NY-1920: Hugh Ferriss y la utopía vertical

Peer Reviewe

Coherent carrier dynamics in semiconductor superlattices

We investigate the coherent dynamics of carriers in semiconductor superlattices driven by ac-dc electric fields. We solve numerically the time-dependent effective-mass equation for the envelope function. We find that carriers undergo Rabi oscillations when the driving frequency is close to the separation between minibands.Comment: REVTEX (6 pages) and 3 figures (PostScript). Accepted in Physics Letters

Relación entre ética laboral y liderazgo desde la perspectiva de los colaboradores de un banco en Chiclayo 2022

Los fraudes en las empresas se asocian con la apropiación indebida de activos afectando las operaciones organizacionales; por tanto, el estudio planteó como objetivo general determinar la relación de la ética laboral y el liderazgo desde la perspectiva de los colaboradores de un Banco en la ciudad de Chiclayo, el enfoque metodológico es cuantitativo, correlacional, utilizando la técnica de la encuesta con una muestra de 97 colaboradores, en dónde el 52.6% son del género femenino, y el 47.4% son del género masculino de los cuales el 52.6% se encontraban en un rango de 45 – 64 años, quienes fueron evaluados mediante la escala de ética laboral y la escala de liderazgo. Los resultados demuestran que existe una relación positiva alta entre la ética laboral y el liderazgo (r=0.731). Concluye que, es necesario alentar el liderazgo desde la ética para desarrollar capacidades que puedan beneficiar a la entidad

Efficiency of an Exciplex DBD Lamp Excited Under Different Methods

Three different electrical generators have been designed and used to supply an exciplex dielectric barrier discharge lamp in order to elucidate the influence of each one of these supplying strategies over the system performance ; the first method consists on supplying the lamp with short bipolar voltage pulses; the second and third methods are based on semiresonant converters were current pulses, of controlled duration and magnitude, are injected into the lamp. For each one of the generators, measurements of the lamp and supply efficiency, are performed and analyzed, at different levels of power (up to 130 W) and operating frequencies (60–90 kHz). From the experimental results, the pulsed voltage-mode approach has allowed obtaining the highest lamp efficiency (7%), yet the maximum supply efficiency is offered by the resonant mode supplies. On the basis of the lamp and the supply efficiencies, the whole system performance is analyzed

Polyanionic carbosilane dendrimers against viral infections: Human Immunodeficiency Virus Type 1, Herpes Simplex Type 2 and Respiratory Syncytial Virus

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 14-12-2017Esta tesis tiene embargado el acceso al texto completo hasta el 14-06-2019This thesis has been conducted at Laboratorio de Inmuno-Biología Molecular, Sección de Inmunología and Spanish HIV HGM Biobank at Hospital General Universitario Gregorio Marañón under the direction of Mª Ángeles Muñoz Fernández. This thesis has been (partially) funded by the RD12/0017/0037 and RD16/0025/0019, projects as part of Acción Estratégica en Salud, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (2008-2011; 2013-2016) and cofinanced by Instituto de Salud Carlos III (Subdirección General de Evaluación) and Fondo Europeo de Desarrollo Regional (FEDER), RETIC PT13/0010/0028, Fondo de Investigación Sanitaria (FIS) (grant number PI16/01863), CYTED 214RT0482 and EPIICAL project. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, the Consolider Program, and CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fun

Alimentation de puissance d'une lampe exciplexe à décharge à barrière diélectrique, en vue du contrôle du rayonnement

Ce travail présente une approche raisonnée pour alimenter en énergie électrique une lampe exciplexe à décharge à barrière diélectrique, en vue du contrôle du rayonnement UV produit. Un modèle électrique de la lampe a été développé et identifié, permettant d'étudier les interactions alimentation-lampe. Ce modèle est également utilisé pour effectuer la synthèse des structures candidates du convertisseur ; celles-ci, procèdent à un contrôle direct du courant dans la lampe. Une étude expérimentale a été menée afin de valider l'approche théorique. Les degrés de liberté apportés par le réglage des convertisseurs sont exploités, pour analyser la corrélation entre le courant du gaz et le rayonnement UV. ABSTRACT : This work presents a reasoned approach to deliver electric energy into a dielectric barrier discharge exciplex lamp, with the aim of controlling its UV emission. An electrical model of the lamp has been developed and identified, in order to study the interactions between the power supply and the lamp. This model is also employed to perform the synthesis of the candidate structures for the converter. These structures, accomplish a direct control of the lamp current. An experimental study was achieved to validate the theoretical approach. The degrees of freedom of these converters are exploited to analyze the correlation between the lamp current and the UV emissio

