Zk\mathbb{Z}_k-stratifolds

Generalizing the ideas of $\mathbb{Z}_k$-manifolds from Sullivan and the theory of stratifolds from Kreck, we define $\mathbb{Z}_k$-stratifolds. We introduce the bordism theory of $\mathbb{Z}_k$-stratifolds in order to represent every homology class with $\mathbb{Z}_k$-coefficients. We present a geometric interpretation of the Bockstein long exact sequence and the Atiyah-Hirzebruch spectral sequence for $\mathbb{Z}_k$-bordism ($k$ odd)

Subthreshold 3 Phase Mixers

This thesis will discuss subthreshold FET mixers with a focus on conversion loss derivations. To begin understanding the mixers, a look into the FET model is first taken in Chapter II. Then in Chapter III, a single FET device mixer is studied and its conversion loss is found from its small-signal model. The chapter will then include a two FET device mixer and a four device FET mixer. Finally a new type of mixer will be discussed in Chapter IV. The new type of mixer is a 3 phase mixer with the phase angles being 0°, 120°, and 240°. The theoretical conversion loss is found by treating the FETs as simple switches and a square wave as the RF signal. The resulting conversion loss is shown to be better than the previous mixers mentioned. The thesis will conclude with a discussion of future areas of work for the mixer

Control interno en las entidades del estado colombiano

"El control interno constituye una serie de acciones que se interrelacionan y se extienden a todas las actividades de una organización, éstas son inherentes a la gestión del negocio (actividades de una entidad). El control interno es parte y está integrado a los procesos de gestión básicos: planificación, ejecución y supervisión, y se encuentra entrelazado con las actividades operativas de una organización. Los controles internos son más efectivos cuando forman parte de la esencia de una organización, cuando son ""incorporados"" e ""internalizados"" y no ""añadidos""."Pregrad

Tribological assessment of oil condition sensors for marine launching equipment.

Problems in hydraulic systems associated with hydraulic fluids are an important area of research. Time has proven that contamination control in hydraulic and lubricating systems are fundamental to reliability and performance. Contamination control is needed to guarantee the quality of the oil and machine reliability. Among the several condition monitoring techniques, oil and wear analysis are the most effective for contamination control in hydraulic equipment. An emerging maintenance philosophy is oil condition based maintenance, in which the active monitoring of oil parameters determines the machine health and the variable service intervals. This new maintenance philosophy requires sensor technology able to provide real time indicators of the status of the system.Nowadays, oil condition monitoring sensors are not a mature technology and their performance has not been widely assessed under controlled experimental conditions. This research explains the physical fundamentals of commercially available sensors and it discusses and evaluates their effectiveness under controlled experimental conditions.Tribology tests were performed for sliding contacts as they are the most predominant type of contacts within hydraulic systems. Results reveal that several characteristics of the sensors must be improved for a more meaningful output and for an earlier detection of abnormal trends which are typical indicators of the onset of faults.Finally, of all the future trends of oil condition monitoring sensors, the novel methodology to calculate the particle size distribution from ferrous debris density measurements is the most useful and important contribution to knowledge of this research. The proposed method when compared to current technology would bring a new type of particle counter that could break the technological size limitation of particle counters based on magnetometry (the most extended type in industrial and military machinery), leading to earlier fault detection. Improvements of this methodology would allow further development of low cost particle counters in the micrometer and submicrometer range which can be widely applied in many industrial processes and scientific disciplines

MobilitApp: Analysing mobility data of citizens in the metropolitan area of Barcelona

MobilitApp is a platform designed to provide smart mobility services in urban areas. It is designed to help citizens and transport authorities alike. Citizens will be able to access the MobilitApp mobile application and decide their optimal transportation strategy by visualising their usual routes, their carbon footprint, receiving tips, analytics and general mobility information, such as traffic and incident alerts. Transport authorities and service providers will be able to access information about the mobility pattern of citizens to o er their best services, improve costs and planning. The MobilitApp client runs on Android devices and records synchronously, while running in the background, periodic location updates from its users. The information obtained is processed and analysed to understand the mobility patterns of our users in the city of Barcelona, Spain

Low power and high efficency energy acquisition systems for volcano monitoring

Peer Reviewe