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Telecommunications, 2003. ConTEL 2003. Proceedings of the 7th International Conference on

Date 11-13 June 2003

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  • Proceedings of the 7th International Conference on Telecommunications ConTEL 2003 [front matter]

    Publication Year: 2003 , Page(s): i - xvi
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    Freely Available from IEEE
  • Modeling of optical link using finite-difference method

    Publication Year: 2003 , Page(s): 383 - 388 vol.2
    Cited by:  Papers (1)
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    Propagation of optical pulses in nonlinear dispersive lossy fiber is numerically analyzed using finite-difference method. Nonlinear Schrodinger equation is solved using split-step method and Crank-Nicholson finite-difference scheme. Polarization mode dispersion model, based on coupled nonlinear Schrodinger equations, is included into calculations. The models of erbium doped fiber amplifiers in time domain and filters in frequency domain are developed in order to simulate the most important components of optical link. The computer program named FiberProp is developed based on these models. The examples of soliton-soliton interaction, Gordon-Haus effect, as well as their compensation in 40 Gb/s soliton systems are given. The signal transmission in the presence of polarization mode dispersion is also shown. View full abstract»

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  • Benes configurations of circuit in node with space cross connections for transparent optical networks

    Publication Year: 2003 , Page(s): 389 - 393 vol.2
    Cited by:  Papers (1)
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    There is a consideration of the transparent optical network with space cross connections in nodes realized with Benes configuration of circuit. The equations for the Benes configuration are recalculated and improved for relations among number of entrances and exits in circuit N and number of direct symmetric two channel couplers C, number of voltage electrode circuits V, characteristic of attenuation A and characteristic of signal to noise ratio SNR. The numerical analyze has been performed for Benes configuration of direct two channel symmetric couplers on circuit for space division multiplexing and cross connecting relating to specified essential characteristics. View full abstract»

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  • Atmospheric effects on optical wireless links

    Publication Year: 2003 , Page(s): 395 - 401 vol.2
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB)  

    The optical coherent wave propagation is affected by the atmosphere in many ways. Several theoretical models for propagation of light through the atmosphere are well known. To predict link availability in different climate zones it is necessary to do field tests for data acquisition. Therefore reliability- and availability-tests on free space optics (FSO)-systems have been done at the Department of Communications and Wave Propagation (by the research-group "OptiKom"). There have been obtained evaluation results for commercial available and also for self-developed optical point-to-point and point-to-multipoint FSO-systems. Test data at 155 Mbps (STM-1) were transmitted from one FSO-unit to a distant (2.7 km) FSO-unit. The received data were sent back (loop) to the first unit. The primary interest in this long-time investigation was the time of link failure, because it turned out that BERs be low in general, less than 10/sup -8/ at very bad weather conditions in winter and less than 10/sup -12/ at clear sky. In a second measurement campaign the influence of turbulences in the air was investigated. The measurements clearly show variations in the fluctuation of the incoming optical power during a day. In principle there are two periods with strong variations, during the day and during the night, and two periods of rather stable air, these are around sunset and sunrise. The power variations have the highest amplitude and show the fastest changes at noon and they are less distinct and show slower changes in the night. As a medium value power variations of 4 dB over the distance of 2.7 km were measured in summer. The duration of fades/scintillations was in the order of 4 to 60 milliseconds at daytime and about 10 to 150 ms in the night. View full abstract»

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  • Performance analysis of first-fit wavelength assignment algorithm in optical networks

    Publication Year: 2003 , Page(s): 403 - 409 vol.2
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (423 KB)  

    This paper proposes a new analytical technique for the performance analysis of all optical networks which use the first-fit algorithm for wavelength assignment. We analyze the wavelength usage on the links to calculate the blocking probability of a source destination pair, taking into account wavelength correlation and load correlation between links. Our model is accurate even in a system with large number of wavelengths. View full abstract»

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  • Wavelength assignment in GMPLS networks with multiclass service