Machine Learning for RANS Turbulence Modelling of Variable Property Flows

This paper presents a machine learning methodology to improve the predictions of traditional RANS turbulence models in channel flows subject to strong variations in their thermophysical properties. The developed formulation contains several improvements over the existing Field Inversion Machine Learning (FIML) frameworks described in the literature, as well as the derivation of a new modelling technique. We first showcase the use of efficient optimization routines to automatize the process of field inversion in the context of CFD, combined with the use of symbolic algebra solvers to generate sparse-efficient algebraic formulas to comply with the discrete adjoint method. The proposed neural network architecture is characterized by the use of an initial layer of logarithmic neurons followed by hyperbolic tangent neurons, which proves numerically stable. The machine learning predictions are then corrected using a novel weighted relaxation factor methodology, that recovers valuable information from otherwise spurious predictions. The study uses the K-fold cross-validation technique, which is beneficial for small datasets. The results show that the machine learning model acts as an excellent non-linear interpolator for DNS cases well-represented in the training set, and that moderate improvement margins are obtained for sparser DNS cases. It is concluded that the developed machine learning methodology corresponds to a valid alternative to improve RANS turbulence models in flows with strong variations in their thermophysical properties without introducing prior modeling assumptions into the system

An Alternate Representation of the Vector of Apparent Power and Unbalanced Power in Three-Phase Electrical Systems

[EN] Low-voltage distribution systems are typically unbalanced. These ine¿ciencies cause unbalanced powers that can significantly increase the apparent power of the system. Analysing and measuring these ine¿cient powers appropriately allows us to compensate for them and obtain a more e¿cient system. Correcting the imbalance at some nodes can worsen the rest of the system; therefore, it is essential that all nodes are analysed such that action can be taken when necessary. In most studies, the unbalanced power is measured from the modulus. Other more recent studies have proposed phasor expressions of unbalanced powers; however, in both cases, these are not enough to address the compensation of unbalanced powers in systems with unbalanced voltages. In this work, a di¿erent representation of the vector expressions for analysis of the unbalanced powers and the apparent powers of the three-phase linear systems is proposed. Additionally, these vector expressions are extended to nonlinear systems to quantify the harmonic apparent powers. These expressions have been formulated from the power of Buchholz and are valid for systems with unbalanced voltages and currents. To help understand the use of the proposed formulation, a practical case of a three-phase four-wire system with unbalanced loads and voltages is demonstrated.This work is supported by the Spanish Ministry of Science, Innovation and Universities (MICINN) and the European Regional Development Fund (ERDF) under Grant RTI2018-100732-B-C21.Blasco Espinosa, PA.; Montoya-Mira, R.; Diez-Aznar, J.; Montoya Villena, R. (2020). An Alternate Representation of the Vector of Apparent Power and Unbalanced Power in Three-Phase Electrical Systems. Applied Sciences. 10(11):1-16. https://doi.org/10.3390/app10113756S1161011Emanuel, A. E. (1993). On the definition of power factor and apparent power in unbalanced polyphase circuits with sinusoidal voltage and currents. IEEE Transactions on Power Delivery, 8(3), 841-852. doi:10.1109/61.252612Willems, J. L. (2004). Reflections on Apparent Power and Power Factor in Nonsinusoidal and Polyphase Situations. IEEE Transactions on Power Delivery, 19(2), 835-840. doi:10.1109/tpwrd.2003.823182Emanuel, A. E. (1999). Apparent power definitions for three-phase systems. IEEE Transactions on Power Delivery, 14(3), 767-772. doi:10.1109/61.772313Czarnecki, L. S. (1994). Misinterpretations of some power properties of electric circuits. IEEE Transactions on Power Delivery, 9(4), 1760-1769. doi:10.1109/61.329509Kersting, W. H. (2001). Causes and effects of unbalanced voltages serving an induction motor. IEEE Transactions on Industry Applications, 37(1), 165-170. doi:10.1109/28.903142Pillay, P., & Manyage, M. (2006). Loss of Life in Induction Machines Operating With Unbalanced Supplies. IEEE Transactions on Energy Conversion, 21(4), 813-822. doi:10.1109/tec.2005.853724Poblador, M. L. A., & Lopez, G. A. R. (2013). Power calculations in nonlinear and unbalanced conditions according to IEEE Std 1459-2010. 2013 Workshop on Power Electronics and Power Quality Applications (PEPQA). doi:10.1109/pepqa.2013.6614957Langella, R., Testa, A., & Emanuel, A. E. (2012). Unbalance Definition for Electrical Power Systems in the Presence of Harmonics and Interharmonics. IEEE Transactions on Instrumentation and Measurement, 61(10), 2622-2631. doi:10.1109/tim.2012.2209909Kukačka, L., Kraus, J., Kolář, M., Dupuis, P., & Zissis, G. (2016). Review of AC power theories under stationary and non‐stationary, clean and distorted conditions. IET Generation, Transmission & Distribution, 10(1), 221-231. doi:10.1049/iet-gtd.2015.0713Chicco, G., Postolache, P., & Toader, C. (2007). Analysis of Three-Phase Systems With Neutral Under Distorted and Unbalanced Conditions in the Symmetrical Component-Based Framework. IEEE Transactions on Power Delivery, 22(1), 674-683. doi:10.1109/tpwrd.2006.887095Paap, G. C. (2000). Symmetrical components in the time domain and their application to power network calculations. IEEE Transactions on Power Systems, 15(2), 522-528. doi:10.1109/59.867135León-Martínez, V., & Montañana-Romeu, J. (2018). Formulations for the apparent and unbalanced power vectors in three-phase sinusoidal systems. Electric Power Systems Research, 160, 37-43. doi:10.1016/j.epsr.2018.01.028Castilla, M., Bravo, J. C., Ordonez, M., & Montano, J. C. (2008). Clifford Theory: A Geometrical Interpretation of Multivectorial Apparent Power. IEEE Transactions on Circuits and Systems I: Regular Papers, 55(10), 3358-3367. doi:10.1109/tcsi.2008.924885Diez, J. M., Blasco, P. A., & Montoya, R. (2016). Formulation of phasor unbalance power: application to sinusoidal power systems. IET Generation, Transmission & Distribution, 10(16), 4178-4186. doi:10.1049/iet-gtd.2016.0730Tongxin Zheng, Makram, E. B., & Girgis, A. A. (2003). Evaluating power system unbalance in the presence of harmonic distortion. IEEE Transactions on Power Delivery, 18(2), 393-397. doi:10.1109/tpwrd.2002.807460Mohamadian, S., & Shoulaie, A. (2011). Comprehensive Definitions for Evaluating Harmonic Distortion and Unbalanced Conditions in Three- and Four-Wire Three-Phase Systems Based on IEEE Standard 1459. IEEE Transactions on Power Delivery, 26(3), 1774-1782. doi:10.1109/tpwrd.2011.2126609Blasco, P. A., Montoya-Mira, R., Diez, J. M., Montoya, R., & Reig, M. J. (2019). Compensation of Reactive Power and Unbalanced Power in Three-Phase Three-Wire Systems Connected to an Infinite Power Network. Applied Sciences, 10(1), 113. doi:10.3390/app10010113Montoya-Mira, R., Blasco, P. A., Diez, J. M., Montoya, R., & Reig, M. J. (2020). Unbalanced and Reactive Currents Compensation in Three-Phase Four-Wire Sinusoidal Power Systems. Applied Sciences, 10(5), 1764. doi:10.3390/app10051764Salmerón, P., Vázquez, J. R., Herrera, R. S., & Litrán, S. P. (2007). Apparent power and power factor in unbalanced and distorted systems. Applications in three phase load compensations. Renewable Energy and Power Quality Journal, 1(05), 442-447. doi:10.24084/repqj05.31

