Room reflections and constancy in speech-like sounds: within-band effects

The experiment asks whether constancy in hearing precedes or follows grouping. Listeners heard speech-like sounds comprising 8 auditory-filter shaped noise-bands that had temporal envelopes corresponding to those arising in these filters when a speech message is played. The ���context��� words in the message were ���next you���ll get _to click on���, into which a ���sir��� or ���stir��� test word was inserted. These test words were from an 11-step continuum that was formed by amplitude modulation. Listeners identified the test words appropriately and quite consistently, even though they had the ���robotic��� quality typical of this type of 8-band speech. The speech-like effects of these sounds appears to be a consequence of auditory grouping. Constancy was assessed by comparing the influence of room reflections on the test word across conditions where the context had either the same level of reflections, or where it had a much lower level. Constancy effects were obtained with these 8-band sounds, but only in ���matched��� conditions, where the room reflections were in the same bands in both the context and the test word. This was not the case in a comparison ���mismatched��� condition, and here, no constancy effects were found. It would appear that this type of constancy in hearing precedes the across-channel grouping whose effects are so apparent in these sounds. This result is discussed in terms of the ubiquity of grouping across different levels of representation.

Modula����o quantizada para sistemas com codifica����o wavelet sujeitos ao desvanecimento rayleigh

Wavelet coding is an efficient technique to overcome the multipath fading effects, which are characterized by fluctuations in the intensity of the transmitted signals over wireless channels. Since the wavelet symbols are non-equiprobable, modulation schemes play a significant role in the overall performance of wavelet systems. Thus the development of an efficient design method is crucial to obtain modulation schemes suitable for wavelet systems, principally when these systems employ wavelet encoding matrixes of great dimensions. In this work, it is proposed a design methodology to obtain sub-optimum modulation schemes for wavelet systems over Rayleigh fading channels. In this context, novels signal constellations and quantization schemes are obtained via genetic algorithm and mathematical tools. Numerical results obtained from simulations show that the wavelet-coded systems derived here have very good performance characteristics over fading channels

Avalia����o de desempenho da codifica����o wavelet em canais seletivos em frequ��ncia

Wavelet coding has emerged as an alternative coding technique to minimize the fading effects of wireless channels. This work evaluates the performance of wavelet coding, in terms of bit error probability, over time-varying, frequency-selective multipath Rayleigh fading channels. The adopted propagation model follows the COST207 norm, main international standards reference for GSM, UMTS, and EDGE applications. The results show the wavelet coding s efficiency against the inter symbolic interference which characterizes these communication scenarios. This robustness of the presented technique enables its usage in different environments, bringing it one step closer to be applied in practical wireless communication systems

Multi-node TOA-DOA cooperative LOS-NLOS localization : enabling high accuracy and reliability

