Materials Characterization and Economic Considerations of Cold-Mix Recycled Asphalt Pavements

Recycling of asphalt pavements has become a common rehabilitation and maintenance process since the mid 1970s. The state of the art of designing and constructing pavements composed of recycled materials has now advanced to a point where recycling is considered as an alternative to conventional procedures for most paving projects. An in-depth evaluation of cold-mix recycling techniques was undertaken and the findings are presented in this report. The variability of the existing materials found in city streets and county roads throughout the State of Indiana was evaluated by means of laboratory test procedures. The data obtained from these experiments were statistically analyzed and the results were examined and discussed in an attempt to characterize those pavements. The significance of various factors believed to influence the final performance of cold recycled mixes, was determined by means of extensive sampling of various types of asphalt pavements from counties and cities within the State. Reclaimed asphalt pavement materials (RAP), with asphalt contents, aggregate gradation, recovered asphalt penetration and viscosity properties, etc., closely resembling values obtained from field-core samples, were used in the laboratory in a series of mix design procedures. These laboratory studies were performed in an attempt to determine the effects that factors such as mixing water, recycling agent content, gradation of the RAP, curing time, etc., will have on the performance of cold recycled mixes produced with existing asphalt pavement materials from Indiana\u27s county roads and city streets. A detailed analysis and discussion of the main factors that affect the selection and implementation of urban and rural pavements cold recycling, is presented by means of information and findings reported in the literature. A set of guidelines for cold-mix recycling of county roads and city streets asphalt pavements in Indiana, is recommended with the objective of directing and informing county and city engineers of the advantages and disadvantages and potential applications associated with asphalt pavement cold-mix recycling

Actitud de los universitarios ante las nuevas tecnologías de la información

[Resumen] En la actualidad las Universidades Españolas están impulsando nuevas propuestas de innovación educativa que llevan a una mejor calidad de la enseñanza. Esto se debe, en parte, al esfuerzo en pro de conseguir una convergencia europea de la enseñanza superior y, en parte, al impacto que están ejerciendo las Nuevas Tecnologías de la Información y Comunicación (NTIC). Bajo la acción de estos dos impulsos, la enseñanza universitaria se halla inmersa en un proceso de cambio profundo y de renovación de los esquemas didácticos. Esta investigación tiene como objetivo primordial el de analizar las actitudes hacia las NTIC en una muestra compuesta por 582 estudiantes de la Universidad de Vigo (Campus de Ourense). De ellos 403 eran mujeres y 179 hombres. El rango de edad oscilaba entre los 18 y 30 años. La media de edad era de 20.86 años y una desviación típica de 2.55. Los resultados obtenidos nos ponen de manifiesto que la gran mayoría afirma que Internet puede ser una fuente de información que facilita el aprendizaje, que las páginas educativas son útiles para adquirir conocimientos teóricos y prácticos y reconocen que las NTIC les permiten ser más activos en el proceso de enseñanza-aprendizaje y construir su propio conocimiento. No obstante, el 25.5% sigue prefiriendo la lectura de textos escritos a los presentados por ordenador y más de un tercio sostiene que el uso de Internet les supone mucho tiempo y esfuerzo[Abstract] At the present time the Spanish Universities are impelling new proposals of educative innovation that take to one better quality of education. This must, in part, to the effort for obtaining an European convergence of superior education and, partly, to the impact that is exerting the New Technologies of the Information and Comunicación (NTIC). Under the action of these two impulses, university education is immersed in a process of deep change and renovation of the didactic schemes. This investigation has as objective fundamental the one to analyze the attitudes towards the NTIC in a sample composed by 582 students of the University of Vigo (Campus of Ourense). Of them 403 were women and 179 men. The age rank oscillated between the 18 and 30 years. The age average was of 20,86 years and one standard deviation of 2.55. The obtained results show to us that the great majority affirms that Internet can be a source of intelligence that facilitates the learning, that the educative pages are useful to acquire theoretical and practical knowledge and recognize that the NTIC allow them to be more active in the education- learning process and to construct their own knowledge. However, the 25,5% continue preferring the reading of texts written the presented/ displayed ones by computer and more of a third it maintains that the use of Internet supposes long time and effort to the

