Search results for "WM"
showing 10 items of 175 documents
Switching Frequency Effects on the Efficiency and Harmonic Distortion in a Three-Phase Five-Level CHBMI Prototype with Multicarrier PWM Schemes: Expe…
2022
The current climatic scenario requires the use of innovative solutions to increase the production of electricity from renewable energy sources. Multilevel Power Inverters are a promising solution to improve the penetration of renewable energy sources into the electrical grid. Moreover, the performance of MPIs is a function of the modulation strategy employed and of its features (modulation index and switching frequency). This paper presents an extended and experimental analysis of three-phase five-level Cascaded H-Bridges Multilevel Inverter performance in terms of efficiency and harmonic content considering several MC PWM modulation strategies. In detail, the CHBMI performance is analyzed …
The genus Sympetrum Newmann, 1833 (Odonata Libellulidae)
2020
The genus Sympetrum Newmann, 1833 (Odonata Libellulidae)
Introducing Thermal Inertia for Monitoring Snowmelt Processes With Remote Sensing
2019
Thermal inertia has been successfully used in remote sensing applications that span from geology, geomorphology to hydrology. In this paper, we propose the use of thermal inertia for describing snow dynamics. Two different formulations of thermal inertia were tested using experimental and simulated data related to snowpack dynamics. Experimental data were acquired between 2012 and 2017 from an automatic weather station located in the western Italian Alps at 2,160 m. Simulations were obtained using the one‐dimensional multilayer Crocus model. Results provided evidences that snowmelt phases can be recognized, and average snowpack density can be estimated reasonably well from thermal inertia o…
Implementation on NI-SOM sbRIO-9651 and Experimental Validation of Multi-Carrier PWM Techniques for Three-Phase Five Level Cascaded H-Bridge Inverter
2021
Multilevel Power Inverters (MPIs) represent a valid solution to improve the performances of energy production systems from renewable energy sources. Furthermore, the use of novel FPGA control systems allows simplifying the implementation of multicarrier PWM techniques for MPIs with computational benefits. This paper describes the implementation of several multicarrier PWM techniques on NI-SOM sbRIO-9651 for the control of a three-phase five-level cascaded H-bridge inverter. In detail, sbRIO-9651 is a control system in the field of Power Electronics and Drives (PED) programmable in the LabVIEW graphical programming environment. The paper is focused on modulation techniques implementation, te…
Experimental Comparative Analysis of Efficiency and THD for a Three-phase Five-level Cascaded H-Bridge Inverter Controlled by Several MC-PWM Schemes
2021
Cascaded H-Bridges Multilevel Inverters are an innovative and promising solution in different application fields. This topology allows obtaining an improvement in the performance (e.g. reduced harmonic content, the low voltage stress on power components, and high efficiency) in respect to the traditional two-level inverters. In this context, the Multicarrier-PWM strategies play an important role thanks to their features. This paper presents an experimental investigation on the performance of a three-phase five-level Cascaded H-Bridge inverter by using different PWM modulation strategies. In particular, the paper is focused on the experimental validation of the main features of Multicarrier …
Propiedad y riesgo en los inicios de la expansión citrícola valenciana durante el último tercio del siglo XIX
1998
This paper analyses factors linked to the level of economic development that influenced the rate at which part of the Valencian agriculture transformed in line with the incentives generated by the increase in demand. It focuses on the expansion of orange tree operations during the last third of the 19th century where production options are typified according to their economic results, the risk, relationship with the market, and the production resource needs. The impact of these factors depended on the size of the individual`s property. The results thus suggest that smaller landowners preferred crops that were more labour intensive that helped their auto-reproduction whereas the larger ones …
Which Factors Favour Becoming a Technology-Based & Highly Innovative Firm? The Role of Knowledge, Technological and Managerial Capabilities, …
2018
Which resources and capabilities ease the change to become a Technology-Based and Highly Innovative Firm – TB&InnF –, focused in the creation of value to market? We analyse this question using a novel data panel assembled for 326 Spanish industrial firms, along the period 1984-2012. Our findings show the probability of becoming a TB&InnF growths when firms are able to accumulate a high endowment of knowledge and technological capabilities, and a managerial team with: experience, strong power position and previous technical and managerial education. Results also indicate the CEO´s educational profile in management is preferable to a pure technical profile, because this complements firm´s kno…
How technology-based firms become also highly innovative firms? The role of knowledge, technological and managerial capabilities, and entrepreneurs’ …
2019
To what extent is the likelihood that a Technology-Based Firm – TBF – turns into a Technology-Based and Highly Innovative Firm – TB&InnF – is influenced by technical capabilities or managerial capabilities and education background? We analyse this question using a novel data panel assembled for 326 Spanish industrial firms, along the period 1998–2014. Our findings show the probability of becoming a TB&InnF growths when firms are able to accumulate a high endowment of knowledge and technological capabilities, and a managerial team with experience, a strong power position and previous technical or managerial education background. Results also indicate the CEO's educational profile in manageme…
Estimation of Value-at-Risk on Romanian Stock Exchange Using Volatility Forecasting Models
2013
This paper aims to analyse the market risk (estimated by Value-at-Risk) on the Romanian capital market using modern econometric tools to estimate volatility, such as EWMA, GARCH models. In this respect, I want to identify the most appropriate volatility forecasting model to estimate the Value-at-Risk (VaR) of a portofolio of representative indices (BET, BET-FI and RASDAQ-C). VaR depends on the volatility, time horizon and confidence interval for the continuous returns under analysis. Volatility tends to happen in clusters. The assumption that volatility remains constant at all times can be fatal. It is determined that the most recent data have asserted more influence on future volatility th…
Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller
2021
This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…