Pulsed neutron capture (PNC) logs are commonly used for formation evaluation behind casing and to assess time-lapse variations of hydrocarbon pore volume. Because conventional interpretation methods for sigma logs assume homogeneous formations, errors may arise, especially in thinly-bedded formations, when appraising petrophysical properties of hydrocarbon-bearing beds. There exist no quantitative interpretation methods to account for shoulder-bed effects on sigma logs acquired in sand-shale laminated reservoirs. Because of diffusion effects between dissimilar beds, sigma logs acquired in such formations do not obey mixing laws between the sigma responses of pure-sand and pure-shale end members of the sedimentary sequence. We introduce a new numerical method to simulate rapidly and accurately PNC logs. The method makes use of late-time, thermal-neutron flux sensitivity functions (FSFs) to describe the contribution of multi-layer formations toward the measured capture cross section. It includes a correction procedure based on 1D neutron diffusion theory that adapts the transport-equation-derived, base-case FSF of a homogeneous formation to simulate the response of vertically heterogeneous formations. Benchmarking exercises indicate that our simulation method yields average differences smaller than 2 c.u. within seconds of CPU time with respect to PNC logs simulated with rigorous Monte Carlo methods for a wide range of geometrical, petrophysical, and fluid properties. We develop an inversion method to reduce shoulder-bed effects on pulsed neutron capture (PNC) logs in the estimation of layer-by-layer capture cross sections, Σ. The method is based on the previously developed rapid approximation of PNC logs. Tests performed on synthetic examples that include a variety of lithology, saturating-fluid, and bed-thickness configurations confirm the efficiency, reliability, and stability of the inversion procedure. Inversion consistently improves the vertical resolution and Σ definition of PNC logs across beds thinner than 45 cm. Our fast, iterative algorithm inverts sigma logs in seconds of CPU time, and is therefore suitable for joint petrophysical interpretation with other open- and cased-hole logs. / text

Relay communication has been shown to be effective to extend service coverage and mitigate channel impairments. This thesis focuses on relay selection (RS) of both unidirectional and bidirectional relay networks employing the amplify-and-forward (AF) and decode-and-forward (DF) protocols. This thesis presents four works on RS in two-hop relay networks. In the first work, we study opportunistic relaying (OR) and selection cooperation (SC) in DF-based unidirectional multi-antennas relay networks. We first propose two joint relay-and-antenna selection schemes which combine OR and SC, respectively, with transmit antenna selection. For each joint selection scheme, a single best transmit antenna at the source, a single best relay, and a single best transmit antenna at this selected relay are jointly determined. Then we derive the outage probabilities, and show that the two schemes achieve the same outage performance. In the second work, we study RS with the physical-layer network coding (PNC) in DF-based bidirectional relay networks. By modifying the well-known SC and OR, we first propose two RS schemes for the PNC network: SC-PNC and OR-PNC. Then we derive the outage probability and diversity order of the SC-PNC. Finally, we show that the OR-PNC achieves the same outage performance as the SC-PNC. In the third work, we study RS with the analog network coding (ANC) and time division broadcast (TDBC), in AF-based bidirectional relay networks. We first consider RS schemes for the ANC and TDBC protocols based on a max-min criterion. Then we derive outage probabilities for the ANC and TDBC protocols. In the fourth work, we study joint relay-and-source selection in an AF-based bidirectional relay network. Since RS and opportunistic source selection (OSS) could individually improve performance of relay networks, we propose a joint RS-OSS protocol. In this network, a best source is selected to transmit data to the other source with the help of a selected best relay. Then, we derive the outage probability and average bit-error rate. The considered RS schemes and obtained outage probability expressions will help the design of two-hop wireless communications in determining the system parameters such as relay location and the transmission power at each terminal. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2010-08-23 15:29:50.026

