Дисертації з теми "Adaptive thermal protection systems"

Carefree handling refers to the ability of a pilot to operate an aircraft without the need to continuously monitor aircraft operating limits. At the heart of all carefree handling or maneuvering systems, also referred to as envelope protection systems, are algorithms and methods for predicting future limit violations. Recently, envelope protection methods that have gained more acceptance, translate limit proximity information to its equivalent in the control channel. Envelope protection algorithms either use very small prediction horizon or are static methods with no capability to adapt to changes in system configurations. Adaptive approaches maximizing prediction horizon such as dynamic trim, are only applicable to steady-state-response critical limit parameters. In this thesis, a new adaptive envelope protection method is developed that is applicable to steady-state and transient response critical limit parameters. The approach is based upon devising the most aggressive optimal control profile to the limit boundary and using it to compute control limits. Pilot-in-the-loop evaluations of the proposed approach are conducted at the Georgia Tech Carefree Maneuver lab for transient longitudinal hub moment limit protection. Carefree maneuvering is the dual of carefree handling in the realm of autonomous Uninhabited Aerial Vehicles (UAVs). Designing a flight control system to fully and effectively utilize the operational flight envelope is very difficult. With the increasing role and demands for extreme maneuverability there is a need for developing envelope protection methods for autonomous UAVs. In this thesis, a full-authority automatic envelope protection method is proposed for limit protection in UAVs. The approach uses adaptive estimate of limit parameter dynamics and finite-time horizon predictions to detect impending limit boundary violations. Limit violations are prevented by treating the limit boundary as an obstacle and by correcting nominal control/command inputs to track a limit parameter safe-response profile near the limit boundary. The method is evaluated using software-in-the-loop and flight evaluations on the Georgia Tech unmanned rotorcraft platform- GTMax. The thesis also develops and evaluates an extension for calculating control margins based on restricting limit parameter response aggressiveness near the limit boundary.

The electrical distribution system in the United States is considered one of the most complicated machines in existence. Electrical phenomena in such a complex system can inflict serious self-harm. This requires damage prevention from protection schemes. Until recently, there was a safe gap between capacity to deliver power and the demand. Therefore, these protection schemes focused on dependability allowing the disconnection of lines, transformers, or other devices with the purpose of isolating the faulted element. On some occasions, the disconnections made were not necessary. The other extreme of reliability calls for security. This aspect of reliability calls for the operation of the protective devices only for faults within the intended area of protection. There is a tradeoff here; where a dependable protection scheme will assuredly prevent damage, it is prone to unnecessary operation which can lead to cascading outages. Where a secure scheme will not operate unnecessarily, it is prone to pieces of the system becoming damaged when relays fail to operate properly. With microprocessor based relaying schemes, a hybrid reliability focus is attainable through adaptive relaying. Adaptive relaying describes protection schemes that adjust settings and/or logic of operations based on the prevailing conditions of the system. These adjustments can help to avoid relay miss-operation. Adjustments could include, but are not limited to, the logging of data for post-mortem analysis, communication throughout the system, as well changing relay parameters. Several concepts will be discussed, one of which will be implemented to prove the value of the new tools available.
Master of Science

Thermal systems involve multiple components assembled to store or transfer heat for power, cooling, or insulation purpose, and this research focuses on modeling the performance of two novel thermal systems that are capable of functioning in environments subjected to high heat fluxes. The first investigated thermal system is a cascaded thermoelectric generator (TEG) that directly converts heat into electricity and offers a green option for renewable energy generation. The presented cascaded TEG allows harvesting energy in high temperatures ranging from 473K to 973K, and being a solid-state device with no moving parts constitutes an excellent feature for increase device life cycle and minimum maintenance in harsh, remote environments. Two cascaded TEG designs are analyzed in this research: the two-stage and three-stage cascaded TEGs, and based on the findings, the two-stage cascaded TEG produces a power output of 42 W with an efficiency of 8.3% while the three-cascaded TEG produces 51 W with an efficiency of 10.2%. The second investigated novel thermal system is a thermal protection system inspired by the porous internal skeleton of the cuttlefish also known as cuttlebone. The presented bio- inspired thermal protection has excellent features to serve as an integrated thermal protection system for spacecraft vehicles including being lightweight (93% porosity) and possessing high compressive strength. A large amount of heat flux is generated from friction between air and spacecraft vehicle exterior, especially during reentry into the atmosphere, and part of the herein presented research involves a thermomechanical modeling analysis of the cuttlebone bio-inspired integrated thermal protection system along with comparing its performance with three conventional structures such as the wavy, the pyramid, and cylindrical pin structures. The results suggest that the cuttlebone integrated thermal protection system excels the best at resisting deformation caused by thermal expansion when subjected to aerodynamic heat fluxes.
Doctor of Philosophy
Operating engineering systems in extremely hot environments often decreases systems' reliability, life cycle, and creates premature failure. This research investigates two novel thermal systems capable of functioning in high temperatures including a cascaded thermoelectric generator (TEG) and a bio-inspired thermal protection system. The first evaluated novel thermal systems is a cascaded TEG that directly converts waste heat into power, and being a solid-state device with no moving parts forms an excellent feature for device life cycle improvement and minimum maintenance in harsh, remote environments. The research findings show that the designed cascaded TEGs can produce power when subjected to high temperatures ranging from 473K to 973K. The remaining part of the research presented in this dissertation models the thermomechanical performance of a lightweight structure, which is inspired by the internal skeleton of the cuttlefish, also knows as the cuttlebone. The cuttlefish's natural ability to support high-deep sea pressure translates into possessing high compressive strength, and when added the fact of being lightweight (up to 93% porosity), the cuttlebone forms an excellent candidate to serve as integrated thermal protection for spacecraft vehicles. The last part of the presented research discuss the thermomechanical analysis of the cuttlebone when subjected to high aerodynamics heat flux generated from friction between the air and spacecraft vehicle exterior, and it was found that the cuttlebone structure resists deformation associated with the steep temperature gradient experienced by the spacecraft vehicle during travel.

Reconfiguration is needed to meet the fight-through and survivability requirements of a shipboard power system. Reconfiguration involves the re-arrangement of power system topology through the opening and switching of breakers, and adjusting of total generators and load values. When the power system is reconfigured, the protection system needs to be attuned to the new power system state. This thesis focuses on developing an adaptive protection scheme for shipboard power systems that will automatically update relay settings after changes in power system topology and operational state. The developed adaptive protection scheme employs four main algorithms to achieve its goal. A topology-recognition algorithm uses the statuses (open/close) of breakers to determine the topological-configuration of the system. A power-flow and a fault-analysis algorithm are used to determine the system?s normal and fault currents, respectively. A protection-setting algorithm is used to determine and set the operating parameters of all the relays in the system. The scheme was implemented in MATLAB m-files and tested on various configurations of a notional shipboard power system. The tests results were verified in CAPE.

Дисертація присвячена розробці систем для забезпечення теплового захисту напівпровідникових перетворювачів електроенергії за рахунок суміщеного моделювання електромагнітних та теплових процесів в перетворювачах. В роботі проведено аналіз сучасних методів розрахунку електромагнітних та теплових процесів, аналіз моделей ключових та пасивних компонентів. Показана доцільність використання моделей пасивних та активних компонентів перетворювачів параметри яких залежать від температури та електричних режимів роботи. Запропонована суміщена модель для розрахунку електротеплових процесів в перетворювачах з врахуванням швидкоплинності процесів та розділенням на системи рівнянь, що описують швидкі та повільні процеси. Запропоновані дві системи теплового захисту, які працюють за рахунок нормалізації перехідних електромагнітних процесів в колі перетворювача з врахуванням температури компонентів та перезапуску плавного пуску після зняття короткого замикання з програмним врахуванням температури компонентів.

The traditional transmission centric approach to generation connection using large-scale thermal units is evolving as the electricity supply industry and end users both move to play their part in tackling climate change. Government targets and financial incentive mechanisms have created a generation portfolio that is becoming more diverse as both large and small-scale distributed generation projects are commissioned. The net result of these events is that generation now appears across all voltage levels and is a trend that is almost certainly set to continue. Moreover, the manner in which networks are operated is also changing to become more flexible with novel management intended to facilitate the dispersed connection of generation, whilst at the same time improving the quality of supply for end users. As a consequence of the foregoing changes, new challenges emerge with regard to guaranteeing that the performance of power system protection is not degraded. This thesis documents research that has considered the myriad of issues arising throughout distribution networks. The concept of adaptive protection has been explored as a solution to many of these issues as a means of ensuring that protection better reflects the current state of the primary power system. Although adaptive protection has been a theoretical possibility for some time it has not generally been applied in practice. The emerging drivers that could change this have been considered along with the challenges of its application. It was concluded from this work that the concept and structure for adapting protection needs to be examined in abstraction from the underlying low level protection algorithms. A layered architecture has been proposed that helps to structure process of adaptation, define key functionality and ultimately clarify how it could be practically realised using currently available substation protection and automation equipment. To demonstrate the application of the architecture two examples have been used that cover both low and high voltage networks. The first considers a low voltage microgrid and the difficulties resulting from inverter interfaced microgeneration. As a second example, the problem of intentionally islanding an area of high voltage network is considered. Taken together, these two examples cover a range of future scenarios that could emerge within so called smart grids.

Includes abstract.
Includes bibliographical references (leaves 161-171).
This thesis presents the application of a nonlinear adaptive filter to selected areas in power systems. The filter has demonstrated excellent performance against con-ventional methods in biomedical applications. The algorithm is robust in structure and highly immune to noise. Applications in this thesis include (1) sag detection, (2) symmetrical component estimation, (3) phase and frequency estimation, (4) sag analysis and (5) distributed generation synchronisation and protection. The appli-cations were chosen such that the amplitude, phase and frequency tracking ability are thoroughly tested.

