Magnetron High Power System Design

This paper describes the design of an X-Band Magnetron to Linear Accelerator (LINAC) High Power Transfer System consisting in an 8 resonant cavities Magnetron connected to a dedicated vacuum Dielectric Window (DW). A main analytical design of devices is shown with compact formulas and is followed by numerical optimization. Electromagnetic and Thermomechanical coupling between these devices is described, particular attention has been given to the Magnetron power coupling and DW matching. A Multiphysics modeling is proposed to consider thermal-structural effects due to the cathode heating for the Magnetron and the Joule effect for the DW. Thermal induced degradation of the device performances are estimated and proper materials and shapes are chosen in order to ensure the desired behavior of the system in operative conditions. The proposed study provided the evaluation of the Magnetron Working Points and DW Scattering parameters in Thermo-mechanical operative conditions. Technological strategies for device coupling are shown

Impedance Transformers

Non

Wearable sensors networks for safety applications in industrial scenarios

Industrial contexts, and in particular the port areas, are very complex systems to be monitored and controlled due to the combined presence of vehicles and people. The port areas are the gateway between navigation and terrestrial transportation and are of great importance in transport logistics. Unfortunately, the management of port areas is quite complex because the safety of the workers must be always assured. Therefore, in such a context, a centralized control system for the monitoring and the prevention of risks is of particular importance. In this thesis, a real-time control system for the monitoring of people and vehicles in industrial areas is proposed. The proposed system is based on the Internet of Things paradigm, i.e. a network of “things” (such as sensors, tag RFID, actuators etc.) which can communicate and interact with each other within a shared IP addressing range, in order to share data and contribute to the management and development of advanced applications. Specifically, the thesis is focused on the design of a wearable sensors network based on RFID technology, and specifically on WISP sensors, for assuring the safety of the workers. In this network, wearable devices that can be inserted directly on the textile have been selected. Differently from conventional sensors, wearable sensors ensure a higher level of comfort, and provide higher electromagnetic performance. Furthermore, textile materials are easily available. Microstrips are good candidates for these applications because they mainly radiate perpendicularly to the planar structure, and their ground plane allows a good shielding on the body tissues. Therefore, I have designed specific antennas for RFID, that unlike the classical microstrip antennas have the radiating surface composed of several "side by side" conductive "threads of textile". Since the microwave model does not allow the design of an antenna with these characteristics with a good approximation, a specific microwave model for coupled lines has been designed. With this model, the specific antenna for RFID has been designed, with Jeans as substrate. The particular antenna’s substrate allows direct integration into garments, but since the wearable antennas are placed very close to the human body, biological issues which may arise on the human body from the use of these sensors have been analysed. The Specific Absorption Rate (SAR) has been considered and simulations have been conducted for evaluating the effects on the human body, and especially on the head, when irradiated with the electromagnetic waves generated by the wearable antenna realized with different materials. Dosimetric effects have been evaluated in function of the distance from the body, in order to define a safe distance for placing the antenna on the human body. The SAR has been evaluated also for full patches with different textile substrates, whose surface is larger than that of the proposed model of coupled lines. Therefore, if the SAR values evaluated for the full patch are satisfying, the SAR values for the model of coupled lines will surely be acceptable

Wearable sensors networks for safety applications in industrial scenarios

Industrial contexts, and in particular the port areas, are very complex systems to be monitored and controlled due to the combined presence of vehicles and people. The port areas are the gateway between navigation and terrestrial transportation and are of great importance in transport logistics. Unfortunately, the management of port areas is quite complex because the safety of the workers must be always assured. Therefore, in such a context, a centralized control system for the monitoring and the prevention of risks is of particular importance. In this thesis, a real-time control system for the monitoring of people and vehicles in industrial areas is proposed. The proposed system is based on the Internet of Things paradigm, i.e. a network of “things” (such as sensors, tag RFID, actuators etc.) which can communicate and interact with each other within a shared IP addressing range, in order to share data and contribute to the management and development of advanced applications. Specifically, the thesis is focused on the design of a wearable sensors network based on RFID technology, and specifically on WISP sensors, for assuring the safety of the workers. In this network, wearable devices that can be inserted directly on the textile have been selected. Differently from conventional sensors, wearable sensors ensure a higher level of comfort, and provide higher electromagnetic performance. Furthermore, textile materials are easily available. Microstrips are good candidates for these applications because they mainly radiate perpendicularly to the planar structure, and their ground plane allows a good shielding on the body tissues. Therefore, I have designed specific antennas for RFID, that unlike the classical microstrip antennas have the radiating surface composed of several "side by side" conductive "threads of textile". Since the microwave model does not allow the design of an antenna with these characteristics with a good approximation, a specific microwave model for coupled lines has been designed. With this model, the specific antenna for RFID has been designed, with Jeans as substrate. The particular antenna’s substrate allows direct integration into garments, but since the wearable antennas are placed very close to the human body, biological issues which may arise on the human body from the use of these sensors have been analysed. The Specific Absorption Rate (SAR) has been considered and simulations have been conducted for evaluating the effects on the human body, and especially on the head, when irradiated with the electromagnetic waves generated by the wearable antenna realized with different materials. Dosimetric effects have been evaluated in function of the distance from the body, in order to define a safe distance for placing the antenna on the human body. The SAR has been evaluated also for full patches with different textile substrates, whose surface is larger than that of the proposed model of coupled lines. Therefore, if the SAR values evaluated for the full patch are satisfying, the SAR values for the model of coupled lines will surely be acceptable