Nowadays data networks occupy an important place in our world. Since the 70, data communications have evolved quickly, and data transmission, voice and video may be transmitted over different media (copper, fiber optic and wireless). For example we can mention video-conference, voice and IP telephony, electronic transactions, medical applications, industrial sensor networks, etc. These applications are carried out successfully through data communications protocols. Protocol is a set of rules and conventions that govern how network devices exchange information. The protocols analysis lets optimize network performance. The study and analysis of wireless personal area networks (WPAN) are developed in this thesis. The application fields include industrial monitoring and control, public safety, measured in vehicles, smart cards or boards, precision agriculture, among others. WPANs are suitable for use in small mobile devices such as sensors, cell phones, Personal Digital Assistants (PDAs), etc. The Institute of Electrical and Electronics Engineers (IEEE) specifies the rules for this type of networks under the IEEE 802.15.x. It have different subgroups:  802.15.1 specifications based on the Special Interest Group (SIG) Bluetooth.  802.15.2 developed a model of coexistence between networks Wireless LAN (Wireless Local Area Networks) and WPANs  803.15.3 transmission delivers high speed, low power consumption, low cost and quality of service.  802.15.4 researches and develops solutions that require low data transmission and thus the batteries lasting for months or even years. This thesis presents the development of proposals to improve the network performance over different real-time scheduling disciplines. First this thesis describes the standard 802.15.3, and then the real-time scheduling algorithms are explained. Then, several variants at MAC level are developed in order improve the real-time WPAN performance. / Las redes de datos hoy en día ocupan un lugar preponderante en mundo en que vivimos. Desde los años 70 los avances sobre las comunicaciones de datos han evolucionado a gran velocidad, pudiendo en la actualidad realizarse transmisiones de datos, voz y video sobre distintos medios (cobre, fibra óptica y sin cable). Como ejemplo podemos mencionar video-conferencias, voz y telefonía sobre IP, transacciones electrónicas bancarias, aplicaciones en medicina, red de sensores industriales, etc. Para que todas estas aplicaciones se lleven a cabo con éxito son indispensables los protocolos que rigen los distintos tipos de comunicaciones. Tal como su definición lo dice un protocolo es un conjunto de normas y convenciones que rigen de qué forma los dispositivos de una red intercambian información. El estudio de éstos permite optimizar el funcionamiento de la red. En esta tesis se desarrolla el estudio y análisis de redes inalámbricas (wireless) de área personal (WPAN). Este tipo de redes se emplean en diversos campos como control y monitoreo industrial, seguridad pública, medición en automóviles, tarjetas o placas inteligentes, agricultura de precisión entre otros. En términos generales, las redes WPANs son adecuadas para el uso en dispositivos móviles pequeños, como sensores, teléfonos celulares, Asistente Digital Personal (PDAs), etc. El Instituto de Ingenieros Electricistas y Electrónicos (IEEE) especifica las normas para este tipo de redes bajo el estándar IEEE 802.15.x, dentro de éste tenemos distintos subgrupos los cuales son:  802.15.1 basado en las especificaciones del Grupo de Interés Especial (SIG) de Bluetooth.  802.15.2 desarrolló un modelo de coexistencia entre las redes Wireless LAN (Redes de Área Local Inalámbricas) y las WPANs  803.15.3 ofrece alta velocidad de transmisión, bajo consumo de energía, bajo costo y calidad de servicio.  802.15.4 investiga y desarrolla soluciones que requieren una baja transmisión de datos y con ello una duración en las baterías de meses e incluso de años. Sobre el estándar 802.15.3 se desarrollarán distintos análisis que nos permitirán realizar propuestas para mejorar el rendimiento de las redes WPANs bajo distintas disciplinas de diagramación sobre sistemas de tiempo real; este es el objetivo de la tesis. Para cumplir con este objetivo, se inicia explicando el funcionamiento del estándar 802.15.3, luego se enfoca sobre los sistemas de tiempo real analizando los distintos algoritmos de diagramación. A continuación se desarrollan diversas metodologías con el objetivo de mejorar el rendimiento de las redes WPANs evaluando su desempeño bajo distintos esquemas de diagramación en tiempo real.

