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The evolution of electricity in Romania took place in the last century. This paper presents the development of electricity sector in a seasonal evolution form. This approach has a cyclical character and highlights options for the future. The main stages of evolution, with a duration of several decades each, are associated with the four seasons: winter, spring, summer and autumn. The similarity features relate to the quantitative and qualitative ways of electricity production evolution, which is in line with the technological development level of a country. The conclusions highlight the idea of proactive rational action with regard to ensuring in the future the necessary human resources.

AbstractThe article aims to bring into discussion architecture as cultural ingredient, and to investigate the current status of the consecrated or of the recently established heritage (patrimony) as well as to ask questions about the contribution that the experiments of professionals may have in the space of the city. If the architecture educates, innovates, launches questions and controversies, it continuously complements the in situ image of the place, city, or, at global level, of the conceptual, technological and innovative developments. Whether it addresses the town-dweller, the user, the tourist or the curious, architecture continually writes new expressions in city space, negotiating with tradition, arguing and reconstructing fragments of urban life. How much is it accepted, pleasant / loved or challenged - or how much it pleases the initial or subsequent demands, are sensitive discussions in the dedicated domain. Regarded at the level of the object or the ensemble, architecture can be a scenographic background for the city or a piece in the set, a point on a route - landmark of urban paths, or simply an unfolded surface which accommodates activities. From level of the area of discussion, architecture is also another space, the one of debates - from the principles in line with the problems of the world for which it strives to find an answer to the philosophical, the local and the ones related to the built application.

Abstract An alkaline earth boro-aluminosilicate glass (Eagle XG), a soda-lime glass, and a light-weight polyethylene-terephthalate (PET) foil, used as typical substrates for photovoltaics, were treated by an energetic proton beam (3 MeV, dose 106–107 Gy) corresponding to approx. 30 years of operation at low Earth orbit. Properties of the irradiated substrates were characterized by atomic force microscopy, optical absorption, optical diffuse reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and terahertz (THz) spectroscopy. Minimal changes of optical and morphological properties are detected on the bare Eagle XG glass, whereas the bare PET foil exhibits pronounced increase in optical absorption, generation of photoluminescence, as well as mechanical bending. On the other hand, the identical substrates coated with Indium-tin-oxide (ITO), which is a typical material for transparent electrodes in photovoltaics, exhibit significantly higher resistance to the modifications by protons while ITO structural and electronic properties remain unchanged. The experimental results are discussed considering a potential application of these materials for missions in space.

Nowadays, companies are in the process of renewing their manufacturing lines by equipping them with modern five-axis CNC (computer numerical control) machining centers. The decision to select between different five-axis CNC machining centers, with similar technological capabilities is a difficult process, so the main goal of this work was to develop a method for assisting it. The proposed approach relies on seven technical criteria, four quantitative ones (traverse speed, thrust, spindle power, and spindle speed) which can be expressed by crisp numerical values, while the other three (flexibility, operation easiness, and setup time) are qualitative ones. The analytic hierarchy process (AHP) was used for ordering four variants of five-axis CNC milling machining centers. The qualitative criteria were processed using fuzzy systems to be expressed by crisp numerical values, suitable for AHP. Finally, the four variants of five-axis CNC milling machining centers were hierarchized and the best one was chosen. A sensitivity analysis was also unfolded to certify the robustness of the AHP.

The paper presents the hydraulic system for the operation of a lifting platform in two constructive variants. One of the drive schemes is with energy recovery. A hydraulic, energy and economic analysis is performed for the two proposed drive schemes using the numerical simulation technique. The conclusions are useful in design and exploitation. The platform can be used for various applications in agricultural farms or construction.

Optimal control is a key element in today’s control applications, being widely used in many different fields. The linear-quadratic regulator (LQR) is an optimal control method which is frequently used in optimal control applications because of its efficiency and simplicity. Having this in mind, the authors studied the level control of a cascaded multitank system using the LQR algorithm. The approach of the authors consists of a piecewise linearization method, converting this nonlinear problem into a linear one. Results show that LQR is a very efficient method for this type of system, yielding good performances with reduced controller effort.

Abstract The sustainable indicators are characterized by a low degree of aggregation and a high amount of information. An indicator must show a synthetic representation of a real environmental, by using a value or a parameter, so that they can be easily used by policy makers. It is necessary to connect, therefore, the various systems in an appropriately integrated sustainable system. The indicators need to be aggregated based on the structure of the data. Each indicator must to be defined through a weight with reference to another weighted indicator. In this paper is illustrated the calculation of the assigned weights that uses a procedure based on fuzzy logic and to define a model that allows us to estimate the sustainability of a city. The final result is, therefore, a combination of values assigned by expert opinion for the various criteria, processed using fuzzy logic to obtain a weight with significant objectivity and as it is possible to estimate the sustainability of the city through the weights.

Cost-effective CO2 capture and storage (CCS) is critical for the rapid global decarbonization effort recommended by climate science. The increase in levelized cost of electricity (LCOE) of plants with CCS is primarily associated to the large energy penalty involved in CO2 capture. This study therefore evaluates three high-efficiency CCS concepts based on integrated gasification combined cycles (IGCC): (1) gas switching combustion (GSC), (2) GSC with added natural gas firing (GSC-AF) to increase the turbine inlet temperature, and (3) oxygen production pre-combustion (OPPC) that replaces the air separation unit (ASU) with more efficient gas switching oxygen production (GSOP) reactors. Relative to a supercritical pulverized coal benchmark, these options returned CO2 avoidance costs of 37.8, 22.4 and 37.5 €/ton (including CO2 transport and storage), respectively. Thus, despite the higher fuel cost and emissions associated with added natural gas firing, the GSC-AF configuration emerged as the most promising solution. This advantage is maintained even at CO2 prices of 100 €/ton, after which hydrogen firing can be used to avoid further CO2 cost escalations. The GSC-AF case also shows lower sensitivity to uncertain economic parameters such as discount rate and capacity factor, outperforms other clean energy benchmarks, offers flexibility benefits for balancing wind and solar power, and can achieve significant further performance gains from the use of more advanced gas turbine technology. Based on all these insights, the GSC-AF configuration is identified as a promising solution for further development.