40 resultados para Sistemas de comunicación de banda ancha -- Aspectos ecnómicos
em Universidade Federal do Rio Grande do Norte(UFRN)
Resumo:
The World has tried diverse democratic waves at distinct moments. Some nations have adopted the idea of the democracy for years; others have not yet and other ones are still in a slow process of transition. The field of studies on the Arabian political systems has testified since the last quarter of 20th century a notorious development. This advance disclosed in the existence of a set of trends that has turned around a number of concepts and main theoretical frames such as the political pluralism and the democratic transition and the civil society and its relation with the State. The speech on the process of democratic transition consists in part in the capture and the analysis of the role of the forces and the organizations of the civil society in this process. The peculiarities of the Arab World excite questions concerning the establishment of one governmental system in this universe in the mold of that one that develops with hegemony in the Occident, which has become an interesting field of inquiries for the Political Science. This study comprises the analysis of some aspects of the political situation in the Arab World towards the process of democratization in which Egypt and Lebanon are models of study. Thus the theoretical basis of the term democracy is introduced, presenting different considerations about this expression, since the sprouting of the term until its current conception; later the civil society is analyzed as well as the systems of the political parties and the electoral systems of both countries in attempt to identify the level of democratization existing there and also to find the possible ways to magnify the democratic horizons
Resumo:
This work presents a theoretical and experimental investigation about the properties of microstrip antennas for ultra-wideband systems. Configurations of elliptic monopoles with different eccentricities and circular monopoles are considered. Two prototypes for each antenna configuration were built, one with the typical microstrip configuration and the other is similar to the first, except for a small aperture in the ground plane. Therefore, this work proposes to modify the configuration of the ground plane of the monopoles designed adding a rectangular stub, in order to optimize and improve the performance of such structures. The obtained results show that the introduction of that rectangular aperture in the ground plane allows an improvement of the frequency response for the considered antenna propotypes. It is observed a good agreement between the measured and simulated results. Finally, some proposals for future works are presented
Resumo:
This work proposes a model based approach for pointcut management in the presence of evolution in aspect oriented systems. The proposed approach, called conceptual visions based pointcuts, is motivated by the observation of the shortcomings in traditional approaches pointcuts definition, which generally refer directly to software structure and/or behavior, thereby creating a strong coupling between pointcut definition and the base code. This coupling causes the problem known as pointcut fragility problem and hinders the evolution of aspect-oriented systems. This problem occurs when all the pointcuts of each aspect should be reviewed due to any software changes/evolution, to ensure that they remain valid even after the changes made in the software. Our approach is focused on the pointcuts definition based on a conceptual model, which has definitions of the system's structure in a more abstract level. The conceptual model consists of classifications (called conceptual views) on entities of the business model elements based on common characteristics, and relationships between these views. Thus the pointcuts definitions are created based on the conceptual model rather than directly referencing the base model. Moreover, the conceptual model contains a set of relationships that allows it to be automatically verified if the classifications in the conceptual model remain valid even after a software change. To this end, all the development using the conceptual views based pointcuts approach is supported by a conceptual framework called CrossMDA2 and a development process based on MDA, both also proposed in this work. As proof of concept, we present two versions of a case study, setting up a scenario of evolution that shows how the use of conceptual visions based pointcuts helps detecting and minimizing the pointcuts fragility. For the proposal evaluation the Goal/Question/Metric (GQM) technique is used together with metrics for efficiency analysis in the pointcuts definition
Resumo:
New programming language paradigms have commonly been tested and eventually incorporated into hardware description languages. Recently, aspect-oriented programming (AOP) has shown successful in improving the modularity of object-oriented and structured languages such Java, C++ and C. Thus, one can expect that, using AOP, one can improve the understanding of the hardware systems under design, as well as make its components more reusable and easier to maintain. We apply AOP in applications developed using the SystemC library. Several examples will be presented illustrating how to combine AOP and SystemC. During the presentation of these examples, the benefits of this new approach will also be discussed
Resumo:
Nowadays, there are many aspect-oriented middleware implementations that take advantage of the modularity provided by the aspect oriented paradigm. Although the works always present an assessment of the middleware according to some quality attribute, there is not a specific set of metrics to assess them in a comprehensive way, following various quality attributes. This work aims to propose a suite of metrics for the assessment of aspect-oriented middleware systems at different development stages: design, refactoring, implementation and runtime. The work presents the metrics and how they are applied at each development stage. The suite is composed of metrics associated to static properties (modularity, maintainability, reusability, exibility, complexity, stability, and size) and dynamic properties (performance and memory consumption). Such metrics are based on existing assessment approaches of object-oriented and aspect-oriented systems. The proposed metrics are used in the context of OiL (Orb in Lua), a middleware based on CORBA and implemented in Lua, and AO-OiL, the refactoring of OIL that follows a reference architecture for aspect-oriented middleware systems. The case study performed in OiL and AO-OiL is a system for monitoring of oil wells. This work also presents the CoMeTA-Lua tool to automate the collection of coupling and size metrics in Lua source code
Resumo:
CARVALHO, Andréa Vasconcelos ; ESTEBAN NAVARRO, Miguel Ángel. . Auditoria de Inteligência: um método para o diagnóstico de sistemas de inteligência competitiva e organizacional. In: XI ENANCIB - Encontro Nacional de Pesquisa em Ciência da Informação, 2010, Rio de Janeiro. Anais do XI ENANCIB. Rio de Janeiro: ANCIB, 2010.