Today’s software landscape features a high degree of complexity, frequent changes in requirements and stakeholder goals, and uncertainty. Uncertainty and high complexity imply a threat landscape where cybersecurity attacks are a common occurrence, while their consequences are often severe. Self-adaptive systems have been proposed to mitigate the complexity and frequent degree of change by adapting at run-time to deal with situations not known at design time. They, however, are not immune to attacks, as they themselves suffer from high degrees of complexity and uncertainty. Therefore, systems that can dynamically defend themselves from adversaries are required. Such systems are called self-protecting systems and aim to identify, analyse and mitigate threats autonomously. This thesis contributes two approaches towards the goal of providing systems with self-protection capabilities. The first approach aims to enhance the security of architecture-based selfadaptive systems and equip them with (proactive) self-protection capabilities that reduce the exposed attack surface. We target systems where information about the system components and its adaptation decisions is available, and control over its adaptation is also possible. We formally model the security of the system and provide two methods to analyze its security that help us rank adaptations in terms of their security level: a method based on quantitative risk assessment and a method based on probabilistic verification. The results indicate an improvement to the system security when either of our solutions is employed. However, only the second method can provide self-protecting capabilities. We have identified a direct relationship between security and performance overhead, i.e., higher security guarantees impose analogously higher performance overhead. The second approach targets open decentralized systems where we have limited information about and control over the system entities. Therefore, we attempt to employ decentralized information flow control mechanisms to enforce security by controlling interactions among the system elements. We extend a classical decentralized information flow control model by incorporating trust and adding adaptation capabilities that allow the system to identify security threats and self-organize to maximize the average trust between the system entities. We arrange entities of the system in trust hierarchies that enforce security policies among their elements and can mitigate security issues raised by the openness and uncertainty in the context and environment, without the need for a trusted central controller. The experiment results show that a reasonable level of trust can be achieved and at the same time confidentiality and integrity can be enforced with a low impact on the throughput and latency of messages exchanged in the system.

La sélection des matériaux utilisés dans les moteurs aéronautiques est un enjeu majeur pour assurer la sécurité des passagers, optimiser les performances de l’avion et maîtriser les coûts. Dans les parties les plus chaudes des moteurs (i.e. chambre de combustion et turbine), les pièces sont généralement constituées de superalliages à base nickel en raison de leurs excellentes propriétés mécaniques à haute température. Vulnérables aux phénomènes de corrosion et d’oxydation à haute température, les superalliages doivent la plupart du temps être revêtus afin de prolonger leur durée de vie (ingénierie de surface). La composition chimique et l’architecture des revêtements sont alors adaptées en fonction du régime de température et des phénomènes de dégradation rencontrés (i.e. corrosion à chaud, oxydation et/ou érosion). En vue de répondre aux nouvelles réglementations environnementales, de nouvelles voies de synthèse et de fonctionnalisation sont à l’étude comme alternatives aux procédés industriels actuels. Dans le cadre du projet Européen « PARTICOAT », le LaSIE a démontré la faisabilité d’élaborer des systèmes barrières thermiques complets (couche de diffusion + barrière thermique) en une seule étape à partir de barbotines (« slurries ») à base aqueuse contenant des microparticules d’Al. Dans cette étude, l’ajout de Cr comme dopant a été étudié. L’addition de Cr a permis d’abaisser l’activité de l’Al lors de l’étape d’aluminisation et de limiter les réactions exothermiques entre Al et substrat à base de nickel. L’optimisation des ratios entre Al et Cr a permis d’obtenir différentes microstructures de revêtement. Diverses architectures de dépôts ont également pu être testées grâce à la souplesse d’élaboration des revêtements par barbotines. L’influence de l’atmosphère (Ar, air) et celle des conditions de traitement thermique ont également été étudiées. Enfin, la durabilité des revêtements développés au cours de la thèse a été évaluée au cours d’essais de corrosion à chaud et d’oxydation
The selection of materials is of utmost importance in gas turbine engines to ensure the security of the passengers, optimize the performances of the aircraft and be cost efficient. In the hottest region of the engines (i.e. combustion chamber and turbine), the components are usually made of nickel-based superalloys. These materials can resist to high mechanical loads at high temperature but are vulnerable to aggressive environments. Therefore, nickel-based superalloys are usually coated to increase their durability in the engine (surface engineering). The chemical composition and the coating architecture are carefully adjusted depending on the temperature regime and the mechanisms of degradation encountered (hot corrosion, oxidation and/or erosion). New synthesis routes and functionalization are currently developed as alternative solutions to industrial processes. As a promising alternative approach, different studies were carried out in the LaSIE laboratory under the European project “PARTICOAT” and confirmed the possibility to elaborate complete thermal barrier systems (diffusion coating + thermal barrier coating) from Al-containing water-based slurries. In this work, the role of Cr as a doping agent was investigated. The addition of Cr decreased the thermodynamic activity of Al upon aluminizing and limited the exothermic reactions usually reported between Al and nickel-based materials. Different architectures of coatings were obtained thanks to the flexibility and the adaptability of the slurry coating process. The gas composition (Ar, air) and the heat treatment conditions were also investigated. Finally, the high temperature resistance of the slurry coatings developed during this work was evaluated under hot corrosion and oxidation conditions

The motivation for this research is to overcome the costs of using the current wind tunnels which replicate the high speed, temperatures and Reynolds numbers of new concept vehicles such as Hyper-Sonic passenger jets. The idea is that by employing accurate computational methods, costs can be reduced and more scenarios can be investigated. It will be argued that the characteristic based split scheme is a modified central difference temporal scheme, and can be utilized to capture the flow regimes of interest to the European Space Agency (ESA). The hypothesis of this thesis is that it is possible to model Hyper-Sonic applications with shock capturing reliably in a collocated, unstructured polyhedral, Finite Volume (FV) software framework. The reason for this hypothesis is a desire to develop an alternative approach for accurate, non-oscillatory solutions to the conservation laws for high speed flows that does away with calculating the upwind flow direction, donor nodes, Riemann solvers and can avoid Jacobian evaluations. The finite volume method is generally preferred for industrial Computational Fluid Dynamics (CFD) because it is relatively inexpensive and lends itself well to the solution of large sets of equations associated with complex flows according to Greenshields et al. Usually physical variables such as velocity, temperature, density and pressure are co-located, which means that the values at the centroid of a control volume are chosen to represent these physical variables in the enclosed control volume. Co-location is popular in industrial CFD, because it allows greater freedom in mesh structure for complex 3D geometries and for refinement of boundary layers as mentioned in Greenshields et al. It is no coincidence that collocated, polyhedral, FV numerical methods are adopted by several of the best known industrial CFD software packages, including FLUENT, STAR CCM+ and CFD-ACE+. There is a current preference for unstructured meshes o f polyhedral cells with six faces (hexahedra) or more, rather than tetrahedral cells that are prone to numerical inaccuracy and other problems. For example, Ferguson and Peric mention that they are unsuitable for features such as boundary layers. Discontinuities, such as shocks, in Hyper-Sonic compressible computations require numerical schemes that can accurately capture these features while avoiding spurious numerical oscillations. Current methods that are effective in producing accurate non-oscillating solutions are first of all monotone upstreamcentred schemes for conservation laws- by Van Leer; secondly the nonoscillatory (ENO) schemes by Harten A, Engquist B, Osher S, and lastly the weighted ENO schemes known as WENO schemes by Liu, X. D., Osher, and Chan. Unfortunately these methods typically involve Riemann solvers and Jacobian evaluation, making them complex and difficult to implement in a collocated, 3D unstructured framework. This work seeks to find a method which overcomes these disadvantages.

The objective of this thesis is to predict shape change due to ablation and to find temperature distribution of the thermal protection system of a supersonic vehicle under aerodynamic heating by using finite element method. A subliming ablative is used as thermal protection material. Required material properties for the ablation analyses are found by using DSC (Differential Scanning Calorimetry) and TGA (Thermogravimetric Analysis) thermal analysis techniques. DSC is a thermal analysis technique that looks at how a material'
s specific heat capacity is changed by temperature and TGA is a technique in which the mass of a substance is monitored as a function of temperature. Moreover, oxyacetylene ablation tests are conducted for the subliming ablative specimens and measured recession values are compared with the analytically calculated values. Maximum difference between experimental results and analytical results is observed as 3% as seen in Table 7. For the finite element analyses, ANSYS Software is used. A numerical algorithm is developed by using programming language APDL (ANSYS Parametric Design Language) and element kill feature of ANSYS is used for simulation of ablation process. To see the effect of mesh size and time step on the solution of analyses, oxyacetylene test results are used. Numerical algorithm is also applied to the blunt-nosed section of a supersonic rocket which is made from subliming ablative material. Ablation analyses are performed for the nose section because nose recession is very important for a rocket to follow the desired trajectory and nose temperature is very important for the avionics in the inner side of the nose. By using the developed algorithm, under aerodynamic heating, shape change and temperature distribution of the nose section at the end of the flight are obtained. Moreover, effects of ablation on the trajectory of the rocket and on the flow around the rocket are examined by Missile DATCOM and CFD (computational fluid dynamics) analysis tools.

Doctor of Philosophy
Electrical and Computer Engineering
Anil Pahwa
Noel N. Schulz
Microgrids with distributed generators have changed how protection and control systems are designed. Protection systems in conventional U.S. distribution systems are radial with the assumption that current flows always from the utility source to the end user. However, in a microgrid with distributed generators, currents along power lines do not always flow in one direction. Therefore, protection systems must be adapted to different circuit paths depending on distributed generator sites in the microgrid and maximum fuse ampere ratings on busses. Adaptive overcurrent protection focuses on objectives and constraints based on operation, maximum load demand, equipment, and utility service limitations. Adaptive overcurrent protection was designed to protect the power lines and bus feeders of the microgrid with distributed generators by coordinating fuses and relays in the microgrid. Adaptive overcurrent protection was based on the relay setting group and protection logic methods. Non-real-time simulator (NRTS) and real-time simulator (RTS) experiments were performed with computer-based simulators. Tests with two relays in the loop proved that primary relays tripped faster than backup relays for selectivity coordination in the adaptive overcurrent protection system. Relay test results from tripping and non-tripping tests showed that adaptive inverse time overcurrent protection achieved selectivity, speed, and reliability. The RTS and NRTS with two relays in the loop techniques were described and compared in this work. The author was the first graduate student to implement real-time simulation with two relays in the loop at the Burns & McDonnell - K-State Smart Grid Laboratory. The RTS experimental circuit and project are detailed in this work so other graduate students can apply this technique with relays in the loop in smart grid research areas such as phasor measurement units, adaptive protection, communication, and cyber security applications.

