Design of a bidirectional energy buffer using a switched-capacitor converter and supercapacitors for an auxiliary EIS converter for fuel cell stacks

Fuel cell as an attractive clean energy source has gained a great deal of interest. To increase the durability and reliability of fuel cells, diagnostics systems that can detect degradation and faults inside fuel cell stacks in end applications are highly in need. Electrochemical impedance spectroscopy (EIS), among other methods, is a promising characterizing tool for diagnostics and condition monitoring of fuel cells. It was traditionally only applied to single-cell or short stacks at low-power levels and required special laboratory equipment, but was recently brought to high-power stacks too which was made possible by many technological advancements. This is mainly owing to a growing interest in performing in situ EIS as a non-destructive method without the need for dismantling the stack. Unlike traditional approaches which relied on extra equipment, converter-based EIS provides attractive solutions for this purpose. In this thesis, the design and utilization of a bidirectional energy buffer module composed of a switched-capacitor converter (SCC) and a supercapacitor string for a new auxiliary EIS converter solution is presented. The module is designed towards having a more compact auxiliary converter unit. The design of the proposed energy buffer module is investigated in detail and a guideline is provided considering the application-specific optimal conversion ratio, supercapacitor string capacitance, and the probable limitations imposed by high EIS frequencies on certain situations. In a nutshell, the proposed switched-capacitor converter module (SCCM) consists of a bidirectional high voltage-gain SCC connected with supercapacitor string helps with the compactness and miniaturization of the entire auxiliary EIS converter and eliminating the potential problems of electrolytic capacitors such as bulkiness and limited lifetime due to the impact of ripples. The SCCM energy buffer with a high voltage gain offers a high buffering ratio for utilizing supercapacitors as the energy storage device

Real-Time Containers: A Survey

Container-based virtualization has gained a significant importance in a deployment of software applications in cloud-based environments. The technology fully relies on operating system features and does not require a virtualization layer (hypervisor) that introduces a performance degradation. Container-based virtualization allows to co-locate multiple isolated containers on a single computation node as well as to decompose an application into multiple containers distributed among several hosts (e.g., in fog computing layer). Such a technology seems very promising in other domains as well, e.g., in industrial automation, automotive, and aviation industry where mixed criticality containerized applications from various vendors can be co-located on shared resources. However, such industrial domains often require real-time behavior (i.e, a capability to meet predefined deadlines). These capabilities are not fully supported by the container-based virtualization yet. In this work, we provide a systematic literature survey study that summarizes the effort of the research community on bringing real-time properties in container-based virtualization. We categorize existing work into main research areas and identify possible immature points of the technology