Resumo:
The information technology - IT- benefits have been more perceived during the last decades. Both IT and business managers are dealing with subjects like governance, IT-Business alignment, information security and others on their top priorities. Talking about governance, specifically, managers are facing it with a technical approach, that gives emphasis on protection against invasions, antivirus systems, access controls and others technical issues. The IT risk management, commonly, is faced under this approach, that means, has its importance reduced and delegated to IT Departments. On the last two decades, a new IT risk management perspective raised, bringing an holistic view of IT risk to the organization. According to this new perspective, the strategies formulation process should take into account the IT risks. With the growing of IT dependence on most of organizations, the necessity of a better comprehension about the subject becomes more clear. This work shows a study in three public organizations of the Pernambuco State that investigates how those organizations manage their IT risks. Structured interviews were made with IT managers, and later, analyzed and compared with conceptual categories found in the literature. The results shows that the IT risks culture and IT governance are weakly understood and implemented on those organizations, where there are not such an IT risk methodology formally defined, neither executed. In addition, most of practices suggested in the literature were found, even without an alignment with an IT risks management process
Resumo:
This work aimed to develop a suitable magnetic system for administration by the oral route. In addition to that, it was intended to review the current uses of magnetic systems and the safety related to magnetic field exposure. Methods: Coprecipitation and emulsification/crosslinking were carried out in order to synthesize magnetite particles and to coat them, respectively. Results: According to literature review, it was found that magnetic particles present several properties such as magnetophoresis in magnetic field gradient, production of a surrounding magnetic field, and heat generation in alternated magnetic field. When the human organism is exposed to magnetic fields, several interaction mechanisms come into play. However, biological tissues present low magnetic susceptibility. As a result, the effects are not so remarkable. Concerning the development of a magnetic system for oral route, uncoated magnetite particles did undergo significant dissolution at gastric pH. On the other hand, such process was inhibited in the xylan-coated particles. Conclusions: Due to their different properties, magnetic systems have been widely used in biosciences. However, the consequent increased human exposure to magnetic fields has been considered relatively safe. Concerning the experimental work, it was developed a polymer-coated magnetic system. It may be very promising for administration by the oral route for therapy and diagnostic applications as dissolution at gastric pH hardly took place
Resumo:
The main purpose of this work was the development of ceramic dielectric substrates of bismuth niobate (BiNbO4) doped with vanadium pentoxide (V2O5), with high permittivity, used in the construction of microstrip patch antennas with applications in wireless communications systems. The high electrical permittivity of the ceramic substrate provided a reduction of the antenna dimensions. The numerical results obtained in the simulations and the measurements performed with the microstrip patch antennas showed good agreement. These antennas can be used in wireless communication systems in various frequency bands. Results were satisfactory for antennas operating at frequencies in the S band, in the range between 2.5 GHz and 3.0 GHz.
Resumo:
The characteristic properties of the fractal geometry have shown to be very useful for the construction of filters, frequency selective surfaces, synchronized circuits and antennas, enabling optimized solutions in many different commercial uses at microwaves frequency band. The fractal geometry is included in the technology of the microwave communication systems due to some interesting properties to the fabrication of compact devices, with higher performance in terms of bandwidth, as well as multiband behavior. This work describes the design, fabrication and measurement procedures for the Koch quasi-fractal monopoles, with 1 and 2 iteration levels, in order to investigate the bandwidth behavior of planar antennas, from the use of quasi-fractal elements printed on their rectangular patches. The electromagnetic effect produced by the variation of the fractal iterations and the miniaturization of the structures is analyzed. Moreover, a parametric study is performed to verify the bandwidth behavior, not only at the return loss but also in terms of SWR. Experimental results were obtained through the accomplishment of measurements with the aid of a vetorial network analyzer and compared to simulations performed using the Ansoft HFSS software. Finally, some proposals for future works are presented
Resumo:
Ceramic substrates have been investigated by researchers around the world and has achieved a high interest in the scientific community, because they had high dielectric constants and excellent performance in the structures employed. Such ceramics result in miniaturized structures with dimensions well reduced and high radiation efficiency. In this work, we have used a new ceramic material called lead zinc titanate in the form of Zn0,8Pb0,2TiO3, capable of being used as a dielectric substrate in the construction of various structures of antennas. The method used in constructing the ceramic combustion synthesis was Self- Sustained High Temperature (SHS - "Self-Propagating High-Temperature Synthesis") which is defined as a process that uses highly exothermic reactions to produce various materials. Once initiated the reaction area in the reaction mixture, the heat generated is sufficient to become self-sustaining combustion in the form of a wave that propagates converting the reaction mixture into the product of interest. Were analyzed aspects of the formation of the composite Zn0,8Pb0,2TiO3 by SHS powders and characterized. The analysis consisted of determining the parameters of the reaction for the formation of the composite, as the ignition temperature and reaction mechanisms. The production of composite Zn0,8Pb0,2TiO3 by SHS performed in the laboratory, was the result of a total control of combustion temperature and after obtaining the powder began the development of ceramics. The product was obtained in the form of regular, alternating layers of porous ceramics and was obtained by uniaxial pressing. 