Power distribution systems have underwent a lot of significant changes in the last two decades. Wide-scale integration of Distributed Energy Resources (DERs) have made the distribution grid more resilient to abnormal conditions and severe weather induced outages. These DERs enhance the reliability of the system to bounce back from an abnormal situation rather quickly. However, the conventional notion of a radial system with unidirectional power flow does not hold true due to the addition of these DERs. Bidirectional power flow has challenged the conventional protection schemes in place. The most notable effects on the protection schemes can be seen in the field of islanding or Loss of Mains(LOM) detection and general fault identification and isolation. Adaptive protection schemes are needed to properly resolve these issues. Although, previous works in this field have dealt with this situation, a more comprehensive approach needs to be taken considering multiple topologies for developing adaptive protection schemes. The most common protective devices widely deployed in the distribution system such as overcurrent relays, reverse power relays at Point of Common Coupling(PCC), fuses, reclosers and feeder breakers need to studied in implementing these schemes. The work presented in this dissertation deals with simulation based and analytical approaches to tackle the issues of islanding and adaptive protection schemes. First we propose a multiprinciple passive islanding detection technique which relies on local PCC measurements, thus reducing the need of additional infrastructure and still ensuring limited Non Detection Zone (NDZ). The next step to islanding detection would be to sustain a islanded distribution system in order to reduce the restoration time and still supply power to critical loads. Such an approach to maintain generator load balance upon islanding detection is studied next by appropriate shedding of non-critical and low priority critical loads based upon voltage sensitivity analysis. Thereafter, adaptive protection schemes considering limited communication dependency is studied with properly assigning relay settings in directional overcurrent relays (DOCRs), which are one of the most widely deployed protective devices in distribution systems by catering to multiple topologies and contingencies. A simulation based technique is discussed first and then an analytical approach to solve the conventional optimal relay coordination problem using Mixed Integer Linear Programming (MILP) with the usage of multiple setting groups is studied. All these approaches make the distribution more robust and resilient to system faults and ensure proper fault identification and isolation, ensuring overall safety of system.
Doctor of Philosophy
With widespread integration of inverter-based distributed energy resources (DERs) in the distribution grid, the conventional protection and control schemes no longer hold valid. The necessity of an adaptive protection scheme increases as the DER penetration in the system increases. Apart from this, changes in system topology and variability in DER generation, also change the fault current availability in the system in real-time. Hence, the protection schemes should be able to adapt to these variations and modify their settings for proper selectivity and sensitivity towards faults in the system, especially in systems with high penetration of DERs. These protection schemes need to be modified in order to properly identify and isolate faults in the network as well as correctly identify Loss of Mains (LOM) or islanding phenomenon. Special attention is needed to plan the next course of action after the islanding occurrence. Additionally, the protective devices in distribution system should be utilized to their maximum capability to create an adaptive and smart protection system. This document elaborately explains the research work pertaining to these areas.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
Currently, a void exists in the development of small, unmanned aerial vehicles (UAVs) that can fly at speeds faster than 100 meters per second while maximizing endurance. Operating in such a regime requires the use of a slow-burning solid rocket motor. To achieve long burn times, an end-burning grain configuration is required in addition to a burn rate suppressant. Such a propulsion system presents unique thermal challenges due to the long exposure times and the close proximity of temperature sensitive vehicle components to the combustion reactions. This thesis presents the development of a thermal management system appropriate for small, slow burning solid rocket motors. Thermal protection is provided primarily by a thermally ablative liner with additional layers of fibrous insulation to protect the motor casing and avionics. Due to the complex nature of thermochemical ablation and scarcity of previous research in slow, end burning solid rockets, this problem is approached through both experimental and computational means. Experimental tests are performed on a full-scale model of an end-burning motor. Experimental results are used to validate a computational model of ablation. The ultimate goal is to provide an adequate amount of thermal insulation to protect the vehicle casing and avionics while maximizing propellant volume and hence endurance. Building such thermal management schemes requires innovative materials and machining methods to incorporate thermal protection in a tight space. This thesis adds to the greater body of knowledge of thermal protection design in slow-burning solid rockets, especially as it applies to a new class of small, fast UAVs.
by Jonathan R. Spirnak.
S.M.

Condition based monitoring of Thermal Protection Systems (TPS) is necessary for safe operations of space shuttles. In the current research Terahertz radiation (T-ray) has been used to detect mechanical and heat induced damages in TPS tiles. Voids and cracks inside the foam tile are denoted as mechanical damage while property changes due to long and short term exposures of tiles to high heat are denoted as heat induced damage.Ultrasonic waves cannot detect cracks and voids inside the tile because the tile material (silica foam) has high attenuation for ultrasonic energy. Instead, electromagnetic terahertz radiation can easily penetrate into the foam material and detect the internal voids although this electromagnetic radiation finds it difficult to detect delaminations between the foam tile and the substrate plate. Thus these two technologies are complementary to each other for TPS inspection.Ultrasonic and T-ray field modeling in free and mounted tiles with different types of mechanical and thermal damages has been the focus of this research. Shortcomings and limitations of FEM method in modeling 3D problems especially at high-frequencies has been discussed and a newly developed semi-analytical technique called Distributed Point Source Method (DPSM) has been used for this purpose.A FORTRAN code called DPSM3D has been developed to model both ultrasonic and electromagnetic problems using the conventional DPSM method. DPSM has been extended from ultrasonic applications to electromagnetic to model THz Gaussian beams, multilayered dielectrics and Gaussian beam-scatterer interaction problems. Since the conventional DPSM has some drawbacks, to overcome it two modification methods called G-DPSM and ESM have been proposed.The conventional DPSM in the past was only capable of solving time harmonic (frequency domain) problems. In this research DPSM has been extended to model DPSM transient problems. This modified technique has been denoted as t-DPSM.Using DPSM, scattering of focused ultrasonic fields by single and multiple cavities in fluid&solid media is studied. A comparison between the radiation forces generated by the ultrasonic energies reflected from two small cavities versus a single big cavity is also carried out.

Many cutting-edge computer and electronic products are powered by advanced Systems-on-Chip (SoC). Advanced SoCs encompass superb performance together with large number of functions. This is achieved by efficient integration of huge number of transistors. Such very large scale integration is enabled by a core-based design paradigm as well as deep-submicron and 3D-stacked-IC technologies. These technologies are susceptible to reliability and testing complications caused by thermal issues. Three crucial thermal issues related to temperature variations, temperature gradients, and temperature cycling are addressed in this thesis. Existing test scheduling techniques rely on temperature simulations to generate schedules that meet thermal constraints such as overheating prevention. The difference between the simulated temperatures and the actual temperatures is called temperature error. This error, for past technologies, is negligible. However, advanced SoCs experience large errors due to large process variations. Such large errors have costly consequences, such as overheating, and must be taken care of. This thesis presents an adaptive approach to generate test schedules that handle such temperature errors. Advanced SoCs manufactured as 3D stacked ICs experience large temperature gradients. Temperature gradients accelerate certain early-life defect mechanisms. These mechanisms can be artificially accelerated using gradient-based, burn-in like, operations so that the defects are detected before shipping. Moreover, temperature gradients exacerbate some delay-related defects. In order to detect such defects, testing must be performed when appropriate temperature-gradients are enforced. A schedule-based technique that enforces the temperature-gradients for burn-in like operations is proposed in this thesis. This technique is further developed to support testing for delay-related defects while appropriate gradients are enforced. The last thermal issue addressed by this thesis is related to temperature cycling. Temperature cycling test procedures are usually applied to safety-critical applications to detect cycling-related early-life failures. Such failures affect advanced SoCs, particularly through-silicon-via structures in 3D-stacked-ICs. An efficient schedule-based cycling-test technique that combines cycling acceleration with testing is proposed in this thesis. The proposed technique fits into existing 3D testing procedures and does not require temperature chambers. Therefore, the overall cycling acceleration and testing cost can be drastically reduced. All the proposed techniques have been implemented and evaluated with extensive experiments based on ITC’02 benchmarks as well as a number of 3D stacked ICs. Experiments show that the proposed techniques work effectively and reduce the costs, in particular the costs related to addressing thermal issues and early-life failures. We have also developed a fast temperature simulation technique based on a closed-form solution for the temperature equations. Experiments demonstrate that the proposed simulation technique reduces the schedule generation time by more than half.

This thesis is based on the work carried out in the field of safety systems for Autonomous Guided Vehicles(AGV). With autonomous vehicles being more prominent today, safe traversing of these is a major concern. The same is true for AGVs working in industry environment like forklift trucks etc. Our work applies to industrial robots. The method described here is developed by closely following an algorithm developed for safe traversing of a robot using a warning field. The report describes the literature review with work related to the safe traversing, path planning and collision avoidance in robots. The next part is dedicated to describing the methodology of implementation of the Adaptive Warning Field Method and the Dynamic Window Approach. The evaluation of the Adaptive Warning Method with the previous developed Warning Field Methods is done and test cases are designed to test the working of the designed method. Vrep simulation environment and Industrial data is used to run a simulation of the robot using the method developed in this work. We find that the method performs better compared to the previous methods in the designed scenarios. Lastly we conclude the report with the future work that can be carried out to improve and extend the algorithm.

