879 resultados para digital systems
Resumo:
Intrusion Detection Systems (IDSs) provide an important layer of security for computer systems and networks, and are becoming more and more necessary as reliance on Internet services increases and systems with sensitive data are more commonly open to Internet access. An IDS’s responsibility is to detect suspicious or unacceptable system and network activity and to alert a systems administrator to this activity. The majority of IDSs use a set of signatures that define what suspicious traffic is, and Snort is one popular and actively developing open-source IDS that uses such a set of signatures known as Snort rules. Our aim is to identify a way in which Snort could be developed further by generalising rules to identify novel attacks. In particular, we attempted to relax and vary the conditions and parameters of current Snort rules, using a similar approach to classic rule learning operators such as generalisation and specialisation. We demonstrate the effectiveness of our approach through experiments with standard datasets and show that we are able to detect previously undetected variants of various attacks. We conclude by discussing the general effectiveness and appropriateness of generalisation in Snort based IDS rule processing. Keywords: anomaly detection, intrusion detection, Snort, Snort rules
Resumo:
Liquid crystals (LCs) have revolutionized the display and communication technologies. Doping of LCs with inorganic nanoparticles such as carbon nanotubes, gold nanoparticles and ferroelectric nanoparticles have garnered the interest of research community as they aid in improving the electro-optic performance. In this thesis, we examine a hybrid nanocomposite comprising of 5CB liquid crystal and block copolymer functionalized barium titanate ferroelectric nanoparticles. This hybrid system exhibits a giant soft-memory effect. Here, spontaneous polarization of ferroelectric nanoparticles couples synergistically with the radially aligned BCP chains to create nanoscopic domains that can be rotated electromechanically and locked in space even after the removal of the applied electric field. The resulting non-volatile memory is several times larger than the non-functionalized sample and provides an insight into the role of non-covalent polymer functionalization. We also present the latest results from the dielectric and spectroscopic study of field assisted alignment of gold nanorods.
Resumo:
Intrusion Detection Systems (IDSs) provide an important layer of security for computer systems and networks, and are becoming more and more necessary as reliance on Internet services increases and systems with sensitive data are more commonly open to Internet access. An IDS’s responsibility is to detect suspicious or unacceptable system and network activity and to alert a systems administrator to this activity. The majority of IDSs use a set of signatures that define what suspicious traffic is, and Snort is one popular and actively developing open-source IDS that uses such a set of signatures known as Snort rules. Our aim is to identify a way in which Snort could be developed further by generalising rules to identify novel attacks. In particular, we attempted to relax and vary the conditions and parameters of current Snort rules, using a similar approach to classic rule learning operators such as generalisation and specialisation. We demonstrate the effectiveness of our approach through experiments with standard datasets and show that we are able to detect previously undetected variants of various attacks. We conclude by discussing the general effectiveness and appropriateness of generalisation in Snort based IDS rule processing. Keywords: anomaly detection, intrusion detection, Snort, Snort rules
Resumo:
This work presents the modeling and FPGA implementation of digital TIADC mismatches compensation systems. The development of the whole work follows a top-down methodology. Following this methodology was developed a two channel TIADC behavior modeling and their respective offset, gain and clock skew mismatches on Simulink. In addition was developed digital mismatch compensation system behavior modeling. For clock skew mismatch compensation fractional delay filters were used, more specifically, the efficient Farrow struct. The definition of wich filter design methodology would be used, and wich Farrow structure, required the study of various design methods presented in literature. The digital compensation systems models were converted to VHDL, for FPGA implementation and validation. These system validation was carried out using the test methodology FPGA In Loop . The results obtained with TIADC mismatch compensators show the high performance gain provided by these structures. Beyond this result, these work illustrates the potential of design, implementation and FPGA test methodologies.
