6,331 research outputs found
Deformations of G_2 and Spin(7) Structures on Manifolds
We consider some infinitesmal and global deformations of G_2 structures on
7-manifolds. We discover a canonical way to deform a G_2 structure by a vector
field in which the associated metric gets "twisted" in some way by the vector
cross product. We present a system of partial differential equations for an
unknown vector field whose solution would yield a manifold with holonomy G_2.
Similarly we consider analogous constructions for Spin(7) structures on
8-manifolds. Some of the results carry over directly, while others do not
because of the increased non-linearity of the Spin(7) case.Comment: 51 pages, no figures, part of author's Ph.D. Thesis. Version 4:
Changes made after publication: There were sign errors in equations (2.26)
and (2.34) and in the proof of Lemma 2.4.3 that have now been corrected in
this arXiv version. Also Remark 3.3.7 was incorrect and has been removed.
Finally, hyperlinks now adde
Power Factor Corrector Design applied to an 85-kHz Wireless Charger
Wireless charging technology extends the battery autonomy by allowing more flexible and practical ways of recharging it even when the electric vehicle is on move. The frequency conversion, which is required to generate a kHz-ranged magnetic field, also leads to considerable harmonics. As a result, the power factor and the corresponding efficiency decrement. This paper proposes a Power Factor Corrector which overcomes this drawback. The most relevant feature of the designed Power Factor Corrector is that it does not need any electrical signal from the secondary side to adjust its operation properly. The simulation results show the ability of the proposed scheme to increment the system efficiency for different State-Of-Charge in the Battery.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Evolving Aesthetic Maps for a Real Time Strategy Game
Artículo publicado en congreso SEED'2013 (I Spanish Symposium on Entertainment Computing), Septiembre 2013, Madrid.This paper presents a procedural content generator method that have
been able to generate aesthetic maps for a real-time strategy game. The
maps has been characterized based on several of their properties in order
to de ne a similarity function between scenarios. This function has guided
a multi-objective evolution strategy during the process of generating and
evolving scenarios that are similar to other aesthetic maps while being
di erent to a set of non-aesthetic scenarios. The solutions have been
checked using a support-vector machine classi er and a self-organizing
map obtaining successful results (generated maps have been classi ed as
aesthetic maps)
La tutela penal de la función pública. Recientes tendencias legislativas y jurisprudenciales
tradicionalmente en España la corrupción ha sido un problema social de segundo orden tanto para la ciudadanía como para el legislador. Esto se ha reflejado en las escasas cifras de enjuiciamiento y condena por estos delitos. La ausencia de este tipo de datos se puede explicar por diferentes motivos, pero, principalmente, por la existencia de una corriente jurisprudencial que ha empleado determinados argumentos para evitar a toda costa sancionar a este tipo sujetos. Uno de los más empleados por los jueces penales ha sido el de los principios de la intervención mínima, concretamente, el del principio de subsidiariedad o ultima ratio. Así, los tribunales han eximido de responsabilidad a funcionarios criminalmente responsables afirmando la escasa gravedad de la conducta o la suficiencia de las instancias extrapenales para hacer frente de forma eficaz al comportamiento cometido. Sin embargo, tras el periodo de recesión económica, la conciencia sobre la dañosidad que irrogan estos delitos ha aumentado considerablemente, lo que ha dado lugar a que los tribunales hayan empezado a abandonar este razonamiento. Dicho esto, el objetivo del presente trabajo es exponer cómo ha evolucionado este argumento en los últimos años en la doctrina y en la jurisprudencia y apuntar algunos reproches que se le pueden formular desde un punto de vista dogmático y político-criminal.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
PWM Control of a Buck Converter with an Amorphous Core Coil
Pulse-width modulation is widely used to control electronic converters. One of the most topologies used for high DC voltage/low DC voltage conversion is the Buck converter. It is obtained as a second order system with a LC filter between the switching subsystem and the load. The use of a coil with an amorphous magnetic material core instead of air core lets design converters with smaller size. If high switching frequencies are used for obtaining high quality voltage output, the value of the auto inductance L is reduced throughout the time. Then, robust controllers are needed if the accuracy of the converter response must not be affected by auto inductance and load variations. This paper presents a robust controller for a Buck converter based on a state space feedback control system combined with an additional virtual space variable which minimizes the effects of the inductance and load variations when a not-toohigh switching frequency is applied. The system exhibits a null steady-state average error response for the entire range of parameter variations. Simulation results are presented
