best suited to small size MEMS implementations, but the power output from such devices is at present limited to a few microwatts. An electromagnetic generator implemented with discrete components has produced a power 120 ?W with the highest recorded efficiency to date of 51% for a device of this size reported to date. The packaged device is 0.8 cm3 and weighs 1.6 grams. The suitability of the technology in space applications will be determined by the nature of the available kinetic energy and the required level of output power. A radioactively coupled device may present an opportunity where suitable vibrations do not exist
Vacuum Insulation Panels Applied in Building Constructions
No full textDue to sustainability and due to international treaties, it is desired and required to reduce greenhouse gas emissions drastically. One contributor to these emissions is the burning of fossil fuels for generating power and electricity to be used in and for buildings. Buildings and building-related processes are responsible for about 40% of the primary energy consumption in the European Union. More than half of this energy is applied for heating systems in dwellings and commercial buildings. The European Union therefore has laid down new energy performance requirements for buildings in the European Directive on the Energy Performance of Buildings. Moreover, a reduction of energy losses of buildings during their occupational phase is important for facilitating the implementation of sustainable energy sources in the built environment. Increasing the insulation value of the envelope of buildings may contribute to this reduction of primary energy use. Two strategies can be followed. The first strategy is to increase the thickness of the thermal insulation layer. Until recently, this strategy has primarily been adopted. If, however, German or Swiss Passivhaus standard is applied, the thickness of this insulation layer would increase to beyond 30 cm, resulting in very thick building enclosures. The second, more innovative, strategy for reducing energy losses through the building skin would be the application of more effective thermal insulators. One such more effective thermal insulator is a vacuum insulation panel, abbreviated as VIP. A VIP consists of an open-celled core material which is evacuated and then tightly sealed into a barrier envelope to maintain this vacuum. The vacuum inside the pores of the core material reduces the thermal conductivity of the product significantly, as a result of which the thickness of the insulation layer can be reduced to obtain a certain performance. This reduction of thickness is among the most promising features for large-scale application of VIPs in the building industry. However, integration of VIPs into buildings must be performed very meticulously for several reasons; first, due to its nature a VIP cannot be processed on site and needs careful planning in advance; second, it is very sensitive to mechanical damage thus requiring careful handling; third, thermal bridges along the panel’s edges reduce its performance; fourth, the composite system is highly subjected to aging. This dissertation therefore looks into many of these aspects, presents several calculation tools and shows how VIPs can be applied in façade panels, EPS insulation boards and as under-floor insulation. With the wide-spread proliferation of VIPs in buildings a more sustainable and healthy environment can then be achieved.Building TechnologyArchitectur
High average power end-pumped Nd:YVO<sub>4</sub> master oscillator power amplifier
No full textWe demonstrate 94 W average power from an all-solid-state fibre-coupled diode end-pumped Nd:YVO4 master oscillator and multi-stage power amplifier
Switched-Device Power Amplier using Bias Control
No full textIn this work, a switched-device power amplier using bias control is designed and realized. The PA operates at a frequency of 100MHz. Test results show that the PA achieves a PAE of 63% at −6dB power back-off and 60% at the peak output power of 40dBm. First, an overview of the state-of-the-art PA technology and performance in high PAPR applications is given. The state-of-the-art analysis is then used to set up the requirements of the PA and to compare the results to in the end. The design of the PA is explained in detail, followed by an evaluation of the simulated and measured results. Notable observations of the performance measurements are also discussed. After the concluding remarks regarding this work are given, recommendations on how to improve the performance and to extend the concept of the proposed switched-device PA are presented.Electrical Engineering, Mathematics and Computer ScienceElectronics Research Laboratory (ELCA
High power single-frequency continuous-wave Nd:YVO<sub>4</sub> master-oscillator power amplifier
No full textWe report a highly-efficient, high-power, single-frequency Nd:YVO4 master-oscillator power-amplifier with near-diffraction-limited output beam quality. A diode-pumped Nd:YVO4
ring laser incorporating a passive method for suppressing
axial-mode-hopping was employed as the master-oscillator, and was
amplified by a three-stage diode-end-pumped Nd:YVO4
amplifier, yielding 79 W of output with an extraction efficiency of 29%.
The overall power gain was 15 dB for an input power from the
master-oscillator of 2.4 W, and the M2 parameter was less
than 1.5 at the maximum power. The prospects for a further increase of
power and brightness via this approach are considered
Energy harvesting from train vibrations
No full textIn this paper, linear mechanical oscillators are designed to harvest energy from train-induced vibrations. The harvested energy could be used, for example, to charge sensors mounted on the rail track for structural health monitoring. The dominant frequencies due to a passing train are determined for a specific train and speed from a recorded acceleration time-history. Using a simple model of an oscillator, the total energy harvested for the passage of one train is calculated. The stiffness, and hence the tuning frequency of the device, is varied in simulations to determine the optimum frequency at which to tune the device for a constant value of mass and damping in the device. Further simulations are conducted to investigate the power that could be harvested from multiple oscillators tuned at several dominant frequencies, and their performances are analysed and compared. The constraint for maximum relative displacement is considered in the design of each harvester, and this is adopted to assure that the amplitude of the oscillation is finite and does not exceed the physical size of the device. The robustness of the harvester is also analysed for different train speeds
Evaluation of a Local Fault Detection Algorithm for HVDC Systems
No full textPublisher Copyright: © 2019, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.A great increase in the amount of energy generated from clean and renewable sources integrated in the electric power system is expected worldwide in the coming years. High Voltage Direct Current (HVDC) systems are seen as a promising alternative to the traditional Alternating Current (AC) systems for the expansion of the electric power system. However, to achieve this vision, there are some remaining challenges regarding HVDC systems which need to be solved. One of the main challenges is related to fault detection and location in HVDC grids. This paper reviews the main protection algorithms available and presents the evaluation of a local fault detection algorithm for DC faults in a multi-terminal Voltage Source Conversion (VSC) based HVDC grid. The paper analyses the influence of the DC voltage sampling frequency and the cable length in the performance of the algorithm. © 2019, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ).Peer reviewe
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