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排序方式: 共有1001条查询结果,搜索用时 15 毫秒
41.
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
42.
43.
Barbara Walther Aaron M. Lett Alessandra Bordoni Lidia Toms‐Cobos Juan Antonio Nieto Didier Dupont Francesca Danesi Danit R. Shahar Ana Echaniz Roberta Re Aida Sainz Fernandez Amlie Deglaire Doreen Gille Alexandra Schmid Guy Vergres 《Molecular nutrition & food research》2019,63(21)
Nutritional research is currently entering the field of personalized nutrition, to a large extent driven by major technological breakthroughs in analytical sciences and biocomputing. An efficient launching of the personalized approach depends on the ability of researchers to comprehensively monitor and characterize interindividual variability in the activity of the human gastrointestinal tract. This information is currently not available in such a form. This review therefore aims at identifying and discussing published data, providing evidence on interindividual variability in the processing of the major nutrients, i.e., protein, fat, carbohydrates, vitamins, and minerals, along the gastrointestinal tract, including oral processing, intestinal digestion, and absorption. Although interindividual variability is not a primary endpoint of most studies identified, a significant number of publications provides a wealth of information on this topic for each category of nutrients. This knowledge remains fragmented, however, and understanding the clinical relevance of most of the interindividual responses to food ingestion described in this review remains unclear. In that regard, this review has identified a gap and sets the base for future research addressing the issue of the interindividual variability in the response of the human organism to the ingestion of foods. 相似文献
44.
Aoues Younès Pagnacco Emmanuel Lemosse Didier Khalij Leila 《Structural and Multidisciplinary Optimization》2017,55(4):1471-1482
Structural and Multidisciplinary Optimization - The reliability-based design optimization (RBDO) aims to find the most balanced design through a compromise between cost and safety when... 相似文献
45.
Free-living amoebae (FLA) are protozoa that can be found in water networks where they prey on bacteria within biofilms. Most bacteria are digested rapidly by phagocytosis, however some are able to survive within amoebae and some are even able to multiply, as it is the case for Legionella pneumophila. These resisting bacteria are a potential health problem as they could also resist to macrophage phagocytosis. Several publications already reported intra-amoebal bacteria but the methods of identification did not allow metagenomic analysis and are partly based on co-culture with one selected amoebal strain. The aim of our study was to conduct a rRNA-targeted metagenomic analysis on amoebae and intra-amoebal bacteria found in drinking water network, to provide the first FLA microbiome in environmental strains. Three sites of a water network were sampled during four months. Culturable FLA were isolated and total DNA was prepared, allowing purification of both amoebal and bacterial DNA. Metagenomic studies were then conducted through 18S or 16S amplicons sequencing. Hartmannella was by far the most represented genus of FLA. Regarding intra-amoebal bacteria, 54 genera were identified, among which 21 were newly described intra-amoebal bacteria, underlying the power of our approach. There were high differences in bacterial diversity between the three sites. Several genera were highly represented and/or found at least in two sites, underlying that these bacteria could be able to multiply within FLA. Our method is therefore useful to identify FLA microbiome and could be applied to other networks to have a more comprehensive view of intra-amoebal diversity. 相似文献
46.
Influence of the amorphous phase molecular mobility on impact and tensile properties of polyamide 6,6 下载免费PDF全文
In this work, the relationship between molecular mobility of polyamide 6,6 amorphous phase and mechanical properties is studied. PA66 formulations having different glass transition temperatures (Tg) obtained by additivation, chemical modification of the polyamide chains, and/or water conditioning at different hygrometry levels, are considered. The main emphasis is put on the impact strength, as measured by instrumented Charpy impact tests over a broad temperature range. It is observed that the brittle‐tough transition temperature TB/T is closely correlated with the Tg of the samples rather than to the β secondary relaxation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43457. 相似文献
47.
An overview of recent developments in volatile compounds analysis from edible oils: Technique‐oriented perspectives 下载免费PDF全文
48.
Analysis of target volatile compounds related to fishy off‐flavor in heated rapeseed oil: A comparative study of different headspace techniques 下载免费PDF全文
49.
Alexis Prieto Mlissa Landart Olivier Baudoin Nuno Monteiro Didier Bouyssi 《Advanced Synthesis \u0026amp; Catalysis》2015,357(13):2939-2943
The copper‐catalyzed C(sp2) H trifluoromethylation of N,N‐disubstituted hydrazones using the Togni reagent is demonstrated to proceed efficiently for aliphatic aldehyde‐derived substrates. The success of the reactions relied on the choice of the N,N‐diphenylamino group as the terminal hydrazone amino group where N,N‐dialkylamino groups were preferred for (hetero)aromatic aldehyde‐derived substrates. In addition, the trifluoromethylated N‐arylhydrazones are shown to be ideal substrates for Fischer indole synthesis allowing a straightforward, three‐step access to 2‐trifluoromethylindole derivatives from simple aldehydes.
50.
基于Livermore模型CT图片构建人体躯干数字体模及其在肺部计数器虚拟刻度中的应用 总被引:2,自引:0,他引:2
基于Livermore 人体躯干物理模型CT图片构建数字体模,并结合蒙特卡罗程序MCNP对一套由四个宽能高纯锗探测器(BEGe)构成的肺部计数器进行了虚拟刻度.首先,利用点源(241Am,137Cs,60Co,54Mn,57Co,109Cd) 实验数据,对高纯锗晶体尺寸进行调整以获得正确的探测器几何参数,在γ射线能量13.9 keV~1332.5 keV范围内,调整后四个探测器全能峰效率实验测量的平均值与蒙特卡罗计算值的差别在±10%范围内.之后,对不同胸壁厚度(CWT=19 mm, 25 mm, 30 mm, 43 mm)躯干体模进行CT扫描获得其CT图片,利用Dosigray软件对CT图片进行分割后,连同探测器几何描述文件输入到OEDIPE软件,生成数字体模虚拟刻度用MCNP输入程序.最后,利用241Am、152Eu肺部源对数字体模虚拟刻度结果进行了实验验证,结果表明:在59.5 keV~1408 keV能量范围内,虚拟刻度结果与实验结果的差别在±10%之间;对于17.5 keV能量,差别在±30%之间. 相似文献