This dissertation investigates high performance cooperative localization in wireless environments based on multi-node time-of-arrival (TOA) and direction-of-arrival (DOA) estimations in line-of-sight (LOS) and non-LOS (NLOS) scenarios. Here, two categories of nodes are assumed: base nodes (BNs) and target nodes (TNs). BNs are equipped with antenna arrays and capable of estimating TOA (range) and DOA (angle). TNs are equipped with Omni-directional antennas and communicate with BNs to allow BNs to localize TNs; thus, the proposed localization is maintained by BNs and TNs cooperation. First, a LOS localization method is proposed, which is based on semi-distributed multi-node TOA-DOA fusion. The proposed technique is applicable to mobile ad-hoc networks (MANETs). We assume LOS is available between BNs and TNs. One BN is selected as the reference BN, and other nodes are localized in the coordinates of the reference BN. Each BN can localize TNs located in its coverage area independently. In addition, a TN might be localized by multiple BNs. High performance localization is attainable via multi-node TOA-DOA fusion. The complexity of the semi-distributed multi-node TOA-DOA fusion is low because the total computational load is distributed across all BNs. To evaluate the localization accuracy of the proposed method, we compare the proposed method with global positioning system (GPS) aided TOA (DOA) fusion, which are applicable to MANETs. The comparison criterion is the localization circular error probability (CEP). The results confirm that the proposed method is suitable for moderate scale MANETs, while GPS-aided TOA fusion is suitable for large scale MANETs. Usually, TOA and DOA of TNs are periodically estimated by BNs. Thus, Kalman filter (KF) is integrated with multi-node TOA-DOA fusion to further improve its performance. The integration of KF and multi-node TOA-DOA fusion is compared with extended-KF (EKF) when it is applied to multiple TOA-DOA estimations made by multiple BNs. The comparison depicts that it is stable (no divergence takes place) and its accuracy is slightly lower than that of the EKF, if the EKF converges. However, the EKF may diverge while the integration of KF and multi-node TOA-DOA fusion does not; thus, the reliability of the proposed method is higher. In addition, the computational complexity of the integration of KF and multi-node TOA-DOA fusion is much lower than that of EKF. In wireless environments, LOS might be obstructed. This degrades the localization reliability. Antenna arrays installed at each BN is incorporated to allow each BN to identify NLOS scenarios independently. Here, a single BN measures the phase difference across two antenna elements using a synchronized bi-receiver system, and maps it into wireless channel���s K-factor. The larger K is, the more likely the channel would be a LOS one. Next, the K-factor is incorporated to identify NLOS scenarios. The performance of this system is characterized in terms of probability of LOS and NLOS identification. The latency of the method is small. Finally, a multi-node NLOS identification and localization method is proposed to improve localization reliability. In this case, multiple BNs engage in the process of NLOS identification, shared reflectors determination and localization, and NLOS TN localization. In NLOS scenarios, when there are three or more shared reflectors, those reflectors are localized via DOA fusion, and then a TN is localized via TOA fusion based on the localization of shared reflectors.

Household risk factors and the health and nutritional status of children in rural Honduras

During this cross-sectional study, both quantitative and qualitative research methods were used to elucidate the role that household environment and sanitation play in the nutritional status of children in a rural Honduran community. Anthropometric measurements were taken as measures of nutritional status among children under five years of age, while interviews regarding the household environment were conducted with their primary caregivers. Community participatory activities were conducted with primary caregivers, and results from water quality testing were analyzed for E. coli contamination. Anthropometric results were compared using the 1977 NCHS Growth Charts and the 2006 WHO Child Growth Standard to examine the implications of using the new WHO standard. The references showed generally good or excellent agreement between z-score categories, except among height-for-age classifications for males 24-35.9 months and weight-for-age classifications for males older than 24 months. Comparing the proportion of stunted, underweight, and wasted children, using the WHO standard generally resulted in higher proportions of stunting, lower underweight proportions, and higher overweight proportions. Logistic regression was used to determine which household and sanitation factors most influenced the growth of children. Results suggest only having water from a spring, stream, or other type of surface water as the primary source of drinking water is a significant risk factor for stunting. A protective association was seen between the household wealth index and stunting. Through participatory activities, the community provided insight on health issues important for improving child health. These activities yielded findings to be harnessed as a powerful resource to unify efforts for change. The qualitative findings were triangulated with the quantitative interview and water testing results to provide intervention recommendations for the community and its primary health care clinic. Recommendations include educating the community on best water consumption practices and encouraging the completion of at least some primary education for primary caregivers to improve child health. It is recommended that a community health worker program be developed to support and implement community interventions to improve water use and household sanitation behaviors and to encourage the involvement of the community in targeting and guiding successful interventions. ^

