Numerical study on aerodynamic drag reduction of passenger cars

The scope of this work is to identify potential improvements on Passenger cars Aerodynimcs (Drag reduction and Downforce increase) to help to minimize fuel consumption and hence reduce exhaust emisions. The Ahmed body (Bluff body) is representative of a passenger car under aerodynamical point of view. A lot of studies and literature exists as far as test reports of the Ahmed body on wind tunel tests. This work can be divided onto 2 steps. First step is to perform qualitative numerical simulations of a 3D model of an Ahmed body modified with different aerodynimc improvements such as difuser integration downstream on the underbody of the vehicle (studying different configurations such as diferent lenghts, diferent angles and number an d location of vanes), study of aerodynamic modifications on the rear bumper to improve the weak low pressure region, study of by-pass ducts integration from the front glass to the rear glass, Rear Spoiler integration, vortex generators integration downstream over the roof and a new "double roof" concept. After evaluation of the perormance of such modifications on the Ahmed body, the second step of this work consists to implement a single modification or multiple moidifications on the geometry of a real passenger car and compare (as conclusion of this work) the CFD results of the passenger car quantitative simulations before and after the modifications were implemented

Unseen the other in post-urban utopia. Sensitive bodies II

Modern architecture has resulted an utopia not only possible but, in practice, effective. Post-urban utopia has actually been built along the twentieth century throughout a complex network of operations, including both be- havioral orientation and systemic simplification. All these operations have acted specifically on the human bod- ies, bodies in movement, bodies that inter-act, bodies that observe (see) and are observed (seen), in a seminal cybernetic operation of construction of the urban system. The recent urban utopia is sustained, however, in a progressive unseen of the other, replacing the ideals of transparency of the original modern architecture with a practical communicative opacity. We have developed the concept of sensitive body as a method of research, knowledge, recognition and representation of urban events and processes, even hidden or veiled. Our hypothesis is that by using bodies trained in the representation of emotions, experiences carried out in performative arts, performance or street performance, it is possible to unveil hidden information or just make visible the system of social relations that takes place in the public space

Variation of the ultraviolet extinction law across the Taurus-Auriga star forming complex. A GALEX based study

The Taurus-Auriga molecular complex (TMC) is the main laboratory for the study of low mass star formation. The density and properties of interstellar dust are expected to vary across the TMC. These variations trace important processes such as dust nucleation or the magnetic field coupling with the cloud. In this article, we show how the combination of near ultraviolet (NUV) and infrared (IR) photometry can be used to derive the strength of the 2175 \AA\ bump and thus any enhancement in the abundance of small dust grains and PAHs in the dust grains size distribution. This technique is applied to the envelope of the TMC, mapped by the GALEX All Sky Survey (AIS). UV and IR photometric data have been retrieved from the GALEX-AIS and the 2MASS catalogues. NUV and K-band star counts have been used to identify the areas in the cloud envelope where the 2175 \AA\ bump is weaker than in the diffuse ISM namely, the low column density extensions of L1495, L1498 and L1524 in Taurus, L1545, L1548, L1519, L1513 in Auriga and L1482-83 in the California region. This finding agrees with previous results on dust evolution derived from Spitzer data and suggests that dust grains begin to decouple from the environmental galactic magnetic field already in the envelope.Comment: Accepted in Monthly Notices of the Royal Astronomical Societ

Effects of different post-activation potentiation warm-ups on repeated sprint ability in soccer players from different competitive levels

