Página 35 dos resultados de 2566 itens digitais encontrados em 0.045 segundos

Application of a back-propagation neural network to isolated-word speech recognition

Le, Chau Giang.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
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Approved for public release; distribution is unlimited.; The primary objective of this research is to explore how a back- propagation neural network (BNN) can be applied to isolated-word speech recognition. Simulation results show that a BNN provides an effective approach for small vocabulary systems. The recognition rate reaches 100% for a 5-word system and 94% for a 10-word system. The general techniques developed in this thesis can be further extended to other applications, such as sonar target recognition, missile seeking and tracking functions in modern weapon systems, and classification of underwater acoustic signals.

Modeling and simulation of a fiber distributed data interface local area network

Schenone, Aldo Bruno.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
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Approved for public release; distribution is unlimited.; In this thesis, the performance of the fiber distributed data interface (FDDI) local area network is evaluated by software simulation. The network is modeled with OPNET, a communication network simulation tool. The main focus of the model is on the medium access control (MAC) and the timing requirements that need to be met for the correct behavior of the protocol. Simulation data is presented to support results from previous analytic studies of distinctive features of the protocol, including the behavior of the token rotation time, synchronous frame delays, fairness of channel access for nodes transmitting asynchronous traffic, etc. Comparisons between the simulated and theoretical results confirm the accuracy of the OPNET simulation tools and demonstrate that it may be used to model other protocols of particular interest.

Optimization of the Feed Impedance for an Arbitrary Crossed-Feed-Arm Impulse Radiating Antenna

Tyo, J. Scott
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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Sensor and Simulation Notes, Note 438; This note considers the optimization of feed arm geometry of 4-arm, coplanar plate IRAs when the angular position and extent of the arms are taken as free parameters. Previously, optimization of this class of antenna considered only the symmetric case where the two pairs of crossed feed arms were perpendicular to each other. Comparison is made using the prompt aperture efficiency, and the results indicate that the efficiency of 4-arm IRAs can be increased from -25% for the perpendicularly crossed arms to -35% for the optimum configuration. In addition to the optimization, the feed impedance of coplanar feeds is presented for general values of feed arm angle and plate width, and the optimum feed impedance is computed for each feed arm angle. The results in this note can be used to design the optimal 4-arm IRA with an arbitrary specified input impedance.

M-layer: NPS version

Lee, Hung-Mou; Han, Yin Yuan
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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The M-Layer program developed by NOSC has been substantially revised into a Naval Postgraduate School (NPS) version. The mode locating algorithm was re-written to take advantage of I d an alyticity of the mode function. The exponential complex number representation was adopted to simplify multiplication and to improve accuracy when adding two complex numbers which nearly cancel each other. A consistency condition was formulated to assure accurate and efficient evaluation of the height-gain function. As a result, this NPS version executes faster with greater stability.

Improving maritime domain awareness using neural networks for target of interest classification

Schaus, Brian M.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
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Approved for public release; distribution is unlimited; Techniques for classifying maritime domain targets-of-interest within images are explored in this thesis. Geometric and photometric features within each image are extracted from processed images and are used to train a neural network. The trained neural network is tested with features of a known object. In the binary classification case, the neural network is used to determine whether a ship is present or not present in the image. In the multi-class and multi-level classification cases, the neural network is used to determine if the object belongs to one of four classes specified: warship, cargo ship, small boat, or other. The Hough transformation is used to identify and characterize linear patterns exhibited by objects in images. As an alternative to geometric and photometric features to classify targets-of-interest, these linear patterns are used to train a neural network. The performance of the neural network is then tested for binary, multi-class, and multi-level classification schemes. The development of neural-network-based techniques for automated target-of-interest classification is a significant result of this thesis.