Heatshield design and analysis has traditionally been a decoupled process, the designer creates the geometry generally without knowledge about how the design variables affect the thermostructural response or how the system will perform under off nominal conditions. Heatshield thermal and structural response analyses are generally performed as separate tasks where the analysts size their respective components and feedback their results to the designer who is left to interpret them. The analysts are generally unable to provide guidance in terms of how the design variables can be modified to meet geometric constraints and not exceed the thermal or structural design specifications. In general, the thermal response analysis of ablative thermal protection systems has traditionally been performed using a one-dimensional finite difference calculation. The structural analyses are generally one, two, or three-dimensional finite element calculations. In this dissertation, the governing differential equations for ablative thermal response are solved in three-dimensions using the finite element method. Darcy' Law is used to model the flow of pyrolysis gas through the ablative material. The three-dimensional governing differential equations for Darcy flow are solved using the finite element method as well. Additionally, the equations for linear elasticity are solved by the finite element method for the thermal stress using temperatures directly from the thermal response calculations. This dissertation also links the analysis of thermal protection systems to their design. The link to design comes from understanding the variation in the thermostructural response over the range of the design variables. Material property sensitivities are performed and an optimum design is determined based on a deterministic analysis minimizing the design specification of bondline temperature subject to appropriate constraints. A Monte Carlo simulation is performed on the optimum design to determine the probability of exceeding the design specifications. The design methodology is demonstrated on the Orion Crew Exploration Vehicle's compression pad design.

The idea of performing power systems dynamic analysis in the power-angle domain has been hinted at by previous researchers, but this may be the first published document to develop detailed techniques by which entire power systems can be represented and solved in the power-angle domain. With the widespread deployment of phasor measurement units and frequency data recorders the industry is looking for more real-time analytical tools to turn real-time wide-area measurements into useful information. Applications based on power-angle domain analysis are simple enough that they may be used online. Power-angle domain analysis is similar to DC load-flow techniques in that a flat voltage profile is used and it is assumed that real power and voltage angle are completely decoupled from reactive power and voltage magnitude. The linearized equations for the dynamics of generators and loads are included in the model, which allows the electromechanical response to be solved using conventional circuit analysis techniques. The effect of generation trips, load switching, and line switching can be quickly approximated with nodal analysis or mesh analysis in the power-angle domain. The analysis techniques developed here are not intended to be as accurate as time-domain simulation, but they are simpler and fast enough to be put online, and they also provide a better analytical insight into the system. Power-angle domain analysis enables applications that are not readily available with conventional techniques, such as the estimation of electromechanical propagation delays based on system parameters, the formulation of electromechanical equivalents, modal analysis, stability analysis, and event location and identification based on a small number of angle or frequency measurements. Fault studies and contingency analysis are typically performed with detailed time-domain simulations, where the electromechanical response of the system is a function of every machine in the interconnection and the lines connecting them. All of this information is rarely known for the entire system for each operating condition; as a result, for many applications it may be more suitable to compute an approximation of the system response based on the current operating state of only the major lines and generators. Power-angle domain analysis is adept at performing such approximations.
Ph. D.

The differences between shipboard and land based power systems are explored to support the main focus of this work. A model was developed for simulating hidden failures on shipboard integrated propulsion plants, IPP. The model was then used to evaluate the segregation of the IPP high voltage, HV, buses in a similar fashion as a shipboard firemain. The HV buses were segregated when loss of propulsion power would put the ship as risk. This new treatment reduces the region of vulnerability by providing a high impedance boundary that limits the effects of a hidden failure of a current magnitude or differential based protective element, without the installation of any additional hardware or software. It is shown that this protection could be further improved through the use of a simple adaptive protection scheme that disarms unneeded protective elements in certain configurations.
Master of Science

The focus of this dissertation is aimed at advancing autonomous structural health monitoring. All the research is based on developing the impedance method for monitoring structural health. The impedance technique utilizes piezoelectric patches to interrogate structures of interested with high frequency excitations. These patches are bonded directly to the structure, so information about the health of the structure can be seen in the electrical impedance of the piezoelectric patch. However, traditional impedance techniques require the use of a bulky and expensive impedance analyzer. Research presented here describes efforts to miniaturize the hardware necessary for damage detection. A prototype impedance-based structural health monitoring system, incorporating wireless based communications, is fabricated and validated with experimental testing. The first steps towards a completely autonomous structural health monitoring sensor are also presented. Power harvesting from ambient energy allows a prototype to be operable from a rechargeable power source. Aerospace vehicles are equipped with thermal protection systems to isolate internal components from harsh reentry conditions. While the thermal protection systems are critical to the safety of the vehicle, finding damage in these structures presents a unique challenge. Impedance techniques will be used to detect the standard damage mechanism for one type of thermal protection system. The sensitivity of the impedance method at elevated temperatures is also investigated. Sensors are often affixed to structures as a means of identifying structural defects. However, these sensors are susceptible to damage themselves. Sensor diagnostics is a field of study directed at identifying faulty sensors. The influence of temperature on these techniques is largely unstudied. In this dissertation, a model is generated to identify damaged sensors at any temperature. A sensor diagnostics method is also adapted for use in developed hardware. The prototype used is completely digital, so standard sensor diagnostics techniques are inapplicable. A new method is developed to work with the digital hardware.
Ph. D.

Magistro darbo tema yra aktuali, nes tai naujas ir efektyvus žingsnis tobulinant elektros pavaras ir pagerinant daugelio mechanizmų valdymo kokybę. Adaptyvios pavarų valdymo sistemos sudaromos taikant parametrinės arba signalinės adaptacijos principą. Parametriškai adaptyvioje valdymo sistemoje, kintant valdymo objekto parametrams, keičiami reguliatorių parametrai taip, kad valdymo kokybė nepakistų. Naudojant signalinės adaptacijos principą, adaptacijos blokas formuoja papildomą valdymo signalą, kuris veikia reguliatoriaus įėjime ir garantuoja pastovią valdymo kokybę kintant valdymo objekto parametrams. Tyrimų metu nustatyta, kad parametrinė adaptacija turi trūkumų – adaptuojamasi tik po kelių ciklų, pajungus apkrovą gaunamas statinis greičio nuokrypis. Taigi parametrinės adaptacijos metu yra kompensuojamas inercijos momento pokytis, tačiau nėra kompensuojama apkrovos momento įtaka. Signalinės adaptacijos principo taikymo elektromechanėse sistemose tyrimo rezultatai rodo, kad adaptuojamasi iš karto to paties ciklo metu. Statinės apkrovos įtaka yra pašalinama tuo išvengiant greičio statinio nuokrypio bei užtikrinant pageidaujamą pereinamąjį procesą. Taigi taikant signalinę adaptaciją kompensuojami tiek inercijos, tiek ir apkrovos momentų pokyčiai. Nustatyta, kad taikant P-PI kintamos struktūros reguliatorių yra kompensuojamas tik statinės apkrovos momento pokytis, tuo išvengiant greičio statinio nuokrypio. Signalinės adaptacijos ir P-PI kintamos struktūros reguliatoriaus... [toliau žr. visą tekstą]
The theme of this Master project is actual, because it is new and effective step to elevate electrical drives, and also improves the quality of mechanism control. Adaptive speed control system allows the application of the parametric and the signal adaptation principle. In an adaptive control system, which is consist of parametric adaptation principle the change of the controlled object parameters causes the change of the controller settings so that control quality of the system remains constant. Using the signal adaptation principle, the adaptation block forms additional control signal, which acts in a regulator input and guarantees a constant quality of system control, when the object parameters are changing. There has been made research of the parametric adaptation principle application in the electromechanical servo drives. It has been determined that this adaptation principle has disadvantages – adaptation is not instantaneously, but after few cycles. Static load causes the static deviation of the speed. So using the parametric adaptation the moment of inertia is compensated, but load torque can‘t be compensated. The results of the investigation of the signal adaptation principle application in the electromechanical servo drives demonstrate that this adaptation is instantaneously and it does not affected by the load. The signal adaptation compensates the change of the moment of inertia and load torque. The P-PI variable structure controller compensates only the change of... [to full text]

This thesis examines the modeling of the shock-layer radiative heating associated with hypersonic vehicles entering the atmospheres of Earth and Titan. For Earth entry, flight conditions characteristic of lunar-return are considered, while for Titan entry, the Huygens probe trajectory is considered. For both cases, the stagnation region flowfield is modeled using a two-temperature chemical nonequilibrium viscous shock layer (VSL) approach. This model is shown to provide results that are in agreement with the more computationally expensive Navier-Stokes solutions. A new radiation model is developed that applies the most up-to-date atomic and molecular data for both the spectrum and non-Boltzmann modeling. This model includes a new set of atomic-lines, which are shown to provide a significant increase in the radiation (relative to previous models) resulting from the 1 - 2 eV spectral range. A new set of electronic-impact excitation rates was compiled for the non-Boltzmann modeling of the atomic and molecular electronic states. Based on these new rates, a novel approach of curve-fitting the non-Boltzmann population of the radiating atomic and molecular states was developed. This new approach provides a simple and accurate method for calculating the atomic and molecular non-Boltzmann populations. The newly-developed nonequilibrium VSL flowfield and nonequilibrium radiation models were applied to the Fire II and Apollo 4 cases, and the resulting radiation predictions were compared with the flight data. For the Fire II case, the present radiation-coupled flowfield model provides intensity values at the wall that predicted the flight data better than any other previous study, on average, throughout the trajectory for the both the 0.2 - 6.0 eV and 2.2 - 4.1 eV spectral ranges. The present results over-predicted the calorimeter measurements of total heat flux over most of the trajectory. This was shown to possibly be a result of the super-catalytic assumption for the wall boundary condition, which caused the predicted convective heating to be too high. For the Apollo 4 case, over most of the trajectory the present model over-predicted the flight data for the wall radiative intensity values between 0.2 - 6.2 eV. For the analysis of Huygens entry into Titan, the focus of the radiation model was the CN violet band. An efficient and accurate method of modeling the radiation from this band system was developed based on a simple modification to the smeared rotational band (SRB) model. This modified approach, labeled herein as SRBC, was compared with a detailed line-by-line (LBL) calculation and shown to compare within 5% in all cases. The SRBC method requires many orders-of-magnitude less computational time than the LBL method, which makes it ideal for coupling to the flowfield. The non-Boltzmann modeling of the CN electronic states, which govern the radiation for Huygens entry, is discussed and applied. The radiation prediction resulting from the non-Boltzmann model is up to 70% lower than the Boltzmann result. A new method for treating the escape factor in detail, rather than assuming a value equal to one, was developed. This treatment is shown to increase the radiation from the non-Boltzmann model by about 10%.
Ph. D.

