Papers by Euclides Junior
IEEE Personal Communications, 1999
Driven by the twin forces of industry-wide deregulation and the explosive demand for Internet acc... more Driven by the twin forces of industry-wide deregulation and the explosive demand for Internet access and bandwidth-intensive multimedia services, broadband local access has emerged as one of the key issues in modern telecommunications. We describe a broadband local access network consisting of small, densely spaced packet-switching nodes interconnected by focused free-space optical links in a multihop mesh arrangement. Each switch serves a client, which may be an office building (containing, for example, conventional PBXs and LANs), a picocellular base station, or both. It is the responsibility of our local access network to economically and reliably extend broadband local access service (perhaps OC-3 or OC-12 for building LANs and PBXs; perhaps several tens of megabits per second to base stations) from an infrastructure end office or fiber ring add/drop multiplexer without requiring the installation of new buried optical cabling. Computed is the capacity of the multihop mesh, defined to be the maximum number of virtual connections which can be delivered to the infrastructure access point such that, independent of the traffic distribution among clients, all quality of service guarantees are maintained
Journal of Biomedical …, 2005
Among novel scaffold fabrication techniques, 3D fiber deposition (3DF) has recently emerged as a ... more Among novel scaffold fabrication techniques, 3D fiber deposition (3DF) has recently emerged as a means to fabricate well-defined and custom-made scaffolds for tissue regeneration, with 100% interconnected pores. The mechanical behavior of these constructs is dependent not only on different three-dimensional architectural and geometric features, but also on the intrinsic chemical properties of the material used. These affect the mechanics of the solid material and eventually of 3D porous constructs derived from them. For instance, poly(ethylene oxide terephthalate)-poly-(butylene terephthalate) (PEOT/PBT) block copolymers are known to have mechanical properties, depending on the PEOT/PBT weight ratio in block form and on the molecular weight of the initial poly(ethylene glycol) (PEG) blocks. These differences are enhanced even more by their different swelling properties in aqueous media. Therefore, this article examines the influence of copolymer compositions in terms of their swelling on dynamic mechanical properties of solid material and porous 3DF scaffolds. The molecular weight of the starting PEG blocks used in the copolymer synthesis varied from 300 to 1000 g/mol. The PEOT/PBT weight ratio in the blocks used varied from 55/45 to 80/20. This corresponded to an increase of the swelling ratio Q from 1.06 to 2.46, and of the mesh size from ϳ 9 Å to ϳ 47 Å. With increased swelling, dynamic mechanical analysis (DMA) revealed a decrease in elastic response and an increase of viscoelasticity. Thus, by coupling structural and chemical characteristics, the viscoelastic properties of PEOT/PBT 3DF scaffolds may be fine tuned to achieve mechanical requirements for a variety of engineered tissues. Ultimately, the combination of 3DF and DMA may be useful to validate the hypothesis that mimicking the biomechanical behavior of a specific tissue for its optimal replacement is an important issue for at least some tissue-engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 75A: [957][958][959][960][961][962][963][964][965] 2005
Operations Research, 2000
… 2005. 24th Annual Joint Conference of …, 2005
Even though multiple non-overlapped channels exist in the 2.4GHz and 5GHz spectrum, most IEEE 802... more Even though multiple non-overlapped channels exist in the 2.4GHz and 5GHz spectrum, most IEEE 802.11-based multi-hop ad hoc networks today use only a single channel. As a result, these networks rarely can fully exploit the aggregate bandwidth available in the radio spectrum provisioned by the standards. This prevents them from being used as an ISP's wireless last-mile access network or as a wireless enterprise backbone network. In this paper, we propose a multi-channel wireless mesh network (WMN) architecture (called Hyacinth) that equips each mesh network node with multiple 802.11 network interface cards (NICs). The central design issues of this multi-channel WMN architecture are channel assignment and routing. We show that intelligent channel assignment is critical to Hyacinth's performance, present distributed algorithms that utilize only local traffic load information to dynamically assign channels and to route packets, and compare their performance against a centralized algorithm that performs the same functions. Through an extensive simulation study, we show that even with just 2 NICs on each node, it is possible to improve the network throughput by a factor of 6 to 7 when compared with the conventional single-channel ad hoc network architecture. We also describe and evaluate a 9-node Hyacinth prototype that is built using commodity PCs each equipped with two 802.11a NICs.
