Página 29 dos resultados de 2566 itens digitais encontrados em 0.045 segundos

Least square projection: A fast high-precision multidimensional projection technique and its application to document mapping

PAULOVICH, Fernando V.; NONATO, Luis Gustavo; MINGHIM, Rosane; LEVKOWITZ, Haim
Fonte: IEEE COMPUTER SOC Publicador: IEEE COMPUTER SOC
Tipo: Artigo de Revista Científica
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The problem of projecting multidimensional data into lower dimensions has been pursued by many researchers due to its potential application to data analyses of various kinds. This paper presents a novel multidimensional projection technique based on least square approximations. The approximations compute the coordinates of a set of projected points based on the coordinates of a reduced number of control points with defined geometry. We name the technique Least Square Projections ( LSP). From an initial projection of the control points, LSP defines the positioning of their neighboring points through a numerical solution that aims at preserving a similarity relationship between the points given by a metric in mD. In order to perform the projection, a small number of distance calculations are necessary, and no repositioning of the points is required to obtain a final solution with satisfactory precision. The results show the capability of the technique to form groups of points by degree of similarity in 2D. We illustrate that capability through its application to mapping collections of textual documents from varied sources, a strategic yet difficult application. LSP is faster and more accurate than other existing high-quality methods...

Load balancing of Java applications by forecasting garbage collections

Portillo-Domínguez, Andrés Omar; Wang, Miao; Magoni, Damien; Perry, Philip; Murphy, John
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: info:eu-repo/semantics/conferenceObject; all_ul_research; ul_published_reviewed
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peer-reviewed; Modern computer applications, especially at enterprise-level, are commonly deployed with a big number of clustered instances to achieve a higher system performance, in which case single machine based solutions are less cost-effective. However, how to effectively manage these clustered applications has become a new challenge. A common approach is to deploy a front-end load balancer to optimise the workload distribution between each clustered application. Since then, many research efforts have been carried out to study effective load balancing algorithms which can control the workload based on various resource usages such as CPU and memory. The aim of this paper is to propose a new load balancing approach to improve the overall distributed system performance by avoiding potential performance impacts caused by Major Java Garbage Collection. The experimental results have shown that the proposed load balancing algorithm can achieve a significant higher throughput and lower response time compared to the round-robin approach. In addition, the proposed solution only has a small overhead introduced to the distributed system, where unused resources are available to enable other load balancing algorithms together to achieve a better system performance.

Using Sonic Enhancement to Augment Non-Visual Tabular Navigation

Cofino, Jonathan M; Barreto, Armando
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
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More information is now readily available to computer users than at any time in human history; however, much of this information is often inaccessible to people with blindness or low-vision, for whom information must be presented non-visually. Currently, screen readers are able to verbalize on-screen text using text-to-speech (TTS) synthesis; however, much of this vocalization is inadequate for browsing the Internet. An auditory interface that incorporates auditory-spatial orientation was created and tested. For information that can be structured as a two-dimensional table, links can be semantically grouped as cells in a row within an auditory table, which provides a consistent structure for auditory navigation. An auditory display prototype was tested. Sixteen legally blind subjects participated in this research study. Results demonstrated that stereo panning was an effective technique for audio-spatially orienting non-visual navigation in a five-row, six-column HTML table as compared to a centered, stationary synthesized voice. These results were based on measuring the time- to-target (TTT), or the amount of time elapsed from the first prompting to the selection of each tabular link. Preliminary analysis of the TTT values recorded during the experiment showed that the populations did not conform to the ANOVA requirements of normality and equality of variances. Therefore...

Implications of Using Computer-Based Training with the AN/SQQ-89(v) Sonar System: Operating and Support Costs

Gibson, William A.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
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The U.S. Navy transitioned to Computer-Based Training (CBT) in A and C schools in 2003 after a 2001 Revolution in Training report claimed that the Navy would realize savings in cost and training time without negatively affecting the quality of sailors arriving to the Fleet. This thesis analyzes Operating and Support (O and S) cost data for the AN/SQQ-89(v) sonar system to determine whether the transition to CBT contributed to increased Fleet maintenance costs. Determining how actions to change one aspect of a system affects other areas of the system will provide insight for future decisions affecting O and S cost, system life cycles, and Fleet material readiness.

Design of an interactive satellite communications system analysis program

Howard, Charles Craig
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.; This thesis addresses the design of an interactive satellite communications system analysis program. The program provides the capability to analyzedesign a system comprised of two earth terminals and one or two geosynchronous satellites. The principal goal is to simplify the analysisdesign process via a graphically-oriented, menu-driven computer program. The program leads the user methodically through the process and provides feedback that enables the user to visualize the elements of the system and their role relative to the other system components. Hypertext concepts are employed in an object- oriented programming environment to achieve the graphics orientation. The success of the program validates the use of innovative software tools to design programs that can enhance user understanding and increase productivity.

Design, Implementation, and Experimental Results of a Quaternion-Based Kalman Filter for Human Body Motion Tracking

Yun, Xiaoping; Bachmann, Eric R.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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This paper was presented in part at the IEEE International Conference on Robotics and Automation, Barcelona, Spain, April 2005.; Real-time tracking of human body motion is an important technology in synthetic environments, robotics, and other human–computer interaction applications. This paper presents an extended Kalman filter designed for real-time estimation of the orientation of human limb segments. The filter processes data from small inertial/magnetic sensor modules containing triaxial angular rate sensors, accelerometers, and magnetometers. The filter represents rotation using quaternions rather than Euler angles or axis/angle pairs. Preprocessing of the acceleration and magnetometer measurements using the Quest algorithm produces a computed quaternion input for the filter. This preprocessing reduces the dimension of the state vector and makes the measurement equations linear. Real-time implementation and testing results of the quaternion-based Kalman filter are presented. Experimental results validate the filter design, and show the feasibility of using inertial/magnetic sensor modules for real-time human body motion tracking.; This work was supported in part by the Army Research Office (ARO), and in part by the Navy Modeling and Simulation Management Office (NMSO).

Interdigitated back-surface-contact solar cell modeling using Silvaco Atlas

Green, Shawn E.
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 Silvaco Atlas semiconductor modeling software was used to simulate an interdigitated back-surface-contact solar cell. The cell is modeled after the silicon-based Sunpower Corporation A-300 solar cell, which contains a number of unique features that give it advantages over conventional solar cells. This simulation attempted to match as closely as possible the results measured by the National Renewable Energy Laboratory from the A-300 cell in order to validate the model. This model was then used to investigate the effects of making the A-300 thinner, which would permit its use in military solar blanket applications. A thin and flexible solar cell is ideal for this application due to its lighter weight, making it portable and flexible, which increases its ruggedness. The ability to simulate an interdigitated back-surface-contact cell also allows future work using computer algorithms to improve power output results as well as investigations into using materials other than silicon, which may further improve power output.; ; Lieutenant, United States Navy

Logics in Animal Cognition: Are They Important to Brain Computer Interfaces (BCI) And Aerospace Missions?

Ma, Zhanshan (Sam); Millar, Richard; Hiromoto, Robert; Krings, Axel
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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Conventional wisdom is that logic and language are tightly connected to logics in human cognition. However, recent studies have revealed that, in animal cognition, there exist logics that do not depend on languages. In other words, logical behavior is not human brain specific. At least four logics: perceptual logic, technical logic, social logic, and inference logic have been studied in animal cognition. Despite the obvious differences between animals and humans in using languages, recent studies confirm that both humans and animals utilize the socalled sensor brain maps for most sensory modalities: populations of neurons are selectively tuned to different stimulus features or feature combinations (Ewert 2005, Ma and Krings 2009). This commonality suggests that the studies of animal logics should also be insightful for understanding human logics. After briefly reviewing some of the recent advances in animal logics research, we turn to a more practical research field—the Brain Computer Interface (BCI) [also known as Brain Machine Interface (BMI)] in biomedicine. BCI promises to provide nonmuscular communication and control for people with severe motor disabilities. A fundamental goal of BCI is to translate thought or intent into action with brain activity only (Birbaumer 2006). If we recognize that logic is about the way of thinking and it is probably the most reliable and possibly most efficient way to understand thoughts...

Improving software characteristics of a real-time system using reengineering techniques

Book, Scott Allan
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 109 p.;28 cm.
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Approved for public release; distribution is unlimited; The major problem addressed by this research is how to improve an existing real-time software system's readability, maintainability, stability and portability using reengineering techniques. A fundamental portion of the Model- based Mobile robot Language (MML) was the real-time system chosen as the basis for this study. The approach taken was to create a new system design. The new design was based on system specifications obtained by conducting static and dynamic analysis on the existing system. The results are that a new core system was implemented using a design that focused on creating independent software sub-systems while encapsulating data. Hardware dependencies were localized and assembly code minimized. The new system is easier to understand and modify and is portable to other hardware platforms. Autonomous vehicle, Robot, Software engineering, Real-time system; http://archive.org/details/improvingsoftwar00book; Lieutenant, United States Navy

Design principles for security

Benzel, Terry V.; Irvine, Cynthia E.; Levin, Timothy E.; Nguyen, Thuy D.; Clark, Paul C.; Bhaskare, Ganesha
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório Formato: iv, 23 p.: ill.;28 cm.
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As a prelude to the clean-slate design for the SecureCore project, the fundamental security principles from more than four decades of research and development in information security technology were reviewed. As a result of advancing technology, some of the early principles required re-examination. For example, previous worked examples of combinations of hardware, and software may have encountered problems of performance and extensibility, which may no longer exist in today's environment. Moore's law in combination with other advances has yielded better performance processors, memory and context switching mechanisms. Secure systems design approaches to networking and communication are beginning to emerge and new technologies in hardware-assisted trusted platform development and processor virtualization open hither to previously unavailable possibilities. The results of this analysis have been distilled into a review of the principles that underlie the design and implementation of trustworthy systems.; CNS-0430566;National Science Foundation

Content repurposing of electrical diagrams for presentation in handheld devices

Papaliakos, Vasilios
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 67 p. : ill.
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Approved for public release, distribution is unlimited; This thesis proposes a design for content repurposing of electrical diagrams for presentation in small-screen wireless handheld devices. Content repurposing is the on-line adaptation of content to fit device capabilities and user's preferences. The focus of this thesis is on electrical diagrams of the schematic type used for maintenance purposes. Nevertheless, many of the proposed techniques are suitable for other technical drawings as well. A significant amount of work has been done in summarization of Web documents and in diagram recognition, but not for presentation of diagrams in handheld devices. In the design proposed here, techniques are proposed for understanding the semantics of electrical diagrams and for partitioning the drawing images in intelligent ways to formulate coherent units for presentation to the user.; Lieutenant, Hellenic Navy

System requirements analysis and technological support for the Ballistic Missile Defense System (BMDS): FY07 progress report

M. Auguston,; Drusinsky, D.; Hutchins, R.; Michael, J.B.; Knorr, J.B.; Otani, T.; Pace, P.E.; Shing, M.; Tummala, M.; Cook, T.; Katopodis, P.; Walker, T.O.; Chen, Y.Q.; Katsis, G.; Little, D.; Patsikas, D.; Pace, Z.P.; Rakdham, B.; Sampson, A.J.; Tummal
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório Formato: viii, 53 p.: ill.;28 cm.
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Engineering of the Ballistic Missile Defense System (BMDS) requires one to take a holistic approach that includes the physical modeling and analysis of the missile defense operating environment, development of metrics and techniques to analyze the communication requirements of the net-centric Ballistic Missile Defense warfare, and the use of architectural patterns and other software technologies to shape the emergent behavior of the BMDS taking into account of the system's interoperability, composability, extensibility, and dynamic reconfigurability. This report summarizes the work in FY07 to investigate new technologies to support the development of the BMDS. We developed new scoring functions for the fusion of sensor data, an algorithm for multiple hypothesis tracking, a distributed medium access control protocol and data dissemination algorithm for wireless networks of cooperative radar systems, simulation models for network-centric electronic warfare metrics study and for the prediction of the over the horizon radar system footprints, technologies for the correct specification and validation of temporal behaviors in a Service-Oriented Architecture (SOA) based system-of-systems, runtime verification of system-level requirements of distributed reactive systems using MSC-Assertions...

Complexity

Gershenson, Carlos
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/08/2011 Português
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The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.; Comment: Draft entry for the Encyclopedia of Philosophy and Social Sciences, Sage, 2013

Software Development Standard and Software Engineering Practice: A Case Study of Bangladesh

Begum, Zerina; Khan, Mohammed Shafiul Alam; Hafiz, Mohd. Zulfiquar; Islam, Md. Saiful; Shoyaib, Md.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/08/2010 Português
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Improving software process to achieve high quality in a software development organization is the key factor to success. Bangladeshi software firms have not experienced much in this particular area in comparison to other countries. The ISO 9001 and CMM standard has become a basic part of software development. The main objectives of our study are: 1) To understand the software development process uses by the software developer firms in Bangladesh 2) To identify the development practices based on established quality standard and 3) To establish a standardized and coherent process for the development of software for a specific project. It is revealed from this research that software industries of Bangladesh are lacking in target set for software process and improvement, involvement of quality control activities, and standardize business expertise practice. This paper investigates the Bangladeshi software industry in the light of the above challenges.; Comment: 13 pages, 3 figures, 11 tables

Scalable BGP Prefix Selection for Effective Inter-domain Traffic Engineering

Shao, Wenqin; Iannone, Luigi; Rougier, Jean-Louis; Devienne, Francois; Viste, Mateusz
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/11/2015 Português
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Inter-domain Traffic Engineering for multi-homed networks faces a scalability challenge, as the size of BGP routing table continue to grow. In this context, the choice of the best path must be made potentially for each destination prefix, requiring all available paths to be characterised (e.g., through measurements) and compared with each other. Fortunately, it is well-known that a few number of prefixes carry the larger part of the traffic. As a natural consequence, to engineer large volume of traffic only few prefixes need to be managed. Yet, traffic characteristics of a given prefix can greatly vary over time, and little is known on the dynamism of traffic at this aggregation level, including predicting the set of the most significant prefixes in the near future. %based on past observations. Sophisticated prediction methods won't scale in such context. In this paper, we study the relationship between prefix volume, stability, and predictability, based on recent traffic traces from nine different networks. Three simple and resource-efficient methods to select the prefixes associated with the most important foreseeable traffic volume are then proposed. Such proposed methods allow to select sets of prefixes with both excellent representativeness (volume coverage) and stability in time...

Automating Abstract Interpretation of Abstract Machines

Johnson, James Ian
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/04/2015 Português
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Static program analysis is a valuable tool for any programming language that people write programs in. The prevalence of scripting languages in the world suggests programming language interpreters are relatively easy to write. Users of these languages lament their inability to analyze their code, therefore programming language analyzers are not easy to write. This thesis investigates a systematic method of creating abstract interpreters from traditional interpreters, called Abstracting Abstract Machines. Abstract interpreters are difficult to develop due to technical, theoretical, and pragmatic problems. Technical problems include engineering data structures and algorithms. I show that modest and simple changes to the mathematical presentation of abstract machines result in 1000 times better running time - just seconds for moderately sized programs. In the theoretical realm, abstraction can make correctness difficult to ascertain. I provide proof techniques for proving the correctness of regular, pushdown, and stack-inspecting pushdown models of abstract computation by leaving computational power to an external factor: allocation. Even if we don't trust the proof, we can run models concretely against test suites to better trust them. In the pragmatic realm...