Rationale – Climate disasters represent a significant and growing proportion of the humanitarian burden and are a key factor in increasing poverty and insecurity. A myriad of studies demonstrate that aid delivered in an ex-ante fashion can be effective in mitigating losses of life, assets and livelihoods associated with climate hazards. This inquiry supplements the nascent body of research and empirical evidence base pertaining to the building of anticipatory capacity into large-scale national systems, namely via linking a Forecast-based Financing mechanism to an existing social protection system. Research question – Using the case of flood disasters in Bardiya district, Nepal, the research inquired the following: How can social protection be combined with Forecast-based Financing in order to optimise anticipatory humanitarian relief for climate-related disasters? Sub-questions – Research sub-questions guided the inquiry: (1) To what extent are current social protection beneficiaries exposed to climate-related disasters? (2) What is the specific climate vulnerability of social protection beneficiaries? (3) What are the anticipatory relief needs of climate vulnerable social protection beneficiaries? Methodology – Grounded in empirical research via the conduct of a qualitative single case study, the inquiry adopted a conceptual perspective and an exploratory design. A remote data collection strategy was applied, which included (1) a thorough desk review of key scientific literature and secondary data provided by in-field humanitarian organisations; and (2) semi-structured interviews with key informants. Key findings – The data demonstrated that the exposure of social protection beneficiaries to flood hazards is comparable to the general population. Nevertheless, an elevated climate vulnerability is evident secondary to an increased sensitivity and diminished adaptive capacity. The flood anticipatory relief needs/preferences identified include cash-based assistance, food provisions, evacuation assistance and/or enhanced Early Warning Systems. Conclusion – The research supports the utilisation of the proposed conceptual model for an integrated social protection and Forecast-based Financing mechanism, inclusive of vertical and horizontal expansion, in order to effectively identify the most climate vulnerable groups and to guide the provision of targeted anticipatory actions. The mechanism is optimised when a people-centred approach is utilised, with reference to the idiosyncratic, lifecycle and corresponding intersectional vulnerabilities of the targeted population. These findings will contribute to prospective programming in Nepal; additionally, the extent to which they can be generalised will be informed by future applied efficacy studies and comparative analyses with research from differing contexts.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
This paper proposes an adaptive protection system (SPA) developed in Matlab, in order to make the smart grid for greater flexibility reliability and security of the electric power system the protection system proposed is able to assist in the study of protection by the choice of settings to be entered in the relay once the mains relays are parameterized adaptive protection is responsible for discerning between a change of setting group or send new settings this decision is taken by the SPA in the control center and sent to the grid relays in real time the SPA was tested in a medium voltage distribution grid and the sending of change protection setting was validated using SEL-751 relay using communication via Telnet based on testing the proposed SPA acted properly ensuring selectivity and coordination of the protection system
Este trabalho propÃe um sistema de proteÃÃo adaptativa (SPA) desenvolvido em Matlab com o intuito de tornar a rede elÃtrica inteligente para maior flexibilidade confiabilidade e seguranÃa do sistema elÃtrico de potÃncia o sistema de proteÃÃo proposto à capaz de auxiliar no estudo de proteÃÃo para a escolha dos ajustes a serem inseridos no relà uma vez que os relÃs da rede elÃtrica estejam parametrizados a proteÃÃo adaptativa à responsÃvel por discernir entre uma mudanÃa de grupo de ajuste ou envio de novos ajustes essa decisÃo à tomada pelo SPA no centro de controle e enviada aos relÃs da rede em tempo real o SPA foi testado em uma rede de distribuiÃÃo de mÃdia tensÃo e o envio de mudanÃa de ajuste da proteÃÃo foi validado em relà SEL-751 usando comunicaÃÃo via Telnet com base nos testes realizados o SPA proposto atuou corretamente garantindo seletividade e coordenaÃÃo do sistema de proteÃÃo

The thermal response analysis of an ablative material on a two dimensional external surface is performed. The method is applied to both rectangular and cylindrical coordinate systems, where rectangular coordinate system is used for comparison with results available in literature. The current study solves the decomposition of the material at high temperatures by using the nth order Arrhenius equation but excludes the removal of char from the surface due to mechanical erosion or phase change and considers that the ablation process takes place in a finite zone. The method considers the whole domain as one computational domain, eliminating the necessity to check the positions of the start and end of decomposition zone. The decomposition of pyrolysis gases and/or char that may occur at high temperatures and the chemical reaction between pyrolysis gases and char is neglected while pyrolysis gases are assumed to behave as ideal gas. The pressure is taken as a constant value on a whole physical domain. The formulation for one-dimensional case is validated by experimental results obtained from literature. The two-dimensional case in a Cartesian geometry is formulated and an algebraic transformation is used to normalize the region in both directions and transformed at same time into a square computational domain in order to get a solution for the variable thickness domains. The formulation for two-dimensional case is revised for the cylindrical coordinates with finite length in the axial direction. To solve geometries where the outer surface deviates from cylindrical, the formulation is scaled and transformed into a non-dimensional square computational domain. The method is also applied to a two layer material problem in axisymmetric geometry. In all problems, the radiation and constant heat flux boundary conditions exist on the outer surface while whole domain is initially at a constant temperature. Case studies are performed to demonstrate the application of the solution method in optimizing the insulation material thickness.

Modeling the atmospheric entry of spacecraft is challenging because of the large number of physical phenomena that occur during the process. In order to study thermal protection systems, engineers rely on high fidelity solvers to provide accurate predictions of both the thermochemical environment surrounding the heat shield, and its material response. Therefore, it is necessary to guarantee that the numerical models are correctly implemented and thoroughly validated. In recent years, a high-fidelity modeling tool has been developed at the University of Kentucky for the purpose of studying atmospheric entry. The objective of this work is to verify and validate this code. The verification consists of the development of an automated regression testing utility. It is intended to both aid code developers in the debugging process, as well as verify the correct implementation of the numerical models as these are developed. The validation process will be performed through comparison to relevant ablation experiments, namely arc-jet tests. Two modules of the code are used: fluid dynamics, and material response. First the fluid dynamics module is verified against both computational and experimental data on two distinct arc-jet tests. The material response module is then validated against arc-jet test data using PICA.

The pyrolysis mechanics of Phenolic Impregnated Carbon Ablators (PICA) makes it a valued material for use in thermal protection systems for spacecraft atmospheric re-entry. The present study of the interaction of pyrolysis gases and char with plasma gases in the boundary layer over PICA and its substrate, FiberForm, extends previous work on this topic that has been done in the UVM 30 kW Inductively Coupled Plasma (ICP) Torch Facility. Exposure of these material samples separately to argon, nitrogen, oxygen, air, and carbon dioxide plasmas, and combinations of said test gases provides insight into the evolution of the pyrolysis gases as they react with the different environments. Measurements done to date include time-resolved absolute emission spectroscopy, location-based temperature response, flow characterization of temperature, enthalpy, and enthalpy flux, and more recently, spatially resolved and high-resolution emission spectroscopy, all of which provide measure of the characteristics of the pyrolysis chemistry and material response. Flow characterization tests construct an general knowledge of the test condition temperature, composition, and enthalpy. Tests with relatively inert argon plasmas established a baseline for the pyrolysis gases that leave the material. Key pyrolysis species such as CN Violet bands, NH, OH and Hydrogen Alpha (Hα) lines were seen with relative repeatability in temporal, spectral, and intensity values. Tests with incremental addition, and static mixtures, of reactive plasmas provided a preliminary image of how the gases interacted with atmospheric flows and other pyrolysis gases. Evidence of a temporal relationship between NH and Hα relating to nitrogen addition is seen, as well as a similar relationship between OH and Hα in oxygen based environments. Temperature analysis highlighted the reaction of the material to various flow conditions and displayed the in depth material response to argon and air/argon plasmas. The development of spatial emission analysis has been started with the hope of better resolving the previously seen pyrolysis behavior in time and space.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The representation of dynamic systems or plants via mathematical models occupies an important position in control system design that allow the performance evaluation of the controller during his development stage. These models are also used as an alternative to solve the problem of the hardness or impracticability to install sensors that measure the controlled variables, the dynamic systems representations enable non-invasive measurement of these variables. As consequence the designer has an alternative way to perform adaptive and optimal sensorless control for a given process. In this dissertation is presented a proposal for control systems schemas and algorithms, based on recurrent neural networks (ANN) and Box-Jenkins models, that are dedicated to sensorless or indirect control of dynamic systems. The proposed models and algorithms are associated with the systems identification and recurrent ANN approaches. The algorithms developed for the AAN training are Backpropagation Accelerated and RLS types that are compared with classical methods and strategies to obtain it online parameters of indirect control of system for a thermal plant, where the actuator is Peltier cell. The performance the parametric models of the plant and adaptive PID digital controllers and linear quadratic regulator (DLQR) that are the main elements of the sensorless temperature control system, are evaluated by means of hybrid simulations, where the algorithms implemented in micro controllers and the plant represented by mathematical models. The performance results of the proposed sensorless control algorithms are promissory, not only, in terms of the control system performance, but also due to the reexibility to deploy it in other dynamic systems.
A representação de sistemas dinâmicos ou plantas por meio modelos matemáticos ocupa uma posição relevante no projeto de sistemas de controle, permitindo que o projetista avalie o desempenho dos controladores durante a fase de desenvolvimento do projeto. Estes modelos também são utilizados para resolver o problema da dificuldade ou impossibilidade da inserção de sensores em plantas para medição de variáveis controladas, onde os modelos viabilizam a mediação não invasiva destas variáveis, fornecendo uma alternativa para realização do controle indireto adaptativo e ótimo de um dado processo. Nesta dissertação apresenta-se o desenvolvimento de modelos propostos baseados em redes neurais artificiais recorrentes para o controle sensorless ou indireto da planta. Os modelos propostos estão associados com as abordagens de Identificação de Sistemas e de RNA's recorrentes. OS algoritmos desenvolvidos para o treinamento das RNAs são do tipo Backpropagation acelerado e RLS, que são comparados com estratégias e métodos clássicos, para obtenção online dos parâmetros do sistema de controle indireto de uma planta térmica, tendo como atuador uma célula Peltier. Para uns de avaliação de desempenho do sistema de controle indireto da planta, os modelos paramétricos e controladores digitais adaptativos do tipo PID e regulador linear quadrático (DLQR) são avaliados por meio de simulações híbridas, sendo os algoritmos dos controladores implementados em microcontroladores e a planta representada por modelos matemáticos. Os resultados apresentados são promissores, não são sentido do desempenho do sistema de controle, mas também nos custos reduzidos para seu desenvolvimento, operação e flexibilidade de aplicação em outros sistemas dinâmicos.