Wideband Hybrid Precoding Using Time Modulated Arrays

[Abstract] Hybrid digital-analog precoding is a cost effective solution for transmitting over the large bandwidths and huge antenna arrays available in the millimeter wave frequency bands. In this work we focus on the transmission of wideband signals over hybrid precoders that utilize Time-Modulated Arrays in the analog domain. We consider analog precoders constructed with Single-Pole-Double-Throw switches which are both flexible and efficient. We pose two Orthogonal Frequency-Division Multiplexing symbol configurations to cope with the harmonic interference introduced by the Time-Modulated Array. One does not take advantage of the wireless channel frequency diversity and the other does. We optimize digital and analog precoders to maximize the achievable rate in both symbol configurations. Optimization takes into account the switching devices efficiency and the inherent losses of this antenna technique. Finally, we show the excellent performance obtained with the proposed approach, in terms of achievable rate, compared to that of conventional phased arrays.Xunta de Galicia; ED431G2019/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-RAgencia Estatal de Investigación de España; RED2018-102668-TAgencia Estatal de Investigación de España; PID2019-104958RB-C4

Power Efficient Scheduling and Hybrid Precoding for Time Modulated Arrays

[Abstract] We consider power efficient scheduling and precoding solutions for multiantenna hybrid digital-analog transmission systems that use Time-Modulated Arrays (TMAs) in the analog domain. TMAs perform beamforming with switches instead of conventional Phase Shifters (PSs). The extremely low insertion losses of switches, together with their reduced power consumption and cost make TMAs attractive in emerging technologies like massive Multiple-Input Multiple-Output (MIMO) and millimeter wave (mmWave) systems. We propose a novel analog processing network based on TMAs and provide an angular scheduling algorithm that overcomes the limitations of conventional approaches. Next, we pose a convex optimization problem to determine the analog precoder. This formulation allows us to account for the Sideband Radiation (SR) effect inherent to TMAs, and achieve remarkable power efficiencies with a very low impact on performance. Computer experiments results show that the proposed design, while presenting a significantly better power efficiency, achieves a throughput similar to that obtained with other strategies based on angular selection for conventional architectures.Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-RAgencia Estatal de Investigación de España; RED2018-102668-TXunta de Galicia; ED431G2019/0

Transmission of Analog Information Over the Multiple Access Relay Channel Using Zero-Delay Non-Linear Mappings

[Abstract]: We consider the zero-delay encoding of discrete-time analog information over the Multiple Access Relay Channel (MARC) using non-linear mapping functions. On the one hand, zero-delay non-linear mappings are capable to deal with the multiple access interference (MAI) caused by the simultaneous transmission of the information. On the other, the relaying operation is a Decode-and-Forward (DF) strategy where the decoded messages are merged into a single message using a specific continuous mapping depending on the correlation level of the source information. At the receiver, an approximated Minimum Mean Squared Error (MMSE) decoder is developed to obtain an estimate of the transmitted source symbols which exploits the information received from the relay node in combination with the messages received from the transmitters through the direct links. The resulting system provides better performance than the other alternative encoding strategies for the MARC with similar complexity and delay and also approaches the performance of theoretical strategies which require a significantly higher delay and computational cost.This work was supported in part by the Office of the Naval Research Global of United States under Grant N62909-15-1-2014, in part by the Xunta de Galicia under Grant ED431C 2016-045, Grant ED341D R2016/012, and Grant ED431G/01, in part by the Agencia Estatal de Investigación of Spain under Grant TEC2015-69648-REDC and Grant TEC2016-75067-C4-1-R, and in part by the ERDF funds of the EU (AEI/FEDER, UE).Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED341D R2016/012Xunta de Galicia; ED431G/0

