Bayesian Modeling For Dealing With Uncertainty In Cognitive Radios

Wireless communication systems can be affected by several factors, including propagation losses, co-channel interference, and multipath fading. Uncertainty affects all of these factors making it even more difficult to model these systems. This dissertation proposes the use of probabilistic graphical models (PGM), such as Bayesian Networks and Influence Diagrams, as the core for reasoning and decision making in adaptive radios operating under uncertainty. PGM constitute a tool to understand and model complex relations among random variables. This dissertation explains how to build effective communication models that perform its functions under uncertainty. In addition, this work also presents a spectrum sensing technique based on the autocorrelation of samples to estimate the utilization level of wireless channels

Software-based Implementation of Secure AES Frame Encryption (SAFE) for CAN FD in Multicore Environment

The SAFE kernel software implementation was born as an inexpensive alternative from the original implementation which uses a field programmable gate array (FPGA). This paper proposes to replace the FPGA with a microprocessor, which will drastically reduce the cost of the implementation. The new implementation includes the MIMXRT1170 EVK that integrates two microprocessors, a Cortex M4 running at 400 MHz and a Cortex M7 running at 1 GHz. After the software implementation, the multicore environment met the required time deadlines and achieved the desire performance, keeping the CAN FD bus occupation at 100% and the encryption and decryption time less than 50 microseconds, which represents 25% of the microprocessor overhead. In future works the implementation could be adjusted to one microprocessor, such as the cortex M7 due to it is powerful capability to process data which also reduces the cost and the complexity of the implementation.ITESO, A. C

Progress in halide-perovskite nanocrystals with near-unity photoluminescence quantum yield

Colloidal halide perovskite nanocrystals (PNCs) are an outstanding case study due to their remarkable optical features, such as a high photoluminescence (PL) quantum yield (PLQY), tunable band gap, and narrow emission. Despite the impressive first reports of PLQYs beyond 70%, it has been observed that PLQY is limited by structural defects arising from labile interactions between the organic capping ligand and the inorganic core. Structural defects acting as trap states are key factors limiting both PNC PLQY and stability. In this review, we present the most studied, common, and alternative protocols to fully compensate for surface defects (e.g., halide vacancies, loss of protective capping ligands) as well as how to increase their stability and PLQY to unity (i.e., 100% when PLQY is expressed as a percentage)

Experience with dalbavancin use in various gram-positive infections within Aberdeen Royal Infirmary OPAT service

Open Access via the Springer/JISC agreementPeer reviewe

Stabilization of Black Perovskite Phase in FAPbI3 and CsPbI3

Although halide perovskites allow a great versatility, the application on single-absorber solar cells restricts significantly the number of available materials. In this context, CsPbI3 and FAPbI3 (FA, formamidinium) present a huge potential for the inorganic approach with enhanced stability and narrow bandgap, respectively. However, for these materials, Cs+ and FA+ are relatively too small and too big to stabilize the perovskite black phase at room temperature, both presenting a nonphotoactive yellow phase as the most stable phase. This fact limits dramatically their application and also helps in the understanding of the main research lines in the halide perovskite photovoltaic field in the quest for the stabilization of FAPbI3. In this Perspective, we present an overview of different strategies for the stabilization of the perovskite black phase of these two materials. We evaluate the stability approaches envisioning efficient and stable materials, with a particular focus on the positive and limiting aspects of the exploitation of low dimensionality and chemi-structural mechanisms

Producción de hidrógeno a través de la gasificación de glucosa usando catalizadores de γ-Al2O3 con Ni, Ce y La e interpretación de resultados usando un modelo No-estequiométrico

La situación energética y medio ambiental hace que la generación de energía mediante sistemas basados en energías renovables tome cada vez mayor relevancia. Dentro de las distintas energías alternas la biomasa es una gran opción, ya que es considerada un recurso renovable debido a su bajo contenido de azufre y emisiones de 2. De los diferentes procesos que son utilizados para la conversión de biomasa, su gasificación para producir hidrogeno se realiza con un balance cero de carbono. El hidrógeno es un vector energético cuya combustión es limpia, además de que tiene un elevado poder calorífico debido a que su densidad energética es la más grande de todos los combustibles. Por esto se deben sintetizar catalizadores que maximicen la cantidad de hidrógeno producido, los catalizadores basados en níquel son más activos por lo que resultan efectivos en la producción de hidrógeno, mientras que incrementan la relación 22⁄ lo que mejora la calidad del gas de síntesis. En este trabajo se sintetizaron catalizadores de níquel soportado sobre gama alúmina (5%Ni/γ-Al2O3), níquel y promotores de cerio y lantano soportados sobre gama alúmina (5%Ni-X%La/γ Al2O3 y 5%Ni-X%Ce/γ Al2O3, donde X=0.5, 1 y 2%), los cuales se caracterizaron con las técnicas de difracción de rayos X, absorción atómica, determinación de área superficial por BET, distribución de tamaño de partícula y microscopia de barrido electrónico. Estos materiales se probaron en el reactor CREC-Riser Simulator. Se estudio el efecto de las variables tiempo de reacción de 5,10,20,30 y 40s, relación vapor biomasa de 0.5 1 y 1.5, carga del promotor cerio o lantano para ambos con los valores 0.5, 1 y 2% en peso, manteniendo constante la carga del níquel de 5% y el pH de síntesis de los catalizadores con promotor de 1 y 4. Los resultados indican una disminución del área superficial de los catalizadores impregnados con metales (114-130 m2/g) con respecto al área del soporte gama alúmina (197 m2/g), con respecto a los experimentos térmicos o no catalíticos, el uso del catalizador con níquel (5%Ni/-Al2O3) permitió obtener incrementos de 30% y 36%, en las fracciones mol de H2 y CO2 respectivamente. Con respecto a los resultados con níquel, la adición del promotor de lantano permitió obtener, en el mejor de los casos (5%Ni-2La/γ-Al2O3-pH1) un incremento del 9% en la fracción mol de H2, lo que indica el efecto positivo de la presencia del lantano. Por otra parte, cuando se hicieron varias inyecciones sin que se regeneraran los catalizadores de cerio y lantano se obtuvieron resultados semejantes, lo que indica que estos promotores no tienen mucha influencia en la estabilidad del catalizador, ya que no se desactivaron. El uso de este tipo de catalizadores sin regenerar puede significar una gran promesa tecnológica ya que evitan los gastos de oxidación y de reducción. El efecto de las variables tiempo de reacción y relación vapor biomasa (S/B), en la relación de H2/CH4 indica que la mayor producción de H2 se obtiene con 30 segundos de reacción y S/B=1. Para interpretar los resultados se usó un modelo no-estequiométrico. Se ejecutó con el software Aspen Plus el cual consistió en un reactor de rendimiento (RYIELD) unido en serie a un reactor de equilibrio (RGIBBS). La comparación de los resultados del modelo con los datos experimentales indico que el modelo describe correctamente las tendencias de los perfiles de fracción mol de los diversos compuestos con la temperatura, para las relaciones S/B=1 y 1.5. La propuesta de modelos termodinámicos permite interpretar los resultados experimentales y generar las bases de diseño de un reactor para gasificación de biomasa