The thermal protection system (TPS) represents the greatest risk factor after propulsion for any transatmospheric mission (Dr. Charles Smith, NASA ARC). Any damage to the TPS leaves the space vehicle vulnerable and could result in the loss of human life as happened in the Columbia accident. Aboard the current Space Shuttle Orbiters no system exists to notify the astronauts or ground control if the thermal protection system has been damaged. Through this research, a proof-of-concept monitoring system was developed. The system has two specific applications for thermal protection systems: (1) Improving models used to predict thermal and mechanical response of TPS materials, and (2) Self-diagnosing damage within regions of the TPS and communicating the damage to the appropriate personnel over a potentially unstable network. Mechanical damage is among the most important things to protect the TPS against. Methods to detect the primary types of mechanical damage suffered by thermal protection systems have been developed. Lightweight, low-power sensors were developed to detect any cracks in small regions of a TPS. Implementation of a network of these sensors within 10's to 1000's of regions will eventually provide high spatial resolution of damage detection; allowing for detection of holes in the TPS. Also important in thermal protection material development is to know the ablation rates and time/temperature response of the materials. A new type of sensor has been developed to monitor temperature at different depths within thermal protection materials. The signals being transmitted through the sensors can be multiplexed to allow for mechanical damage and temperature to be monitored using the same sensor.

碩士
國立臺灣大學
電子工程學研究所
100
In this thesis, we proposed Traffic- and Thermal- balanced Adaptive Beltway Routing (TTABR) algorithm and architecture design for performance reduction due to the traffic load and thermal distribution imbalance in thermal-aware 3D network-on-chip (NoC). The minimal path routing on 3D NoC cause the unbalance traffic load, which also induce the thermal distribution imbalance. To ensure thermal safety and avoid huge performance back-off from the temperature constraint, run time thermal management is required. However the regulation of temperature requires throttling of the near-overheated router, which makes the topology become Non-Stationary Irregular Mesh (NSI-mesh). It still has performance degradation, and the traffic load imbalance gets worse. Hence the thermal distribution might also become worse and trigger more routers to be throttled. We manage to break this loop to get a better performance and stable 3D NoC systems. TTABR aims to balance the lateral traffic load. It has providing the non-minimal path to increase path diversity and using novel cascade routing to heave the lateral traffic. TTABR also proposed to solve the traffic load imbalance in the vertical direction. Based on the experimental results, the proposed routing scheme can significantly improve the performance and balance traffic load. For low cost implementation, we also propose memory reduction techniques, and we gain 2.7x throughput improvement for only 26.7% area overhead. The throughput per area of our proposed algorithm is 2.1x compared to other related work.

Dissertação de Mestrado em Astrofísica e Instrumentação para o Espaço apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Nesta tese, é apresentado um sensor não-intrusivo para medir, em tempo real, a ablação de um sistema de proteção térmica, durante uma entrada atmosférica. Os sistemas de proteção térmica são indispensáveis para garantir que veículos espaciais possam aterrar noutros planetas. O próximo grande passo da humanidade ao nível espacial é enviar humanos para Marte. Para uma missão desse género, será fundamental ter um sensor que consiga medir a perda de massa em tempo real e que esses dados sejam enviados para a Terra. O regresso do espaço é um risco para todos os tipos de missões, quer sejam tripuladas ou não tripuladas. Os modelos utlizados para estudar o risco necessitam de um grande volume de dados experimentais para refinar as calibrações e serem mais precisos. Espera-se que os dados recolhidos pelo sensor sejam de grande valor para a otimização dos sistemas de proteção térmica. Este sensor pode reduzir os custos e os riscos destas missões. Este sensor usa a técnica da impedância mútua para medir a espessura da proteção térmica durante o processo ablativo.

M.Sc. (Information Technology)
The purpose of the research presented in this dissertation is to explore the uses of an adaptive multi-agent system for critical information infrastructure protection (CIIP). As the name suggests, CIIP is the process of protecting the information system which are connected to the infrastructure essential to the continued running of a country or organisation. CIIP is challenging due largely to the diversity of these infrastructures. The dissertation examines a number of artificial intelligence techniques that can be applied to CIIP; these techniques range from multi-agent systems to swarm optimisation. The task of protection is broken into three distinct areas: preventing unauthorised communication from outside the system; identifying anomalous actions on computers within the system; and ensuring that communication within the system is not modified externally. A multi-agent learning model, MALAMANTEAU, is proposed as a way to address the problem of CIIP. Due to various problems facing CIIP, multi-agent systems present good opportunities for solving these many problems in a single model. Agents within the MALAMANTEAU model will use diverse artificial and computational intelligence techniques in order to provide an adaptable approach to protecting critical networks. The research presented in the dissertation shows how computational intelligence can be employed alongside multi-agent systems in order to provide powerful protection for critical networks without exposing further security risks.

