Waveform-independent frame-timing acquisition for UWB signals

In this paper, the problem of frame-level symbol timing acquisition for UWB signals is addressed. The main goal is the derivation of a frame-level timing estimator which does not require any prior knowledge of neither the transmitted symbols nor the received template waveform. The independence with respect to the received waveform is of special interest in UWB communication systems, where a fast and accurate estimation of the end-to-end channel response is a challenging and computationally demanding task. The proposed estimator is derived under the unconditional maximum likelihood criterion, and because of the low power of UWB signals, the low-SNR assumption is adopted. As a result, an optimal frame-level timing estimator is derived which outperforms existing acquisition methods in low-SNR scenarios.Peer Reviewe

NDA waveform estimation in the low-SNR regime

This correspondence addresses the problem of nondata-aided waveform estimation for digital communications. Based on the unconditional maximum likelihood criterion, the main contribution of this correspondence is the derivation of a closed-form solution to the waveform estimation problem in the low signal-to-noise ratio regime. The proposed estimation method is based on the second-order statistics of the received signal and a clear link is established between maximum likelihood estimation and correlation matching techniques. Compression with the signal-subspace is also proposed to improve the robustness against the noise and to mitigate the impact of abnormals or outliers.Peer Reviewe

Asymptotic equivalence between the unconditional maximum likelihood and the square-law nonlinearity symbol timing estimation

This paper provides a systematic approach to the problem of nondata aided symbol-timing estimation for linear modulations. The study is performed under the unconditional maximum likelihood framework where the carrier-frequency error is included as a nuisance parameter in the mathematical derivation. The second-order moments of the received signal are found to be the sufficient statistics for the problem at hand and they allow the provision of a robust performance in the presence of a carrier-frequency error uncertainty. We particularly focus on the exploitation of the cyclostationary property of linear modulations. This enables us to derive simple and closed-form symbol-timing estimators which are found to be based on the well-known square timing recovery method by Oerder and Meyr. Finally, we generalize the OM method to the case of linear modulations with offset formats. In this case, the square-law nonlinearity is found to provide not only the symbol-timing but also the carrier-phase error.Peer Reviewe

Detection of PPM-UWB random signals

This paper focuses on the symbol detection problem of random pulse-position modulation (PPM) ultrawideband (UWB) signals in the absence of interframe interference. Particular attention is devoted to severely time-varying channels where optimal detectors are proposed for both uncorrelated and correlated scattering scenarios. This is done by assuming the received waveforms to be unknown parameters. In UWB communication systems, the assumption of unknown random waveforms is consistent with the fact that the received waveform has very little resemblance with the original transmitted pulse. In order to circumvent this limitation, a conditional approach is presented herein by compressing the likelihood ratio test with the information regarding the second-order moments of the end-to-end channel response. Both full-rank and rank-one detectors are derived. For the reduced complexity rank-one detector, an iterative procedure is presented that maximizes the J-divergence between the hypotheses to be tested. Finally, simulation results are provided to compare the performance of the proposed detectors in different propagation environments.Peer Reviewe

Estudio de las materias y su correlación para innovación e implantación de las enseñanzas de ingeniería en una escuela técnica de Galicia

[Resumen]El presente trabajo de investigación aborda el problema del bajo rendimiento académico alcanzado en los estudios de Ingeniería. Se realiza el análisis estadístico descriptivo y de correlación de los resultados académicos del alumnado que ha cursado las titulaciones de Ingeniería Técnica Industrial, especialidades Electricidad y Electrónica Industrial, pertenecientes a la Universidad de A Coruña, tal como figuran en su expediente académico. Mediante la aplicación de técnicas avanzadas de regresión, se desarrollan modelos de predicción del itinerario académico del estudiantado a lo largo de toda su carrera universitaria, de tal forma que, se logra predecir las calificaciones obtenidas y las convocatorias agotadas en las materias que cada alumno curse durante el primer año académico, a partir de la nota de acceso a la universidad. El resto de calificaciones y convocatorias de las materias que componen la titulación se pueden predecir en cualquier momento de la trayectoria académica del estudiante, incorporando al modelo las notas de las materias según se vayan superando. Los modelos desarrollados permiten conseguir el principal objetivo propuesto de conocer por adelantado el rendimiento académico de cada estudiante, y se pueden aplicar para la predicción del rendimiento individual del alumnado[Resumo]O presente traballo de investigación aborda o problema do baixo rendemento académico alcanzado nos estudos de Enxeñaría. Realízase a análise estatístico descritivo e de correlación dos resultados académicos do alumnado que cursou as titulacións de Enxeñaría Técnica Industrial, especialidades Electricidade e Electrónica Industrial, pertencentes á Universidade da Coruña, tal como figuran no seu expediente académico. Mediante a aplicación de técnicas avanzadas de regresión, desenvólvense modelos de predición do itinerario académico do alumnado ao longo de toda a súa carreira universitaria, de tal forma que, se logra predicir as cualificacións obtidas e as convocatorias esgotadas nas materias que cada alumno curse durante o primeiro ano académico, a partir da nota de acceso á universidade. O resto de cualificacións e convocatorias das materias que compoñen a titulación pódense predicir en calquera momento da traxectoria académica do estudante, incorporando ao modelo as notas das materias segundo se vaian superando. Os modelos desenvolvidos permiten conseguir o principal obxectivo proposto de coñecer por adiantado o rendemento académico de cada estudante, e pódense aplicar para a predición do rendemento individual do alumnado.[Abstract]In this work, we deal with the problem of poor academic performance among students of Engineering Degrees. We carry out the statistical descriptive and correlation analysis of the academic achievements of the undergraduates of the Electrical and Industrial Electronics specialities in the Technical Industrial Engineering from the University of A Coruña. Applying advanced regression techniques, prediction models for the academic performance of the students are developed. Therefore, the marks and the number of failed exams throughout the first year of the degree are obtained from the corresponding of secondary education. The marks and the number of left exams needed in order to pass the remaining courses can be predicted at any time during the degree. In order to do that, the marks already achieved are included into the model. Eventually, the main goal of this work is accomplished; the performance of each student can be anticipated. Moreover, the developed models can be applied for the prediction of the individual academic achievements of each student

