Impact of Modulation Methods on the Trade-Off between Investment and Operation Costs of a Medium-Voltage MMC-based STATCOM

The Modular Multilevel Converter (MMC) has become a preferred topology in HVDC applications due to its full controllability and the huge number of voltage steps. The excellent waveform generation, even at low switching frequencies, makes the MMC also very attractive for medium-voltage applications. In this context, both the converter design and the modulation methods need to be properly studied. Minimum switching frequencies are achieved by appropriate modulation, however, sufficient energy needs to be stored in the capacitors. This is particularly a challenge for STATCOM applications because the stored energy in the system needs to be controlled from the ac grid. In this paper different modulation methods with various capacitor designs are investigated for this application to find an optimum trade-off between capacitor design (investment costs) and switching frequency (operation costs). The appropriate MMC design and operation have been proven by simulation and experimental results showing excellent waveforms without additional filtering

Health Tourism Contribution to the Structural Dynamics of the Territorial Systems with Tourism Functionality

AbstractThe study aims to identify the role of health tourism (SPA) in developing the territorial systems, characterized by the tourism functionality, in Romania, for the period 2000-2012, a period marked by spectacular transformations, especially for this economic sector. Tourism has now become a true economic engine, generating an increase in the functional complexity of the territorial system, which is based on exploiting tourism resources. To quantify how tourism has contributed to the economic development of these territorial systems in Romania a database of NACE codes was set up, specific for the tourism activity, for the period 2000-2012, for territorial mainframe systems with functionality resort. Based on this statistical support analyzes on the evolution of the number of companies, number of employees, turnover and profit were made. The results show the important role of health tourism in generating multiplier effects on other components of the economic subsystem. They were defined two categories of territorial systems: territorial systems where tourism plays a complementary role function and territorial systems in which health tourism has a preeminent role in the local economy

THE IMPACT OF DIGITAL EDUCATION TOWARDS A SUSTAINABLE DIGITAL CONSUMER IN THE ERA OF CIRCULAR ECONOMY

A more sustainable economy and society presume more sustainable behavior in terms of consumption. A change in this behavior could be brought by a change in demand. In other words, a change in the demand could be facilitated by one’s financial and digital education. The circular economy implies the reuse and recycling of products and materials over and over again; thus, the life cycle of products and materials is extended. Engaging in recycling should have future benefits. Recycling behavior and sustainability are interrelated, the recycling process is viewed as a key issue in sustainability and prevails as pro-environmental consumer behavior. It is already known that significant changes in individual behavior are essential for society to move toward sustainability. This paper aims to explore from a quantitative perspective if digital education has an impact on consumer behavior in terms of sustainability in the era of the circular economy. This research is useful for all providers, consumers, and stakeholders involved in different businesse

THE IMPACT OF DIGITAL EDUCATION TOWARDS A SUSTAINABLE DIGITAL CONSUMER IN THE ERA OF CIRCULAR ECONOMY

A more sustainable economy and society presume more sustainable behavior in terms of consumption. A change in this behavior could be brought by a change in demand. In other words, a change in the demand could be facilitated by one’s financial and digital education. The circular economy implies the reuse and recycling of products and materials over and over again; thus, the life cycle of products and materials is extended. Engaging in recycling should have future benefits. Recycling behavior and sustainability are interrelated, the recycling process is viewed as a key issue in sustainability and prevails as pro-environmental consumer behavior. It is already known that significant changes in individual behavior are essential for society to move toward sustainability. This paper aims to explore from a quantitative perspective if digital education has an impact on consumer behavior in terms of sustainability in the era of the circular economy. This research is useful for all providers, consumers, and stakeholders involved in different businesse

The Effect of SEBS/Halloysite Masterbatch Obtained in Different Extrusion Conditions on the Properties of Hybrid Polypropylene/Glass Fiber Composites for Auto Parts

Masterbatches from a linear poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and halloysite nanotubes (HNT-QM) were obtained in different conditions of temperature and shear using two co-rotating twin-screw extruders. The influence of screw configuration and melt processing conditions on the morpho-structural, thermal and mechanical properties of masterbatches at macro and nanoscale was studied. A good dispersion of halloysite nanotubes and better thermal stability and tensile and nanomechanical properties were obtained at a lower temperature profile and higher screw speed. The effect of masterbatches, the best and worst alternatives, on the properties of a polypropylene (PP)–glass fiber (GF) composite was also evaluated. Double hardness, tensile strength and modulus and four times higher impact strength were obtained for PP/GF composites containing masterbatches compared to pristine PP. However, the masterbatch with the best properties led further to enhanced mechanical properties of the PP/GF composite. A clear difference between the effects of the two masterbatches was obtained by nanoindentation and nanoscratch tests. These analyses proved to be useful for the design of polymer composites for automotive parts, such as bumpers or door panels. This study demonstrated that setting-up the correct processing conditions is very important to obtain the desired properties for automotive applications

Low-Temperature Synthesis and Thermodynamic and Electrical Properties of Barium Titanate Nanorods

Studies regarding the morphology dependence of the perovskite-type oxides functional materials properties are of recent interest. With this aim, nanorods (NRs) and nanocubes (NCs) of barium titanate (BaTiO3) have been successfully synthesized via a hydrothermal route at temperature as low as 408 K, employing barium acetate, titanium isopropoxide, and sodium hydroxide as reagents without any surfactant or template. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD), used for the morphology and structure analyses, showed that the NRs were formed by an oriented attachment of the NCs building-blocks with 20 nm average crystallites size. The thermodynamic properties represented by the relative partial molar free energies, enthalpies, and entropies of the oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressure of oxygen, indicated that NRs powders have lower oxygen vacancies concentration than the NCs. This NRs characteristic, together with higher tetragonallity of the structure, leads to the enhancement of the dielectric properties of BaTiO3 ceramics. The results presented in this work show indubitably the importance of the nanopowders morphology on the material properties