Parametric study of dielectric barrier discharge excimer UV lamps supplied with controlled square current pulses

A parametric study of a system dedicated to non-coherent UV emission, by means of DBD excilamps, supplied by a controlled square shape current source is proposed. The presentation highlights on the one hand the performances experimentally obtained by combining together a set of 20 different bulbs with different diameters, gap and wall thicknesses (all the bulbs have the same length and are filled with the same Xe-Cl gas mixture), with different electrical power supplying conditions: magnitude, frequency (in the 30 kHz – 200 kHz range) and duty cycle of the square shape current pulses injected into the bulb. The performances concern the average UV power, the efficiency of the bulb conversion (electrical power to UV) and the adjustability of the power. On the second hand, we present design considerations of the power supply which has been especially developed for the purpose of these experiments

Propuesta para la creación de la Cooperativa de Ahorro y Crédito de trabajadores de la Universidad Católica Santo Toribio de Mogrovejo en la ciudad de Chiclayo

En los últimos años, el movimiento cooperativista ha generado un crecimiento positivo de participación en la sociedad en búsqueda de la satisfacción de las necesidades de sus asociados. Este efecto ha sido extensivo a todos los sectores laborales, como el de educación, donde la necesidad de financiamiento de sus trabajadores permitió cuestionar si: ¿es factible la creación de una Cooperativa de Ahorro y Crédito de trabajadores de la Universidad Católica Santo Toribio de Mogrovejo?. Para esto se realizó un estudio de mercado donde se identificó un alto índice de capacidad crediticia y disposición al financiamiento rápido a bajo costo. Además, se elaboró un análisis organizativo, donde se elaboraron las estructuras orgánicas de la entidad financiera, los manuales organizacionales y el estatuto, instrumentos claves para el manejo óptimo de una cooperativa. Respecto a la evaluación financiera, la propuesta muestra factibilidad, ya que el VAN es de S/ 246,740