Resumo:
Analiza la producción editorial a la luz de los cambios propuestos por los avances de la tecnología de los sistemas de información y comunicación. Señala impactos de internet en la producción y difusión de contenidos en ambientes y organizaciones de enseñanza e investigación. Enfatiza la responsabilidad compartida de la bibliotecología y ciencias de la información con la industria editorial, en el proceso de transferencia de información y la creación de conocimiento.
Resumo:
Nitrous oxide (N2O) is a potent greenhouse gas; the majority of N2O emissions are the result of agricultural management, particularly the application of N fertilizers to soils. The relationship of N2O emissions to varying sources of N (manures, mineral fertilizers, and cover crops) has not been well-evaluated. Here we discussed a novel methodology for estimating precipitation-induced pulses of N2O using flux measurements; results indicated that short-term intensive time-series sampling methods can adequately describe the magnitude of these pulses. We also evaluated the annual N2O emissions from corn-cover crop (Zea mays; cereal rye [Secale cereale], hairy vetch [Vicia villosa], or biculture) production systems when fertilized with multiple rates of subsurface banded poultry litter, as compared with tillage incorporation or mineral fertilizer. N2O emissions increased exponentially with total N rate; tillage decreased emissions following cover crops with legume components, while the effect of mineral fertilizer was mixed across cover crops.
Resumo:
In energy harvesting communications, users transmit messages using energy harvested from nature. In such systems, transmission policies of the users need to be carefully designed according to the energy arrival profiles. When the energy management policies are optimized, the resulting performance of the system depends only on the energy arrival profiles. In this dissertation, we introduce and analyze the notion of energy cooperation in energy harvesting communications where users can share a portion of their harvested energy with the other users via wireless energy transfer. This energy cooperation enables us to control and optimize the energy arrivals at users to the extent possible. In the classical setting of cooperation, users help each other in the transmission of their data by exploiting the broadcast nature of wireless communications and the resulting overheard information. In contrast to the usual notion of cooperation, which is at the signal level, energy cooperation we introduce here is at the battery energy level. In a multi-user setting, energy may be abundant in one user in which case the loss incurred by transferring it to another user may be less than the gain it yields for the other user. It is this cooperation that we explore in this dissertation for several multi-user scenarios, where energy can be transferred from one user to another through a separate wireless energy transfer unit. We first consider the offline optimal energy management problem for several basic multi-user network structures with energy harvesting transmitters and one-way wireless energy transfer. In energy harvesting transmitters, energy arrivals in time impose energy causality constraints on the transmission policies of the users. In the presence of wireless energy transfer, energy causality constraints take a new form: energy can flow in time from the past to the future for each user, and from one user to the other at each time. This requires a careful joint management of energy flow in two separate dimensions, and different management policies are required depending on how users share the common wireless medium and interact over it. In this context, we analyze several basic multi-user energy harvesting network structures with wireless energy transfer. To capture the main trade-offs and insights that arise due to wireless energy transfer, we focus our attention on simple two- and three-user communication systems, such as the relay channel, multiple access channel and the two-way channel. Next, we focus on the delay minimization problem for networks. We consider a general network topology of energy harvesting and energy cooperating nodes. Each node harvests energy from nature and all nodes may share a portion of their harvested energies with neighboring nodes through energy cooperation. We consider the joint data routing and capacity assignment problem for this setting under fixed data and energy routing topologies. We determine the joint routing of energy and data in a general multi-user scenario with data and energy transfer. Next, we consider the cooperative energy harvesting diamond channel, where the source and two relays harvest energy from nature and the physical layer is modeled as a concatenation of a broadcast and a multiple access channel. Since the broadcast channel is degraded, one of the relays has the message of the other relay. Therefore, the multiple access channel is an extended multiple access channel with common data. We determine the optimum power and rate allocation policies of the users in order to maximize the end-to-end throughput of this system. Finally, we consider the two-user cooperative multiple access channel with energy harvesting users. The users cooperate at the physical layer (data cooperation) by establishing common messages through overheard signals and then cooperatively sending them. For this channel model, we investigate the effect of intermittent data arrivals to the users. We find the optimal offline transmit power and rate allocation policy that maximize the departure region. When the users can further cooperate at the battery level (energy cooperation), we find the jointly optimal offline transmit power and rate allocation policy together with the energy transfer policy that maximize the departure region.