10 The product was characterized by analysis of dilatometry, X-ray diffraction analysis and scanning electron microscopy. One of the contributions typically defined in this work is the development of a new dielectric material, nevertheless presented previously in the literature. Therefore, the structures of the antennas presented in this work consisted of new dielectric ceramics based Zn0,8Pb0,2TiO3 usually used as dielectric substrate. The materials produced were characterized in the microwave range. These are dielectrics with high relative permittivity and low loss tangent. The Ansoft HFSS, commercial program employee, using the finite element method, and was used for analysis of antennas studied in this work
Resumo:
The lava Platform is increasing1y being adopted in the development of distributed sys¬tems with higb user demando This kind of application is more complex because it needs beyond attending the functional requirements, to fulfil1 the pre-established performance parameters. This work makes a study on the Java Vutual Machine (JVM), approaching its intemal aspects and exploring the garbage collection strategies existing in the literature and used by the NM. It also presents a set of tools that helps in the job of optimizing applications and others that help in the monitoring of applications in the production envi¬ronment. Doe to the great amount of technologies that aim to solve problems which are common to the application layer, it becomes difficult to choose the one with best time response and less memory usage. This work presents a brief introduction to each one of tbe possible technologies and realize comparative tests through a statistical analysis of the response time and garbage collection activity random variables. The obtained results supply engineers and managers with a subside to decide which technologies to use in large applications through the knowledge of how they behave in their environments and the amount of resources that they consume. The relation between the productivity of the technology and its performance is also considered ao important factor in this choice
Resumo:
This master dissertation introduces a study about some aspects that determine the aplication of adaptative arrays in DS-CDMA cellular systems. Some basics concepts and your evolution in the time about celular systems was detailed here, meanly the CDMA tecnique, specialy about spread-codes and funtionaly principies. Since this, the mobile radio enviroment, with your own caracteristcs, and the basics concepts about adaptive arrays, as powerfull spacial filter was aborded. Some adaptative algorithms was introduced too, these are integrants of the signals processing, and are answerable for weights update that influency directly in the radiation pattern of array. This study is based in a numerical analysis of adaptative array system behaviors related to the used antenna and array geometry types. All the simulations was done by Mathematica 4.0 software. The results for weights convergency, square mean error, gain, array pattern and supression capacity based the analisis made here, using RLS (supervisioned) and LSDRMTA (blind) algorithms
Resumo:
ln this work, planar quasi- Y agi antennas are investigated based on the concept of the classic Y agi_Uda antennas. These antennas represent improvements on the topologies of the antennas existing printed because they present characteristics of broad bandwidth, excellent radiation diagrams and simple construction. New configurations are adapted for the driver of the antennas, introducing patches elements into the driver. These new configurations are named Patches Elements Anteonas (PEA). This adaptation is obtained from simulations that are executed usiog the software C8T Microwave 8tudio 5. After doing the optimizations, procedures for construction and measurement ofthe prototypes are executed in order to improve the performance of the antennas in such way that they could be used in wireless communication applications, such as Bluetooth, WLAN' s and Wi-Fi. Next, the quasi- Y agi antennas are studied in order to implement them in arrangements. The arrangements construction is based 00 the best driver configuration of the antenna developed in this work. First, a linear arrangement composed by two elements of quasi¬Yagi antennas is constructed in such way that the radiation characteristics and the mutual coupling effects could be analyzed. After that, a 90° angle arrangement composed by two elements is studied to observe the effect of circular polarization. Experiments are executed in order to evaluate the arrangements performance. The experimental results show that the analysis made in this work is efficient and accurate. The numerical values obtained for the analyzed parameters of each structure developed are compared with the experimental values. 80, it is possible to observe a good concordance between them. Finally, some future works proposals are presented
Resumo:
This work aims to present how the reconfigurable microstrip antennas and frequency selective surfaces can be used to operate at communication systems that require changing their operation frequency according to system requirements or environmental conditions. The main purpose is to present a reconfigurable circular microstrip antenna using a parasitic ring and a reconfigurable dipole frequency selective surface. Thereupon there are shown fundamental topics like microstrip antennas, PIN diodes and the fundamental theory of reconfigurable antennas and frequency selective surfaces. There are shown the simulations and measurements of the fabricated prototypes and it is done an analysis of some parameters like the bandwidth and radiation pattern, for the antennas, and the transmission characteristics, for the frequency selective surface. Copper strips were used in place of the diodes for proof of the reconfigurability concept