On UML statechart with variabilities

El uso de métodos formales para el diseño de software contribuye a la confiabilidad y robustez del sistema a construir. A medida que los sistemas se vuelven complejos, el enfoque formal es esencial, debido a que permite la demostrabilidad y verificabilidad del diseño. El diseño formal es un proceso que comienza con la etapa de especificación, en la cual el sistema es de nido utilizando un lenguaje de modelado; luego la etapa de verificación, en la cual el sistema es analizado mediante un enfoque de corrección basado en pruebas formales utilizando herramientas matemá ticas y, por último, la etapa de implementación, en la cual la especificación se convierte en código ejecutable. El Lenguaje de Modelado Unificado (UML por sus siglas en inglés) es un lenguaje específico ampliamente utilizado en la industria y la academia. Desafortunadamente, carece de una semántica formal que permita el desarrollo de modelos utilizando un enfoque de corrección basado en pruebas formales. Este trabajo se centra en la especificación formal de familias de sistemas, y, en particular, en la semán- tica de máquinas de estados de UML (UML Statecharts) con variabilidades y sus aplicaciones a líneas de productos de software. La principal contribución es la definición de un formalismo que permite modelar el comportamiento de una familia de sistemas. Tal comportamiento se describe utilizando UML Statecharts en combinación con Diagramas de funcionalidades (Feature Diagrams), con el fin de representar las funcionalidades comunes y variantes de una familia. Para ello se define una relación de orden entre los UML Statecharts, que representa el hecho de que un statechart posee una estructura mas rica que otro. Luego se defi ne con precisión la forma de combinar diferentes extensiones de un mismo statechart. Utilizando estos conceptos, es posible definir el efecto que cada funcionalidad tiene en los productos en los cuales se encuentra presente.Estas definiciones proporcionan una forma muy simple de obtener la especificación del comportamiento de un producto de la línea como la combinación de los UML Statecharts que implementan todas las funcionalidades presentes en un producto en particular. Mas aún, se prueba que la relación de extensión propuesta constituye un refinamiento de comportamiento. El presente enfoque se compara con el estado del arte y se estudia su aplicación práctica con el n de visualizar sus bene cios y posibles debilidades. Adicionalmente, con el fin de comprobar la adecuación de la propuesta, una gran parte de las ideas fueron implementadas en un prototipo utilizando Prolog

The telecommunications and data acquisition report

Developments in Earth based radio technology with applications to space communications, geodynamics, and astrophysics are reported

Journal of Telecommunications and Information Technology, 2003, nr 1

kwartalni

Numerical and experimental modelling of microwave applicators

This thesis presents a time domain finite element method for the solution of microwave heating problems. This is the first time that this particular technique has been applied to microwave heating. It is found that the standard frequency domain finite element method is unsuitable for analysing multimode applicators containing food-like materials due to a severe ill-conditioning of the matrix equations. The field distribution in multimode applicators loaded with low loss materials is found to be very sensitive to small frequency changes. Several solutions at different frequencies are therefore required to characterise the behaviour of the loaded applicator. The time domain finite element method is capable of producing multiple solutions at different frequencies when used with Gaussian pulse excitation; it is therefore ideally suited to the analysis of multimode applicators. A brief survey of the methods available for the solution of the linear equations is provided. The performance of these techniques with both the frequency domain and time domain finite element methods is then studied. Single mode applicators are also analysed and it is found that the frequency domain method is superior in these cases. Comparisons are given between the calculated results and experimental data for both single mode and multimode systems. The importance of experimental verification being stressed. The choice of element type is an important consideration for the finite element method. Three basic types of element are considered; nodal, Whitney edge elements and linear edge elements. Comparisons of the errors with these elements show that Whitney elements produce a consistently lower error when post-processing is used to smooth the solution. The coupled thermal-electromagnetic problem is investigated with many difficulties being identified for the application to multimode cavity problems

Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified

Interference Mitigation in Wireless Communications

The primary objective of this thesis is to design advanced interference resilient schemes for asynchronous slow frequency hopping wireless personal area networks (FH-WPAN) and time division multiple access (TDMA) cellular systems in interference dominant environments. We also propose an interference-resilient power allocation method for multiple-input-multiple-output (MIMO) systems. For asynchronous FH-WPANs in the presence of frequent packet collisions, we propose a single antenna interference canceling dual decision feedback (IC-DDF) receiver based on joint maximum likelihood (ML) detection and recursive least squares (RLS) channel estimation. For the system level performance evaluation, we propose a novel geometric method that combines bit error rate (BER) and the spatial distribution of the traffic load of CCI for the computation of packet error rate (PER). We also derived the probabilities of packet collision in multiple asynchronous FH-WPANs with uniform and nonuniform traffic patterns. For the design of TDMA receivers resilient to CCI in frequency selective channels, we propose a soft output joint detection interference rejection combining delayed decision feedback sequence estimation (JD IRC-DDFSE) scheme. In the proposed scheme, IRC suppresses the CCI, while DDFSE equalizes ISI with reduced complexity. Also, the soft outputs are generated from IRC-DDFSE decision metric to improve the performance of iterative or non-iterative type soft-input outer code decoders. For the design of interference resilient power allocation scheme in MIMO systems, we investigate an adaptive power allocation method using subset antenna transmission (SAT) techniques. Motivated by the observation of capacity imbalance among the multiple parallel sub-channels, the SAT method achieves high spectral efficiency by allocating power on a selected transmit antenna subset. For 4 x 4 V-BLAST MIMO systems, the proposed scheme with SAT showed analogous results. Adaptive modulation schemes combined with the proposed method increase the capacity gains. From a feasibility viewpoint, the proposed method is a practical solution to CCI-limited MIMO systems since it does not require the channel state information (CSI) of CCI.Ph.D.Committee Chair: Professor Gordon L. StBe

Comparação do desempenho de arquiteturas híbridas para comunicações na banda das ondas milimétricas

Mestrado em Engenharia Electrónica e TelecomunicaçõesA proliferação massiva das comunicações sem os faz prever que o número de utilizadores aumente exponencialmente até 2020, o que tornar a necessário um suporte de tráfego milhares de vezes superior e com ligações na ordem dos Gigabit por segundo. Este incremento exigir a um aumento significativo da e ciência espectral e energética. Impõe-se portanto, uma mudança de paradigma dos sistemas de comunicação sem os convencionais, imposta pela introdução da 5a geração. Para o efeito, e necessário desenvolver novas e promissoras técnicas de transmissão, nomeadamente a utilização de ondas milimétricas em sistemas com um número massivo de antenas. No entanto, consideráveis desafios emergem ao adotar estas técnicas. Por um lado, este tipo de ondas sofre grandes dificuldades em termos de propagação. Por outro lado, a adoção de arquiteturas convencionais para sistemas com um número massivo de antenas e absolutamente inviável, devido ao custo e ao nível de complexidade inerentes. Isto acontece porque o processamento de sinal ao nível da camada f sica e maioritariamente feito em banda base, ou seja, no domínio digital requerendo uma cadeia RF por cada antena. Neste contexto as arquiteturas híbridas são uma proposta relativamente recente que visa simplificar a utilização de um grande número de antenas, dividindo o processamento entre os domínios analógico e digital. Para além disso, o número de cadeias RF necessárias e bastante inferior ao número total de antenas do sistema, contribuindo para obvias melhorias em termos de complexidade, custo e energia consumida. Nesta dissertação e implementada uma arquitetura híbrida para ondas milimétricas, onde cada cadeia RF está apenas conectada a um pequeno conjunto de antenas. E considerado um sistema contendo um transmissor e um recetor ambos equipados com um grande número de antenas e onde, o número de cadeias RF e bastante inferior ao número total de antenas. Pré-codificadores híbridos analógico/digital, recentemente propostos na literatura são utilizados e novos equalizadores híbridos analógico/digital são projetados. E feita uma avaliação de performance à arquitetura implementada e posteriormente comparada com uma outra arquitetura, onde todas as antenas estão conectadas a todas as cadeias RF.The expected massive proliferation of wireless systems points out an exponential increase in the number of users until 2020, which is needed to support up to one thousand times more tra c and connections in order of Gigabit per second. However, these goals require a signi cantly improvement in the spectral and energy e ciency. As a result, it is essential to make a paradigm shift in conventional wireless systems, imposed by the introduction of fth generation (5G). For this purpose, new and promising transmission techniques will be needed, namely the use of millimeter Waves (mmWave) in systems with a massive number of antenna elements. Nevertheless, considerable challenges emerge in the adoption of these techniques. On one hand, mmWave su er great di culties in terms of propagation. On the other hand, the using of conventional architectures for systems with a large number of antennas is absolutely impracticable because of the costs and the level of complexity. This happens because the signal processing in physical layer is mostly done in baseband, which means, that one RF chain for each antenna is required. In this context the hybrid architectures are a relatively recent proposal where the aim is to simplify the use of a large number of antenna elements, dividing the processing between the analog and digital domains. Moreover, the number of RF chains needed are much lower than the total number of antenna elements of the system, which contribute to obvious improvements in terms of complexity, costs and energy consumption. In this Dissertation a hybrid mmWave based architecture, where each RF chain is only connected to a small set of antennas, is implemented. It is considered a system comprising a transmitter and a receiver both equipped with a massive number of antennas and where the number of RF chains is much lower than the number of antennas. Hybrid analog/digital precoders recently proposed in the literature are used and a new hybrid analog/digital equalizer is designed. The implemented architecture is then evaluated and compared with other architecture, where all the antennas are connected to all RF chains