    Publication Year: 2003 , Page(s): 411 - 418 vol.2
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    In generalized multiprotocol label switching (GMPLS) networks, the routing and wavelength assignment (RWA) problem is important to realize the quality of service (QoS). In this paper, we put forward the blocking probability model with sparse wavelength conversion. As for the wavelength assignment subproblem, we formulate it as a Markov decision process (MDP) in order to realize the multiclass service and the resource allocation dynamically. And the simulation results show that the method not only provides service differentiation but also reduces the overall average blocking probability. View full abstract»

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  • A multicast reinforcement learning algorithm for WDM optical networks

    Publication Year: 2003 , Page(s): 419 - 426 vol.2
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    The popularity of multimedia applications has resulted in increased interest in efficient implementation of multicasting. Wavelength division multiplexing (WDM) is a promising technology for backbone networks, because they provide high bandwidth and methods for control and management. Since not every switches are equipped with wavelength conversion facility, it is a really important issue to design multicast trees, which result in less blocking-probability in the networks. In this paper we propose a reinforcement learning algorithm for the multicast routing and wavelength assignment (MRWA) problem. This distributed algorithm is compared with a multicast algorithm used by a well-known multicast protocol (MOSPF). The proposed algorithm is a good solution to the (MRWA) problem, since it reduces the blocking probability of the multicast communication requests. View full abstract»

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  • IP based optical control plane

    Publication Year: 2003 , Page(s): 427 - 433 vol.2
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    The exponential growth in demand for Internet service is reshaping telecom industry and driving the model for next generation infrastructure towards converged, multiservice network with IP-over-glass at its heart. Current vision of the Internet transport network is a model with routers, switches, optical crossconnects (OXCs), DWDM optical line systems (OLSs), and add-drop multiplexers (ADMs) that use a common control plane [e.g., generalized MPLS (GMPLS)] to dynamically provision resources and to provide network survivability using protection and restoration techniques. The idea is to base this common control plane on existing IP/MPLS technology. Some new protocols have to be created (like LMP), and also some existing protocols have to be enhanced (like OSPF and IS-IS). In this article we point out needed modifications and also discuss some issues that still need to be solve. View full abstract»

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  • Generalized MPLS - an overview

    Publication Year: 2003 , Page(s): 435 - 442 vol.2
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    GMPLS, being developed by IETF and OIF, has been proposed to address traffic engineering to a variety of networking technology, and to serve in a variety of network signaling layers, extending capabilities beyond those networks that are only packet-based. GMPLS is an extension of MPLS and it provides a control plane for devices that switch in the time, packet, wavelength, and fiber domains. This common control plane promises to simplify network operation and management by automating end-to-end provisioning of connections, managing network resources, and providing QoS. One of the main architecture enhancements proposed by GMPLS is the complete separation of the control and data planes, allowing high performance, intelligent networking while simplifying networks by combining transport and multiservice switching into a single layered network. View full abstract»

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  • The application of Steiner trees to delay constrained multicast routing: a tabu search approach

    Publication Year: 2003 , Page(s): 443 - 448 vol.2
    Cited by:  Papers (6)
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    With today's development of information technology comes the increased development of numerous real-time multimedia network applications. Some examples include video and teleconferencing, telemedicine, video-on-demand, distance education, applications in finance, etc. Several of these applications require multicasting with a certain quality of service (QoS). One of the most important QoS parameters is the maximum end-to-end delay from the source to any destination in a multicast session. This paper deals with the problem of delay-constrained multicast routing (DCMR). The DCMR problem can be reduced to the constrained minimum Steiner tree problem in graphs (CMStTG). Since the minimum Steiner tree problem in graphs (MStTG) has been proven to be NP-complete, several heuristics have been developed for solving MStTG and CMStTG. In this paper, we suggest a tabu search heuristic for the DCMR problem. This heuristic was developed on the basis of a tabu search heuristic designed for solving unconstrained minimum Steiner tree problems. Preliminary testing on data from a publicly available library, SteinLib, has shown that this heuristic gives near optimal solutions in moderate time and a moderate number of iterations for medium sized problems (50-100 nodes). Comparing with a well known algorithm for solving the CMStTG problem, tests have shown that our tabu search heuristic is superior in quality for medium sized problems. View full abstract»

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  • Applications of service curve theory