Study of the crosslinking reaction between Bisphenol A diglycidyl ether (BADGE) and a Zinc Porphyrin by Fourier transform infrared spectroscopy

The 19th International Electronic Conference on Synthetic Organic Chemistry session Polymer and Supramolecular ChemistryThe curing reaction of a system consisting of a diglycidyl ether of bisphenol-A (n= 0) and ZnTPyP (Zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin) was studied by Fourier Transform infrared spectroscopy (FTIR). A semi-empirical quantum chemistry program (MOPAC) was used to corroborate the experimental data. The tertiary amine ZnTPyP not only initiates the reaction but also reacts with the resin forming pyridone. This study demonstrates that macrocycles can be used as cross-linking agents for curing epoxy resins and that when metallomacrocycles are used, metal ions can be introduced into the network structur

Tècnica per millorar la tecnologia de banda ultra-ampla

En l'àmbit de la comunicació sense fils, la tecnologia de banda ultra-ampla permet d'obtenir comunicacions de molt elevada velocitat i té aplicacions molt diverses, entre elles els radars d'alta precisió o les transmissions multimèdia. D'altra banda, les peculiars característiques dels senyals de banda ultra-ampla fan que la seva recepció i sincronització presenti importants problemes. Investigadors de la UAB i de la UPC han dissenyat una tècnica per solventar-los.En el ámbito de la comunicación sin hilos, la tecnología de banda ultra- ancha permite obtener comunicaciones de muy elevada velocidad y tiene aplicaciones muy diversas, entre ellas los radares de alta precisión o las transmisiones multimedia. Por otra parte, las peculiares características de las señales de banda ultra-ancha hacen que su recepción y sincronización presente problemas importantes. Investigadores de la UAB y de la UPC han diseñado una técnica para solventarlos.In the field of wireless communication, ultra-wideband technology allows obtaining very high data-rates with diverse applications such as high accuracy radars and multimedia transmissions. However, the particular characteristics of ultra-wideband signals make their synchronization and reception very difficult. Researchers at UAB and UPC have designed a technique to solve this problem

EXPERIMENTS SIMULATION AND DESIGN TO SET TRAFFIC LIGHTS’ OPERATION RULES

[EN] In this paper it is used the experimental design to minimize the travel time of motor vehicles, in one of the most important avenues of Celaya City in Guanajuato, Mexico, by means of optimal synchronization of existing traffic lights. In the optimization process three factors are considered: the traffic lights’ cycle times, the synchrony defined as stepped, parallel and actual, and speed limit, each one with 3 evaluation levels. The response variables to consider are: motor vehicles’ travel time, fuel consumption and greenhouse effect gas (CO2) emissions. The different experiments are performed using the simulation model developed in the PTV-VISSIM software, which represents the vehicle traffic system. The obtained results for the different proposed scenarios allow to find proper levels at which the vehicle traffic system must be operated in order to improve mobility, to reduce contamination rates and decrease the fuel consumption for the different motor vehicles that use the avenue.Espinoza Mondragón, J.; Jimenez García, J.; Medina Flores, JM.; Vázquez López, JA.; Téllez Vázquez, S. (2016). EXPERIMENTS SIMULATION AND DESIGN TO SET TRAFFIC LIGHTS’ OPERATION RULES. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 907-919. https://doi.org/10.4995/CIT2016.2015.4093OCS90791

Rotura traumática del tendón del supraespinoso en un niño de seis años

Presentamos un caso de un niño de seis años que sufrió un traumatismo por caída sobre su hombro derecho, con rotura completa del tendón del supraespinoso. Comprobado con Resonancia Magnética. Se operó para efectuar una reinserción transósea del tendón mediante cirugía abierta. Después de un mes de inmovilización se comenzaron los ejercicios activos progresivos con recuperación completa a los tres meses de la intervención.A six year old boy sustained a right shoulder injury after a causal fall. Magnetic Resonance Imaging showed a complete rupture of the supraespinatus tendon. Open surgery was indicated by transosseus reinsertion of the tendon on the humeral head. After one month of shoulder immobilization, the patient physical therapy with progressive active exercises. The patient achivied complete joint motion and function three months after surgery