Design, monitoring and performance evaluation of high capacity optical networks

Premi Extraordinari de Doctorat, promoció 2018-2019. Àmbit de les TICInternet traffic is expected to keep increasing exponentially due to the emergence of a vast number of innovative online services and applications. Optical networks, which are the cornerstone of the underlying Internet infrastructure, have been continuously evolving to carry the ever-increasing traffic in a more flexible, cost-effective, and intelligent way. Having these three targets in mind, this PhD thesis focuses on two general areas for the performance improvement and the evolution of optical networks: i) introducing further cognition to the optical layer, and ii) introducing new networking solutions revolutionizing the optical transport infrastructure. In the first part, we present novel failure detection and identification solutions in the optical layer utilizing the optical spectrum traces captured by cost-effective coarse-granular Optical Spectrum Analyzers (OSA). We demonstrate the effectiveness of the developed solutions for detecting and identifying filter-related failures in the context of Spectrum-Switched Optical Networks (SSON), as well as transmitter-related laser failures in Filter-less Optical Networks (FON). In addition, at the subsystem level we propose an Autonomic Transmission Agent (ATA), which triggers local or remote transceiver reconfiguration by predicting Bit-Error-Rate (BER) degradation by monitoring State-of-Polarization (SOP) data obtained by coherent receivers. I have developed solutions to push further the performance of the currently deployed optical networks through reducing the margins and introducing intelligence to better manage their resources. However, it is expected that the spectral efficiency of the current standard Single-Mode Fiber (SMF) based optical network approaches the Shannon capacity limits in the near future, and therefore, a new paradigm is required to keep with the pace of the current huge traffic increase. In this regard, Space Division Multiplexing (SDM) is proposed as the ultimate solution to address the looming capacity crunch with a reduced cost-per-bit delivered to the end-users. I devote the second part of this thesis to investigate different flavors of SDM based optical networks with the aim of finding the best compromise for the realization of a spectrally and spatially flexible optical network. SDM-based optical networks can be deployed over various types of transmission media. Additionally, due to the extra dimension (i.e., space) introduced in SDM networks, optical switching nodes can support wavelength granularity, space granularity, or a combination of both. In this thesis, we evaluate the impact of various spectral and spatial switching granularities on the performance of SDM-based optical networks serving different profiles of traffic with the aim of understanding the impact of switching constraints on the overall network performance. In this regard, we consider two different generations of wavelength selective switches (WSS) to reflect the technology limitations on the performance of SDM networks. In addition, we present different designs of colorless direction-less, and Colorless Directionless Contention-less (CDC) Reconfigurable Optical Add/Drop Multiplexers (ROADM) realizing SDM switching schemes and compare their performance in terms of complexity and implementation cost. Furthermore, with the aim of revealing the benefits and drawbacks of SDM networks over different types of transmission media, we preset a QoT-aware network planning toolbox and perform comparative performance analysis among SDM network based on various types of transmission media. We also analyze the power consumption of Multiple-Input Multiple-Output (MIMO) Digital Signal Processing (DSP) units of transceivers operating over three different types of transmission media. The results obtained in the second part of the thesis provide a comprehensive outlook to different realizations of SDM-based optical networks and showcases the benefits and drawbacks of different SDM realizations.Se espera que el tráfico de Internet siga aumentando exponencialmente debido a la continua aparición de gran cantidad de aplicaciones innovadoras. Las redes ópticas, que son la piedra angular de la infraestructura de Internet, han evolucionado continuamente para transportar el tráfico cada vez mayor de una manera más flexible, rentable e inteligente. Teniendo en cuenta estos tres objetivos, esta tesis doctoral se centra en dos áreas cruciales para la mejora del rendimiento y la evolución de las redes ópticas: i) introducción de funcionalidades cognitivas en la capa óptica, y ii) introducción de nuevas estructuras de red que revolucionarán el transporte óptico. En la primera parte, se presentan soluciones novedosas de detección e identificación de fallos en la capa óptica que utilizan trazas de espectro óptico obtenidas mediante analizadores de espectros ópticos (OSA) de baja resolución (y por tanto de coste reducido). Se demuestra la efectividad de las soluciones desarrolladas para detectar e identificar fallos derivados del filtrado imperfecto en las redes ópticas de conmutación de espectro (SSON), así como fallos relacionados con el láser transmisor en redes ópticas sin filtro (FON). Además, a nivel de subsistema, se propone un Agente de Transmisión Autónomo (ATA), que activa la reconfiguración del transceptor local o remoto al predecir la degradación de la Tasa de Error por Bits (BER), monitorizando el Estado de Polarización (SOP) de la señal recibida en un receptor coherente. Se han desarrollado soluciones para incrementar el rendimiento de las redes ópticas mediante la reducción de los márgenes y la introducción de inteligencia en la administración de los recursos de la red. Sin embargo, se espera que la eficiencia espectral de las redes ópticas basadas en fibras monomodo (SMF) se acerque al límite de capacidad de Shannon en un futuro próximo, y por tanto, se requiere un nuevo paradigma que permita mantener el crecimiento necesario para soportar el futuro aumento del tráfico. En este sentido, se propone el Multiplexado por División Espacial (SDM) como la solución que permita la continua reducción del coste por bit transmitido ante ése esperado crecimiento del tráfico. En la segunda parte de esta tesis se investigan diferentes tipos de redes ópticas basadas en SDM con el objetivo de encontrar soluciones para la realización de redes ópticas espectral y espacialmente flexibles. Las redes ópticas basadas en SDM se pueden implementar utilizando diversos tipos de medios de transmisión. Además, debido a la dimensión adicional (el espacio) introducida en las redes SDM, los nodos de conmutación óptica pueden conmutar longitudes de onda, fibras o una combinación de ambas. Se evalúa el impacto de la conmutación espectral y espacial en el rendimiento de las redes SDM bajo diferentes perfiles de tráfico ofrecido, con el objetivo de comprender el impacto de las restricciones de conmutación en el rendimiento de la red. En este sentido, se consideran dos generaciones diferentes de conmutadores selectivos de longitud de onda (WSS) para reflejar las limitaciones de la tecnología en el rendimiento de las redes SDM. Además, se presentan diferentes diseños de ROADM, independientes de la longitud de onda, de la dirección, y sin contención (CDC) utilizados para la conmutación SDM, y se compara su rendimiento en términos de complejidad y coste. Además, con el objetivo de cuantificar los beneficios e inconvenientes de las redes SDM, se ha generado una herramienta de planificación de red que prevé la QoT usando diferentes tipos de fibras. También se analiza el consumo de energía de las unidades DSP de los transceptores MIMO operando en redes SDM con tres tipos diferentes de medios de transmisión. Los resultados obtenidos en esta segunda parte de la tesis proporcionan una perspectiva integral de las redes SDM y muestran los beneficios e inconvenientes de sus diferentes implementacionesAward-winningPostprint (published version

