Object-oriented programming has had a significant impact on software development because it provides programmers with a clear structure of a large system. It encapsulates data and operations into objects, groups objects into classes and dynamically binds operations to program code. With the emergence of multi-core processors, application developers have to explore concurrent programming to take full advantage of multi-core technology. However, when it comes to concurrent programming, object-oriented programming remains elusive as a useful programming tool. Most object-oriented programming languages do have some extensions for concurrency, but concurrency is implemented independently of objects: for example, concurrency in Java is managed separately with the Thread object. We employ a programming model called Lime that combines action systems tightly with object-oriented programming and implements concurrency by extending classes with actions and guarded methods. This provides programmers with a unified and straightforward design view for a concurrent object-oriented program. In this work, using coroutines with guarded methods and actions is proposed as a means of implementing the concurrency extension for objects. Mapping objects to coroutines can result in stack overflow as the number of objects increases. A dynamically segmented stack mechanism, which does not introduce runtime overhead, is implemented to support large-scale concurrency. Since Lime allows guarded methods and actions to "get stuck," a new user-level cooperative scheduler, and a fast coroutine context switch mechanism are implemented to improve the performance. Compared with the traditional segmented stack mechanisms, the new dynamically segmented stack mechanism gets equal performance for more common scenarios. Besides, it outperforms the contemporary stack mechanisms for deep recursion scenarios. Above all, Lime does not only provide the programmers with a unified and straightforward object-oriented programming model for concurrency, but also accomplishes a better performance than concurrent programming languages such as Erlang and Go, in fine-grained, highly concurrent benchmarks. / Thesis / Doctor of Philosophy (PhD)

L'examen de la filière EVHT (Electrolyse de Vapeur d'eau à Haute Température) montre qu'elle est en train de passer de la phase de recherche à la phase de développement. Il devient maintenant nécessaire de prouver et si possible d'améliorer la compétitivité de cette technologie. Pour cela nous avons fait ressortir le besoin de posséder un outil capable de faire le lien entre les producteurs d'hydrogène, propriétaires d'usine, et les fabricants d'empilements de cellules d'électrolyse. Pour répondre à cet objectif principal, deux contraintes fortes sont identifiées : être insérable dans un schéma usine (logiciel de simulation de procédé), et être représentatif de la technologie de cellule et du stack utilisée. La modélisation d'un objet dans un logiciel de simulation de procédé implique généralement une représentation très simplifiée de celui-ci. Pour pouvoir satisfaire ces contraintes, nous avons bâti une chaîne de modèles partant des modèles d'électrodes et aboutissant finalement à une modélisation de procédé représentative de la technologie EVHT utilisée. Le travail et la valeur ajoutée de cette thèse sont focalisés sur cette démarche d'optimisation énergétique globale et locale, qui permet, à chaque échelle, une analyse adaptée des phénomènes principaux se déroulant dans chaque objet et le chiffrage de l'impact énergétique et économique de la technologie utilisée. Cette démarche permet d'aboutir à un outil capable de réaliser une optimisation technico-économique poussée sur une unité de production EVHT / HTSE field (High Temperature Steam Electrolysis) is moving from the research phase to development phase. It?s now necessary to prove and to possibly improve the technology competitiveness. Therefore we need a tool able to allow communication between hydrogen producers and electrolysis cell stack designers. Designers seek where their efforts have to focus, for example by searching what are the operating best conditions for HTSE (voltage, temperature). On the contrary, the producer wants to choose the most suitable stack for its needs and under the best conditions: hydrogen has to be produced at the lowest price. Two main constraints have been identified to reach this objective: the tool has to be inserted into a process simulation software and needs to be representative of the cell and stack used technology. These constraints are antagonistic. Making an object model in a process simulation usually involves a highly simplified representation of it. To meet these constraints, we have built a model chain starting from the electrode models and leading to a representative model of the HTSE technology used process. Work and added value of this thesis mainly concern a global and local energy optimization approach. Our model allows at each scale an appropriate analysis of the main phenomena occurring in each object and a quantification of the energy and economic impacts of the technology used. This approach leads to a tool able to achieve the technical and economic optimization of a HTSE production unit.

