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Tow-stage configurations used in photovoltaic (PV) architectures (microinverter, string inverter or multistring inverter), are commonly used because of the advantages in front of mismatch conditions. In case of a partial shading scenario (produced by cloudy days and dust accumulation), two-stage architectures reach higher efficiencies compared with the traditional central inverter. It is because,...
Structural Health Monitoring (SHM) is one of the most interesting research topics into civil engineering field. SHM consists of the processing and interpretation of the acquired data of a structure in order to evaluate its condition. An accurate early damage detection is an important task in SHM, as a reduction of both required time and repairing costs can be achieved. One of the most common damage...
Microgrids have become an alternative to increase the controlability and resilience of the electrical system due to the local and efficient energy management they provide. Additionally, when the microgrid has a main DC bus it does not require synchronization hence the control scheme is simplified allowing to improve the dynamics of currents and voltages. These DC microgrids are usually controlled...
This work describes a simple method to produce highly luminescent carbon quantum dots (CQDs) emitting blue or green light. The method consists of the carbonization of citric acid at 250 °C under ambient condition and a further surface functionalization. The UV-Vis spectrum of these carbon nanostructures exhibited a well-resolved absorption band at 320 nm which was attributed to the n-π∗ transition...
In this paper we propose a couple of fractional order observers for nonlinear commensurate fractional order systems i.e. a reduced order observer and a fractional Luenberger observer in the algebraic and differential setting. We introduce the Fractional Algebraic Observability (FAO) property, like a measurement degree of fractional observability of states variables. Finally a comparison between two...
The control of multiterminal HVDC systems based on local variables has shown a better performance, in terms of dynamical response and implementation simplicity, than constant DC voltage and droop control. However, power oscillations can be produced due to the interaction among different HVDC stations. In this paper, a modified control logic for this type of control is proposed in order to reduce the...
In this paper, we propose a new multiple ciphering scheme based on a Deficit Weighted Round Robin (DWRR) algorithm to improve the randomness results in the keystream generated by a stream cipher. This scheme has been implemented and tested in a Xilinx Virtex 7 FPGA. The randomness test results of the resulting keystream have proved that this scheme can be used to improve the quality of a stream cipher...
Real time monitoring of vegetation conditions is of paramount importance, particularly for food insecure countries, to detect possible crop and pastures production drops as early as possible. This monitoring is classically based on remote sensing indicators of vegetation conditions (typically NDVI and rainfall produced every ten days at a resolution of 1 km or more) and many web portals now offer...
High brightness semiconductor laser sources with modulation capacity are emerging candidates for an increasing number of applications. We have recently presented an integrated three section Master Oscillator Power Amplifier (MOPA) [1] to be used in space-borne Random Modulated Continuous Wave (RM-CW) Integrated Path Differential Absorption (IPDA) lidar systems for atmospheric CO2 detection [2]. The...
Numerous applications such as free space optical communications, metrology and differential absorption lidar systems require high brightness laser sources with spectral purity. Monolithically integrated Master Oscillator Power Amplifiers (MOPAs) are promising candidates to fulfil these requirements. In particular, a three-section bent mOpA at 1.5 μm was recently proposed as laser source for an integrated...
Decidability of the determinization problem for weighted automata over the semiring (ℤ∪{−∞}, max; +), WA for short, is a long-standing open question. We propose two ways of approaching it by constraining the search space of deterministic WA: k-delay and r-regret. A WA N is k-delay determinizable if there exists a deterministic automaton D that defines the same function as N and for all words α in...
Normally-on MOSFETs were fabricated on 3C-SiC epilayers (Si face) using high temperature (1300 °C) wet oxidation. XPS analysis found little carbon at the MOS interface yet the channel mobility (60 cm2/V.s) is considerably low. Si suboxides (SiOx, x<2) exist at the wet oxidised 3C-SiC/SiO2 interface, which may act as interface traps and degrade the conduction performance.
Two commercial 1.2 kV SiC MOSFETs have been extensively characterised from 30 to 320 K. The temperature dependence of their I/V characteristics, threshold voltage, and breakdown voltage has been examined and are presented in this paper. Overall, the measured characteristics of both devices demonstrate very similar temperature dependencies and it is shown that below ∼100 K any further decrease in temperature...
This paper presents the designs of second-order analog bandpass and bandstop filters using switched-capacitor techniques to achieve independent tunability of center frequency and bandwidth. The filter core is a lattice network that implements a structurally allpass section, in the sense that the transfer function remains allpass regardless of coefficient realization errors produced by fabrication...
In this work, we have used a new concept of sensor-based seed generator in order to generate the keys for a stream cipher based on a new algorithm mixing a Skew Tent Map and a Linear Feedback Shift Register. The cryptosystem has been implemented in a Xilinx Virtex 7 FPGA and has been proven to be fast and secure for application in IoT networks.
Structural analysis for the design of bridges begins by determining actions acting on the structure, which are distributed through the superstructure, causing particular effects for each structural element of composition. Vehicle load is the main live action acting on the superstructure of a vehicular bridge. To estimate the distribution of this charge in the structural elements, different distribution...
In this work, a fiber ring laser sensor has been employed to analyze the influence of passive Er-doped fiber acting as saturable absorber. Lasing modes of fiber ring lasers can be reduced by properly locating a saturable absorber that narrows the spectral width of the FBG that selects the lasing wavelength. Employing commercial Er-doped fiber, different configurations have been evaluated, reaching...
Non-invasive electrocardiographic imaging has been seen as a painless and economic method to map the electrical functions of the heart. However, it is still a great challenge to obtain accurate reconstruction of cardiac electrical activity from body surface potentials (BSP) due to the ill-posed behaviour of the cardiac inverse-problem. Though some advances have been made in solving the inverse-problem,...
The impedance source inverter family has become one of the most interesting alternatives for wind and photo-voltaic energies applications which require high conversion ratio. The main drawback of these inverters is related to the modulation signal which must be used to control the output current and voltage conversion ratio simultaneously. To deal with this problem several modulation techniques and...
Solar PV energy systems have become one of the most researched and developed renewable energy alternatives due to the long lifetime and reduced maintenance of its components. However, considering the low efficiency in the conversion from light to electrical energy, the optimization of the power electronics converters which deliver the energy from the panels to the electrical grid has fundamental importance...
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