Oligocene magnetostratigraphy for equatorial Pacific ODP Sites

An Oligocene magnetostratigraphy from ODP Sites 1218 and 1219 (Equatorial Pacific) has been obtained by measurements made on u-channel samples, augmented by about 221 discrete samples. U-channel samples were measured at 1 cm intervals and were stepwise demagnetized in alternating fields (AF) up to a maximum peak field of 80 mT. The magnetization directions were determined at 1 cm intervals by principal component analysis of demagnetization steps in the 20 to 60 mT peak field range. A similar treatment was carried out on the discrete samples, which confirmed the results obtained with u-channel measurements. Sites 1218 and 1219 were precisely correlated based on multisensor track, paleontological and shipboard magnetostratigraphic data; this correlation is substantiated by u-channel measurements. Although the magnetostratigraphy obtained from the u-channels is similar to the interpretation deduced from shipboard measurements based on blanket demagnetization at peak AF of 20 mT, the u-channel results are substantially more robust since many interpretative uncertainties are resolved by the stepwise demagnetization and higher stratigraphic resolution. The temporal resolution of u-channel-based magnetic stratigraphy in the Oligocene section of Sites 1218 and 1219 is better than 5 kyr, and it is therefore suitable for detection of brief polarity subchrons. However, in spite of the high resolution, we did not find any reversals corresponding to the numerous cryptochrons identified in this time span by Cande and Kent (1995, doi:10.1029/94JB03098).

Proceso de replanteo de un nodo urbano

El continuo desarrollo que est�� teniendo el mundo de las telecomunicaciones m��viles hace que la red m��vil est�� sufriendo progresivos cambios para adaptarse a las nuevas tecnolog��as m��viles que ofrecen un mejor servicio. El cambio en la red m��vil no solo se produce por el desarrollo de las nuevas generaciones m��viles. La red m��vil se adapta tambi��n a la demanda de usuarios la cual no deja de incrementar a lo largo de los ��ltimos a��os. Por tanto, los operadores tienen que ampliar su red instalando nodos que tengan las nuevas tecnolog��as y tambi��n las anteriores. Aparte de crear nuevos nodos tambi��n tienen que modificar sus nodos antiguos y convertirlos en nodos que soporten mayor n��mero de usuarios. Hoy en d��a, en Espa��a, se est��n instalando nuevos nodos con 2G, 3G y 4G y adem��s se est��n realizando ampliaciones de portadora para 3G. Este proyecto se divide en cuatro partes, la primera de ella se centra en explicar el proceso a seguir para la instalaci��n de un nuevo nodo urbano. Este proceso es muy parecido para instalar un nodo con una tecnolog��a u otra, en el caso del proyecto se explicar��n los pasos a seguir para la instalaci��n de un nodo con 2G y 3G. Posteriormente se explicar�� c��mo se realizan las medidas para corroborar el correcto funcionamiento de un nodo rural y se comparar��n a las medidas de zona urbana mediante capturas de un nodo espec��fico. En la pen��ltima parte del proyecto se estudia la cobertura en interiores y las diversas soluciones que se toman normalmente para mejorar dicha cobertura en edificios, almacenes y centros comerciales. Por ��ltimo aparecen las conclusiones del proyecto y los trabajos futuros en donde se realiza una visi��n de posibles estudios relacionados con este proyecto y una visi��n de c��mo puede quedar formada la red en unos a��os. ABSTRACT. Due to the continuous development of mobile telecommunications the mobile networks have undergone rapid changes to adapt to new mobile technologies that offer a better service. The mobile network change hasn��t only occurred because of the development of new generations of mobile radio-communications. The mobile network adapts itself to user demand, which has been growing over the last few years faster than expected. Therefore, mobile operators have to enlarge its network by installing nodes that share the old and new technologies. Apart from creating new nodes, the operators have to modify the old ones and turn them into nodes that support an increasing number of users. Nowadays, in Spain new nodes with 2G 3G and 4G are being installed, and carrier extensions for 3G are being made as well. This project is divided into four parts. The first chapter focuses on explaining the process that should be followed to install a new urban node. This process is similar to install a node with any of the technologies available. In the case of this project, the steps to follow in setting up a wireless node with 2G and 3G will be detailed. Afterwards, in the second chapter the document continues explaining the measurements that should be carried out to ensure proper performance of a rural node. Then, those measurements will be compared with the ones of an urban node. In the third part of the project it is explained how coverage indoor studies are performed, and the different solutions that are usually proposed to improve coverage in buildings, stores and shopping centers. The last chapter explains the conclusions that have been reached and future works. It is provided a widespread view of possible studies related to this project and how the mobile will improve in the following years.