Este trabalho teve por objetivo avaliar a aplicação de diversas tecnologias de células a combustível tipo PEMFC desenvolvidas no IPEN para obtenção de um módulo de potência de 500 We. Foram estudados o aumento de escala na produção de MEAs de 25 cm2 para 144 cm2 pelo método de impressão a tela; a simulação por fluidodinâmica computacional de canais de fluxo de gases em placas bipolares utilizando o programa COMSOL e; o estudo de desempenho de eletrodos Pt/C desenvolvidos pelo método de redução por álcool, em células individuais de 144 cm2. Assim, desenvolveu-se um módulo de 500 We de potência nominal, produzido com tecnologia nacional, e com apoio da indústria para possíveis aplicações comerciais. A indústria nacional contribuiu com o hardware do módulo e os sistemas de vedação e refrigeração. Foi realizado um teste de 100 horas em célula unitária de 144 cm2 para observação do comportamento do MEA fabricado pelo processo de impressão à tela, bem como das outras tecnologias descritas, e a célula mostrou-se estável neste intervalo de tempo. O módulo desenvolvido com tecnologia nacional apresentou a potência máxima de 574 We à corrente de 100 A (694,4 mA cm-2). A potência de operação de 500 We foi obtida à corrente de 77,7 A (540,1 mA cm-2) ao potencial de 6,43 V, com uma eficiência de 43,3%. Em termos de cogeração, a potência térmica ou calor gerado pelo módulo foi de 652 Wt. Deste modo, foram consolidados os experimentos em P&D realizados no IPEN em células a combustível, para produção de potência elétrica. Uma estimativa inicial de custo para o módulo de 500 We estudado foi de R$ 4.500,00, baseando-se apenas nos materiais empregados em sua construção. / This work is part of a research project on PEMFC technologies carried out in IPEN to develop and optimize a 500 We fuel cell stack. The MEAs scaling up from 25 cm2 to 144 cm2 produced by the method of sieve printing; computational fluid dynamics by computer simulation of gas flow channels in bipolar plates using COMSOL® program and the use of Pt/C electrodes developed by alcohol reduction method in single cells were used to build a stack of 500 We nominal power for possible commercial applications, produced with national technology and industrial support. A 100 hours fuel cell´s test was carried out in a 144 cm2 single cell to study the stability of the MEA fabricated by sieve printing method. This single cell showed good stability within this period of time. The developed stack has reached the maximum power of 574 We at 100 A (694.4 mA cm-2). The operating power of 500 We was obtained at 77.7 A (540.1 mA cm-2) and potential of 6.43 V, with efficiency of 43.3%. In terms of cogeneration, the thermal power or generated heat by the stack was 652 Wt. The initial estimated cost for the 500 We stack was about R$ 4,500.00, considering only the used materials for its construction.

This essay describes the work to document and evaluate tools for front-end development at the company B3 Consulting Group. The methods that are evaluated is AMP-stack and JAM-stack. AMP-stack uses Apache, MySQL and PHP, Wordpress is used to build with that method. JAM-stack uses JavaScript, API and Markup, for that method GatsbyJS and Contentful is used. The evaluation is done both through user tests and how the methods are percived from a developer perspective. The project also includes work with customers at the company the project is done, Wordpress is used for those web pages. / Denna rapport beskriver arbetet med att dokumentera och utvärdera verktyg för frontend-utveckling vid företaget B3 Consulting Group. Metoderna som utvärderas är AMP-stack och JAM-stack. AMP-stack bygger på Apache, MySQL och PHP, för att bygga med den metoden har Wordpress använts. JAMstack bygger på JavaScript, API samt Markup, för den metoden har GatsbyJS samt Contentful använts. Utvärdering sker både genom användartester och hur metoderna upplevs ur ett utvecklarperspektiv. I arbetet ingår även arbete med kunder till företaget projektet utförts hos, för deras webbplatser har Wordpress använts.

Este trabalho teve por objetivo avaliar a aplicação de diversas tecnologias de células a combustível tipo PEMFC desenvolvidas no IPEN para obtenção de um módulo de potência de 500 We. Foram estudados o aumento de escala na produção de MEAs de 25 cm2 para 144 cm2 pelo método de impressão a tela; a simulação por fluidodinâmica computacional de canais de fluxo de gases em placas bipolares utilizando o programa COMSOL e; o estudo de desempenho de eletrodos Pt/C desenvolvidos pelo método de redução por álcool, em células individuais de 144 cm2. Assim, desenvolveu-se um módulo de 500 We de potência nominal, produzido com tecnologia nacional, e com apoio da indústria para possíveis aplicações comerciais. A indústria nacional contribuiu com o hardware do módulo e os sistemas de vedação e refrigeração. Foi realizado um teste de 100 horas em célula unitária de 144 cm2 para observação do comportamento do MEA fabricado pelo processo de impressão à tela, bem como das outras tecnologias descritas, e a célula mostrou-se estável neste intervalo de tempo. O módulo desenvolvido com tecnologia nacional apresentou a potência máxima de 574 We à corrente de 100 A (694,4 mA cm-2). A potência de operação de 500 We foi obtida à corrente de 77,7 A (540,1 mA cm-2) ao potencial de 6,43 V, com uma eficiência de 43,3%. Em termos de cogeração, a potência térmica ou calor gerado pelo módulo foi de 652 Wt. Deste modo, foram consolidados os experimentos em P&D realizados no IPEN em células a combustível, para produção de potência elétrica. Uma estimativa inicial de custo para o módulo de 500 We estudado foi de R$ 4.500,00, baseando-se apenas nos materiais empregados em sua construção. / This work is part of a research project on PEMFC technologies carried out in IPEN to develop and optimize a 500 We fuel cell stack. The MEAs scaling up from 25 cm2 to 144 cm2 produced by the method of sieve printing; computational fluid dynamics by computer simulation of gas flow channels in bipolar plates using COMSOL® program and the use of Pt/C electrodes developed by alcohol reduction method in single cells were used to build a stack of 500 We nominal power for possible commercial applications, produced with national technology and industrial support. A 100 hours fuel cell´s test was carried out in a 144 cm2 single cell to study the stability of the MEA fabricated by sieve printing method. This single cell showed good stability within this period of time. The developed stack has reached the maximum power of 574 We at 100 A (694.4 mA cm-2). The operating power of 500 We was obtained at 77.7 A (540.1 mA cm-2) and potential of 6.43 V, with efficiency of 43.3%. In terms of cogeneration, the thermal power or generated heat by the stack was 652 Wt. The initial estimated cost for the 500 We stack was about R$ 4,500.00, considering only the used materials for its construction.