    Publication Year: 2003 , Page(s): 449 - 453 vol.2
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    In this paper, we study well-known utilization-based admission control schemes which are derived by ad-hoc mathematical manipulations in previous literatures. We show that the same results can easily be achieved by using service curve theory (SCT). We also investigate the problem of providing statistical quality of service (QoS) in wireless network. With the same idea as the service curve theory, we can find an approximation formula to estimate drop probabilities in the Cruz (1995) and Agarwal et. al. (1999) delay system. In general, this analysis methodology is effective and can be used in the delay analysis of other applications. View full abstract»

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  • On the quality and performance of active networking based media transcoding in multicast sessions

    Publication Year: 2003 , Page(s): 455 - 462 vol.2
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    In this paper an advanced network service is described, which enables customisation of data services and adds extra flexibility to the network's data transporting capabilities. More specifically, a multicast service providing media transcoding inside the network is detailed. Whereas in traditional multicast services only one specific version of the data is available, in this service customers can choose from a range of different versions of the data. Customers can select a specific version according to their own wishes or to the capabilities of their connection and terminal. Based on active networking concepts, the different versions of the streamed data are created inside the network, by performing transformations of the original data in the network nodes. As a consequence, server load can be reduced and bandwidth usage in the multicast tree can be optimised. After the introduction of the multicast tree set-up strategies for this service, the focus of the discussion will be on performance aspects and on the resulting quality. In this discussion, a voice streaming service is considered, providing different encodings of the voice data. View full abstract»

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  • Network resource management for the services with variable QoS requirements

    Publication Year: 2003 , Page(s): 463 - 467 vol.2
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    A development of recent complex and demanding applications continuously increases the requirements on a quality of the service, provided by communication's infrastructure. The variable QoS requirements could become from variable demands of an user and an application and from the variable network characteristics, respectively. It is very possible that the same complex applications and the services will be executed by different level of quality that would satisfy every single user. A proper relation between the quality and the cost of the service will result in adequate user satisfaction. This paper introduces an experimental laboratory QoS model which efficiently manages the variable QoS requirements, caused by the user or by the network, respectively. A few laboratory QoS classes were proposed together with the simple mechanisms necessary to achieve desired QoS. The measurements confirm the efficient management of the network resources, by different QoS requirements. View full abstract»

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  • CDMA2000 for a satellite environment

    Publication Year: 2003 , Page(s): 469 - 473 vol.2
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    CDMA2000 is the American telecommunication standard for 3G. It is a wideband spread spectrum radio interface designed to provide high data rates and multimedia services to the wireless user. It has two modes of operation, 1X (DS-CDMA) and 3X (MC-CDMA). In this paper, we compare the forward link performance of the two modes for a satellite environment. In order to focus our comparison on the transmission technology (DS-CDMA, MC-CDMA), two services with similar data rates and the same coding scheme, are studied. View full abstract»

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  • Quality of service management in IP networks

    Publication Year: 2003 , Page(s): 475 - 481 vol.2
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    The DiffServ architecture provides a scalable mechanism for QoS introduction in an IP network. The idea of DiffServ is based on the aggregation of traffic flows at an ingress (or egress) point of a network and IP packet marking for different priority flows, according to several classification criteria. In this paper the problem of the improvement and fairness of absolute QoS provisioning to paths established along a DiffServ network on a per router basis is considered. The service rate reconfiguration problem of a router's output link is formally defined, mathematically formulated and solved by means of efficient heuristic algorithms, providing good solutions in reasonable time. Finally, an indicative set of results is provided and concluding remarks are made. View full abstract»

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  • Proportional delay differentiation employing the CBQ service discipline

    Publication Year: 2003 , Page(s): 483 - 489 vol.2
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    The DiffServ architecture provides a scalable mechanism for QoS introduction in a TCP/IP network. The idea of DiffServ is based on the aggregation of traffic flows at an ingress (or egress) point of a network and the IP packet marking for different priority flows, according to several classification criteria. Two approaches exist in the DiffServ architecture: the absolute and the relative. In absolute DiffServ, an admission control scheme is used to provide QoS guarantees as absolute bounds of specific QoS parameters. The relative DiffServ model provides QoS guarantees per class expressed with reference to guarantees given to the other classes defined. Our study targets at providing relative proportional delay differentiation service based on class based queue (CBQ) scheduler. The main idea is to frequently adjust the service rates allocated to classes of a CBQ scheduler in order to achieve relative delay spacing among classes. The simulation experiments conducted show that our model can attain relative delay, provided that the required delay differentiation parameters (DDPs) are feasible. View full abstract»