Modeling and Optimization Techniques of Electronic Devices Using Genetic Algorithm

Michael, Sherif
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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The article of record as published may be located at http://dx.doi.org/10.2498/cit.1001399; A new method for developing a realistic physicalmodel of any type of solid state device is presented. Application to model advanced multi-junction solar cells; Thermophotovoltaics; sensors; as well as other novel solid state devices are introduced in this presentation. The primary goal of multijunction solar cell design is to maximize the output power for a given solar spectrum [1-4].

Genetic Algorithm Application for the Optimization of Solid State Devices using a Novel Modeling Technique

Michael, Sherif
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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A new method for developing a realistic physical model of any type of solid state device is presented. Application to model advanced multi-junction solar cells; Thermo-photovoltaics; sensors; as well as other novel solid state devices are introduced in this presentation. The primary goal of multijunction solar cell design is to maximize the output power for a given solar spectrum. The construction of multijunction cells places the individual junction layers in series, thereby limiting the overall output current to that of the junction layer producing the lowest current. The solution to optimizing a multijunction design involves both the design of individual junction layers which produce an optimum output power and the design of a series-stacked configuration of these junction layers which yields the highest possible overall output current. This paper demonstrates the use of Genetic Algorithm in a two-part process to refine a given multijunction solar cell design for near-optimal output power for a desired light spectrum. This approach can similarly be utilized to optimize the parameters of any Solid state device to yield any desired performance.

Energy-aware Fault-tolerant Scheduling for Hard Real-time Systems

Han, Qiushi
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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Over the past several decades, we have experienced tremendous growth of real-time systems in both scale and complexity. This progress is made possible largely due to advancements in semiconductor technology that have enabled the continuous scaling and massive integration of transistors on a single chip. In the meantime, however, the relentless transistor scaling and integration have dramatically increased the power consumption and degraded the system reliability substantially. Traditional real-time scheduling techniques with the sole emphasis on guaranteeing timing constraints have become insufficient. In this research, we studied the problem of how to develop advanced scheduling methods on hard real-time systems that are subject to multiple design constraints, in particular, timing, energy consumption, and reliability constraints. To this end, we first investigated the energy minimization problem with fault-tolerance requirements for dynamic-priority based hard real-time tasks on a single-core processor. Three scheduling algorithms have been developed to judiciously make tradeoffs between fault tolerance and energy reduction since both design objectives usually conflict with each other. We then shifted our research focus from single-core platforms to multi-core platforms as the latter are becoming mainstream. Specifically...

Crafting a global teaming model for architectural knowledge

Beecham, Sarah; Noll, John; Richardson, Ita; Ali, Nour
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: Conference item; all_ul_research; ul_published_reviewed; none
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peer-reviewed; In this paper, we present the Global Teaming Model (GTM), which is empirically grounded, and outlines practices that managers need to consider when managing virtual teams. We explain how the model can be adapted to specific areas of software development, and use architectural knowledge management (AKM) as our exemplar. We focus on specific practices relating to how teams collaborate and share essential architectural knowledge across multiple sites. Through a review of the literature, we develop an in-depth view of recommended practices associated with AKM in a global environment. We then consider how we can incorporate these AKM practices into our Global Teaming model to ensure managers are given the necessary support. Our contribution to research therefore is to present AKM practices within the context of all other Global Software Development processes.

Self-diagnostics digitally controlled pacemaker/defibrillators a design plan for incorporating diagnostics and digital control in the schema of a pacemaker/defibrillator design

Nedd, Steven.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xvi, 73 p. : ill. (chiefly col.) ;
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This research addresses the need for a pacemaker/defibrillator that could perform an automatic system self-diagnostics check to assure operational functionality and give doctors a chance to assess a patient's status in the event they are experiencing complications, as pointed out in an article in the journal Health Scout, which stated that 'St. Jude Medical Inc., the nation's second-largest pacemaker manufacturer, has warned doctors that at least 90 of its pacemakers being used by heart patients could stop emitting the electrical signal that regulates heartbeat'. The proposed functionality would also serve the military in determining the whereabouts or state of being of an individual on the battlefield. This thesis investigates the use of Unified Modeling Language (UML) Diagrams, Object-Oriented Analysis and Design, and Structured Query Language (SQL) to develop the high level architecture of a system to store and retrieve digital/wireless communication information from a pacemaker/defibrillator, or other device, and to alert medical personnel when a person is experiencing problems with their health. It presents the requirements and architectural design of the Self-Diagnostics Digitally Controlled Pacemaker/Defibrillator Device. Applications of the SDDCPDD design concept for military missions are explored.

