136 resultados para Communication networks


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Currently, wireless technology is revolutionizing the way we share information and communicate. The demands for mobility have made wireless technology the primary source for voice communication. Code-division multiple-access (CDMA) is a very popular spread spectrum application due to its claims of low transmission power, higher system capacity, ability to mitigate multipath fading and user interference. In that case, frequency-hopping code-division multiple access (FH-CDMA) has received considerable attention over the past few years. This technique will allow a better performance over a fading channel, message privacy, and immunity to narrowband interference. This paper addresses the characteristics of FH-CDMA in WPAN networks, with an emphasis on frequency-hopped Bluetooth systems. A performance evaluation of FH-CDMA is discussed and simulated. The analysis shows the interaction between the designed parameters and their effect on the network system. Most specifically, the FH-CDMA scheme provides frequency and temporal diversity to combat the effects of interference.

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One of the goals of the ARC funded Eresearch project called Sharing access and analytical tools for ethnographic digital media using high speed networks, or simply EthnoER is to take outputs of normal linguistic analytical processes and present them online in a system we have called the EthnoER online presentation and annotation system, or EOPAS.

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In this paper, we propose a fast adaptive importance sampling method for the efficient simulation of buffer overflow probabilities in queueing networks. The method comprises three stages. First, we estimate the minimum cross-entropy tilting parameter for a small buffer level; next, we use this as a starting value for the estimation of the optimal tilting parameter for the actual (large) buffer level. Finally, the tilting parameter just found is used to estimate the overflow probability of interest. We study various properties of the method in more detail for the M/M/1 queue and conjecture that similar properties also hold for quite general queueing networks. Numerical results support this conjecture and demonstrate the high efficiency of the proposed algorithm.

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Objective: A needs analysis was undertaken to determine the quality and effectiveness of mental health services to Indigenous consumers within a health district of Southern Queensland. The study focussed on identifying gaps in the service provision for Indigenous consumers. Tools and methodologies were developed to achieve this. Method: Data were collected through the distribution of questionnaires to the target populations: district health service staff and Indigenous consumers. Questionnaires were developed through consultation with the community and the Steering Committee in order to achieve culturally appropriate wording. Of prime importance was the adaptation of questionnaire language so it would be fully understood by Indigenous consumers. Both questionnaires were designed to provide a balanced perspective of current mental health service needs for Indigenous people within the mental health service. Results: Results suggest that existing mental health services do not adequately meet the needs of Indigenous people. Conclusions: Recommendations arising from this study indicate a need for better communication and genuine partnerships between the mental health service and Indigenous people that reflect respect of cultural heritage and recognises the importance of including Indigenous people in the design and management of mental health services. Attention to the recommendations from this study will help ensure a culturally appropriate and effective mental health service for Indigenous consumers.

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The reconstruction of power industries has brought fundamental changes to both power system operation and planning. This paper presents a new planning method using multi-objective optimization (MOOP) technique, as well as human knowledge, to expand the transmission network in open access schemes. The method starts with a candidate pool of feasible expansion plans. Consequent selection of the best candidates is carried out through a MOOP approach, of which multiple objectives are tackled simultaneously, aiming at integrating the market operation and planning as one unified process in context of deregulated system. Human knowledge has been applied in both stages to ensure the selection with practical engineering and management concerns. The expansion plan from MOOP is assessed by reliability criteria before it is finalized. The proposed method has been tested with the IEEE 14-bus system and relevant analyses and discussions have been presented.