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  • BFC heuristic approach for constraint-based path selection in QoS routing

    Publication Year: 2003 , Page(s): 491 - 496 vol.2
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    In DiffServ networks QoS-based routing for only one QoS measure (e.g. constrained bandwidth) is known as the restricted shortest path (RSP) problem. It can be treated as the minimum cost network flow problem in the multicommodity single source multiple destination network. For constrained-based path selection in QoS routing with N quality of service levels in function to serve predicted traffic demands, an efficient heuristic algorithm is being developed. The algorithm approach is of BFH (backward-forward heuristic) type. The optimal flow theory enables separation of these extreme flows which can be a part of an optimal expansion solution from those which cannot be. Algorithm is compared with algorithm based on exact approach. In all numerical test-examples the best possible result is achieved, but with significant reduction of complexity and computation savings. View full abstract»

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  • Improving quality of service in cellular IP domains

    Publication Year: 2003 , Page(s): 497 - 504 vol.2
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    In today's networks there is a convergence to an integrated IP-based network. lETF's mobile IP handles global macromobility in the IP based infocommunication networks. It is, however, not adapted to micromobility environment; in this local mobility management there are several proposals both for IPv4 and IPv6. These approaches use local entities to support mobility in a well-defined area (domain), and hide the movements inside the domain from mobile IP. Future communication networks will transport not only voice calls but also other multimedia traffic. This type of data is sensible for packet delay, delay variation, packet loss, etc. To meet the requirements of users transmitting such data through the network we have to support better quality of service. In this paper we introduce an efficient solution for improving quality of service in cellular IP micromobility domains. We also show simulation results for our new method. View full abstract»

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  • Measurement and analysis of users' perception of QoS for IP telephony service

    Publication Year: 2003 , Page(s): 505 - 512 vol.2
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    Along with a technological evolution of the Internet that enables providers to offer ever-higher access speeds, applications' demands for the quality of service (QoS) are growing as well. Services like IP telephony are highly dependent on the quality of the transport services as well as the application QoS-awareness. Users' acceptability of the service and their willingness to pay is depending on their perception of the service and its quality. Therefore is users' perception of the offered service and its quality important for the provider, so he can adjust and design his network to fulfill users demands. This paper presents the results of the subjective testing of a user perception of a quality that IP telephony service is delivered with. Both listening and conversational tests are considered. The results are further used to test the existing commercial QoS mechanisms and their suitability for the immediate service offering. The analysis of tests enables a provider offering IP telephony to understand not only technical features of the service, but also to recognize the users needs, behavior and their acceptance of the service and its quality. Furthermore, test results may be used as a basis when designing a network supporting the IP telephony service while using existing QoS mechanisms. View full abstract»

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  • Dynamic and XML-based river navigation maps for the Web

    Publication Year: 2003 , Page(s): 513 - 520 vol.2
    Cited by:  Patents (1)
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    In this paper, an efficient generation of river navigation maps based on user input on the Web is described. XML-based approach can provide concepts and solutions to significantly improve the overall quality of the Web application relating to map maintenance, performance and usability problems. Therefore, dynamic map generation capabilities of the chosen Internet GIS are analyzed in order to optimize the application system architecture. The main principles and components of XML-based map generation are explained. Web application for efficient presentation of waterway signs and river navigation marks was developed by using the XML-based approach in agreement with the European Inland ECDIS standard for creation and exchange of digital maps. The application architecture is based on the three-tier client-server architecture for the Web. Detailed application flow procedures are described. The concrete application examples concern information about the position, characteristics and functioning of different waterway signs and river navigation marks. These activities are part of the Croatian programme for River Information Services (CRORIS). View full abstract»