Multilevel coherence effects in a two-level atom driven by a trichromatic field

We study the absorption and dispersion properties of a weak probe field monitoring a two-level atom driven by a trichromatic field. We calculate the steady-state linear susceptibility and find that the system can produce a number of multilevel coherence effects predicted for atoms composed of three and more energy levels. Although the atom has only one transition channel, the multilevel effects are possible because there are multichannel transitions between dressed states induced by the driving field. In particular, we show that the system can exhibit multiple electromagnetically induced transparency and can also produce a strong amplification at the central frequency which is not attributed to population inversion in both the atomic bare states and in the dressed atomic states. Moreover, we show that the absorption and dispersion of the probe field is sensitive to the initial relative phase of the components of the driving field. In addition, we show that the group velocity of the probe field can be controlled by changing the initial relative phases or frequencies of the driving fields and can also be varied from subluminal to superluminal. (C) 2003 Elsevier Science B.V. All rights reserved.

Optimum wireless power transmission for sensors embedded in concrete

Various nondestructive testing (NDT) technologies for construction and performance monitoring have been studied for decades. Recently, the rapid evolution of wireless sensor network (WSN) technologies has enabled the development of sensors that can be embedded in concrete to monitor the structural health of infrastructure. Such sensors can be buried inside concrete and they can collect and report valuable volumetric data related to the health of a structure during and/or after construction. Wireless embedded sensors monitoring system is also a promising solution for decreasing the high installation and maintenance cost of the conventional wire based monitoring systems. Wireless monitoring sensors need to operate for long time. However, sensor batteries have finite life-time. Therefore, in order to enable long operational life of wireless sensors, novel wireless powering methods, which can charge the sensors��� rechargeable batteries wirelessly, need to be developed. The optimization of RF wireless powering of sensors embedded in concrete is studied here. First, our analytical results focus on calculating the transmission loss and propagation loss of electromagnetic waves penetrating into plain concrete at different humidity conditions for various frequencies. This analysis specifically leads to the identification of an optimum frequency range within 20���80 MHz that is validated through full-wave electromagnetic simulations. Second, the effects of various reinforced bar configurations on the efficiency of wireless powering are investigated. Specifically, effects of the following factors are studied: rebar types, rebar period, rebar radius, depth inside concrete, and offset placement. This analysis leads to the identification of the 902���928 MHz ISM band as the optimum power transmission frequency range for sensors embedded in reinforced concrete, since antennas working in this band are less sensitive to the effects of varying humidity as well as rebar configurations. Finally, optimized rectennas are designed for receiving and/or harvesting power in order to charge the rechargeable batteries of the embedded sensors. Such optimized wireless powering systems exhibit significantly larger efficiencies than the efficiencies of conventional RF wireless powering systems for sensors embedded in plain or reinforced concrete.

The Spanish Space Weather Service SeNMEs. A Case Study on the Sun-Earth Chain

The Spanish Space Weather Service SeNMEs, www.senores.es, is a portal created by the SRG-SW of the Universidad de Alcala, Spain, to meet societal needs of near real-time space weather services. This webpage-portal is divided in different sections to fulfill users needs about space weather effects: radio blackouts, solar energetic particle events, geomagnetic storms and presence of geomagnetically induced currents. In less than one year of activity, this service has released a daily report concerning the solar current status and interplanetary medium, informing about the chances of a solar perturbation to hit the Earth's environment. There are also two different forecasting tools for geomagnetic storms, and a daily ionospheric map. These tools allow us to nowcast a variety of solar eruptive events and forecast geomagnetic storms and their recovery, including a new local geomagnetic index, LDin, along with some specific new scaling. In this paper we also include a case study analysed by SeNMEs. Using different high resolution and cadence data from space-borne solar telescopes SDO, SOHO and GOES, along with ionospheric and geomagnetic data, we describe the Sun-Earth feature chain for the event.