Resumo:
Ante el vertiginoso crecimiento de la competencia en el campo motiva la creación de una metodología para la Gestión de proyectos teniendo en cuenta las buenas prácticas disponibles a nivel mundial. El uso de TIC’s representará la forma de afrontar a la competencia que actualmente las empresas enfrentan, gestión de procesos, administración de recursos, generar responsabilidades y compromisos en los procesos con los que se llevan a cabo los proyectos marcarán un cambio en el cumplimiento de metas y objetivos. Tomando en cuenta lo anterior y luego de una evaluación a los procesos con los que se manejan actualmente los proyectos, se definirá una metodología para gestionar los proyectos, una vez definidos los procesos que van a intervenir, se abordará el tema de buscar la herramienta idónea para la administración de los proyectos vía Web, manteniendo el control de los mismos, generando un beneficio en lo referente al uso de los recursos con los que dispone la empresa. Generar indicadores de Gestión dentro de la herramienta seleccionada será una ventaja que se deberá tomar en consideración al momento de escoger la plataforma Web para llevar a cabo el control oportuno en el avance de los procesos. El uso de las TIC’s conjugado con una metodología adecuada, fomentará el desarrollo de las compañías logrando así poder planificar la gestión de los recursos: Humanos, Financieros y materiales, con sus respectivos ahorros en tiempo y dinero.
Resumo:
New constraints on isotope fractionation factors in inorganic aqueous sulfur systems based on theoretical and experimental techniques relevant to studies of the sulfur cycle in modern environments and the geologic rock record are presented in this dissertation. These include theoretical estimations of equilibrium isotope fractionation factors utilizing quantum mechanical software and a water cluster model approach for aqueous sulfur compounds that span the entire range of oxidation state for sulfur. These theoretical calculations generally reproduce the available experimental determinations from the literature and provide new constraints where no others are available. These theoretical calculations illustrate in detail the relationship between sulfur bonding environment and the mass dependence associated with equilibrium isotope exchange reactions involving all four isotopes of sulfur. I additionally highlight the effect of isomers of protonated compounds (compounds with the same chemical formula but different structure, where protons are bound to either sulfur or oxygen atoms) on isotope partitioning in the sulfite (S4+) and sulfoxylate (S2+) systems, both of which are key intermediates in oxidation-reduction processes in the sulfur cycle. I demonstrate that isomers containing the highest degree of coordination around sulfur (where protonation occurs on the sulfur atom) have a strong influence on isotopic fractionation factors, and argue that isomerization phenomenon should be considered in models of the sulfur cycle. Additionally, experimental results of the reaction rates and isotope fractionations associated with the chemical oxidation of aqueous sulfide are presented. Sulfide oxidation is a major process in the global sulfur cycle due largely to the sulfide-producing activity of anaerobic microorganisms in organic-rich marine sediments. These experiments reveal relationships between isotope fractionations and reaction rate as a function of both temperature and trace metal (ferrous iron) catalysis that I interpret in the context of the complex mechanism of sulfide oxidation. I also demonstrate that sulfide oxidation is a process associated with a mass dependence that can be described as not conforming to the mass dependence typically associated with equilibrium isotope exchange. This observation has implications for the inclusion of oxidative processes in environmental- and global-scale models of the sulfur cycle based on the mass balance of all four isotopes of sulfur. The contents of this dissertation provide key reference information on isotopic fractionation factors in aqueous sulfur systems that will have far-reaching applicability to studies of the sulfur cycle in a wide variety of natural settings.