IEEE/ACM Transactions on Networking, 2010
p-Cycles have been proposed for pre-provisioned 1:N protection in optical mesh networks. Although... more p-Cycles have been proposed for pre-provisioned 1:N protection in optical mesh networks. Although the protection circuits are preconfigured, the detection of failures and the rerouting of traffic can be a time consuming operation. Another survivable mode of operation is the 1+1 protection mode, in which a signal is transmitted to the destination on two link disjoint circuits, hence recovery from failures is expeditious. However, this requires a large number of protection circuits. In this paper we introduce a new concept in protection: 1+N protection, in which a p-Cycle, similar to FIPP p-cycles, can be used to protect a number of bidirectional connections, which are mutually link disjoint, and also link disjoint from all links of the p-Cycle. However, data units from different circuits are combined using network coding, which can be implemented in a number of technologies, such as Next Generation SONET (NGS), MPLS/GMPLS or IPover-WDM. The maximum outage time under this protection scheme can be limited to no more than the p-Cycle propagation delay. It is also shown how to implement a hybrid 1+N and 1:N protection scheme, in which on-cycle links are protected using 1:N protection, while straddling links, or paths, are protected using 1+N protection. Extensions of this technique to protect multipoint connections are also introduced. A performance study based on optimal formulations of the 1+1, 1+N and the hybrid scheme is introduced. Although 1+N speed of recovery is comparable to that of 1+1 protection, numerical results for small networks indicate that 1+N is about 30% more efficient than 1+1 protection, in terms of the amount of protection resources, especially as the network graph density increases.
Abstract We study a class of circuit switched wavelength routing networks with xed or alternate r... more Abstract We study a class of circuit switched wavelength routing networks with xed or alternate routing and with random wavelength allocation. We present an iterative path decomposition algorithm to accurately and e ciently evaluate the blocking performance of such networks with and without wavelength converters. Our iterative algorithm analyzes the original network by decomposing it into single path sub-systems. These sub-systems are analyzed in isolation by using our previous algorithms for a single path of a wavelength ...
IEEE Transactions on Magnetics, 1982
This report describes a network mesh a n a l y s i s technique which can be used t o c a l c u l ... more This report describes a network mesh a n a l y s i s technique which can be used t o c a l c u l a t e t r a n s i e n t o r steady-state eddy c u r r e n t d i s t r i b u t i o n s on a conducting s u r f a c e .
IEEE Communications Magazine, 2008
IPTV, an emerging Internet application, would revolutionize the entertainment and media industrie... more IPTV, an emerging Internet application, would revolutionize the entertainment and media industries; however, IPTV also has the potential to overwhelm the Internet backbone and access networks with traffic. To date, IPTV over P2P streaming networks has advanced significantly using two different approaches: tree-push versus mesh-pull. In particular, the mesh-pull streaming approach has achieved a number of successful commercial deployments. In this article, we examine the current progress in the research and development of mesh-pull P2P streaming systems. We provide an overview of the general mesh-pull streaming architecture and review various challenges, design issues, and interesting research problems in this approach. We discuss the construction costs for providing an IPTV service with service guarantees. We outline a measurement technique for monitoring the video playback quality of mesh-pull streaming systems. We emphasize that the future P2P IPTV systems should be designed to meet the expectations of users for quality-of-experience. We also identify a few other important issues for IPTV over P2P streaming networks, including the traffic pressure on ISPs, various security concerns, and the necessity to re-examine the most appropriate P2P architecture. Insights obtained in this study will be valuable for the development and deployment of future P2P IPTV systems.
… 2005. 24th Annual Joint Conference of …, 2005
Even though multiple non-overlapped channels exist in the 2.4GHz and 5GHz spectrum, most IEEE 802... more Even though multiple non-overlapped channels exist in the 2.4GHz and 5GHz spectrum, most IEEE 802.11-based multi-hop ad hoc networks today use only a single channel. As a result, these networks rarely can fully exploit the aggregate bandwidth available in the radio spectrum provisioned by the standards. This prevents them from being used as an ISP's wireless last-mile access network or as a wireless enterprise backbone network. In this paper, we propose a multi-channel wireless mesh network (WMN) architecture (called Hyacinth) that equips each mesh network node with multiple 802.11 network interface cards (NICs). The central design issues of this multi-channel WMN architecture are channel assignment and routing. We show that intelligent channel assignment is critical to Hyacinth's performance, present distributed algorithms that utilize only local traffic load information to dynamically assign channels and to route packets, and compare their performance against a centralized algorithm that performs the same functions. Through an extensive simulation study, we show that even with just 2 NICs on each node, it is possible to improve the network throughput by a factor of 6 to 7 when compared with the conventional single-channel ad hoc network architecture. We also describe and evaluate a 9-node Hyacinth prototype that is built using commodity PCs each equipped with two 802.11a NICs.
