Search results for " power"
showing 10 items of 3119 documents
Lielvaru (ASV un Ķīnas) sāncensība 21. gadsimtā
2022
Maģistra darba “Lielvaru (ASV un Ķīnas) sāncensība 21. gadsimtā” mērķis ir vairāku lielvaru augšupejas un lejupslīdes teoriju aplūkošana un analīze, saistot tās ar empīriskajiem novērojumiem par šādu sāncensību. Maģistra darbā apskatītās teorijas tiks pretnostatītas ASV un Ķīnas kā lielvaru sāncensībai mūsdienās, tādējādi veicinot izpratni par iespējamo šādas sāncensības izcelsmi un norisi, izrietot no vēsturiskiem gadījumiem, kas saistīti ar lielvaru sāncensību. Darba teorētiskā bāze ietver izklāstu par lielvaru raksturojumu un vairāku citu jēdzienu apskatīšanu, kā arī apskata četras lielvaru sāncensības teorijas. Maģistra darba empīrisko daļu veido lielvaru sāncensības vēsturiskā ietvara …
Dynamic mean absolute error as new measure for assessing forecasting errors
2018
Abstract Accurate wind power forecast is essential for grid integration, system planning, and electricity trading in certain electricity markets. Therefore, analyzing prediction errors is a critical task that allows a comparison of prediction models and the selection of the most suitable model. In this work, the temporal error and absolute magnitude error are simultaneously considered to assess the forecast error. The trade-off between both types of errors is computed, analyzed, and interpreted. Moreover, a new index, the dynamic mean absolute error, DMAE, is defined to measure the prediction accuracy. This index accounts for both error components: temporal and absolute. Real cases of wind …
Upgrading landfill gas using a high pressure water absorption process
2014
Abstract The upgrading of landfill gas (methane 54.2 ± 2.0%, carbon dioxide 42.1 ± 2.4% and nitrogen 3.7 ± 1.2%) was studied with a pilot-scale high pressure water absorption system consisting of absorption, desorption and gas drying units. The gas was upgraded in two phases and with two absorption columns operating in sequence in pressures up to 180 bar, and with initial pressures of 8 and 10 bar. This type of high pressure process, where water is used for increasing the gas pressure, does not need a separate compression unit to produce the gas pressure required by gas vehicles. Product gas with a methane contents ranging from 83.0% to 92.1% was achieved with differing process parameters, …
Analysis of the U L3-edge X-ray absorption spectra in UO2 using molecular dynamics simulations
2017
This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS) under the project ID s444. The resource allocation within the PSI share at CSCS and on the PSI compute cluster Merlin4 is also acknowledged. D. B. is grateful for a fellowship within the Sciex-NMS programme. A. K. was supported by Latvian Science Council Grant no. 187/2012.
Training Programs – Training and Development Alternatives for Students
2013
Abstract Training programs have been established as a form of training for adults, being generally used within companies’ personal development alternatives starting from the employees’ performance assessment processes. The current century requires a different way of approaching academic education, starting from the employers’ observation in reference to the lack of the graduates’ key competencies in the hiring process. We intend to demonstrate that it is useful to introduce training programs as an alternative form of education in academia, as well as in the high school environment.
Technical Possibilities of Reducing the Sound Pressure Level Emitted into the Environment by a Power Transformer
2011
The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.
Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency
2016
This paper presents a modification to the classical Model Predictive Control algorithm, named Modulated Model Predictive Control, and its application to active power filters. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the generated waveforms harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function-based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excel…
Temporal Control of Pulses from a High-Repetition-Rate Tunable Ti:Sapphire Laser by Active Q-switching
2003
We investigated the lasing characteristics of a Ti:sapphire laser pumped by a pulsed high-repetition-rate Nd:YAG laser. The pump laser has a pulsewidth of 450 ns, while the Ti:sapphire laser shows a significantly shorter pulse width of 25 ns for suitably intense pumping. The energy conversion efficiency of the laser is more than 10%. To synchronize different lasers and to avoid multiple spiking during one pump pulse, we use a Brewster-cut Pockels cell in the resonator for Q-switching. The temporal profile and conversion efficiency are determined and compared to theoretical estimates.
The impact of in-canopy wind profile formulations on heat flux estimation in an open orchard using the remote sensing-based two-source model
2010
Abstract. For open orchard and vineyard canopies containing significant fractions of exposed soil (>50%), typical of Mediterranean agricultural regions, the energy balance of the vegetation elements is strongly influenced by heat exchange with the bare soil/substrate. For these agricultural systems a "two-source" approach, where radiation and turbulent exchange between the soil and canopy elements are explicitly modelled, appears to be the only suitable methodology for reliably assessing energy fluxes. In strongly clumped canopies, the effective wind speed profile inside and below the canopy layer can strongly influence the partitioning of energy fluxes between the soil and vegetation co…
Investment Decision Making and Risk
2013
Abstract The aim of the paper is to present how investment decisions are made and what investment risk is, what role it has in the investment decision. The decision itself is a subjective act, but it is based on both subjective and objective factors. Risk is an important component of every investment, thus it is necessary to analyse it as both, the objective component of the investment, and as the subjective factor of the investment decision making.