Resumo:
Tactile sensing is an important aspect of robotic systems, and enables safe, dexterous robot-environment interaction. The design and implementation of tactile sensors on robots has been a topic of research over the past 30 years, and current challenges include mechanically flexible “sensing skins”, high dynamic range (DR) sensing (i.e.: high force range and fine force resolution), multi-axis sensing, and integration between the sensors and robot. This dissertation focuses on addressing some of these challenges through a novel manufacturing process that incorporates conductive and dielectric elastomers in a reusable, multilength-scale mold, and new sensor designs for multi-axis sensing that improve force range without sacrificing resolution. A single taxel was integrated into a 1 degree of freedom robotic gripper for closed-loop slip detection. Manufacturing involved casting a composite silicone rubber, polydimethylsiloxane (PDMS) filled with conductive particles such as carbon nanotubes, into a mold to produce microscale flexible features on the order of 10s of microns. Molds were produced via microfabrication of silicon wafers, but were limited in sensing area and were costly. An improved technique was developed that produced molds of acrylic using a computer numerical controlled (CNC) milling machine. This maintained the ability to produce microscale features, and increased the sensing area while reducing costs. New sensing skins had features as small as 20 microns over an area as large as a human hand. Sensor architectures capable of sensing both shear and normal force sensing with high dynamic range were produced. Using this architecture, two sensing modalities were developed: a capacitive approach and a contact resistive approach. The capacitive approach demonstrated better dynamic range, while the contact resistive approach used simpler circuitry. Using the contact resistive approach, normal force range and resolution were 8,000 mN and 1,000 mN, respectively, and shear force range and resolution were 450 mN and 100 mN, respectively. Using the capacitive approach, normal force range and resolution were 10,000 mN and 100 mN, respectively, and shear force range and resolution were 1,500 mN and 50 mN, respectively.
Resumo:
As unmanned autonomous vehicles (UAVs) are being widely utilized in military and civil applications, concerns are growing about mission safety and how to integrate dierent phases of mission design. One important barrier to a coste ective and timely safety certication process for UAVs is the lack of a systematic approach for bridging the gap between understanding high-level commander/pilot intent and implementation of intent through low-level UAV behaviors. In this thesis we demonstrate an entire systems design process for a representative UAV mission, beginning from an operational concept and requirements and ending with a simulation framework for segments of the mission design, such as path planning and decision making in collision avoidance. In this thesis, we divided this complex system into sub-systems; path planning, collision detection and collision avoidance. We then developed software modules for each sub-system
Bibliotecas digitais em Arquitetura e urbanismo: um estudo sobre a arquitetura da informação digital
Resumo:
The goal of this paper was to search the state of the art from the Digital Libraries in Architecture and Urbanism in the Higher Education Institutions (IES) through conceptualizations and showing the importance of Digital Libraries in the disclosure and easing of information transferring. Questions about digital information architecture, usability, digital preservation and accessibility were approached. The research was made in the websites of Brazilian Universities, firstly to identify the institutions which offered the Architecture and Urbanism course, focusing on postgraduate education. After identifying the offering, the research was done by analyzing the contents, storage and dissemination and access to information, these libraries. It was found that the digital libraries are increasingly and taking part of organizations and educational institutions focusing on the knowledge dissemination releasing digitally information that may be needed for institution or the individual. A monitoring was done over of the physical and computational restructuring of the Board of Studies and Research in Architecture and Urbanism (Câmara de Estudos e Pesquisa em Arquitetura e Urbanismo, CEPAU), from the Architecture and Urbanism Course of the Federal University of Rio Grande do Norte (UFRN), showing the need of installing a Digital Library to integrate the databases of PPGAU s research groups, which today remain independent, with no interface among themselves. The research chosen area was Architecture and Urbanism, because there is a gap and little documentation about digital libraries in this area