Communications of the ACM, 2000
For pervasive computing performance, exploit the physical limits of these densely distributed net... more For pervasive computing performance, exploit the physical limits of these densely distributed networks of embedded sensors, controls, and processors. W ireless integrated network sensors (WINS) provide distributed network and Internet access to sensors, controls, and processors deeply embedded in equipment, facilities, and the environment. The WINS network represents a new monitoring and control capability for applications in such industries as transportation, manufacturing, health care, environmental oversight, and safety and security. WINS combine microsensor technology and low-power signal processing, computation, and low-cost wireless networking in a compact system.
Personal Communications, IEEE, 1998
Transmitter power control can be used to concurrently achieve several key objectives in wireless ... more Transmitter power control can be used to concurrently achieve several key objectives in wireless networking, including minimizing power consumption and prolonging the battery life of mobile nodes, mitigating interference and increasing the network capacity, and maintaining the required link QoS by adapting to node movements, fluctuating interference, channel impairments, and so on. Moreover, power control can be used as a vehicle for implementing on-line several basic network operations, including admission control, channel selection and switching, and handoff control. We consider issues associated with the design of power-sensitive wireless network architectures, which utilize power efficiently in establishing user communication at required QoS levels. Our focus is mainly on the network layer and less on the physical one. Besides reviewing some recent developments in power control, we also formulate some general associated concepts which have wide applicability to wireless network design. A synthesis of these concepts into a framework for power-sensitive network architectures is done, based on some key justifiable points. Various important relevant issues are highlighted and discussed, as well as several directions for further research in this area. Overall, a first step is taken toward the design of power-sensitive network architectures for next-generation wireless networks. 50 1070-9916/98/$10.00 0 1998 IEEE IEEE Personal Communications
Mutations at codons 12, 13, or 61 of the H-ras, K-ras, and N-ras have been detected in human neop... more Mutations at codons 12, 13, or 61 of the H-ras, K-ras, and N-ras have been detected in human neoplasias by a variety of techniques. Some of these techniques are very sensitive and can detect K-ras mutation in 90% of the cases of pancreatic adenocarcinomas. We analyzed 11 samples of pancreatic adenocarcinoma, three samples of pancreatic mucinous cystadenoma, and two samples without tumors in formalin-fixed paraffin embedded tissue sections. K-ras mutations at codon 12 were detected by a two-step PCR-enriched technique in all the samples of pancreatic adenocarcinoma, but not in cystadenoma or control samples. This technique may be useful for early detection of pancreatic cancer.
Pharmaceutical Biology, 2003
Piper caldense C. DC. is used in Paraíba, Brazil, as a sedative, as an antidote for snake-bite an... more Piper caldense C. DC. is used in Paraíba, Brazil, as a sedative, as an antidote for snake-bite and for toothache. In this Brazilian state, it is known by the vernacular name “pimenta d’ arda” or “pimenta d’ ...
Journal of food …, 2006
Four drying experiments of mate leaves (Ilex paraguariensis St. Hilaire) were carried out in a pa... more Four drying experiments of mate leaves (Ilex paraguariensis St. Hilaire) were carried out in a packed bed superheated steam dryer by varying outlet steam temperature from 120 to 140C and equivalent particle diameter from 4.7 ¥ 10 -3 to 6.95 ¥ 10 -3 m. The influence of these variables on the drying coefficient calculated by assuming a simplified drying kinetic model was investigated. A classical statistical approach revealed the significant effect of both factors on this parameter. Two additional drying runs were performed at identical conditions with conventional hot air and low pressure superheated steam, respectively. The influence of drying atmosphere on the total content of phenols was evaluated. A conventional process of extraction by using an aqueous methanol solution was adopted. Analyses for total phenols were performed by spectrophotometry at 715 nm by applying Folin-Denis assay. The leaves dried with superheated steam had approximately 47% higher retention of these compounds. 4 Corresponding
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Papers by Euclides Junior