Konventionelle Wärmedämmschichtensysteme bestehen aus einer Yttriumoxid-stabilisierten Zirkoniumdioxid-Deckschicht auf einer MCrAIY Haftschicht; wobei M für Co, Ni oder CoNi steht. Während der Nutzung bildet sich durch die Kombination von Wärme und Sauerstoff die Reaktionszone in der BC/TC-Grenzfläche. Diese Reaktionszone besteht aus thermisch wachsenden Übergangsmetalloxiden. In dieser Dissertation wurde das Phänomen der Bildung von TGO in TBC-Systemen betrachtet. Co32Ni21Cr8Al0.5Y Haftschichten wurden mithilfe des Verfahrens des atmosphärischen Plasmaspritzens (APS) auf Inconel 600 Substrate aufgebracht. Jm nächsten Schritt wurden durch DC-Magnetronsputter dünne Aluminumschichten auf die Oberfläche aufgetragen. Schließlich wurde YSZ TC mittels APS auf die Oberfläche gespritzt. Die beiden TBC-Systeme wurden zur Unterscheidung des Einflusses der thermischen Auslagerung unterschiedlich lange ausgelagert, um das thermochemischen Transformationsverhalten der Al-Zwischenschicht zu bestimmen. Die Schichtlebensdauer wurde unter thermischer Zyklierung mit einer definierten Verweilzeit untersucht. Das veränderte TBC-System mit der Al-Zwischenschicht (Al TBC) wurden mit dem TBC-System ohne Al-Zwischenschicht (R TBC) verglichen. Die Ergebnisse zeigen, dass das Hinzufügung der Al-Schichte in der BC/TC Grenzfläche nützlich für die Bildung der kontinuierlichen α Al2O3-Schicht während der Vorbereitungsphase der Wärmebehandlung ist. Diese dichte α Al2O3-Schicht bildet offensichtlich eine Durchgangsbarriere für den Sauerstoff während des Lebensdauertests. Dies hat Potential für die Verringerung der Bildung schädlicher Oxide. Der Ansatz ist nützlich für die Verlängerung der stabilen Wachstumsphase von TGO. In der Folge ermöglicht dies eine höhere Lebensdauer von Al-TBC-Systemen im Vergleich zu R-TBC-Systemen für die betrachteten thermischen Bedingungen und Zyklierungen.:Table of contents 1 Introduction 1 2 Motivation and overall interest 3 3 State of science and technology 5 3.1 Thermal barrier coating (TBC) systems 5 3.1.1 Substrate material 6 3.1.2 Ceramic top coating 6 3.1.3 Metallic bond coating 8 3.1.4 Thermally grown oxides (TGO) 12 3.1.5 Approaches on controlled TGO formation 15 3.1.6 Failure modes of TBC systems 17 3.2 Thermal spray technology 20 3.2.1 Atmospheric plasma spray (APS) technique 20 3.2.2 Formation sequence of the coating 21 3.2.3 Structure of the coating 22 3.3 Technology of thin layer deposition 23 3.4 Conclusions from the state of science and technology 24 4 Scientific objectives and work program 26 5 Experimental procedure 30 5.2 Material selection 30 5.3 Feedstock materials and thermal spray powders 32 5.4 Process selection 33 5.5 Specification of the scientific instruments 33 5.6 Detailed experimental procedure 34 5.6.1 Characterization of thermal spray powders 34 5.6.2 Preparation and characterization of overlaid coatings 35 5.6.3 Thermal treatment of TBC systems 39 5.6.4 Characterization of heat treated coating systems 40 5.6.5 Evaluation of TGO thickness and crack propagation 41 6 Results and discussions 43 6.1 Thermal spray powders and as sprayed coatings 43 6.1.1 Thermal spray powders 43 6.1.1.1 CoNiCrAlY thermal spray powder 43 6.1.1.2 ZrO2 – 8 %Y2O3 thermal spray powders 47 6.1.2 As-sputtered Al layer 50 6.1.2.1 Microstructure features 50 6.1.2.2 Elemental and phase composition analyses 50 6.1.3 As-sprayed coating systems 51 6.1.3.1 Bare and Al-covered CoNiCrAlY coatings 51 6.1.3.2 As-sprayed TBC systems 55 6.2 TBC systems after thermal treatment with different spans of dwell time 58 6.2.1 Thermal treatment with 5 and 30 min dwell time 58 6.2.2 Thermal treatment with 60 and 120 min dwell time 67 6.3 Lifetime test of TBC systems 68 6.3.1 Features in the cross section microstructure 68 6.3.2 Phase composition analyses 71 6.3.3 Elemental and Raman analyses 72 6.3.4 Features in the BC/TC of TBC systems after 80 thermal cycles 87 6.4 Thickness of TGO in the TBC systems 89 6.5 Length of cracks in the TC of the TBC systems 91 6.6 Relation between thickness of TGO and length of cracks 93 6.7 Discussion of loading condition and failure mode 95 6.8 Lifetime prediction of the TBC systems 97 6.9 Oxidation model of the TBC systems 98 7 Complementary work with discussion 100 7.1 Oxidation behavior of the TBC systems based on slow heating and cooling rates 100 7.1.1 Thickness of TGO and length of cracks 108 7.1.2 Raman analyses 112 7.1.3 Oxidation model of the TBC systems 116 7.2 Effect of Al content in the metallic coating 118 8 Complementary discussion 121 8.1 Effect of temperature on the oxidation behavior 121 8.2 Effect of deposition technique for metallic coating on the oxidation behavior 122 8.3 Effect of deposition technique for ceramic coating on the oxidation behavior 122 9 Summary and conclusion 124 10 References 128
Conventional thermal barrier coating (TBC) systems consist of yttria-stabilized zirconia (YSZ) top coat (TC) on a MCrAlY bond coat (BC), where “M” stands for Co, Ni or CoNi. During their service under a combined heat and oxygen load, a reaction zone forms in the BC/TC interface. This reaction zone consists of thermally grown transition metal oxides (TGO). In the present thesis work, a phenomena related to the TGO formation is introduced. Co32Ni21Cr8Al0.5Y BC was overlaid by atmospheric plasma spraying (APS) technique on Inconel 600 substrates. Thin Al layers were deposited subsequently by DC-Magnetron sputtering on top. Finally, YSZ TC was sprayed by APS technique on the Al layers. The TBC systems were subjected to different thermal treatment procedures in order to investigate the thermo-chemical transformation behaviour of the Al-interlayer. The lifetime of the coatings was investigated under thermal cycling loading with dwell time. The altered TBC systems with Al interlayers (Al-TBC) were compared with the reference TBC systems without Al interlayers (R-TBC). The results show, that the addition of Al layers in the BC/TC interfaces is useful to form a continuous α-Al2O3 layer during the preliminary stage of heat treatment. The in-situ formed dense α-Al2O3 layer obviously acts as a diffusion barrier for oxygen during lifetime test. This has the potential to reduce the formation rate of detrimental oxides. This approach is beneficial to prolong the steady-state growth stage of the TGO, hence allows a higher lifetime for the Al-TBC systems in comparison to the R-TBC systems for the applied thermal loads.:Table of contents 1 Introduction 1 2 Motivation and overall interest 3 3 State of science and technology 5 3.1 Thermal barrier coating (TBC) systems 5 3.1.1 Substrate material 6 3.1.2 Ceramic top coating 6 3.1.3 Metallic bond coating 8 3.1.4 Thermally grown oxides (TGO) 12 3.1.5 Approaches on controlled TGO formation 15 3.1.6 Failure modes of TBC systems 17 3.2 Thermal spray technology 20 3.2.1 Atmospheric plasma spray (APS) technique 20 3.2.2 Formation sequence of the coating 21 3.2.3 Structure of the coating 22 3.3 Technology of thin layer deposition 23 3.4 Conclusions from the state of science and technology 24 4 Scientific objectives and work program 26 5 Experimental procedure 30 5.2 Material selection 30 5.3 Feedstock materials and thermal spray powders 32 5.4 Process selection 33 5.5 Specification of the scientific instruments 33 5.6 Detailed experimental procedure 34 5.6.1 Characterization of thermal spray powders 34 5.6.2 Preparation and characterization of overlaid coatings 35 5.6.3 Thermal treatment of TBC systems 39 5.6.4 Characterization of heat treated coating systems 40 5.6.5 Evaluation of TGO thickness and crack propagation 41 6 Results and discussions 43 6.1 Thermal spray powders and as sprayed coatings 43 6.1.1 Thermal spray powders 43 6.1.1.1 CoNiCrAlY thermal spray powder 43 6.1.1.2 ZrO2 – 8 %Y2O3 thermal spray powders 47 6.1.2 As-sputtered Al layer 50 6.1.2.1 Microstructure features 50 6.1.2.2 Elemental and phase composition analyses 50 6.1.3 As-sprayed coating systems 51 6.1.3.1 Bare and Al-covered CoNiCrAlY coatings 51 6.1.3.2 As-sprayed TBC systems 55 6.2 TBC systems after thermal treatment with different spans of dwell time 58 6.2.1 Thermal treatment with 5 and 30 min dwell time 58 6.2.2 Thermal treatment with 60 and 120 min dwell time 67 6.3 Lifetime test of TBC systems 68 6.3.1 Features in the cross section microstructure 68 6.3.2 Phase composition analyses 71 6.3.3 Elemental and Raman analyses 72 6.3.4 Features in the BC/TC of TBC systems after 80 thermal cycles 87 6.4 Thickness of TGO in the TBC systems 89 6.5 Length of cracks in the TC of the TBC systems 91 6.6 Relation between thickness of TGO and length of cracks 93 6.7 Discussion of loading condition and failure mode 95 6.8 Lifetime prediction of the TBC systems 97 6.9 Oxidation model of the TBC systems 98 7 Complementary work with discussion 100 7.1 Oxidation behavior of the TBC systems based on slow heating and cooling rates 100 7.1.1 Thickness of TGO and length of cracks 108 7.1.2 Raman analyses 112 7.1.3 Oxidation model of the TBC systems 116 7.2 Effect of Al content in the metallic coating 118 8 Complementary discussion 121 8.1 Effect of temperature on the oxidation behavior 121 8.2 Effect of deposition technique for metallic coating on the oxidation behavior 122 8.3 Effect of deposition technique for ceramic coating on the oxidation behavior 122 9 Summary and conclusion 124 10 References 128

abstract: In this dissertation, two interrelated problems of service-based systems (SBS) are addressed: protecting users' data confidentiality from service providers, and managing performance of multiple workflows in SBS. Current SBSs pose serious limitations to protecting users' data confidentiality. Since users' sensitive data is sent in unencrypted forms to remote machines owned and operated by third-party service providers, there are risks of unauthorized use of the users' sensitive data by service providers. Although there are many techniques for protecting users' data from outside attackers, currently there is no effective way to protect users' sensitive data from service providers. In this dissertation, an approach is presented to protecting the confidentiality of users' data from service providers, and ensuring that service providers cannot collect users' confidential data while the data is processed or stored in cloud computing systems. The approach has four major features: (1) separation of software service providers and infrastructure service providers, (2) hiding the information of the owners of data, (3) data obfuscation, and (4) software module decomposition and distributed execution. Since the approach to protecting users' data confidentiality includes software module decomposition and distributed execution, it is very important to effectively allocate the resource of servers in SBS to each of the software module to manage the overall performance of workflows in SBS. An approach is presented to resource allocation for SBS to adaptively allocating the system resources of servers to their software modules in runtime in order to satisfy the performance requirements of multiple workflows in SBS. Experimental results show that the dynamic resource allocation approach can substantially increase the throughput of a SBS and the optimal resource allocation can be found in polynomial time
Dissertation/Thesis
Ph.D. Computer Science 2012

Complex flow structures consisting of branching, multi-scale, hierarchically arranged flow paths can be a beneficial in certain applications by providing lower hydraulic and thermal resistances than conventional flow arrangements. In this study, an experimental approach was used to investigate the hydrodynamic and thermal effects of the complexity, or degree of branching, in microscale complex flow structures. The primary focus of this work was to develop new concepts to advance the current capabilities of complex flow structures through management of complexity. The effects of complexity were determined from experiments performed on a set of microfluidic test sections which were identical except for the complexity of the underlying microchannel configuration. Comparison of the relative hydrodynamic and thermal performance indicates that complexity has a strong effect on both the pressure drop and heat transfer. When the pumping power is taken into account, the results suggest that higher complexity arrangements improve the overall thermal-hydraulic performance. This conclusion was confirmed by the trends observed in the coefficient of performance, a measure of the device thermal efficiency. To address the limitations of conventional fixed-complexity designs, the concept of a variable-complexity flow structure is developed. With a variable-complexity design, the configuration of a branched flow structure can be dynamically controlled to improve performance as operational conditions vary. This concept was successfully demonstrated by developing and testing an active variable-complexity microfluidic device in which pneumatically controlled microvalves were used to create different flow channel configurations. The variable-complexity concept was further refined by developing a microfluidic device with a passive variable-complexity design in which the flow channel configuration changed autonomously based on local temperatures. By using microvalves containing a temperature sensitive polymer, the flow configuration of the device was made thermally adaptive. Experiments were performed to characterize the behavior of the polymer microvalves and the overall device performance. The results showed that the device was capable of tracking changes in external heat sources by adapting and reconfiguring its internal flow structure. The experiments also showed how this variable-complexity design can reduce the pumping power expenditure by automatically directing flow only to areas where it is required.
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Smart radial distribution grids will include advanced metering infrastructure (AMI) and significant distributed generators (DGs) connected close to loads. DGs in these radial distribution systems (RDS) introduce bidirectional power flows (BPFs) and contribute to fault current. These BPFs may cause unwanted tripping of existing overcurrent (OC) protection devices and result in permanent outages for a large number of customers. This thesis presents a protection approach that modified an existing overcurrent protection scheme to reduce the number of customers affected by faults in RDS with DGs. Further, a technique is presented that utilizes customers loading information from smart meters in AMI to improve the sensitivity of substation OC relays by adaptively changing the pickup settings. The modified protection approach involves predefining zones in RDS with DGs and installing directional OC relays and circuit breakers at the zonal boundaries. Zonal boundary relays determine faulted zones by sharing information on the direction of detected faults current using binary state signals over a communication medium. The technique to adapt the substation relay pickup settings uses the demand measurements from smart meters for two 12-hour intervals from the previous day to determine the maximum diversified demand at the relay?s location. The pickup settings of the substation relay for the two 12-hour intervals during the following day for the zone supplied by the substation are adaptively set based on the current that corresponds to the maximum diversified demand from the previous day. The techniques were validated through simulations in EMTP/PSCAD using an expanded IEEE 34 node radial test feeder that included DGs and a secondary distribution level. By decentralizing the control of the zonal boundary breakers, the single point of failure was eliminated in the modified protection approach. The cases studied showed that the modified protection approach allows for selective identification and isolation of the faulted zones. Also, the sensitivity of the substation OC relay was improved by at least 24% by using the pickup settings for the two 12-hour intervals from the smart meter demand measurements compared to the pickup settings computed using the conventional methodology based on the maximum loading of the zone.