This study aimed to compare the effects of a traditional warm-up with two post-activation potentiation (PAP) warm-up strategies on the repeated sprint ability (RSA) of soccer players from national (NL) and regional (RL) competitive levels. Sixteen young players (NL, n = 8, age = 20.7 +/- 1.4 y, body mass = 68.5 +/- 7.0 kg, body height = 177.4 +/- 5.2 cm; RL, n = 8, age = 20.8 +/- 1.0 y, body mass = 68.7 +/- 4.0 kg, body height = 176.6 +/- 5.6 cm) were recruited to complete a traditional warm-up (CONTROL), a PAP warm-up incorporating squats with a load (similar to 60% 1RM) that allowed a high speed (1 m/s) of movement and a high number of repetitions (PAP-1), and a PAP warm-up with a load (similar to 90% 1RM) that allowed a moderate speed (0.5 m/s) of movement and a reduced number of repetitions (PAP-0.5). A RSA test (six 20-m sprints with 20 s of recovery) was performed 5 min after the PAP warm-up to assess the effects of the different protocols on the fastest sprint (RSAb) and the mean time of all sprints (RSAm). A meaningful improvement of RSA performance was observed with PAP-0.5, attaining a large effect on NL (RSAb, ES = -1.5; RSAm, ES = -1.3) and only a small effect on RL athletes (RSAb and RSAm, ES = -0.2). Moreover, when each RSA sprint performance was compared between NL and RL players, after PAP-0.5 greater performance for all sprints was observed in the NL players. Therefore, adding a heavy strength-based conditioning exercise during the warm-up prior to a RSA test may induce significant performance improvements in NL, but only small effects in RL players

Physical Layer Security of Large Reflecting Surface Aided Communications with Phase Errors

The physical layer security (PLS) performance of a wireless communication link through a large reflecting surface (LRS) with phase errors is analyzed. Leveraging recent results that express the \ac{LRS}-based composite channel as an equivalent scalar fading channel, we show that the eavesdropper's link is Rayleigh distributed and independent of the legitimate link. The different scaling laws of the legitimate and eavesdroppers signal-to-noise ratios with the number of reflecting elements, and the reasonably good performance even in the case of coarse phase quantization, show the great potential of LRS-aided communications to enhance PLS in practical wireless set-ups.Comment: This work has been submitted to the IEEE for publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

SMARTLAB MAGNETIC: A MODERN PARADIGM FOR STUDENT LABORATORIES

[EN] Undergraduate laboratories should provide means to help the student visualize often complex concepts, to achieve a more lasting understanding and, thus, a more significant learning of the ideas presented in the lectures. However, the laboratories often require students to struggle with complex instrumentation operation and tedious data collection and processing that affect negatively their motivation and distract off the learning objectives. This paper introduces through a specific implementation a recent paradigm for student laboratories, designated as SmartLabs, as an effort to help overcome these drawbacks. SmartLabs Magnetic is a combination of existing magnetic circuits test equipment plus a versatile sensors set combined with a standard and affordable data acquisition card and a portable device App. SmartLab Magnetic collects data during magnetic circuits laboratory tests, processes this data to provide results more easily related to the basic concepts being tested and manages the data into reports that can be sent to the student e-mail account within the App. Students' opinions of the relevance, usefulness, and motivational effect of the new SmartLab Magnetic were very positive.Martinez-Roman, J.; Sapena-Bano, A.; Pineda-Sanchez, M.; Puche-Panadero, R. (2016). SMARTLAB MAGNETIC: A MODERN PARADIGM FOR STUDENT LABORATORIES. Sensors & Transducers. 197(2):58-66. http://hdl.handle.net/10251/99063S5866197

Contribution of psychoactive substance use and other environmental factors to adolescent pregnancies in Mexico

Introduction: Mexico has the highest prevalence of adolescent pregnancies among all the member countries of the Organization for Economic Co-operation and Development (OECD) with a fertility rate of 70.6 births for every 1000 women aged 15–19 years. This study explored the associations between psychoactive substance use and adolescent pregnancy in 3263 adolescents. Methods: This was a cross-sectional study using data from the National Health and Nutrition Survey 2018. We examined adolescent pregnancy among a sample of currently pregnant, ever pregnant and never pregnant teenage girls. The prevalence of psychoactive substance use was estimated at the state level using the 2016 National Survey of Drug, Alcohol, and Tobacco Use. Multilevel logistic models were fitted to evaluate the association between psychoactive substance use and adolescent pregnancy. Results: Girls living in states with high prevalence of illegal drug use, non-prescription use of medical drugs, alcohol abuse and daily tobacco use had higher odds of having adolescent pregnancy (OR=1.22, 95% CI: 1.17–1.27; OR=2.00, 95% CI: 1.66–2.39; OR=1.10, 95% CI: 1.03–1.13; and OR=1.05, 95% CI: 1.03–1.18, respectively). Finally, adolescent pregnancy was positively associated with population density (OR=0.85, 95% CI: 0.82–0.88) and number of homicides (OR=1.08, 95% CI: 1.03–1.13). Conclusions: The exposure of adolescents to psychoactive substances may directly contribute to having a pregnancy. Also, these findings highlight the importance of attending school, having high school education and being beneficiaries of the social program CCT-POP in reducing adolescent fertility rates.S

