Diseño y construcción de un amplificador para micrófono

L'objectiu d'aquest projecte és el disseny i la construcció d'un amplificador de senyal de micròfon a senyal de línia per a ús en un estudi d'enregistrament utilitzant la tecnologia de les vàlvules de buit. En l'àmbit del so professional i audiòfil, les vàlvules són molt reconegudes i desitjades, ja que donen un cert caràcter als enregistraments difícil d'imitar amb altres tecnologies més modernes. Al llarg d'aquesta memòria, es descruiran tots els càlculs i proves pertinents per tal de desenvolupar un equip útil, de la més alta qualitat possible i amb un cost econòmic raonabler un equip útil, de la més alta qualitat possible i amb un cost econòmic raonableThis project’s objective is the design and construction of a microphone signal to line level amplifier for recording studio use, using vacuum tube technology. In the professional audio and audiophile fields, tubes are very renowned and desired, because they give a certain character to the recordings that’s difficult to obtain with other more modern technologies. During this dossier, the calculations and tests will be described as to develop useful equipment, of the highest possible quality and with a restrained economic cos

User Grouping for the Uplink of Multiuser Hybrid mmWave MIMO

[Abstract] Hybrid analog/digital schemes for precoding/combining have proved to be a low-complexity and/or low-power strategy to obtain reasonable beamforming gains in multiuser millimeter-wave (mmWave) multiple-input multiple-output (MIMO) systems. Hybrid precoding/combining performs jointly baseband processing and analog processing in the radio frequency (RF) domain. In these systems, the number of RF chains limits the maximum number of streams simultaneously handled by the transceivers. In the uplink of a multiuser mmWave MIMO system, the hardware reduction based on hybrid transceivers is limited by the number of data streams that must be simultaneously served by the centralized node. Most works approach hybrid transceiver design by considering more RF chains than data streams, an unrealistic assumption when the number of nodes is large. On the other hand, statistically independent information is conventionally assumed in multiuser mmWave systems. This assumption does not hold in scenarios like wireless sensor networks (WSNs), where the sources produce correlated information. In this paper, by enabling inter-user correlation exploitation, we propose a grouping approach to handle a high number of individual sources with a limited number of RF chains through distributed quantizer linear coding (DQLC) mappings. The allocation of the users per group and the hybrid design of the combiner at the common central node to serve the grouped users is also analyzed. We also propose a hybrid minimum mean square error (MMSE) combining design in order to exploit the spatial correlation between the sources in a conventional uncoded mmWave uplink. Simulation results show the performance advantages of the proposed approaches in various hardware-constrained system settings.10.13039/501100010801-Xunta de Galicia (Grant Number: ED431G2019/01) 10.13039/501100011033-Agencia Estatal de Investigaci??n (Grant Number: TEC2016-75067-C4-1-R, RED2018-102668-T and PID2019-104958RB-C42) BES-2017-081955Xunta de Galicia; ED431G2019/0

Wideband User Grouping for Uplink Multiuser mmWave MIMO Systems With Hybrid Combining

[Abstract] Analog-digital hybrid precoding and combining schemes constitute an interesting approach to millimeter-wave (mmWave) multiple-input multiple-output (MIMO) systems due to the low hardware complexity and/or low power required for its deployment. However, the design of the hybrid precoders and combiners of a wideband multiuser (MU) mmWave MIMO system is challenging because the signal processing in the analog domain is constrained to be frequency flat. Furthermore, the number of radio frequency (RF) chains limits the number of individual streams that a common base station (BS) can simultaneously serve. This work jointly addresses the user scheduling, the user precoder design, and the BS hybrid combining design for the uplink of wideband MU mmWave MIMO systems. On the one hand, user precoding and BS hybrid combining are jointly designed to minimize the impact of having frequency-flat RF components. On the other hand, a number of users larger than the number of RF chains are served at the BS by employing a distributed quantizer linear coding (DQLC)-based non-orthogonal multiple access (NOMA) scheme. The use of this encoding strategy also allows exploiting the spatial correlation between the source information. Simulation results show remarkable performance gains of the proposed approaches for wideband mmWave MIMO hardware-constrained systems.10.13039/501100010801-Xunta de Galicia (Grant Number: ED431C 2020/15) 10.13039/501100010801-Centro de Investigación de Galicia CITIC (Grant Number: ED431G2019/01) 10.13039/501100011033-Agencia Estatal de Investigación of Spain (Grant Number: RED2018-102668-T and PID2019-104958RB-C42) European Regional Development Funds (ERDF) of the EU (ERDF Galicia 2014-2020 & AEI/ERDF programs, UE) Predoctoral (Grant Number: BES-2017-081955)Xunta de Galicia; ED431C 2020/15Xunta de Galicia; ED431G2019/0

