Search results for "Energy engineering"
showing 10 items of 1099 documents
A new method in investigations of bubble cluster shapes in two-phase flow
1991
Abstract In this paper a new probabilistic method is used to analyse the distribution of air bubbles in two-phase flow. So far, the method has been applied in astronomy and cosmology to investigate the distribution of galaxies. The basic idea is presented and the method applied to the photographed population of air bubbles in a liquid. The method allows the homogeneity of the flow to be evaluated qualitatively and quantitatively.
Phononic crystals: Harnessing the propagation of sound, elastic waves, and phonons
2016
Comptes Rendus Physique - In Press.Proof corrected by the author Available online since jeudi 3 mars 2016
Challenges and Limits within the Electronic Environment, an Interdisciplinary Approach
2013
Abstract One of the main aims of this paper it to present implications and correlation between economy, religion, and electronic environment in Information Communication Technologies to develop a basic understanding of the field's ontology, by incorporating Web epistemology and theory. By focusing attention on the electronic environment, websites, as the main object of study and by presenting the hidden socio-economic and political aspects that govern this environment structural and operational, this paper offers an investigation and analyze of cyber economic and religious blend.
Hydrogen Dark Fermentation for Degradation of Solid andLiquid Food Waste
2021
The constant increase in the amount of food waste accumulating in landfills and discharged into the water reservoirs causes environment pollution and threatens human health. Solid and liquid food wastes include fruit, vegetable, and meat residues, alcohol bard, and sewage from various food enterprises. These products contain high concentrations of biodegradable organic compounds and represent an inexpensive and renewable substrate for the hydrogen fermentation. The goal of the work was to study the efficiency of hydrogen obtaining and decomposition of solid and liquid food waste via fermentation by granular microbial preparation (GMP). The application of GMP improved the efficiency of the d…
Analysis of Pollutant Emissions on City Arteries—Aspects of Transport Management
2021
The aim of the study is to present a methodology for analyzing pollution emissions in a medium-sized city using modern traffic simulations in the aspect of minimizing exhaust emissions. The scope of the research and the methods of analysis used differ from those applied in big cities projects that can be found in the literature, Therefore the progressive elaboration model has been applied methodically to formulate and carry out the feasibility study. To perform microscopic traffic simulations, the software Simulation of Urban Mobility (SUMO—German Aerospace Center (DLR), Berlin, Germany) was applied. Thanks to the simulations, changes in traffic organization were accurately identified in th…
Novel Computational Method for Harmonic Mitigation for Three-phase Five-level Cascaded H-Bridge Inverter
2018
The efficiency of the system is a very important parameter for high power electrical drives applications,. Moreover, in the system the efficiency of the power converter play a fundamental role and for this reason, the soft switching modulation techniques represent the best choice. This paper presents a novel computational method for harmonic mitigation on the output voltage of a five-level, three-phase Cascaded H-Bridge Inverter without solving non-linear equations. Through this simple approach the Working Areas have been identified in which the harmonics reference have minimum amplitude possible. Moreover, polynomial equations to evaluate the control angels have been found. In this way, th…
A Novel Computational Approach for Harmonic Mitigation in PV Systems with Single-Phase Five-Level CHBMI
2018
In this paper, a novel approach to low order harmonic mitigation in fundamental switching frequency modulation is proposed for high power photovoltaic (PV) applications, without trying to solve the cumbersome non-linear transcendental equations. The proposed method allows for mitigation of the first-five harmonics (third, fifth, seventh, ninth, and eleventh harmonics), to reduce the complexity of the required procedure and to allocate few computational resource in the Field Programmable Gate Array (FPGA) based control board. Therefore, the voltage waveform taken into account is different respect traditional voltage waveform. The same concept, known as “voltage cancelation”, used for single-…
Optical diagnostic of temperature in rocket engines by coherent Raman techniques
2004
Abstract This article reviews the study of Raman line shapes of molecular species involved in reactive media, such flames or engines, at high temperature and high pressure. This study is of interest from a fundamental as well as from a practical point of view with regards to the CARS temperature diagnostic of GH2–LOX combustion systems. We will particularly draw attention to recent investigations by means of Stimulated Raman Spectroscopy (SRS) in H2–H2O mixtures at temperature up to 1800 K. Whereas H2–X systems usually exhibit large inhomogeneous effects, due to the speed dependence of the collisional parameters, the absence of such apparent inhomogeneous signatures in the H2–H2O system all…
Measuring International Competitiveness of Romania by Using Porter's Diamond and Revealed Comparative Advantage
2013
Abstract International competitiveness generate a number of challenges because creates profitability for companies, welfare for citizens, sustainable prosperity for the economy as long as it is perceived as a constructive concept. The aim of present paper is to identify the international competitiveness of Romania by analyze the competitive advantage and disadvantage according to Porter‘s Diamond, on one hand, and by calculate revealed comparative advantage according to Balasa, on the other hand. The results show that Romanian has more competitive disadvantage than competitive advantage, even if by comparison with European Union, Romania has some revealed comparative advantage.
Review of gas diffusion cathodes for alkaline fuel cells
2009
Abstract This paper gives a technical background to alkaline fuel cells (AFCs), introducing the advantages and drawbacks of the technology. AFCs offer the potential for low cost, mass producible fuel cells, without the dependency on platinum based catalysts and (currently) expensive membrane electrolytes. The AFC uses relatively low cost electrolytes based on aqueous bases such as potassium hydroxide. The inherent CO 2 sensitivity of the electrolyte can be addressed by filtering out the CO 2 from the air intake using a simple scrubber and periodically replacing the liquid electrolyte. A review of the state-of-the-art in gas diffusion cathode development is given. The overall cell performanc…