A technique for multiplexing 3x3-coupler terminated interferometric fiber-optic sensors

Reid, Gregory John.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 99 p. :|bill.
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Approved for public release; distribution is unlimited.; This thesis investigates the multiplexing of Mach-Zehnder type 3x3 terminated fiber-optic sensors demodulated by either 'quadrature'or'symmetric' methods using intensity modulation of the source. 3x3-couplers produce signals that permit unmodulated passive demodulation of interferometric signals. The theory is described and the results of a 2xl element array optical demonstration are presented. Possible architectures using this demultiplexing technique are presented for several applications with different return line requirements. The technique was successfully demonstrated and warrants further investigation to increase the number of sensors and reduce the number of return lines for specific applications. The multiplexing technique presents the opportunity for possible cost savings over other phase generated carrier techniques, which require wavelength modulation of the source, and significant optical path differences in the interferometers, and are therefore constrained to presently very expensive sources. The technique presented uses compatible low coherent laser sources such as Compact Disc quality (830 nm) devices.; Lieutenant, Royal Australian Navy

On the number of generators for transeunt triangles

Dueck, Gerhard W.; Shmerko, Vlad P.; Butler, Jon T.; Yanushkevich, S. N.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.; Discrete Applied Mathematics, 108, 2001, pp. 309-316; A transeunt triangle for size n consists of (n+1)x(n+1)x(n+1) 0's and 1's whose values are determined by the sum modulo 2 of two other local values. For a given n, two transeunt triangles of size n can be combined using the element-by-element modulo 2 sum to generate a third transeunt triangle. We show that, for large n ...

Network-based control, monitoring and calibration of shipboard sensors

Silva, Eusebio Pedro da
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xviii, 63 p. : col. ill. ;
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Approved for public release; distribution in unlimited.; The objective of this thesis is to develop a new calibration system for analog and smart digital pressure sensors, operable by only one person, and capable of calibrating local and remote sensors connected via RS232 cables, Bluetooth or an 802.11b wireless LAN. It is proposed that the operator uses a portable calibration standard and a tablet PC to conduct the sensor calibration. In order to handle local sensors directly connected to the tablet PC and remote sensors connected to the tablet PC via a network capable application processor (NCAP), a dual module application is proposed and developed using LabVIEW. The application has a Master Module and a Slave Module. Both modules are able to connect to multiple digital sensors at the same time. The Master Module was designed to run on the operator's tablet PC offering an easy-to-use graphical user interface (GUI) that allows the monitoring or calibration of any connected sensors. The Slave Module was designed to run on any networked PC, including the operator's tablet and an NCAP. A dedicated Virtual Instrument (VI) was designed for an iterative calibration process based on a least squares fitting method. This VI automatically computes the calibration constants that minimize the measurements errors...

Analysis of an image processing algorithm for its implementation in real time

Ventura, Roberto M.
Fonte: Monterey, California : Naval Postgraduate School Publicador: Monterey, California : Naval Postgraduate School
Tipo: Tese de Doutorado Formato: iv, 45 p. ill.
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This thesis deals with the implementation and analysis of an image processing algorithm in order to determine the feasibility of its operation in a real time environment at standard video frame rates. A modification of the Peli and Lim algorithm has been put to work in processing images taken from a submerged camera operating in turbid water environments with uneven light distribution. The algorithm's performance was observed in detail to determine if it met the required specifications. Through analysis, the algorithm's intense computational requirements and large memory storage demands were resolved. It was determined that for the algorithms to operate in real time, a system with characteristics of a supercomputer would most likely be needed. The algorithm was transported to an IBM AT equipped for image processing. Possible optimization techniques were discussed briefly, and other solutions for processing images with this type of equipment were suggested. (rrh); http://archive.org/details/analysisofimagep00vent; Colombian Navy author.