Resumo:
Numa sociedade onde a inovação é uma pedra basilar para o sucesso das empresas, a criatividade tornou-se num dos mais valiosos ativos intangíveis e um fator chave decisivo para a generalidade das organizações. Segundo a consultora Augusto Mateus & Associados, com o evoluir da sociedade, todas as indústrias serão “culturais e criativas” (Augusto Mateus & Associados, 2010). As Indústrias Criativas têm vindo a assumir um papel cada vez mais relevante na sociedade atual sendo, nos dias de hoje, uma forte fonte de riqueza e emprego. Uma das áreas que mais se tem revelado através do seu rápido e notório crescimento é o sector da animação e dos videojogos, sendo este atualmente uma das indústrias mais valiosas do mundo. Porém, e apesar desta realidade, a atuação nesta indústria é muitas vezes conturbada, pois o sector caracteriza-se pela elevada competitividade, pelos altos custos de produção e pela grande incerteza. As dificuldades vivenciadas no sector levam a uma crescente preocupação pela procura de métodos de gestão sustentáveis, que permitam reduzir os riscos e a elevada taxa de incerteza. Dado que a maioria das empresas desta área está estruturada por projetos, um dos métodos de gestão mais aplicados é o modelo de gestão de projetos. Contudo, verifica-se que ainda existe uma evidente dificuldade na implementação deste modelo de gestão, em particular, nas empresas pequenas e de estrutura achatada, pois este torna-se muitas vezes burocrático, pesado e difícil de aplicar. Este estudo teve como objetivo principal compreender de forma as empresas nacionais de animação e videojogos gerem os seus projetos, sendo que, para este efeito, foram estudados três casos nacionais: a Nerd Monkeys, a Battlesheep e a Nebula Studios através de uma investigação exploratória dos métodos de gestão de projetos aplicados nas empresas de animação e videojogos. De modo a permitir a recolha da informação necessária para dar respostas aos objetivos definidos para a investigação, foi realizado um questionário e realizadas entrevistas semiestruturadas aos representantes das empresas em estudo. Nesta investigação foi possível aferir que apesar das empresas em estudo aplicarem alguns instrumentos da gestão de projetos, não aplicam nenhum método oficial de forma integral. Apesar de se verificar a utilização de algumas ferramentas de gestão de projetos, os sistemas aplicados dependem na maior parte dos casos do tipo de projeto desenvolvido, existindo algumas variações nos métodos utilizados. Em projetos de tempo mais reduzido e maior simplicidade, verifica-se que a gestão de projetos perde relevância, acabando por muitas vezes não ser aplicada.
Resumo:
La falta de recursos para mejorar los insumos y herramientas es causa fundamental de la falta de seguridad alimentaria, según las familias y organizaciones entrevistadas en las Comunidades Marginadas y Aisladas (CMA) en América Latina. Las familias que viven en este tipo de comunidades acceden a los insumos adecuados bien a través de la donación, o a través del crédito. La condición de marginación y aislamiento invita a optar por el crédito, al volverse imprescindible el contar con intervenciones sostenibles por la poca atención que este tipo de comunidades recibe de las autoridades públicas y la cooperación al desarrollo. De entre las metodologías para acceder a los créditos en las CMA destacan las líneas de crédito, los Programas de Grupos Solidarios (PGSs), o las Estructuras Financieras Locales (EFLs) o bancos comunales. Tras el análisis realizado en este artículo, se concluye que las EFLs o bancos comunales son la metodología capaz de arrojar mejores resultados.
Resumo:
This report examines the Genesis II irradiator made by Gray*Star Incorporated, Mississippi Department of Health radiation safety regulations, and Nuclear Regulatory Commission (NRC) inspection guidelines for irradiators. The purpose for this report is to evaluate any hazards which may lead to a catastrophic water loss, evaluate protective action distances during a reduced shielding situation, and evaluate the safety engineering measures incorporated by Mississippi and Federal regulations to ensure the mitigation of risk for pool irradiators. Due to safeguard controls prohibiting release of precise data on emergency response measures and radioactivity of the isotopes utilized this report will be focused on regulations mandating specific engineering controls and manufacturer recommended guidelines for best practices.