Case Study On Social Engineering Techniques for Persuasion

Hasan, Mosin; Prajapati, Nilesh; Vohara, Safvan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/06/2010 Português
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There are plenty of security software in market; each claiming the best, still we daily face problem of viruses and other malicious activities. If we know the basic working principal of such malware then we can very easily prevent most of them even without security software. Hackers and crackers are experts in psychology to manipulate people into giving them access or the information necessary to get access. This paper discusses the inner working of such attacks. Case study of Spyware is provided. In this case study, we got 100% success using social engineering techniques for deception on Linux operating system, which is considered as the most secure operating system. Few basic principal of defend, for the individual as well as for the organization, are discussed here, which will prevent most of such attack if followed.; Comment: 7 Pages

Traffic Engineering with Segment Routing: SDN-based Architectural Design and Open Source Implementation

Davoli, Luca; Veltri, Luca; Ventre, Pier Luigi; Siracusano, Giuseppe; Salsano, Stefano
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Traffic Engineering (TE) in IP carrier networks is one of the functions that can benefit from the Software Defined Networking paradigm. By logically centralizing the control of the network, it is possible to "program" per-flow routing based on TE goals. Traditional per-flow routing requires a direct interaction between the SDN controller and each node that is involved in the traffic paths. Depending on the granularity and on the temporal properties of the flows, this can lead to scalability issues for the amount of routing state that needs to be maintained in core network nodes and for the required configuration traffic. On the other hand, Segment Routing (SR) is an emerging approach to routing that may simplify the route enforcement delegating all the configuration and per-flow state at the border of the network. In this work we propose an architecture that integrates the SDN paradigm with SR-based TE, for which we have provided an open source reference implementation. We have designed and implemented a simple TE/SR heuristic for flow allocation and we show and discuss experimental results.; Comment: Extended version of poster paper accepted for EWSDN 2015 (version v4 - December 2015)

Design-for-Test and Test Optimization Techniques for TSV-based 3D Stacked ICs

Noia, Brandon Robert
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014 Português
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As integrated circuits (ICs) continue to scale to smaller dimensions, long interconnects

have become the dominant contributor to circuit delay and a significant component of

power consumption. In order to reduce the length of these interconnects, 3D integration

and 3D stacked ICs (3D SICs) are active areas of research in both academia and industry.

3D SICs not only have the potential to reduce average interconnect length and alleviate

many of the problems caused by long global interconnects, but they can offer greater design

flexibility over 2D ICs, significant reductions in power consumption and footprint in

an era of mobile applications, increased on-chip data bandwidth through delay reduction,

and improved heterogeneous integration.

Compared to 2D ICs, the manufacture and test of 3D ICs is significantly more complex.

Through-silicon vias (TSVs), which constitute the dense vertical interconnects in a

die stack, are a source of additional and unique defects not seen before in ICs. At the same

time, testing these TSVs, especially before die stacking, is recognized as a major challenge.

The testing of a 3D stack is constrained by limited test access, test pin availability...

Autonomous Sensor Path Planning and Control for Active Information Gathering

Lu, Wenjie
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014 Português
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Sensor path planning and control refer to the problems of determining the trajectory and feedback control law that best support sensing objectives, such as monitoring, detection, classification, and tracking. Many autonomous systems developed, for example, to conduct environmental monitoring, search-and-rescue operations, demining, or surveillance, consist of a mobile vehicle instrumented with a suite of proprioceptive and exteroceptive sensors characterized by a bounded field-of-view (FOV) and a performance that is highly dependent on target and environmental conditions and, thus, on the vehicle position and orientation relative to the target and the environment. As a result, the sensor performance can be significantly improved by planning the vehicle motion and attitude in concert with the measurement sequence. This dissertation develops a general and systematic approach for deriving information-driven path planning and control methods that maximize the expected utility of the sensor measurements subject to the vehicle kinodynamic constraints.

The approach is used to develop three path planning and control methods: the information potential method (IP) for integrated path planning and control, the optimized coverage planning based on the Dirichlet process-Gaussian process (DP-GP) expected Kullback-Leibler (KL) divergence...