Systematic Data Extraction in High-Frequency Electromagnetic Fields

The focus of this work is on the investigation of billiards with its statistical eigenvalue properties. Specifically, superconducting microwave resonators with chaotic characteristics are simulated and the eigenfrequencies that are needed for the statistical analysis are computed. The eigenfrequency analysis requires many (in order of thousands) eigenfrequencies to be calculated and the accurate determination of the eigenfrequencies has a crucial significance. Consequently, the research interests cover all aspects from accurate numerical calculation of many eigenvalues and eigenvectors up to application development in order to get good performance out of the programs for distributed-memory and shared-memory multiprocessors. Furthermore, this thesis provides an overview and detailed evaluation of the used numerical approaches for large-scale eigenvalue calculations with respect to the accuracy, the computational time, and the memory consumption. The first approach for an accurate eigenfrequency extraction takes into consideration the evaluated electric field computations in Time Domain (TD) of a superconducting resonant structure. Upon excitation of the cavity, the electric field intensity is recorded at different detection probes inside the cavity. Thereafter, Fourier analysis of the recorded signals is performed and by means of signal-processing and fitting techniques, the requested eigenfrequencies are extracted by finding the optimal model parameters in the least squares sense. The second numerical approach is based on a numerical computation of electromagnetic fields in Frequency Domain (FD) and further employs the Lanczos method for the eigenvalue determination. Namely, when utilizing the Finite Integration Technique (FIT) to solve an electromagnetic problem for a superconducting cavity, which enclosures excited electromagnetic fields, the numerical solution of a standard large-scale eigenvalue problem is considered. Accordingly, if the numerical solution of the same problem is treated by the Finite Element Method (FEM) based on curvilinear tetrahedrons, it yields to the generalized large-scale eigenvalue problem. Afterward, the desired eigenvalues are calculated with the direct solution of the large (generalized) eigenvalue formulations. For this purpose, the implemented Lanczos solvers combine two major ingredients: the Lanczos algorithm with polynomial filtering on the one hand and its parallelization on the other

Processing experiments on non-Czochralski silicon sheet

A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation

NASA Thesaurus. Volume 1: Hierarchical listing

There are 16,713 postable terms and 3,716 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary