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Florian Vidal Herv Legay George Goussetis Maria Garcia Vigueras Sgolne Tubau Jean‐Didier Gayrard 《International Journal of Satellite Communications and Networking》2021,39(1):29-46
This paper proposes a methodology to benchmark satellite payload architectures and find the optimal trade‐offs between high flexibility and low complexity. High flexibility would enable the satellite to adapt to various distributions of user terminals on the ground and fulfill the data rate demand of these users. Besides, low complexity is required to keep satellite networks competitive in the context of emerging 5G networks. To estimate the flexibility of a payload, an indicator to characterize the non‐uniformity of user distributions is proposed. Each benchmarked payload may be characterized by a graph relating the throughput to this parameter further denoted . The payload provides the same throughput trends for different scenarios of user distributions with the same parameter. As a consequence, the average capacity of the system may be estimated by (a) calculating the probability distribution of over the orbit and (b) integrating the throughput based on this payload response. It thus results in a straightforward way for benchmarking payloads directly on an estimation of the averaged capacity, accounting for the user distribution over the earth. A simulation platform has been developed to characterize the payload throughput including the implementation of a resource allocation algorithm that accounts for constraints of various payloads. Using this definition and the developed tool, we benchmark a bent‐pipe architecture, a beam hopping architecture and a hybrid beam‐steering architecture for a LEO megaconstellation use case. The methodology showcases the interest for investigating different payload architectures depending on realistic traffic scenario analysis. 相似文献
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J Llop Talaverón D Comas Sugra?es M Tubau Molas L Pastó Cardona M Ibars Alonso 《Canadian Metallurgical Quarterly》1994,9(2):86-98
The purpose of this paper is to introduce a computer program to control the Pharmacy Service Parenteral Nutrition Unit. The program's main feature is a broad menu of possibilities for the clinical monitoring of patients receiving PN. We explain its operation, potential and applications and give some practical examples of some of those applications. 相似文献
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Tubau Elisabet; Hommel Bernhard; López-Moliner Joan 《Canadian Metallurgical Quarterly》2007,136(1):43
The authors argue that human sequential learning is often but not always characterized by a shift from stimulus- to plan-based action control. To diagnose this shift, they manipulated the frequency of 1st-order transitions in a repeated manual left-right sequence, assuming that performance is sensitive to frequency-induced biases under stimulus- but not plan-based control. Indeed, frequency biases tended to disappear with practice, but only for explicit learners. This tendency was facilitated by visual-verbal target stimuli, response-contingent sounds, and intentional instructions and hampered by auditory (but not visual) noise. Findings are interpreted within an event-coding model of action control, which holds that plans for sequences of discrete actions are coded phonetically, integrating order and relative timing. The model distinguishes between plan acquisition, linked to explicit knowledge, and plan execution, linked to the action control mode. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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A Pasternac JF Tubau D Charpin AR Gervais J de Champlain 《Canadian Metallurgical Quarterly》1980,33(4):357-365
A new instrument has been developed and used to determine the effect of various materials on nail flexibility. It repeatedly flexes longitudinal nail sections through 90 degrees and records the number of flexions required to fracture each section. Immersion in water or a phospholipid-water preparation (PLW) greatly increases the flexibility of untreated and lipid extracted nails; immersion in mineral oil does not. Nail flexibility is directly related to the duration of their immersion in water. During water immersion, nail weight increases by 22% of its original weight within 2 h, and then decreases. The rapid increase in nail flexibility during water immersion is related to nail water content. It is possible to prolong the flexibility of previously hydrated nails by the application of PLW or mineral oil. PLW is more effective than water alone in prolonging flexibility of nails extracted with a mixture of acetone, water and acetic acid. 相似文献
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C Cabellos J Ariza B Barreiro F Tubau J Li?ares R Pallarés F Manresa F Gudiol 《Canadian Metallurgical Quarterly》1998,17(4):265-268
Kidney transplantation offers the opportunity of an improved quality of life for those patients suffering from renal failure. Unfortunately, this treatment is not available to all people as this is influenced by the increasing demand for a limited supply of suitable organs. This situation is particularly alarming for the UK's Asian population with their higher susceptibility to end-stage renal failure which has resulted in a greater demand for transplants. Consequently, the proportion of Asians on transplant waiting lists is growing rapidly. Coupled with this are problems of cross-racial tissue type matching which has led to longer waiting times for a transplant. The situation is clear, there is an urgent need to address the number of Asians requiring a kidney transplant otherwise the human and economic costs will be very severe. In the short term there needs to be a greater number of donors coming forward from the Asian communities to increase the pool of suitable organs. In the long term, there needs to be greater attention on preventive strategies to reduce the number of Asians requiring renal replacement therapy. 相似文献
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