Colorado's Piceance Basin: Variation in the local public finance effects of oil and gas development

A large increase in natural gas production occurred in western Colorado���s Piceance basin in the mid- to late-2000s, generating a surge in population, economic activity, and heavy truck traffic in this rural region. We describe the fiscal effects related to this development for two county governments: Garfield and Rio Blanco, and two city governments: Grand Junction and Rifle. Counties maintain rural road networks in Colorado, and Garfield County���s ability to fashion agreements with operators to repair roads damaged during operations helped prevent the types of large new costs seen in Rio Blanco County, a neighboring county with less government capacity and where such agreements were not made. Rifle and Grand Junction experienced substantial oil- and gas-driven population growth, with greater challenges in the smaller, more isolated, and less economically diverse city of Rifle. Lessons from this case study include the value of crafting road maintenance agreements, fiscal risks for small and geographically isolated communities experiencing rapid population growth, challenges associated with limited infrastructure, and the desirability of flexibility in the allocation of oil- and gas-related revenue.

A simple orientation robust transmit polarization signalling scheme

A special transmit polarization signalling scheme is presented to alleviate the power reduction as a result of polarization mismatch from random antenna orientations. This is particularly useful for hand held mobile terminals typically equipped with only a single linearly polarized antenna, since the average signal power is desensitized against receiver orientations. Numerical simulations also show adequate robustness against incorrect channel estimations.

Empirical IEEE 802.11p performance evaluation on test tracks

IEEE 802.11p is the new standard for inter-vehicular communications (IVC) using the 5.9 GHz frequency band; it is planned to be widely deployed to enable cooperative systems. 802.11p uses and performance have been studied theoretically and in simulations over the past years. Unfortunately, many of these results have not been confirmed by on-tracks experimentation. In this paper, we describe field trials of 802.11p technology with our test vehicles. Metrics such as maximum range, latency and frame loss are examined.

Fabrication of Fe-doped WO3 films for NO2 sensing at lower operating temperature

Fe-doped tungsten oxide thin films with different concentrations (0 to 2.6 at%) were synthesized on glass and alumina substrates at room temperature using DC reactive sputtering and subsequently annealed at 300oC for 1 hour in air. The alumina substrate has pre-printed interdigitated Pt-electrodes for gas sensing measurements. The effects of Fe-doping on the film structure and morphology, electronic and optical properties for gas sensing were investigated. The grain size of the different films on the alumina and Pt regions of the substrate vary only slightly between 43-57 nm with median size of about 50 nm. Raman spectra showed that the integrated intensity of W=O to O���W���O bands increases with increasing Fe concentrations and this indicated an increase in the number of defects. From XPS the different concentrations of the Fe-doped films were 0.03 at%, 1.33 at% and 2.6 at%. All the films deposited on glass substrate have shown similar visible transmittance (about 70%) but the optical band gap of the pure film decreased form 3.30 eV to 3.15 eV after doping with 2.6 at% Fe. The Fe-doped WO3 film with the highest Fe concentration (2.6 at% Fe) has shown an enhanced gas sensing properties to NO2 at relatively lower operating temperature (150oC) and this can be attributed to the decrease in the optical band gap and an increase in the number of defects compared to the pure WO3 film.

Duty cycling and power management with a network of energy harvesting sensors

In this paper, we study duty cycling and power management in a network of energy harvesting sensor (EHS) nodes. We consider a one-hop network, where K EHS nodes send data to a destination over a wireless fading channel. The goal is to find the optimum duty cycling and power scheduling across the nodes that maximizes the average sum data rate, subject to energy neutrality at each node. We adopt a two-stage approach to simplify the problem. In the inner stage, we solve the problem of optimal duty cycling of the nodes, subject to the short-term power constraint set by the outer stage. The outer stage sets the short-term power constraints on the inner stage to maximize the long-term expected sum data rate, subject to long-term energy neutrality at each node. Albeit suboptimal, our solutions turn out to have a surprisingly simple form: the duty cycle allotted to each node by the inner stage is simply the fractional allotted power of that node relative to the total allotted power. The sum power allotted is a clipped version of the sum harvested power across all the nodes. The average sum throughput thus ultimately depends only on the sum harvested power and its statistics. We illustrate the performance improvement offered by the proposed solution compared to other naive schemes via Monte-Carlo simulations.