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia
Ao longo dos tempos, mas sobretudo mais recentemente, Portugal tem sido assolado por fogos florestais, com grandes impactos a vários níveis, sejam eles destruição de paisagens, de habitações, perdas de vidas humanas, são algumas das tragédias causadas pelos fogos florestais. Uma estratégia para fazer face a esta calamidade passa pelo desenvolvimento de sistemas de proteção de elementos expostos ao fogo. É neste âmbito que surge o projeto Fireprotect, no qual este trabalho está inserido.O trabalho desenvolvido nesta dissertação faz parte de um destes sistemas de proteção. Trata-se de um sistema de barreiras térmicas que têm como objetivo a criação de perímetros de segurança em torno dos elementos a proteger, sejam eles casas, locais de trabalho, terrenos etc., providenciando uma barreira dupla composta por uma tela ignífuga à base de fibra de vidro para travar o avanço das chamas e proteger dos efeitos radiativos, e por um sistema de aspersão de água para a humidificação do terreno em volta e da própria tela. Estas barreiras são modulares, permitindo que várias unidades sejam acopladas.Este sistema é composto por uma estrutura articulada que se encontra acoplada a uma torre e que necessita de mecanismos para ser estendida e recolhida, mecanismos esses cujo desenvolvimento constitui um dos objetivos deste trabalho. A estratégia usada consistiu num sistema de motores stepper e atuadores controlados através de uma placa eletrónica Wi-Fi, sendo que todos estes elementos se encontram dentro da torre.Foi também realizada a implementação da estrutura articulada e proposta uma nova abordagem à mesma, através da alteração do formato das barras de suporte verticais, de modo a garantir-lhe mais estabilidade. Para proceder à montagem do sistema, foram usadas várias peças feitas por medida.Um dos fatores mais importantes para o sucesso das barreiras é a sua capacidade de sustentação quando sujeitas a vento. Para isso foram também realizados cálculos que permitiram obter as dimensões da estrutura de forma a suportar a força do vento.De seguida a estrutura foi testada em túnel de vento, para verificar como reagia quando sujeita a velocidades de ar de 1,2,3 e 4 m/s.Por último, verificando-se que as barras em X que compunham a estrutura articulada dobravam facilmente, o que causava problemas de estabilidade, surgiu a necessidade de realizar a otimização da geometria da estrutura através de testes de simulação em computador. Estes tiveram como objetivo sugerir novas geometrias para as barras, de modo a garantir-lhes maior estabilidade, no caso, barras de secção circular e de secção quadrada. Foram calculados os deslocamentos que as diferentes soluções sofriam quando sujeitas a forças de compressão.Tanto os ensaios laboratoriais como os testes de simulação serviram para tirar algumas conclusões. Foram também deixadas algumas sugestões para trabalhos futuros, com o objetivo de aperfeiçoar este sistema de proteção.
Over time, but especially more recently, Portugal has been plagued by forest fires, with major impacts at various levels, whether destruction of landscapes, housing, loss of human lives, are some of the tragedies caused by forest fires. One strategy to address this calamity is the development of fire protection systems. This is where the Fireprotect project emerges, in which this work is inserted.The work developed in this dissertation is part of one of these protection systems. It is a system of thermal barriers that aims to create security perimeters around the elements to be protected, and those can be houses, workplaces, land, etc., providing a double barrier composed of a fireproof screen based on fiberglass to stop the advance of the flame and protect it from radiation effects, and a water sprinkler system to humidify the surrounding terrain and the fabric itself. These barriers are modular, allowing multiple units to be coupled.This system consists of an articulated structure that is coupled to a tower and that needs mechanisms to be extended and retracted, mechanisms whose development constitutes one of the objectives of this work. The strategy used consisted of a system of stepper motors and actuators controlled by a Wi-Fi electronic board, all of which are inside the tower.The articulated structure was also implemented and a new approach to it was proposed, by changing the shape of the vertical support bars, in order to guarantee more stability. To assemble the system, several custom-made parts were used.One of the most important factors in the success of the barriers is their ability to sustain wind force. For this, calculations were performed that allowed to obtain the structure dimensions in order to withstand the wind force.The structure was then tested on a wind tunnel to evaluate how it reacted when subjected to air flow velocities of 1, 2, 3 and 4 m / s.Finally, as the X-bars that made up the articulated structure were easily bendable, which caused stability problems, there was the need to make some shape optimization through computer simulation tests. These were intended to suggest new geometries for the bars, in order to guarantee them greater stability, in this case, circular and square section bars. The displacements that the different solutions suffered when subjected to compressive forces were calculated.Both laboratory tests and simulation tests served to draw some conclusions. Some suggestions were also left for future work in order to improve this protection system.
Outro - Trabalho foi realizado ao abrigo do projeto FireProtect, cofinanciado pelo Fundo Europeu para o Desenvolvimento Regional (Programa Operacional do Centro) Ref. CENTRO-01-0246-FEDER-000015

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Neste trabalho foi desenvolvido e testado um equipamento que permite avaliar o desempenho de sistemas de proteção térmica, aplicáveis em geral aos veículos de transporte ameaçados pelo avanço de frentes de fogo de um incêndio florestal. Em particular a proteção de veículos utilizados na supressão de incêndios florestais, associada à capacidade de proteger a vida dos ocupantes, é o objetivo principal deste trabalho, tornando a cabine num abrigo coletivo contra incêndios. Novos materiais cerâmicos, mantas e espumas, são usados no sentido de reforçar a capacidade de proteção sem exigir o uso de grande quantidade de água, que podem não estar disponíveis no caso de encurralamento pelo fogo Este sistema é relevante principalmente para os bombeiros, para melhorar a sua segurança, é de grande interesse para os proprietários dos meios de transporte que possam estar a vigiar áreas suscetíveis ao incêndio, para evitar a sua distrição Instituições públicas e privadas que empregam pessoal envolvido nas atividades de gestão de incêndios irão beneficiar das soluções desenvolvidas. A cooperação com um dos maiores fabricantes de veículos de combate em Portugal foi criada para melhor desenvolver e incorporar as soluções propostas e apresentadas. Vários testes foram realizados com um sistema de simulação de impacto de frente de fogo da ADAI com cabines dos veículos de bombeiros. Esses veículos foram colocados em frente desta frente de fogo com sistema de proteção e sem sistema de proteção as condições dentro das cabines foram registadas e avaliadas com o objetivo de perceber as condições que permitem a proteção das tripulações e consequentemente dos veículos. Além disso, a distância mínima entre a frente de fogo e um bombeiro exposto fora da cabine foi estudada tendo em conta o calor libertado pela frente de fogo para um modelo de um bombeiro colocado em diferentes posições.
In this work was developed and test a thermal protection system applicable to general transport vehicles endangered by an advancing forest fire. It is aimed in particular to protect vehicles used in forest fire suppression to provide a life guard capacity for its occupants. New materials namely ceramic composites and foams were used to develop enhanced protective capacities without requiring the use of large amounts of water that may not be available in the case of fire entrapment. This system is relevant mainly for fire fighters to improve their safety and is of great interest for owners of transport means that may be travelling in fire prone areas, to avoid their destruction. Public and private agencies employing personnel involved in fire management activities will benefit from the developed solutions. A cooperation with Vehicle manufacturer of Portugal was established to improve to incorporate the proposed solutions. Several tests were performed in a system of simulation of fire front impact of ADAI with cabins of firefighter’s vehicles. Those vehicles were placed in front of the fire fronts with protection and without protection and the conditions inside of the cabins are registered and evaluated with the goal of realise the conditions the allows the protection of the crews. Also the minimum distance between the fire front and a firefighter was studied taking in the account of the heat realised by the fire front to a model of firefighter.

Indiana University-Purdue University Indianapolis (IUPUI)
Lithium ion (Li-ion) batteries have become integral parts of our lives; they are widely used in applications like handheld consumer products, automotive systems, and power tools among others. To extract maximum output from a Li-ion battery under optimal conditions it is imperative to have access to the state of the battery under every operating condition. Faults occurring in the battery when left unchecked can lead to irreversible, and under extreme conditions, catastrophic damage. In this thesis, an adaptive fault diagnosis technique is developed for Li-ion batteries. For the purpose of fault diagnosis the battery is modeled by using lumped electrical elements under the equivalent circuit paradigm. The model takes into account much of the electro-chemical phenomenon while keeping the computational effort at the minimum. The diagnosis process consists of multiple models representing the various conditions of the battery. A bank of observers is used to estimate the output of each model; the estimated output is compared with the measurement for generating residual signals. These residuals are then used in the multiple model adaptive estimation (MMAE) technique for generating probabilities and for detecting the signature faults. The effectiveness of the fault detection and identification process is also dependent on the model uncertainties caused by the battery modeling process. The diagnosis performance is compared for both the linear and nonlinear battery models. The non-linear battery model better captures the actual system dynamics and results in considerable improvement and hence robust battery fault diagnosis in real time. Furthermore, it is shown that the non-linear battery model enables precise battery condition monitoring in different degrees of over-discharge.