Thermoacoustic devices are a group of systems that make use of the thermoacoustic effect to achieve an energy conversion between thermal and acoustic energy. The thermoacoustic effect occurs when a solid boundary is introduced into an acoustic field, and a non-zero net heat transportation takes place while the net mass transfer remains null. Thermoacoustic technologies are gaining an increasing research interest because of their potential applications for building alternative prime movers or heat pumps which do not use working fluids causing environmental damage and require very little maintenance due to their lack of moving part. However, the operation of this type of system is yet to be fully understood: fluid flow and heat transfer processes within the system components such as thermoacoustic stacks and heat exchangers still require a lot of attention. The performance of the system working with relatively low amplitude acoustic wave can be predicted by the linear thermoacoustic theory, which is already well developed. However, a high amplitude acoustic wave is usually required in order to achieve high power density or high power output. Unfortunately, the performance of such systems can be seriously degraded due to nonlinear effects, such as turbulence, minor loss or high proportion of harmonics. The lack of understanding of these effects impedes the design and construction of high efficiency systems. The work described in this thesis is focused on the study of flow phenomena taking place around parallel plate stack placed in a standing wave thermoacoustic resonator, by using advanced flow diagnostics techniques such as particle image velocimetry (PIV) and hot wire anemometry (HWA). In order to carry out the experimental study, a standing wave thermoacoustic device working at relatively low frequency of 13.1Hz was designed, commissioned and tested. The frequency response of this device was carefully investigated and compared with the analytical results using linear acoustic equations and a linear model of the loudspeaker. A further comparison with the analytical results obtained with the modelling tool DeltaEC (Design Environment for Low-amplitude Thermoacoustic Energy Conversion) was also presented. The resonator was driven from low to large pressure amplitudes with drive ratios up to 10%. A good agreement is obtained for small amplitudes, but the discrepancies become larger when the driving amplitude is increased. The analysis reveals that the large discrepancy at high amplitude can be attributed to minor losses. Following the above preliminary work, a more comprehensive study of the flow field around parallel-plate stacks was conducted by means of PIV and HWA. It was shown that the flow around the two studied parallel-plate stacks exhibits rather complicated flow features when the amplitude of the acoustic oscillation varies. Symmetrical and asymmetrical vortex shedding phenomena are observed and two distinct modes of generating 'vortex streets' are identified. It shown that a velocity related parameter such as the Reynolds number, defined on the plate thickness and the velocity amplitude at the entrance to the stack, and a geometrical parameter are not sufficient to define the flow characteristics in this type of flow problem. It is also proposed to introduce an extra frequency related parameter such as the Keulegan-Carpenter number (KC) and to carry out a similarity analysis in order to understand better the physics behind the flow phenomena and their controlling parameters. Typical ensemble-averaged velocity fields are used in the analysis above. However, the detailed flow features obtained from the ensemble averaged flow fields and the instantaneous flow fields could be different in a substantial way. The flow behaviour, its kinematics, dynamics and scales of turbulence, therefore are further investigated by using the classical Reynolds decomposition to separate the instantaneous velocity fields into ensemble-averaged mean velocity fields and fluctuations in a set of predetermined phases within an oscillation cycle. The mean velocity field and the fluctuation intensity distributions are investigated over the acoustic oscillation cycle. By using fast Fourier transform (FFT) spatial filtering techniques, the velocity fluctuation is further divided into large- and small-scale fluctuations, and their physical significance is discussed. The physics behind the flow phenomena are further studied by carrying out an analysis of the wake flow during the ejection part of the flow cycle, where either closed re-circulating vortices or alternating vortex shedding can be observed. A similarity analysis of the governing Navier-Stokes equations is then undertaken in order to derive the similarity criteria governing the wake flow behaviour. Similarity numbers including two types of Reynolds number, the KC number and a non-dimensional stack configuration parameter are considered. The influence of these parameters on the flow behaviour is discussed by investigating the experimental data obtained, along with additional data from literature.

Software is still being produced and used that is vulnerable to exploitation. As well as being in devices in the homes of many people around the world, programs with these vulnerabilities are maintaining life-critical systems such as power-stations, aircraft and medical devices and are managing the creation and distribution of billions of pounds every year. These systems are actively being exploited by governments, criminals and opportunists and have led to loss of life and a loss of wealth. This dependence on software that is vulnerable to exploitation has led to a society with tangible concerns over cyber-crime, cyber-terrorism and cyber-warfare. As well as attempts to eliminate these vulnerabilities, techniques have been developed to mitigate their effects; these prophylactic techniques do not eliminate the vulnerabilities but make them harder to exploit. As software exploitation is an ever evolving battle between the attackers and the defenders, identifying methods to bypass these mitigations has become a new battlefield in this struggle and the techniques that are used to do this require vulnerabilities of their own. As many of the mitigation techniques are dependent upon secrecy of one form or another, vulnerabilities which allow an attacker to view those secrets are now of importance to attackers and defenders. Leaking of the contents of computer memory has always been considered a vulnerability, but until recently it has not typically been considered a serious one. As this can be used to bypass key mitigation techniques, these vulnerabilities are now considered critical to preventing whole classes of software exploitation. This thesis is about detecting these types of leaks and the information they disclose. It discusses the importance of these disclosures, both currently and in the future. It then introduces the first published technique to be able to reliably identify specific classes of these leaks, particularly address disclosures and canary-disclosures. The technique is tested against a series of applications, across multiple operating systems, using both artificial examples and software that is critical, commonplace and complex.