Recent insights for achieving mixed halide perovskites without halide segregation

The incorporation of halide perovskites in optoelectronics has provided a fast advance in the fabrication of new sensitizers with a balanced light-harvesting, free carrier transportation, and a progressive overcoming of the low tolerance to the moisture. Within these emerging materials, mixed halide perovskites as APbX3−xYx, (A = MA+, Cs+, FA+; X, Y=Cl−, Br−, I−) have been highlighted due to their facile band gap tunability in the entire visible region by varying the halide composition, which making these systems enormously appealing for the design of optoelectronic devices. Nonetheless, their performance in real devices is strongly limited as mixed halide perovskites exhibit photoinduced and current-induced phase segregation, losing their original photophysical properties and effective band gap tunability to generate halide-rich domains. The phase segregation has been the key factor to decrease the photovoltaic parameters in solar cells as open-circuit voltage and photoconversion efficiency, also limiting the performance of tandem devices and the potentiality of color design in perovskite LEDs. This review summarizes recent trends to hinder the phase segregation

Body Control Module using the SAM-V71 development board

The Body Control Module is one of the main devices inside a car since it is responsible of the critical aspects for the correct function of the vehicle including the safety and comfort of all passengers. However, these features come at a high cost. Therefore, the aim of this project was to perform a BCM capable of executing the basic functions of a commercial module in a car but with a lower cost. This was achieved using the SAMV71 development board and its embedded CAN protocol communication port and following the V-cycle which has two main branches: planning and integration of their parts and validation. This model facilitates keeping track of any progress during the development stage. The device successfully read analog and digital inputs, processed the information and sent it through the CAN bus for further processing. AUTOSAR was the standard used trough the development process, since it is the most employed in the automotive industry. It specifies that the software components shall be in layers, helping the process of integration and giving portability to the project. With this BCM it is possible to adapt a classic internal combustion engine car that lacks modern electronics to a battery electric vehicle

Development of Guiding Cane with Voice Notification for Visually Impaired individuals

Navigation in the physical environment is a challenge for those people who have very limited sense of sight or no vision at all. Assistive technologies for blind mobilization is not new and always have a room for improvement. Moreover, these assistive devices are limited in terms of its sensing and feedback abilities. This paper presents a microcontroller-based guiding stick capable of detecting several conditions of the environment such as obstacles in front, left and right positions of the user and detects ascending and descending staircases. The feedback is delivered by an audio output which dictates the direction to go or what condition the sensor detects in front of the user. Technical evaluation proves that the device was functional in terms of its accuracy, responsiveness and correctness. On the other hand, in the actual evaluation of the device with the visually impaired individuals, the device did not perform efficiently. It was also found that the device has the potential to be used effectively by the visually impaired who acquired their blindness in later stage of their life provided that they will have a proper training in using the device while navigating in the physical environment

The Cone of Mueller Matrices

In the study of polarized light, there are two basic notions: the Stokes vectors and the matrices which preserve them, called Mueller matrices. The set of Stokes vectors forms a cone: the Future Light Cone. In this work we will see that the Mueller matrices also form a cone in the vector space of real matrices of size 4X4, called the Mueller Cone. We obtain some properties of the Mueller cone, which in turn will be translated into properties of the Stokes vectors. As an application we will give a computational program to calibrate polarimeters by means of the eigenvectors of Mueller matrices (ECM). We include computational programs to 1. Deduce if a matrix is a Mueller matrix, 2. Give an approximation of a matrix by a Mueller matrix, 3. An approximation of a Mueller matrix by Mueller invertibles, 4. An approximation of a Mueller matrix by a Stokes-cone-primitive Mueller matrix, see (4.7) and 5. An Eigenvalue Calibration Method. All these programs and implementations can be found in https://github.com/IvanLopezR22/cone-of-mueller-matrices/tree/masterComment: 20 pages, 1 figure and computer program