IN-SITU ADDITIVE MANUFACTURING OF METALS FOR EMBEDDING PARTS COMPATIBLE WITH LIQUID METALS TO ENHANCE THERMAL PERFORMANCE OF AVIONICS FOR SPACECRAFT

With advances in micromachinery, the aggregation of sensors, and more powerful microcontroller platforms on satellites, the size of avionics for space missions are getting dramatically smaller with faster processing speeds. This has resulted in greater localized heat generation, requiring more reliable thermal management systems to enhance the thermal performance of the avionics. The emergence of advanced additive manufacturing (AM), such as selective laser melting (SLM) and engineering materials, such as low-melting eutectic liquid metal (LM) alloys and synthetics ceramics offer new opportunities for thermal cooling systems. Therefore, there has been an opportunity for adapting in-situ AM to overcome limitations of traditional manufacturing in thermal application, where improvements can be achieved through reducing thermal contract resistance of multi-layer interfaces. This dissertation investigates adapting in-situ AM technologies to embed LM compatible prefabricated components, such as ceramic tubes, inside of metals without the need for a parting surface, resulting in more intimate contact between the metal and ceramic and a reduction in the interfacial thermal resistance. A focus was placed on using more ubiquitous powder bed AM technologies, where it was determined that the morphology of the prefabricated LM compatible ceramic tubes had to be optimized to prevent collision with the apparatus of powder bed based AM. Furthermore, to enhance the wettability of the ceramic tubes during laser fusion, the surfaces were electroplated, resulting in a 1.72X improvement in heat transfer compared to cold plates packaged by conventional assembly. Additionally, multiple AM technologies synergistically complement with cross platform tools such as magnetohydrodynamic (MHD) to solve the corrosion problem in the use of low melting eutectic alloy in geometrically complex patterns as an active cooling system with no moving parts. The MHD pumping system was designed using FEA and CFD simulations to approximate Maxwell and Navier-Stokes equations, were then validated using experiments with model heat exchanger to determine the tradeoff in performance with conventional pumping systems. The MHD cooling prototype was shown to reach volumetric flow rates of up to 650 mm3/sec and generated flow pressure due to Lorentz forces of up to 230 Pa, resulting in heat transfer improvement relative to passive prototype of 1.054

Investigating the learning potential of the Second Quantum Revolution: development of an approach for secondary school students

In recent years we have witnessed important changes: the Second Quantum Revolution is in the spotlight of many countries, and it is creating a new generation of technologies. To unlock the potential of the Second Quantum Revolution, several countries have launched strategic plans and research programs that finance and set the pace of research and development of these new technologies (like the Quantum Flagship, the National Quantum Initiative Act and so on). The increasing pace of technological changes is also challenging science education and institutional systems, requiring them to help to prepare new generations of experts. This work is placed within physics education research and contributes to the challenge by developing an approach and a course about the Second Quantum Revolution. The aims are to promote quantum literacy and, in particular, to value from a cultural and educational perspective the Second Revolution. The dissertation is articulated in two parts. In the first, we unpack the Second Quantum Revolution from a cultural perspective and shed light on the main revolutionary aspects that are elevated to the rank of principles implemented in the design of a course for secondary school students, prospective and in-service teachers. The design process and the educational reconstruction of the activities are presented as well as the results of a pilot study conducted to investigate the impact of the approach on students' understanding and to gather feedback to refine and improve the instructional materials. The second part consists of the exploration of the Second Quantum Revolution as a context to introduce some basic concepts of quantum physics. We present the results of an implementation with secondary school students to investigate if and to what extent external representations could play any role to promote students’ understanding and acceptance of quantum physics as a personal reliable description of the world

Shear-promoted drug encapsulation into red blood cells: a CFD model and μ-PIV analysis

The present work focuses on the main parameters that influence shear-promoted encapsulation of drugs into erythrocytes. A CFD model was built to investigate the fluid dynamics of a suspension of particles flowing in a commercial micro channel. Micro Particle Image Velocimetry (μ-PIV) allowed to take into account for the real properties of the red blood cell (RBC), thus having a deeper understanding of the process. Coupling these results with an analytical diffusion model, suitable working conditions were defined for different values of haematocrit

Structural Integrity and Durability of Reusable Space Propulsion Systems

A two-day conference on the structural integrity and durability of reusable space propulsion systems was held on 14 to 15 May 1991 at the NASA Lewis Research Center. Presentations were made by industry, university, and government researchers organized into four sessions: (1) aerothermodynamic loads; (2) instrumentation; (3) fatigue, fracture, and constitutive modeling; and (4) structural dynamics. The principle objectives were to disseminate research results and future plans in each of four areas. This publication contains extended abstracts and the visual material presented during the conference. Particular emphasis is placed on the Space Shuttle Main Engine (SSME) and the SSME turbopump