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  • Building enterprise information system using model driven architecture on J2EE platform

    Publication Year: 2003 , Page(s): 521 - 526 vol.2
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    Enterprise information systems can be very complex since they provide interoperability for geographically distributed facilities and other business units with distinct business functions and mutual dependencies. Building a system of that complexity is not just a programming effort but almost a multidisciplinary approach to software engineering process. The OMG's model driven architecture (MDA) is one such approach. It defines the approach to IT system specification that separates the specification of the system functionality from the specification of the implementation of that functionality on a specific technology platform. In this paper, we describe the process of building a healthcare enterprise information system using MDA approach on Java 2 enterprise edition (J2EE) platform. View full abstract»

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  • Telematic requirements for a mobile and wireless healthcare system derived from enterprise models

    Publication Year: 2003 , Page(s): 527 - 534 vol.2
    Cited by:  Papers (2)
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    A challenge of current innovation in healthcare processes is to improve the time to treatment. This paper addresses the benefits of telematic services and mobile & wireless devices such as vital sign sensors and head mounted cameras for healthcare processes. It explores the telematic requirements for a distributed healthcare environment of body area networks of the mobile devices which are connected by wireless (public) networks (e.g. GPRS and UMTS) to healthcare centres. Our main contribution is the development of enterprise models, which are expressed in terms of the unified modelling language, for the purpose of identification and justification of the telematic system requirements. The developed enterprise models separate organizational modelling concerns such as the separation of medical roles from the agents acting in these roles. This separation enables roles to be dispatched virtually to a point of care without transporting along with all the agents, but it requires support of a telematic system to bridge the distance gap. We validate the proposed models against a trauma team scenario and consequently obtain the telematic system requirements which enable improved time to treatment for emergency services. View full abstract»

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  • Automating conceptual design of Web warehouses

    Publication Year: 2003 , Page(s): 535 - 542 vol.2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB)  

    Web warehousing plays a key role in providing the managers with up-to-date and comprehensive information about their business domain. On the other hand, since XML is now a standard de facto for the exchange of semistructured data, integrating XML data into web warehouses is a hot topic. In this paper we propose a semiautomated methodology for conceptual design of web warehouses from XML sources modeled by XML schemas. In our methodology, conceptual design is carried out by first creating a schema graph, then navigating the functional dependencies expressed by its arcs in order to derive a correct multidimensional representation. The problem of correctly inferring the needed information is solved by querying the source XML documents and, if necessary, by asking the designer's help. The approach is implemented in a prototype that reads an XML schema and produces in output the conceptual scheme for the Web warehouse. View full abstract»

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  • Modeling ebXML registry service architecture

    Publication Year: 2003 , Page(s): 543 - 550 vol.2
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    Department of Telecommunications, Faculty of Electrical Engineering and Computing, University of Zagreb works on the research project named "networked economy", supported by Croatian Ministry of Science and Technology. The project is also recognized by corporate domain and was made a part of an e-business initiative by the Agrokor group. The Agrokor's intention is to use the ebXML registry/repository layer as the central point of integration among the many Agrokor's affiliates and partners. We have considered different approaches toward ebXML specifications describing registry/repository layer, not only to conform to specifications, but also with vision that careful architecture modeling will enable modularity and flexibility of our solution. This could be vital, as we must bear in mind that specifications are surely going to be improved over certain period of time. This paper describes modeling ebXML registry/repository architecture and concentrates on its registry service part. View full abstract»

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  • Implementation of the ebXML registry client for the ebXML registry services

    Publication Year: 2003 , Page(s): 551 - 556 vol.2
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (402 KB)  

    The implementation of the ebXML registry services is a part of a research project at the University of Zagreb, aimed at defining a strategy for the adoption of e-business in Croatia. Implementing the ebXML registry/repository is a vital step as it implements a standard mechanism for registering, storing and retrieving data about business partners relevant for conducting e-business. This paper describes an implementation of the ebXML registry client as a diagnostic tool to test and debug the ebXML registry/repository implementation under development. The client can generate arbitrary submit objects requests to the registry services. It guarantees the conformance of the requests with the OASIS/ebXML registry services specification. View full abstract»

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