Engineering Automation for Reliable Software - Interim Progress Report (10/01/2000 - 9/30/2001)

Luqi
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
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The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other documentation.; The objective of our effort is to develop a scientific basis for producing reliable software that is also flexible and cost effective for the DoD distributed software domain. This objective addresses the long term goals of increasing the quality of service provided by complex systems while reducing development risks, costs, and time. Our work focuses on "wrap and glue" technology based on a domain specific distributed prototype model. The key to making the proposed approach reliable, flexible, and cost-effective is the automatic generation of glue and wrappers based on a designer's specification. The "wrap and glue" approach allows system designers to concentrate on the difficult interoperability problems and defines solutions in terms of deeper and more difficult interoperability issues, while freeing designers from implementation details. Specific research areas for the proposed effort include technology enabling rapid prototyping, inference for design checking, automatic program generation, distributed real-time scheduling...

Noise adaptation and correlated maneuver gating of an extended Kalman filter

Spehn, Stephen L.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado Formato: vi, 141 p. :|c 28 cm.
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Approved for public release; distribution is unlimited.; Extended Kalman filtering is used to provide estimates of the position and velocity of a target based upon observations of the target's bearing and range. Non-stationary noise is shown to degrade the performance of the filter and cause filter divergence. By estimating the noise power from the variance of the filter's residual we adapt the filter to compensate for varying noise power. This thesis also introduces the method of correlated maneuver gating to adapt the Kalman filter to target dynamics. By spatially and temporally correlating the Mahalanobis Distance of the residual, the Kalman filter's performance is increased while tracking tangentially accelerating targets. Monte Carlo simulations are run for three different sets of target dynamics: stationary, moving linearly, and accelerating tangentially. Results for the simulation show significant performance advantages of using correlated maneuver gating in conjunction with noise adaptation. These results should generalize to other applications of the extended Kalman filter whose state and observation spaces enjoy a one-to-one mapping; Civilian, Defense Mapping Agency

A Fuzzy Preprocessing Module for Optimizing the Access Network Selection in Wireless Networks

Kaleem, Faisal; Mehbodniya, Abolfazl; Yen, Kang K.; Adachi, Fumiyuki
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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A heterogeneous wireless network is characterized by the presence of different wireless access technologies that coexist in an overlay fashion. These wireless access technologies usually differ in terms of their operating parameters. On the other hand, Mobile Stations (MSs) in a heterogeneous wireless network are equipped with multiple interfaces to access different types of services from these wireless access technologies. The ultimate goal of these heterogeneous wireless networks is to provide global connectivity with efficient ubiquitous computing to these MSs based on the Always Best Connected (ABC) principle. This is where the need for intelligent and efficient Vertical Handoffs (VHOs) between wireless technologies in a heterogeneous environment becomes apparent. This paper presents the design and implementation of a fuzzy multicriteria based Vertical Handoff Necessity Estimation (VHONE) scheme that determines the proper time for VHO, while considering the continuity and quality of the currently utilized service, and the end-users' satisfaction.

