U(1) Noncommutative Gauge Fields and Magnetogenesis

The connection between the Lorentz invariance violation in the lagrangean context and the quantum theory of noncommutative fields is established for the U(1) gauge field. The modified Maxwell equations coincide with other derivations obtained using different procedures. These modified equations are interpreted as describing macroscopic ones in a polarized and magnetized medium. A tiny magnetic field (seed) emerges as particular static solution that gradually increases once the modified Maxwell equations are solved as a self-consistent equations system.Comment: 4 page

Arcillas del valle del Guadalquivir empleadas como soporte de azulejos en la industria sevillana. II

The Physical-chemical study is continued and also that of the technological properties of ceramic interest of thirteen samples of clays from Santiponce, Dos Hermanas and Villanueva del Río y Minas, in the province of Sevilla and from Calera de León in the province of Badajoz. In this work, the smaller fraction of 1,12 micras is studier mmeralogically, and from the ceramic point of view the fraction smaller than 1.12 mm.Se continúa el estudio fisicoquímico y de las propiedades tecnológicas de interés cerámico de 13 muestras de arcillas procedentes de Santiponce, Dos Hermanas y Villanueva del Río y Minas, en la provincia de Sevilla, y de Calera de León, en la provincia de Badajoz. En este trabajo se estudia mineralógicamente la fracción menor de 1,12 micras y desde el punto de vista cerámico la fracción menor de 0,12 mm

Crystal engineering using functionalized adamantane

We performed a first principles investigation on the structural, electronic, and optical properties of crystals made of chemically functionalized adamantane molecules. Several molecular building blocks, formed by boron and nitrogen substitutional functionalizations, were considered to build zincblende and wurtzite crystals, and the resulting structures presented large bulk moduli and cohesive energies, wide and direct bandgaps, and low dielectric constants (low-$\kappa$ materials). Those properties provide stability for such structures up to room temperature, superior to those of typical molecular crystals. This indicates a possible road map for crystal engineering using functionalized diamondoids, with potential applications ranging from space filling between conducting wires in nanodevices to nano-electro-mechanical systems

Nonlinear Direct Torque Control of Interior Permanent Magnet Synchronous Motor Drive

This paper presents a nonlinear direct torque control (NDTC) strategy of interior permanent magnet synchronous motors (IPMSMs) for electric vehicle (EV) propulsion. The proposed NDTC scheme applies a nonlinear model of IPMSM to dynamically determine the optimal switching states that optimize the EV drivers’ decision to reduce the workload. Moreover, the proposed NDTC method has a simple control structure and can explicitly handle system constraints and nonlinearities. The performance evaluation is conducted via a prototype IPMSM test-bed with a TMS320F28335 DSP. Comparative experimental results provide the evidence of improvements of the proposed NDTC strategy over the conventional DTC strategy by indicating a fast torque response and an accurate speed tracking even under rapid speed change conditions

Low Voltage Ride through Enhancement for Wind Turbines Equipped With DFIG under Symmetrical Grid Faults

In modern power systems with significant penetration of wind-turbines (WTs), improvement of low voltage ride through (LVRT) capability of WTs equipped with doubly-fed induction generators (DFIGs) is an important issue. Thus, this paper proposes a low voltage ride through (LVRT) strategy, which comprise of a capacitor connected in series with an inductor both connected in parallel to a resistor. The configuration is then connected to a small series resistor via a pair of antiparallel-Thyristors. The circuit and its switching control scheme of the proposed LVRT circuit are designed to: minimize the transition times, maintain the RSC connection to the rotor-windings, and reduce oscillations of dc-link voltage. In this case, the capacitor is entitled to eliminate ripples generated in the rotor voltage while the inductor reduces the ripple in rotor current. Different fault conditions were studied to validate the performance of the proposed scheme using MATLAB/Simulink platform. Comparative results and analysis are presented with conventional LVRT strategies

Performance Analysis of Renewable Energy Resources in Rural Areas: A Case Study of Solar Energy

This paper presents an overview of the recent development trends of solar photovoltaic (PV) systems and the performance in the Tanzanian context. The two types of solar power generation that are considered in this paper are: i) solar PV systems and ii) concentrated solar power (CSP). The two are compared in terms of cost of energy and energy storage mechanism. Moreover, the effect of ambient temperature on the solar PV module is analyzed. In addition, a detailed analysis on using solar axis tracking to increase the power generation is also presented. The extent to which the cell surface temperature and orientation of the solar module which determine the power generation is modeled. Since Tanzania has the possibility to utilize the solar irradiance in the Coastal region to generate solar power, and therefore it is selected as the case study in this paper.&nbsp

A study of the Higgs and confining phases in Euclidean SU(2) Yang-Mills theories in 3d by taking into account the Gribov horizon

We study SU(2) three-dimensional Yang-Mills theories in presence of Higgs fields in the light of the Gribov phenomenon. By restricting the domain of integration in the functional integral to the first Gribov horizon, we are able to discuss a kind of transition between the Higgs and the confining phase in a semi-classical approximation. Both adjoint and fundamental representation for the Higgs field are considered, leading to a different phase structure.Comment: 12 pages. Version accepted for publication in the EPJ