Fault Diagnosis of Rotating Electrical Machines in Transient Regime Using a Single Stator Current's FFT

© 2015 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] The discrete wavelet transform (DWT) has attracted a rising interest in recent years to monitor the condition of rotating electrical machines in transient regime, because it can reveal the time-frequency behavior of the current's components associated to fault conditions. Nevertheless, the implementation of the wavelet transform (WT), especially on embedded or low-power devices, faces practical problems, such as the election of the mother wavelet, the tuning of its parameters, the coordination between the sampling frequency and the levels of the transform, and the construction of the bank of wavelet filters, with highly different bandwidths that constitute the core of the DWT. In this paper, a diagnostic system using the harmonic WT is proposed, which can alleviate these practical problems because it is built using a single fast Fourier transform of one phase's current. The harmonic wavelet was conceived to perform musical analysis, hence its name, and it has spread into many fields, but, to the best of the authors' knowledge, it has not been applied before to perform fault diagnosis of rotating electrical machines in transient regime using the stator current. The simplicity and performance of the proposed approach are assessed by comparison with other types of WTs, and it has been validated with the experimental diagnosis of a 3.15-MW induction motor with broken bars.This work was supported by the Spanish Ministerio de Ciencia e Innovacion through the Programa Nacional de Proyectos de Investigacion Fundamental under Project DPI2011-23740. The Associate Editor coordinating the review process was Dr. Ruqiang Yan.Sapena-Bano, A.; Pineda-Sanchez, M.; Puche-Panadero, R.; Martinez-Roman, J.; Matic, D. (2015). Fault Diagnosis of Rotating Electrical Machines in Transient Regime Using a Single Stator Current's FFT. IEEE Transactions on Instrumentation and Measurement. 64(11):3137-3146. https://doi.org/10.1109/TIM.2015.2444240S31373146641

Low-Cost Diagnosis of Rotor Asymmetries in Induction Machines Working at a Very Low Slip Using the Reduced Envelope of the Stator Current

(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Fault diagnosis of rotor asymmetries in induction machines working at a very low slip, through Fourier-based methods,usually requires a long acquisition time to achieve a high spectral resolution and a high sampling frequency to reduce aliasing effects. However, this approach generates a huge amount of data, which makes its implementation difficult using embedded devices with small internal memory, such as digital signal processors and field programmable gate arrays or devices with low computing power. In this paper, a new simplified diagnostic signal designated as the reduced envelope of the stator current is introduced to address this problem. The reduced envelope signal is built using only one sample of the current per cycle without any further processing, and it is demonstrated that it carries the same spectral information about the fault as the full-length current signal. Based on this approach, an embedded device has only to store and process a minimal set of samples compared with the raw current signal for a desired resolution. In this paper, the theoretical basis of the proposed method is presented, as well as its experimental validation using two different motors with broken bars: 1) a high-power induction motor working in a factory; and 2) a low-power induction motor mounted in a laboratory test bed.This work was supported by the Spanish "Ministerio de Economia y Competitividad" in the framework of the "Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad" under Project DPI2014-60881-R. Paper no. TEC-00762-2014.Sapena-Bano, A.; Pineda-Sanchez, M.; Puche-Panadero, R.; Martinez-Roman, J.; Kanovic, Z. (2015). Low-Cost Diagnosis of Rotor Asymmetries in Induction Machines Working at a Very Low Slip Using the Reduced Envelope of the Stator Current. IEEE Transactions on Energy Conversion. 30(4):1409-1419. doi:10.1109/TEC.2015.24452161409141930