Pulsed-neutron borehole measurements involve a physical process in which a source emits energetic neutrons that lose energy upon collisions with formation nuclei, and are eventually captured by a nucleus to form a heavier, excited state. The excited nucleus decays to its ground state by the emission of gamma rays. Both thermal-neutron and gamma-ray populations decay with time at a rate defined by Sigma, which is a nuclear property that quantifies a material’s ability to capture thermal neutrons. The large contrast in Sigma between hydrocarbon and salty connate water enables calculations of water saturation directly from pulsed-neutron measurements. Sigma logs have proven useful in the assessment of thinly bedded formations because they exhibit a small volume of investigation, and have been deemed superior to resistivity logs in the petrophysical evaluation of carbonate formations. The recognized potential of Sigma logs in formation evaluation initiated the development of multi-detector Logging-While-Drilling (LWD) Sigma measurements. These measurements are acquired using one thermal-neutron and two gamma-ray detectors at different spacings from the source. Such a design is aimed at providing distinct radial depths of investigation to detect filtrate invasion in the near-wellbore zone. Despite their formation-evaluation potential, multi-detector time-decay measurements commonly remain affected by invasion, shoulder-bed, and well-deviation effects. The purpose of this dissertation is to develop a fast-forward simulation method to reproduce multi-detector time decays and combine the method with inversion techniques to improve the petrophysical interpretation of LWD Sigma measurements. First-order perturbation theory and a library of pre-calculated Monte Carlo detector-specific sensitivity functions and time decays are used to numerically simulate borehole Sigma measurements in realistic logging environments. The new simulation method is one hundred thousand times faster than rigorous Monte Carlo calculations and remains within two capture units of disparity. Next, the fast-forward simulation method is embedded within inversion algorithms to estimate layer-by-layer radial length of invasion and formation Sigma corrected for shallow invasion, shoulder-bed, and well-deviation effects. Both fast-forward and inverse modeling algorithms are benchmarked against laboratory and synthetic time decays. The improvement of formation Sigma obtained with inversion-based interpretation leads to an improvement in the estimation of Sigma-derived water saturation. Likewise, the estimated radial length of invasion is combined with neutron and density measurements to correct the latter for invasion effects. Results indicate that the inversion-based interpretation method is well suited for the evaluation of high-porosity formations invaded by salty mud filtrate. Inversion-based interpretation of field LWD time decays enables the estimation of lower values of water saturation when compared to conventional Sigma interpretation or resistivity methods. Estimated values of water saturation are as much as fifty percent lower than predicted by conventional interpretation of Sigma logs in the case of measurements affected by shoulder-bed effects, and as much as one hundred percent lower than predicted by the conventional interpretation method for measurements additionally affected by salty filtrate invasion. The key attributes of the combined petrophysical interpretation of multi-detector Sigma, neutron, and density measurements developed in this dissertation are that it explicitly enforces the physics of all nuclear measurements, honors the pressure and temperature dependency of reservoir fluid nuclear properties, and takes into account a-priori information such as mud-filtrate salinity, connate-water salinity, and bed-boundary locations. / text

We experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system in the presence of turbulence. The atmospheric turbulence channel is emulated by two spatial light modulators (SLMs) on which two randomly generated azimuthal phase patterns are recorded yielding Andrews' azimuthal phase spectrum. Frequency and phase locking are not required in our system thanks to the proposed digital phase noise cancellation (PNC) stage. Besides, the transmittance fluctuation can be monitored accurately by the DC level in this PNC stage, which is free of post-processing noise. The mean excess noise is measured to be 0.014, and the maximum secret key rate of >20Mbit/s can be obtained with the transmittance of 0.85, while employing the commercial PIN photodetectors.

No description available.

The object of this research was to investigate dispersion in surface phononic crystals (PnCs) for application to a newly developed passive surface acoustic wave (SAW) ozone sensor. Frequency band gaps and slow sound already have been reported for PnC lattice structures. Such engineered structures are often advertised to reduce loss, increase sensitivity, and reduce device size. However, these advances have not yet been realized in the context of surface acoustic wave sensors. In early work, we computed SAW dispersion in patterned surface structures and we confirmed that our finite element computations of SAW dispersion in thin films and in one dimensional surface PnC structures agree with experimental results obtained by laser probe techniques. We analyzed the computations to guide device design in terms of sensitivity and joint spectral operating point. Next we conducted simulations and experiments to determine sensitivity and limit of detection for more conventional dispersive SAW devices and PnC sensors. Finally, we conducted extensive ozone detection trials on passive reflection mode SAW devices, using distinct components of the time dispersed response to compensate for the effect of temperature. The experimental work revealed that the devices may be used for dosimetry applications over periods of several days.

