Enterprise resource planning (ERP) systems have emerged as the core of successful information management and the enterprise backbone of organizations. The difficulties of ERP implementations have been widely cited in the literature but research on the critical factors for initial and ongoing ERP implementation success is rare and fragmented. Through a comprehensive review of the literature, 11 factors were found to be critical to ERP implementation success ± ERP teamwork and composition; change management program and culture; top management support; business plan and vision; business process reengineering with minimum customization; project management; monitoring and evaluation of performance; effective communication; software development, testing and troubleshooting; project champion; appropriate business and IT legacy systems. The classification of these factors into the respective phases (chartering, project, shakedown, onward and upward) in Markus and Tanis' ERP life cycle model is presented and the importance of each factor is discussed.

Abstract.This paper discusses the representation of the Hecke algebra of GL2(F

The multi-user multi-relay system is investigated in this paper. Multi-user precoding is utilized at the source node to mitigate the interference among data streams. Since the transmitting power of relay nodes is constrained independently, the interference among data streams can not be completely mitigated at the destination nodes. An energy-efficient relaying scheme is proposed at relay nodes to mitigate the inter-stream interference and save the transmitting power of relay nodes. The average saved transmitting power is derived from simple system parameters. Simulation results demonstrate that the energyefficient relaying scheme outperforms the conventional simple relaying scheme on the system capacity, reliability performance and the transmitting power of relay nodes.

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