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261.
Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and integrated with the circuits of rectennas. The: double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the antenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches. Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200Ω is measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications. 相似文献
262.
为了提供更好的基于流的计费和策略控制,3GPP在IMSR7版本中提出策略与计费控制体系架构,其基本思路是将IMSR6版本中的策略决策功能实体和计费策略功能实体合并为R7中的策略与计费规则功能实体。本文首先简要介绍了IMSR6和IMSR7控制模型;然后重点分析了与策略控制、计费控制相关Gx接口、Rx接口的接口消息及其参数。分析表明,通过定义特定AVP,实现了IMSR6向IMSR7策略控制和计费控制接口的平滑演进。 相似文献
263.
李涛 《电信工程技术与标准化》2008,21(8):27-31
本文通过对中国移动通信集团新疆有限公司的GPRS网络结构及容量需求分析入手,提出了容量备份方案,有效解决了业务发展带来的容量不足问题,并且通过网络结构的调整,使得GPRS网络更加安全可靠,大幅度提升了网络的健壮性,为业务高效稳定的发展奠定了基础。 相似文献
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Mengya Kong Yuyang Gu Yingjie Chai Jiaming Ke Yulai Liu Xincheng Xu Zhanxian Li Wei Feng Fuyou Li 《中国科学:化学(英文版)》2021,(6):974-984
Luminescence nanothermometry makes non-invasive and real-time temperature readings possible in living animals. However,the spectral fluctuation in tissues and fluids, as well as the interaction between fluorophores and environment hinders accuracy of the thermometry. Here, we report a luminescence lifetime-based nanothermometry which specifically addresses this problem. A temporal based calibration(lifetime sensing) in the NIR range, an endogenous thermal response as well as a polymer encapsulation evading environmental factors, altogether help to pinpoint temperature in vivo. Thanks to the highly condensed NdYb ions in a well-protected tiny core-shell nanocrystal(overall 11 nm), a temperature sensitivity about 2.07% K~(-1)(with 5% Yb~(3+) doped nanoparticles) and an accuracy of 0.27 K(with 25% Yb~(3+) doped nanoparticles) in biological fluids are achieved.Hopefully, combining thermally activated energy transfer nanothermometer with anti-interference lifetime thermometry would provide a more accurate temperature measurement for biological and preclinical studies. 相似文献
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As an important part of satellite communication network, LEO satellite constellation network is one of the hot research directions. Since the nonuniform distribution of terrestrial services may cause inter-satellite link congestion, improving network load balancing performance has become one of the key issues that need to be solved for routing algorithms in LEO network. Therefore, by expanding the range of available paths and combining the congestion avoidance mechanism, a load balancing routing... 相似文献
269.
目前,MPEG-2/4 AAC已成为广泛使用的一种音频编码压缩标准,但是MPEG-2/4 AAC标准的音频编码器存在算法复杂度高、计算量和时闻延迟大等缺点,无法满足实时性要求.从MPEG-2/4 AAC音频编码器的内部结构入手,分析了制约其实时性能的主要环节,就心理声学模型、滤波器组、量化与编码模块3个部分,归纳了当前MPEG-2/4 AAC实时音频编码器实现与优化研究的相关内容和进展,给出了若干算法的主要思想、改进结果和优缺点.在此基础上,提出了进一步优化MPEG-2/4 AAC实时性能的研究方向,以及需要解决的主要问题. 相似文献
270.
Ying Lv Bofeng Zhang Guobing Zou Xiaodong Yue Zhikang Xu Haiyan Li 《Entropy (Basel, Switzerland)》2022,24(7)
Domain adaptation aims to learn a classifier for a target domain task by using related labeled data from the source domain. Because source domain data and target domain task may be mismatched, there is an uncertainty of source domain data with respect to the target domain task. Ignoring the uncertainty may lead to models with unreliable and suboptimal classification results for the target domain task. However, most previous works focus on reducing the gap in data distribution between the source and target domains. They do not consider the uncertainty of source domain data about the target domain task and cannot apply the uncertainty to learn an adaptive classifier. Aimed at this problem, we revisit the domain adaptation from source domain data uncertainty based on evidence theory and thereby devise an adaptive classifier with the uncertainty measure. Based on evidence theory, we first design an evidence net to estimate the uncertainty of source domain data about the target domain task. Second, we design a general loss function with the uncertainty measure for the adaptive classifier and extend the loss function to support vector machine. Finally, numerical experiments on simulation datasets and real-world applications are given to comprehensively demonstrate the effectiveness of the adaptive classifier with the uncertainty measure. 相似文献