In today's competitive business and industrial environment, it is becoming more crucial than ever to assess precisely process losses due to non-compliance to customer specifications. To assess these losses, industry is extensively using Process Capability Indices for performance evaluation of their processes. Determination of the performance capability of a stable process using the standard process capability indices such as and requires that the underlying quality characteristics data follow a normal distribution. However it is an undisputed fact that real processes very often produce non-normal quality characteristics data and also these quality characteristics are very often correlated with each other. For such non-normal and correlated multivariate quality characteristics, application of standard capability measures using conventional methods can lead to erroneous results. The research undertaken in this PhD thesis presents several capability assessment methods to estimate more precisely and accurately process performances based on univariate as well as multivariate quality characteristics. The proposed capability assessment methods also take into account the correlation, variance and covariance as well as non-normality issues of the quality characteristics data. A comprehensive review of the existing univariate and multivariate PCI estimations have been provided. We have proposed fitting Burr XII distributions to continuous positively skewed data. The proportion of nonconformance (PNC) for process measurements is then obtained by using Burr XII distribution, rather than through the traditional practice of fitting different distributions to real data. Maximum likelihood method is deployed to improve the accuracy of PCI based on Burr XII distribution. Different numerical methods such as Evolutionary and Simulated Annealing algorithms are deployed to estimate parameters of the fitted Burr XII distribution. We have also introduced new transformation method called Best Root Transformation approach to transform non-normal data to normal data and then apply the traditional PCI method to estimate the proportion of non-conforming data. Another approach which has been introduced in this thesis is to deploy Burr XII cumulative density function for PCI estimation using Cumulative Density Function technique. The proposed approach is in contrast to the approach adopted in the research literature i.e. use of best-fitting density function from known distributions to non-normal data for PCI estimation. The proposed CDF technique has also been extended to estimate process capability for bivariate non-normal quality characteristics data. A new multivariate capability index based on the Generalized Covariance Distance (GCD) is proposed. This novel approach reduces the dimension of multivariate data by transforming correlated variables into univariate ones through a metric function. This approach evaluates process capability for correlated non-normal multivariate quality characteristics. Unlike the Geometric Distance approach, GCD approach takes into account the scaling effect of the variance-covariance matrix and produces a Covariance Distance variable that is based on the Mahanalobis distance. Another novelty introduced in this research is to approximate the distribution of these distances by a Burr XII distribution and then estimate its parameters using numerical search algorithm. It is demonstrates that the proportion of nonconformance (PNC) using proposed method is very close to the actual PNC value.

The study was conducted to describe how socio-economic characteristics (SEC) of women affect their utilization of maternal healthcare services in Abuja Municipal Areas Council (AMAC) in Abuja Nigeria. A non-experimental, facility-based cross-sectional survey was done. Data was collected using structured interviewer administered questionnaire in 5 district hospitals in AMAC. Sample size of 384 was calculated a priori based on the assumption that 50% of the target population utilized maternal healthcare services during their last pregnancy. Equal allocation of samples per facility was done. The ANC register was used as the sampling frame and proportionate allocation of samples per clinic days was undertaken in each facility. Data analysis included descriptive statistics, cross tabulations and measures of inequality. Logistic regression analysis was used to test the hypothesized relationship between socioeconomic characteristics (predictors) and maternal healthcare service utilization. Other than birth order that showed consistent effect, the results of this study indicated that the predictive effect (predisposing and enabling factors) of the SEC of women included in this study (age, education, birth order, location of residence, income group and coverage by health insurance) on maternal healthcare service utilization were not consistent when considered independently (bivariate analysis) as opposed to when considered together through logistic regression. In addition, the study revealed that there was inequality in the utilization of maternal healthcare services (ante-natal care - ANC, delivery care and post natal care - PNC, and contraceptive services) among women with different SEC, and the payment system for maternal healthcare services was regressive. Addressing these predictors in the natural co-existing state (as indicated by the logistic regression) is essential for equitable access and utilization of healthcare during pregnancy, delivery and the postnatal period, and for contraceptive services in AMAC, Abuja Nigeria. Targeted policy measures and programme actions guided by these findings are recommended to optimise returns on investment towards achieving national and global goals on maternal health in Nigeria / Health Studies / D. Litt. et Phil. (Health Studies)

The purpose of the study was to determine the effect of antenatal health education on postnatal care (PNC) among Human Immunodeficiency Virus (HIV) positive women in Francistown city, Botswana. This study followed a quantitative research paradigm. Data was collected with the aid of a questionnaire from eligible women who consented in writing to participate in the study. Forty-five percent (45%) (n=45) HIV positive women came with babies for 6 weeks PNC and 55% (n=55) brought 8 weeks old babies either for weighing or for the two months immunisation from 28 April to 10 June 2014. The responses regarding the source of health education received were as follows: 40% lay counselors, 31% midwives, 15% doctors, 5% nurses without midwifery, 5% cadre unknown, 2% both lay counselors and midwives, 1% by a health education assistant and 1% was not health educated at all. Conclusion: The study revealed that HIV positive pregnant women received health education from different cadres of health and mostly by lay counselors. Literature indicates that lay counselors may give health information but at a very superficial level. / Health Studies / M.A. (Health Studies)