Using the Own Flexibility of a Climbing Robot as a Double Force Sensor
Force sensors are used when interaction tasks are carried out by robots in general, and by climbing robots in particular. If the mechanics and electronics systems are contained inside the own robot, the robot becomes portable without external control. Commercial force sensors cannot be used due to limited space and weight. By selecting the links material with appropriate stiffness and placing strain gauges on the structure, the own robot flexibility can be used such as force sensor. Thus, forces applied on the robot tip can be measured without additional external devices. Only gauges and small internal electronic converters are necessary. This paper illustrates the proposed algorithm to achieve these measurements. Additionally, experimental results are presented
La variable tiempo en el cálculo de acciones para estructuras de edificación
El presente estudio profundiza en los valores las acciones que actúan sobre una estructura conforme a la vida útil para la que se proyecta inicialmente especialmente cuando su vida útil es menor del valos estándar. Esto sucede frecuentemente, en el campo de la rehabilitación
Natural origin products as a source of new antiviral molecules
Motivation: Human adenovirus (HAdV) is a DNA virus that can cause a wide range of diseases, including respiratory and gastrointestinal infections, or conjunctivitis, that in immunocompetent individuals are ausually mild and self-limited. However, in immunosuppresed people and especially in pediatric units, HAdV infections present high morbidity and mortality. Currently there is no specific treatment approved against HAdV. The aim of this work was to characterize the anti-HAdV activity of 18 compounds that were previously selected after high-troughput screening (HTP) of a library of 1340 compounds, coming from our collaboration with the European initiative COSTACTION CM 1407Methods: We had evaluated the anti-HAdV activity of the compounds performing in vitro assays: plaque assays to calculate the IC50 value, citotoxicity assays to calculate the CC50 value, yield reduction assays and qPCR in real time to evaluate the inhibitory effect, and nucleocitoplasm assays to evaluate their mechanism of action.Results: It has been proven that 2 compounds, BBN75 and GSAED772E-1S2R have a safe selectivity index, a great inhibitory effect and they may act in steps subsequent to the arrival of the viral genome at the nucleus of the host cell.Conclusions: The results indicates that BBN75 and GSAED772E-1S2R are promising anti-HAdV drugs to be evaluated at in vivo assays
Cross-sectional associations between exposure to per- and polyfluoroalkyl substances and body mass index among European teenagers in the HBM4EU aligned studies
Per-and polyfluoroalkyl substances (PFAS) are widespread pollutants that may impact youth adiposity patterns. We investigated cross-sectional associations between PFAS and body mass index (BMI) in teenagers/adolescents across nine European countries within the Human Biomonitoring for Europe (HBM4EU) initiative. We used data from 1957 teenagers (12-18 yrs) that were part of the HBM4EU aligned studies, consisting of nine HBM studies (NEBII, Norway; Riksmaten Adolescents 2016-17, Sweden; PCB cohort (follow-up), Slovakia; SLO CRP, Slovenia; CROME, Greece; BEA, Spain; ESTEBAN, France; FLEHS IV, Belgium; GerES V-sub, Germany). Twelve PFAS were measured in blood, whilst weight and height were measured by field nurse/physician or self-reported in ques-tionnaires. We assessed associations between PFAS and age-and sex-adjusted BMI z-scores using linear and logistic regression adjusted for potential confounders. Random-effects meta-analysis and mixed effects models were used to pool studies. We assessed mixture effects using molar sums of exposure biomarkers with toxicological/structural similarities and quantile g-computation. In all studies, the highest concentrations of PFAS were PFOS (medians ranging from 1.34 to 2.79 mu g/L). There was a tendency for negative associations with BMI z-scores for all PFAS (except for PFHxS and PFHpS), which was borderline significant for the molar sum of [PFOA and PFNA] and significant for single PFOA [beta-coefficient (95% CI) per interquartile range fold change =-0.06 (-0.17, 0.00) and-0.08 (-0.15,-0.01), respectively]. Mixture assessment indicated similar negative associations of the total mixture of [PFOA, PFNA, PFHxS and PFOS] with BMI z-score, but not all compounds showed associations in the same direction: whilst [PFOA, PFNA and PFOS] were negatively associated, [PFHxS] associated positively with BMI z-score. Our results indicated a tendency for associations of relatively low PFAS concentrations with lower BMI in European teenagers. More prospective research is needed to investigate this potential relationship and its implications for health later in life.European Commission 733032Swedish Research Council
European Commission 2017-0082
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