Efficient Storage and Domain-Specific Information Discovery on Semistructured Documents

Farfan, Fernando R
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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The increasing amount of available semistructured data demands efficient mechanisms to store, process, and search an enormous corpus of data to encourage its global adoption. Current techniques to store semistructured documents either map them to relational databases, or use a combination of flat files and indexes. These two approaches result in a mismatch between the tree-structure of semistructured data and the access characteristics of the underlying storage devices. Furthermore, the inefficiency of XML parsing methods has slowed down the large-scale adoption of XML into actual system implementations. The recent development of lazy parsing techniques is a major step towards improving this situation, but lazy parsers still have significant drawbacks that undermine the massive adoption of XML. Once the processing (storage and parsing) issues for semistructured data have been addressed, another key challenge to leverage semistructured data is to perform effective information discovery on such data. Previous works have addressed this problem in a generic (i.e. domain independent) way, but this process can be improved if knowledge about the specific domain is taken into consideration. This dissertation had two general goals: The first goal was to devise novel techniques to efficiently store and process semistructured documents. This goal had two specific aims: We proposed a method for storing semistructured documents that maps the physical characteristics of the documents to the geometrical layout of hard drives. We developed a Double-Lazy Parser for semistructured documents which introduces lazy behavior in both the pre-parsing and progressive parsing phases of the standard Document Object Model's parsing mechanism. The second goal was to construct a user-friendly and efficient engine for performing Information Discovery over domain-specific semistructured documents. This goal also had two aims: We presented a framework that exploits the domain-specific knowledge to improve the quality of the information discovery process by incorporating domain ontologies. We also proposed meaningful evaluation metrics to compare the results of search systems over semistructured documents.

Delay-Sensitive Service Request Scheduling for Cloud Computing

Liu, Shuo
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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Cloud computing realizes the long-held dream of converting computing capability into a type of utility. It has the potential to fundamentally change the landscape of the IT industry and our way of life. However, as cloud computing expanding substantially in both scale and scope, ensuring its sustainable growth is a critical problem. Service providers have long been suffering from high operational costs. Especially the costs associated with the skyrocketing power consumption of large data centers. In the meantime, while efficient power/energy utilization is indispensable for the sustainable growth of cloud computing, service providers must also satisfy a user's quality of service (QoS) requirements. This problem becomes even more challenging considering the increasingly stringent power/energy and QoS constraints, as well as other factors such as the highly dynamic, heterogeneous, and distributed nature of the computing infrastructures, etc. In this dissertation, we study the problem of delay-sensitive cloud service scheduling for the sustainable development of cloud computing. We first focus our research on the development of scheduling methods for delay-sensitive cloud services on a single server with the goal of maximizing a service provider's profit. We then extend our study to scheduling cloud services in distributed environments. In particular...

Planeamento estratégico de sistemas de informação em empresa de construção

Costa, Áurea Helena Lopes da; Ribeiro, Rui, orient.
Fonte: Repositório Científico Lusófona Publicador: Repositório Científico Lusófona
Tipo: Dissertação de Mestrado
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Os Sistemas de Informação têm influenciado a vida quotidiana a um ritmo inesperado e com mudanças significativas na setor da construção, cuja importância é crucial para a economia de qualquer país. Sendo Angola, um país de economia emergente, caracterizado por um mercado em expansão e reestruturação, onde as decisões de Sistema Informação ainda são tomadas de forma isolada, e cada vez mais investidores estão a atuar no país, impulsionando o crescimento, é imperioso para o sector a identificação e exploração de Sistemas de Informação flexíveis e adaptáveis para fazer face as forças competitivas do setor. Partindo desta envolvente a presente dissertação visa ressaltar o reconhecimento da importância do Planeamento Estratégico de Sistemas de Informação-PESI para as organizações atuais. Neste contexto realizou-se o estudo de PESI em torno de um caso concreto numa Pequena Media Empresa, Angolana, a Terponte,SA, cujo objectivo é fornecer a construtora um plano em termos de SI para futuro. Os dados foram recolhidos através da utilização dos métodos qualitativos e quantitativos, sendo os mais pertinentes a análise documental, observação direta, entrevistas, questionários aos órgãos da empresa em estudo e demais intuições. A análise dos dados demonstrou uma deficiente gestão da informação...