We present a functional and structural didactic simulator of Cache Memory Systems developed at the Pontifical Catholic University of Minas Gerais, Brazil. The development occurred during the undergraduatecomputer Arc...
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We report on new results on the use of algebraic reconstruction techniques (ART) for reconstructing from helical cone-beam computerized tomography (CT) data. We investigate two variants of ART for this task: a standar...
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We report on new results on the use of algebraic reconstruction techniques (ART) for reconstructing from helical cone-beam computerized tomography (CT) data. We investigate two variants of ART for this task: a standard one that considers a single ray in an iterative step and a block version which groups several cone-beam projections when calculating an iterative step. Both algorithms were implemented using modified Kaiser-Bessel window functions, also known as blobs, placed on the body-centered cubic (bcc) grid. The algorithms were used to reconstruct a modified 3D Shepp-Logan phantom from data collected for the PI-geometry for two different maximum cone-beam angles (/spl plusmn/9.46/spl deg/ and /spl plusmn/18.43/spl deg/). Both scattering and quantum noise (for three different noise levels) were introduced to create noisy projections. The results presented here (for both noiseless and noisy data sets) point to the fact that, as opposed to filtered backprojection algorithms, the quality of the reconstructions produced by the ART methods does not suffer from the increase in the cone-beam angle.
In general, two types of resource reservations in computer networks can be distinguished: immediate reservations which are made in a just-in-time manner and advance reservations which allow to reserve resources a long...
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In general, two types of resource reservations in computer networks can be distinguished: immediate reservations which are made in a just-in-time manner and advance reservations which allow to reserve resources a long time before they are actually used. Advance reservations are especially useful for grid computing but also for a variety of other applications that require network quality-of-service, such as content distribution networks or even mobile clients, which need advance reservation to support handovers for streaming video. With the emerged MPLS standard, explicit routing can be implemented also in IP networks, thus overcoming the unpredictable routing behavior which so far prevented the implementation of advance reservation services. The impact of such advance reservation mechanisms on the performance of the network with respect to the amount of admitted requests and the allocated bandwidth has so far not been examined in detail. We show that advance reservations can lead to a reduced performance of the network with respect to both metrics. The analysis of the reasons shows a fragmentation of the network resources. In advance reservation environments, additional new services can be defined such as malleable reservations and can lead to an increased performance of the network. Four strategies for scheduling malleable reservations are presented and compared. The results of the comparisons show that some strategies increase the resource fragmentation and are therefore unsuitable in the considered environment while others lead to a significantly better performance of the network. Besides discussing the performance issue, the software architecture of a management system for advance reservations is presented.
The objective of this study is to propose a project management model which includes the unified process (UP) and UML language, for e-business software development in a physically distributed environment. The research ...
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Due to a widely use of XML language in various application domains, a well-established mechanism for the definition and enforcement of security controls on specific accesses to XML documents is demanded, in order to e...
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One of the main factors that impede the practice of the telemedicine is not the lack of new technologies for the communication, but the lack of studies on the use of the technology already installed in the distant are...
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One of the main factors that impede the practice of the telemedicine is not the lack of new technologies for the communication, but the lack of studies on the use of the technology already installed in the distant areas, in way to be used of a rational way. The objective of the telemedicine is to provide help to the cares with the health with quality the distant areas of the great attendance centers. Therefore, it cannot ignore the fact that these areas do not make use of point technologies for communication. Then, it is justified the need to accomplish studies that facilitate the practice of the independent telemedicine of the installed technology. Then, the objective of this work is to use as pilot an unit of remote health, contributing with a support system that allows the practice of the telemedicine using the technology of available transmission in the respective place, avoiding that the factor cost is a barrier for the telemedicine projects and can begin an improvement process in the quality of the attendance in units of distant health of the great centers of medical attendance.
This paper presents our experiments for integrating OMG MIOP (Mullicast Inter-ORB Protocol) specifications into a CORBA ORB. We proposed an integration model which allows the coexistence of two different protocol stac...
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Digital transmission of coded speech is becoming increasingly important in a plethora of voice over internet protocol (VOIP) applications, reaching a variety of platforms, which urges for secure, robust, flexible and ...
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Digital transmission of coded speech is becoming increasingly important in a plethora of voice over internet protocol (VOIP) applications, reaching a variety of platforms, which urges for secure, robust, flexible and platform independent software. ITU-T G.723.1 is a speech compression standard for multimedia communications. G.723.1 is a dual rate codec that compresses the speech signal to 6.3 and 5.3 kbps while maintaining the toll quality and relatively low delay. The major objective of this research is to successfully implement the ITU G.723.1 speech compression standard in Java. The need for implementing this standard in Java was to build a secure, robust, object oriented and platform independent speech coding software, however the delay (execution time) is slightly increased around 10 ms, which may slightly affect the implementation
We obtain recombination rate distribution functions for all human chromosomes using an optimal quantization method. This nonparametric method allows us to control over-/under-fitting. The piece-wise constant recombina...
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We obtain recombination rate distribution functions for all human chromosomes using an optimal quantization method. This nonparametric method allows us to control over-/under-fitting. The piece-wise constant recombination rate distribution functions are convenient to store and retrieve. Our experimental results showed more abrupt distribution functions than two recently published results. In the previous results, the over-/under-fitting issues were not addressed explicitly. Our estimation had greater log likelihood over a previous result using Parzen window. It suggests that the optimal quantization technique might be of great advantage for estimation of other genomic feature distributions.
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