Master of Science / Department of Computing and Information Sciences / William Hsu / The Lambda Architecture is the new paradigm for big data, that helps in data processing with a balance on throughput, latency and fault-tolerance. There exists no single tool that provides a complete solution in terms of better accuracy, low latency and high throughput. This initiated the idea to use a set of tools and techniques to build a complete big data system. The Lambda Architecture defines a set of layers to fit in a set of tools and techniques rightly for building a complete big data system: Speed Layer, Serving Layer, Batch Layer. Each layer satisfies a set of properties and builds upon the functionality provided by the layers beneath it. The Batch layer is the place where the master dataset is stored, which is an immutable and append-only set of raw data. Also, batch layer pre-computes results using a distributed processing system like Hadoop, Apache Spark that can handle large quantities of data. The Speed Layer captures new data coming in real time and processes it. The Serving Layer contains a parallel processing query engine, which takes results from both Batch and Speed layers and responds to queries in real time with low latency. Stack Overflow is a Question & Answer forum with a huge user community, millions of posts with a rapid growth over the years. This project demonstrates The Lambda Architecture by constructing a data pipeline, to add a new “Recommended Questions” section in Stack Overflow user profile and update the questions suggested in real time. Also, various statistics such as trending tags, user performance numbers such as UpVotes, DownVotes are shown in user dashboard by querying through batch processing layer.

Det finns idag fortfarande komponenter i det globala mobilnätet som använder teknologi som utvecklades på 70-talet. Nyare, säkrare system har införts i flera länder, men även dessa behåller sin förmåga att kommunicera med de mer sårbara äldre systemen och delar därmed deras säkerhetsproblem. Det är speciellt protokollstacken SS7, grunden till 2G som har stora säkerhetsbrister. Syftet med denna uppsats är primärt att designa samt implementera en Elastic Stack pipeline och avgöra vad för information som kan erhållas vid användandet av denna pipeline på SS7-signaleringstrafik från ett faktiskt mobilnätssystem. Ur detta formulerades även ett antal delsyften. En pipeline implementerades och testades ihop med flera olika format på inläst data. Det gjordes fyra experiment där olika funktionaliteter testades med hjälp av utvalda dataset vars syfte var att agera substitut till den sekretessbelagda faktiska mobilnätsdatan. Elastic Stack är enligt vår uppfattning ett lovande verktyg för att övervaka och analysera SS7-signaleringstrafik, men det finns ett antal hinder som bara delvis beror på att mjukvaran är under utveckling. Dessa går dock till större del att kringgå. / There are currently components of the global mobile network that use technology developed in the 1970s. Newer, more secure systems have been introduced in several countries, but even these retain their ability to communicate with the more vulnerable older systems, and thus share their security issues. The purpose of this thesis is primarily to design and implement an Elastic Stack pipeline and determine what information can be attained through the use of this pipeline on SS7 signalling traffic from an actual mobile network system. To accomplish this, a series of sub-purposes also emerged. A pipeline was implemented and tested with several different formats of data. A series of four experiments were performed where different functionalities were tested with the help of selected data sets whose purpose was to act as substitutes for the classified actual mobile network data. Elastic Stack is, in our opinion, a promising tool for monitoring and analyzing SS7 signalling traffic, but there are a number of issues that can only partially be attributed to the software being still in development. They are however largely circumventable.

Data Logging is the main activity to be considered in maintaining a server or database in working condition without any errors or failures. Data collection can be automatic, so, no human presence is necessary. To store the data of logs for many days and visualizing became a huge problem in recent days. Coming to node SGSN-MME, which is the main component of the GPRS network, which handles all packet switched data within the mobile operator's network. A lot of log data is generated and stored in file systems on the redundant File Server Boards in SGSN-MME node. The evolution of the SGSN-MME is taking it from dedicated, purpose-built, hardware into virtual machines in the Cloud, where virtual file server boards fit very badly. The purpose of this thesis is to give a better way to store the log data and add visualization using the ELK stack concept. Fetching useful information from logs is one of the most important part of this stack and is being done in Logstash using its grok filters and a set of input, filter and output plug-ins which helps to scale this functionality for taking various kinds of inputs ( file,TCP, UDP, gemfire, stdin, UNIX, web sockets and even IRC and twitter and many more) , filter them using (groks,grep,date filters etc.)and finally write output to ElasticSearch. The Research Methodology involved in carrying out this thesis work is a Qualitative approach. A study is carried using the ELK concept with respect to Legacy approach in Ericsson company. A suitable approach and the better possible solution is given to the vSGSN-MME node to store the log data. Also to provide the performance and uses multiple users of input providers and provides the analysis of the graphs from the results and analysis. To perform the tests accurately, readings are taken in defined failure scenarios. From the test cases, a plot is provided on the CPU load in vSGSN-MME which easily gives the suitable and best promising way.