Analog Transmission of Spatio-Temporal Correlated Sources Over MAC With Modulo Mappings

© 2018 IEEE. This version of the article has been accepted for publication, after peer review. 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. The Version of Record is available online at: https://doi.org/10.1109/LCOMM.2018.2807427[Abstract]: Modulo mappings is an appealing scheme for the analog transmission of spatially correlated discrete-time analog source symbols over multiple access channels. In this letter, we show that the modulo mappings are also useful to exploit temporal correlation with zero-delay and without impairing encoding/decoding computational complexity. Spatio-temporal source correlation is exploited with a Kalman filter-based receiver, coupled with a sphere decoder, that takes into account the non-linearities of the modulo mappings. We also explain how to optimize the mapping parameters.This work has been funded by Office of Naval Research Global of United States (N62909-15-1-2014), the Xunta de Galicia (ED431C 2016-045, ED341D R2016/012, ED431G/01), the Agencia Estatal de Investigación of Spain (TEC2015-69648-REDC, TEC2016-75067-C4-1-R) and ERDF funds of the EU (AEI/FEDER, UE). The authors thank Prof. Joaquín Míguez of Universidad Carlos III de Madrid, Spain, for his helpful suggestions.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED341D R2016/012Xunta de Galicia; ED431G/01United States. Office of Naval Research Global of United States; N62909-15-1-201

Transmission of Spatio-Temporal Correlated Sources Over Fading Multiple Access Channels With DQLC Mappings

© 2019 IEEE. This version of the article has been accepted for publication, after peer review. 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. The Version of Record is available online at: https://doi.org/ 10.1109/TCOMM.2019.2912571.[Abstract]: The design of zero-delay Joint Source-Channel Coding (JSCC) schemes for the transmission of correlated information over fading Multiple Access Channels (MACs) is an interesting problem for many communication scenarios like Wireless Sensor Networks (WSNs). Among the different JSCC schemes so far proposed for this scenario, Distributed Quantizer Linear Coding (DQLC) represents an appealing solution since it is able to outperform uncoded transmissions for any correlation level at high Signal-to-Noise Ratios (SNRs) with a low computational cost. In this paper, we extend the design of DQLC-based schemes for fading MACs considering sphere decoding to make the optimal Minimum Mean Squared Error (MMSE) estimation computationally affordable for an arbitrary number of transmit users. The use of sphere decoding also allows to formulate a practical algorithm for the optimization of DQLC-based systems. Finally, non-linear Kalman Filtering for the DQLC is considered to jointly exploit the temporal and spatial correlation of the source symbols. The results of computer experiments show that the proposed DQLC scheme with the Kalman Filter decoding approach clearly outperforms uncoded transmissions for medium and high SNRs.This work has been funded by Office of Naval Research Global of United States (N62909-15-1-2014), the Xunta de Galicia (ED431C 2016-045, ED341D R2016/012, ED431G/01), the Agencia Estatal de Investigación of Spain (TEC2015-69648-REDC, TEC2016-75067-C4-1-R) and ERDF funds of the EU (AEI/FEDER, UE).United States. Office of Naval Research Global of United States; N62909-15-1-2014Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED341D R2016/012Xunta de Galicia; ED431G/0

A WiMAX Conformal Broad-Beam Antenna

[Abstract] The numerical model of a very simple conformal antenna, prepared to work in the 3.4 to 3.6 GHz WiMAX range, is presented. The pattern radiated by the proposed antenna displays high gain and excellent linear polarization within the broad coverage zone.Xunta de Galicia; 09TIC008105PRXunta de Galicia; 07TIC002206PRMinisterio de Ciencia e Innovación; TEC2007-68020-C04-01Ministerio de Ciencia e Innovación; TEC2008-04485Ministerio de Ciencia e Innovación; CSD2008-00010