Neural networks: The natural road to artificial iiitelligence

Despite the many advances of artificial intelligence (Al) technology, most notably in the area of expert systems, efforts to build intelligent systems that would approach the commonsense reasoning and sensory abilities of even a small child have not been rewarding. A small, but growing number of researches believe that the existing AI toolboxes of symbolic representation and heuristic search may not hold the answer, and that massively parallel networks of simple neuron-like processing elements may hold the key. In this overview article, we examine the use of neurally inspired concepts in the construction of intelligent machines, and address their practical applications, advantages, and limitations

Short-term Self-Scheduling of Virtual Energy Hub Plant within Thermal Energy Market

Multicarrier energy systems create new challenges as well as opportunities in future energy systems. One of these challenges is the interaction among multiple energy systems and energy hubs in different energy markets. By the advent of the local thermal energy market in many countries, energy hubs' scheduling becomes more prominent. In this article, a new approach to energy hubs' scheduling is offered, called virtual energy hub (VEH). The proposed concept of the energy hub, which is named as the VEH in this article, is referred to as an architecture based on the energy hub concept beside the proposed self-scheduling approach. The VEH is operated based on the different energy carriers and facilities as well as maximizes its revenue by participating in the various local energy markets. The proposed VEH optimizes its revenue from participating in the electrical and thermal energy markets and by examining both local markets. Participation of a player in the energy markets by using the integrated point of view can be reached to a higher benefit and optimal operation of the facilities in comparison with independent energy systems. In a competitive energy market, a VEH optimizes its self-scheduling problem in order to maximize its benefit considering uncertainties related to renewable resources. To handle the problem under uncertainty, a nonprobabilistic information gap method is implemented in this study. The proposed model enables the VEH to pursue two different strategies concerning uncertainties, namely risk-averse strategy and risk-seeker strategy. For effective participation of the renewable-based VEH plant in the local energy market, a compressed air energy storage unit is used as a solution for the volatility of the wind power generation. Finally, the proposed model is applied to a test case, and the numerical results validate the proposed approach

Urologist-operated ultrasound and its use in urological outpatient clinics

Mohammad Kazem Moslemi1, Behnam Mahfoozi21Department of Urology, Kamkar Hospital, School of Medicine, Qom University of Medical Sciences, Qom, Iran; 2Department of Radiology, Shahid Chamran Hospital, Tehran, IranIntroduction: Ultrasonograghy plays an important role in the evaluation of urinary tract disorders in cases of medical or surgical renal disorders, because of its lower cost, availability, and lack of ionizing radiation and because with it there is no need for contrast material injection or ingestion. It needs no intervention or preparation and specifically can differentiate between the multiple causes of flank pain. Urologist-operated sonography is a quick, cost-effective, and time-saving modality for both the physician and patient for obtaining first or final diagnosis. Based on its results, patients can be selected for appropriate management and further assessment.Materials and methods: The efficacy of ultrasound examination by a trained urologist in the differentiation of urological emergencies admitted in a district private clinic was studied. Between April 2008 and April 2010, a total of 724 patients (1448 renal units) had renal ultrasound performed by a trained urologist on acute admission. The sonographic findings were compared with subsequent definitive radiological investigations performed as needed, such as KUB (kidney, ureter, bladder) or IVP (intravenous pyelogram). Patient satisfaction and permission for ultrasonography were evaluated by oral consent. Loin pain was the presenting symptom in 45% of the patients (n = 326 cases).Results: Diagnosis was achieved in 96% of patients. Further evaluations were requested as needed in suspicious cases. If any hydronephrosis was detected and patients' history and/or complaints were suggestive of renal or ureteral stones, an outpatient KUB was requested. For more complex situations, IVP was the next option. Abnormal findings were recorded in 184 cases (25.5%). Mild to moderate unilateral hydronephrosis with or without hydronephrosis was the most common finding observed sonographically. The sensitivity of our ultrasonography evaluation was 99.7%.Conclusion: Office urologist-operated sonograghy may supplement the information available through routine history, physical examination, and laboratory studies. Our study shows that urological trainees can use ultrasound with high levels of accuracy, thereby improving patient management with a high level of patient satisfaction.Keywords: ultrasonograghy, kidney, bladder, urologist, CT scan, cystourethroscopy, KUB (kidney, ureter, bladder), urologist-operated sonography (UOS