Valoración del desarrollo de competencias de los estudiantes mediante mapas perceptuales: Una aplicación en la Facultad de Economía y Empresa de la Universidad de Barcelona

El presente artículo se centra en la generación de mapas perceptuales de los ránkings de las percepciones y las expectativas de los graduados universitarios, los profesores y los empresarios en cuanto al desarrollo de competencias. La información parte de una encuesta realizada entre licenciados y académicos de la Facultad de Economía y Empresa de la Universidad de Barcelona y empresarios catalanes. En primer lugar se jerarquizan las competencias y habilidades desarrolladas durante los estudios universitarios. Los ránkings se combinan para los tres colectivos con el objetivo de proyectar visualmente el posicionamiento de los tres tipos de competencias (genéricas, personales y específicas) en mapas perceptuales generados mediante diferentes tipos de técnicas multivariantes de reducción de la dimensionalidad para datos ordinales (escalamiento multidimensional y componentes principals categóricos). A partir del análisis realizado, se observa un elevado consenso entre los tres colectivos por lo que respecta a la relevancia de las competencias. Los mapas perceptuales permiten captar el grado de similitud entre las competencias analizadas en términos de su posicionamiento. Así, destacan como mejor posicionadas la organización y planificación entre las competencias genéricas; la comunicación oral y escrita entre las personales; y la capacidad de aprendizaje entre las específicas

Programming Pulse Width Assessment for Reliable and Low-Energy Endurance Performance in Al:HfO2-Based RRAM Arrays

A crucial step in order to achieve fast and low-energy switching operations in resistive random access memory (RRAM) memories is the reduction of the programming pulse width. In this study, the incremental step pulse with verify algorithm (ISPVA) was implemented by using different pulse widths between 10 μ s and 50 ns and assessed on Al-doped HfO 2 4 kbit RRAM memory arrays. The switching stability was assessed by means of an endurance test of 1k cycles. Both conductive levels and voltages needed for switching showed a remarkable good behavior along 1k reset/set cycles regardless the programming pulse width implemented. Nevertheless, the distributions of voltages as well as the amount of energy required to carry out the switching operations were definitely affected by the value of the pulse width. In addition, the data retention was evaluated after the endurance analysis by annealing the RRAM devices at 150 °C along 100 h. Just an almost negligible increase on the rate of degradation of about 1 μ A at the end of the 100 h of annealing was reported between those samples programmed by employing a pulse width of 10 μ s and those employing 50 ns. Finally, an endurance performance of 200k cycles without any degradation was achieved on 128 RRAM devices by using programming pulses of 100 ns width

Aggregation of under canopy and bare soils in a Mediterranean environment affected by different fire intensities

7 páginas, 4 figuras, 3 tablas.Soil macroaggregation in relation to soil organic matter (SOM) and calcium carbonate(CaCO3) content was studied, before and after experimental fires of different intensities, in two environments (under canopy and on bare soil). In 1995, two experimental fire treatments, based on the addition of different biomass amounts, were applied on a set of nine plots at the Permanent Field Station of La Concordia (Valencia, Spain). Three plots were burned with high intensity fire (T1), three with moderate intensity (T2) and three plots were left unburned to be used as control treatment (T3). Soils under canopy were characterized by higher macroaggregate stability (SMS), SOM content and mean weight diameter of aggregates (MWD) than bare soils, which presented higher CaCO3 contents. After the fires, tendencies to increase were observed in the SOM and SMS of all burned soils, probably because of the incorporation of partially burned plant material. The trends of SMS and SOM in T1 burned soils were towards to decrease with the occurrence of the first erosive rainfalls. These trends continued until the end of the study. MWD of under canopy soils on T1 and of soils on T2 showed a decreasing trend immediately after fire treatments. Not significant differences between sampling periods were found for CaCO3 content, with the exception of under canopy soils on T1 which tended to increase, and showed higher values at the end of the studied period. The differences observed initially between under canopy and bare soil disappeared after one year of fire in T1, which suggests a major degradation of soils affected by this treatment. Significant changes of the studied properties were not observed in unburned soils during one year of research. In these soils, organic matter showed significant correlations with macroaggregate stability and mean weight diameter. However, significant statistical relationships were not observed between the Studied properties in burned soils, showing that fire impact probably affected other soil characteristics related to soil aggregation.We thank the financial support from the Agreement Generalitat Valenciana — CSIC (2005020112) “Impacto de los incendios forestalesrepetidos sobre los procesos de erosión hídrica del suelo y la recuperación de la cubierta vegetal. Seguimiento y evaluación en una estación permanente de campo”, and the Ministerio de Educación y Ciencia of the Spanish Government project “Procesos y balances hidrológicos y de sedimentos a diferentes escalas espaciales en ambientes mediterráneos: Efectos de la variabilidad climática y los cambios de uso del suelo” (PROBASE CGL2006-11619).Peer reviewe

