3,462 research outputs found
Analysis of Gaussian Quadratic Forms with Application to Statistical Channel Modeling
Finalmente, en el contexto de modelado de canal, la metodologÃa de análisis de variables propuesta permite obtener dos nuevas generalizaciones del conocido modelo de desvanecimiento kappa-mu shadowed. Estas dos nuevas distribuciones, nombradas Beckmann fluctuante y kappa-mu shadowed correlado, incluyen como casos particulares a la gran mayorÃa de distribuciones de desvanecimientos usadas en la literatura, abarcando desde los modelos clásicos de Rayleigh y Rice hasta otros más generales y complejos como el Beckmann y el kappa-mu. Para ambas distribuciones, se presenta su caracterización estadÃstica de primer orden, i.e., función generadora de momentos (MGF), PDF y CDF; asà como los estadÃsticos de segundo orden del modelo Beckmann fluctuante. Fecha de lectura de Tesis Doctoral: 24 Enero 2020En esta tesis se presenta una nueva aproximación a la distribución de de formas cuadráticas gaussianas (FCGs) no centrales tanto en variables reales como complejas. Para ello, se propone un nuevo método de análisis de variables aleatorias que, en lugar de centrarse en el estudio de la variable en cuestión, se basa en la caracterización estadÃstica de una secuencia de variables aleatorias auxiliares convenientemente definida. Como consecuencia, las expresiones obtenidas, con independencia del grado de precisión adquirido, siempre representan una distribución válida, siendo ésta su principal ventaja.
Aplicando este método, se obtienen simples expresiones recursivas para la función densidad de probabilidad (PDF) y la función de distribución (CDF) de las FCGs reales definidas positivas. En el caso de las formas complejas, esta nueva forma de análisis conduce a aproximaciones para los estadÃsticos de primer orden en términos de funciones elementales (exponenciales y potencias), siendo más convenientes para cálculos posteriores que otras soluciones disponibles en la literatura. La tratabilidad matemática se ejemplifica mediante el análisis de sistemas de combinación por razón máxima (MRC) sobre canales Rice correlados, proporcionando aproximaciones cerradas para la probabilidad de outage y la probabilidad de error de bit
Impact Resistance of Hybrid Metal-Organic Frameworks/Carbon Fibers Composites
The increase in the use of carbon fiber-reinforced polymers (CFRPs) composites in the aerospace industry generated the need of improving the properties and capabilities of these composites by adding nano-reinforcements to the carbon fibers, also called hybrid fiber reinforced polymer composites. In this study, the energy absorption due to impact at low speed will be tested and simulated in four configurations of CFRPs utilizing the same [0/90]S layout throughout them.
The carbon fiber configurations used during this study are de-sized, acid-activated, metal-organic frameworks (MOF), and carbon nanotubes (CNTs). Nickel (II) Nitrate, Methylimidazole, and Methanol were used to grow the MOF nano-reinforcement on the carbon fibers; On the other hand, CNTs were grown by reducing the MOF on the carbon fibers and using Ethylene (C2H4), Nitrogen (N2), and Hydrogen (H2) to grow CNTs on the carbon fibers.
To evaluate the composites’ mechanical properties, such as tensile tests and impact tests were performed; Furthermore, a dynamic mechanical analysis (DMA) was performed to assess the dynamic properties of the composites manufactured. Lastly, an impact simulation was performed on LS-Dyna utilizing the properties obtained in the mechanical testing performed. The results obtained proposed that an appropriate combination and recipe of MOF growth could potentially increase the energy absorption of carbon fiber-reinforced polymers
The κ - μ shadowed fading model with arbitrary intercluster correlation
In this paper, we propose a generalization of the
well-known κ-μ shadowed fading model. Based on the clustering
of multipath waves as the baseline model, the novelty of this
new distribution is the addition of an arbitrary correlation for
the scattered components within each cluster. It also inherits
the random fluctuation of the dominant component, which is
assumed to be the same for all clusters. Thus, it unifies a wide
variety of models: Rayleigh, Rician, Rician shadowed, Nakagami-
m, κ-μ and κ-μ shadowed as well as multivariate Rayleigh,
Rician and Rician shadowed. The main statistics of the newly
proposed model, i.e. moment generating function, probability
density function and cumulative density function, are given in
terms of exponentials and powers, and some numerical results
are provided in order to analyze the impact of the arbitrary
intercluster correlation.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tec
Drug trafficking, corruption and foreign direct investment: Theory and evidence
We develop a microeconomic model to explain why sanction policies used by developed countries have had ambiguous effects to reduce drug trafficking in developing countries. In the model, a country receives FDI depending on its government effort to reduce drug exports. However, local drug producers lobby and offer contributions whose impact depends on the level of government corruption. The government sets the level of enforcement against drug trafficking taking into account the contributions paid and the welfare of the local habitants. Analytically, we use the common agency theory to justify and explain diverse sanction policy outcomes. We also show evidence about the relationships among drug trafficking, corruption and FDI for some Latin-American countries.Drug Trafficking; FDI; Corruption; Latin America
- …