A Comparison of the Environmental Impact of Different AOPs : Risk Indexes

Today, environmental impact associated with pollution treatment is a matter of great concern. A method is proposed for evaluating environmental risk associated with Advanced Oxidation Processes (AOPs) applied to wastewater treatment. The method is based on the type of pollution (wastewater, solids, air or soil) and on materials and energy consumption. An Environmental Risk Index (E), constructed from numerical criteria provided, is presented for environmental comparison of processes and/or operations. The Operation Environmental Risk Index (EOi) for each of the unit operations involved in the process and the Aspects Environmental Risk Index (EAj) for process conditions were also estimated. Relative indexes were calculated to evaluate the risk of each operation (E/NOP) or aspect (E/NAS) involved in the process, and the percentage of the maximum achievable for each operation and aspect was found. A practical application of the method is presented for two AOPs: photo-Fenton and heterogeneous photocatalysis with suspended TiO2 in Solarbox. The results report the environmental risks associated with each process, so that AOPs tested and the operations involved with them can be compared

Hydrological properties of a Mediterranean soil burned with different fire intensities

8 páginas, 5 figuras, 3 tablas.The influence of vegetation cover on soil hydrological properties and its response to the impact of different fire intensities, in a Mediterranean forest environment, has been evaluated. The study was carried out in the Permanent Experimental Field Station of La Concordia (Lliria-Valencia, Spain), on a set of nine erosion plots (4 x 20 m(2)). The Station is located on a calcareous hillside S-SE oriented, with soils of Rendzic Leptosol type and supporting Mediterranean shrubland vegetation. All runoff generated and sediment produced in every rain event was collected from each plot. The set up includes a system of sensors for the continuous monitoring of climatic parameters (air temperature and humidity, rain volume, intensity, etc.). In June 1995, a set of experimental fires was carried out to the Station. Three of the plots were burned with high intensity fire, three with moderate intensity and the remaining were left unaltered. Soil water content and water retention capacity (WRC) were measured in the different plots and in two different vegetation covers: under canopy (UC) and in bare soil (BS). The pF curves were also obtained for each fire treatment. A year after the fires (June 1995-June 1996), great differences, reaching 77.15%, in runoff generation between fire treatments and the control plots were observed. No significant differences were detected on water retention capacity between soils UC and BS in the burned plots. However, these differences appeared in the control plots, giving UC and BS values of 13% and 18%, respectively. Plots corresponding to the high intensity fire treatment showed values of WRC significantly higher than those of the moderate intensity and of the control treatments. The pF curves show that the values of water volume, at the different pressure points studied, were slightly greater on UC soil. Values obtained for BS samples are higher in the fire treatments, showing significant differences in respect to the control plots at pF 1 and 2. These differences were also observed for UC soil, but in this case at pF 2, 2.5 and 4.2.This work has been supported by the European Union (QLRT-2000-00289), the Spanish Ministry of Science and Technology (CICYT) REN2001-1716 and Convenio (Agreement) Generalitat Valenciana – CSIC (02020024).Peer reviewe

Developing a smartphone app based on the unified protocol for the transdiagnostic treatment of emotional disorders: a qualitative analysis of users and professionals' perspectives

Emotional Disorders have become the most prevalent mental disorders in the world. In relation to their high prevalence, mental health care from public health services faces major challenges. Consequently, finding solutions to deliver cost-effective evidence-based treatments has become a main goal of today's clinical psychology. Smartphone apps for mental health have emerged as a potential tool to deal with it. However, despite their effectiveness and advantages, several studies suggest the need to involve patients and professionals in the design of these apps from the first stage of the development process. Thus, this study aimed to identify, from both a group of users and professionals, the needs, opinions, expectations and design aspects of a future smartphone app based in the Unified Protocol (UP), that will allow to develop the subsequent technical work of the app engineers. Two focus groups were conducted, one with 7 professionals and the other with 9 users, both groups familiar with the UP. A thematic content analysis based in grounded theory was performed in order to define emergent categories of analysis derived from the interview data. The results revealed 8 common topics in both focus groups and 5 specific key topics were identified in the professionals' focus group. Of the total proposals, 93 % of the professionals' and 78 % of the users' are implemented in the preliminary version of the app