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111.
5G建设元年已经开始,为节约建设成本,利旧现网室分设备,本文分析了目前室内覆盖的网络现状,研究了现有室分系统面向5G演进的可行性及改造方案,最后以5G价值判断及4G流量需求为场景划分,结合现网各类室内分布系统的特点,给出了面向场景的5G 2.6GHz频段室分系统演进策略。 相似文献
112.
随着蓝牙通信模组的小型化和低功耗、低成本特点逐步推进,应用于室内的蓝牙定位算法和模型逐渐成熟。本文以室内栅格化蓝牙定位为定位基础,通过机器学习方式,对获取到的多单元蓝牙设备定位信息进行迭代校准。本设计能够形成精准的室内栅格化位置信息。 相似文献
113.
An HRGC/ECD method is presented which permits the identification and quantitation of individual components of pyrethrins (cinerin I, jasmolin I, pyrethrin I, cinerin II, jasmolin II, pyrethrin II) in indoor matrices (airborne particles, house dust) after application of an agent containing pyrethrum. In order to prepare calibration standards for the individual components of the pyrethrum extract, the pyrethrins were isolated hy semi-preparative HPLC and their content and purity were determined by 1H-NMR spectroscopy. 相似文献
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Summary Volatile organic compounds (VOC) are present in indoor air at concentrations generally higher than in outdoor air. In this study VOC concentrations in the air of two classrooms differing in insulation, and in the expired air of children in them, were investigated. Qualitative and quantitative determinations were done by gas chromatography-mass spectrometry techniques. Differences in the concentrations of VOC in indoor air and in the expired air of the children were linked to the endogeneous or exogeneous origin of the compounds, to the activities of the children and to the quality of indoor-outdoor air exchanges. 相似文献
117.
Vaclav Synek 《Talanta》2007,71(3):1304-1311
This paper continues in studying the coverage probability of uncertainty intervals. It particularly investigates the uncertainty intervals determined in compliance with the GUM and EURACHEM Guide in case of the results uncorrected for the systematic error, since the experimental bias has been found insignificant. The problem is solved for known values of the experimental bias, its standard uncertainty and the overall standard uncertainty. The obtained findings given in graphs and tables show that coverage probability of the uncertainty intervals defined by expanded uncertainty about the uncorrected results can considerably fall below the chosen level of confidence; this depression depends only on the ratio of the bias and the overall uncertainty. The bias uncertainty does not directly influence this depression, it only determines whether the bias is significant or not and thereby determines whether the results will be corrected or not. The paper proposes three methods how to remove this coverage probability reduction: to apply a higher level of confidence in the significance test, to correct the results with the insignificant but too high biases and to compute the uncertainty intervals defined by some type of the uncertainties enlarged with the insignificant bias. 相似文献
118.
In this paper, we introduce a novel approach for improving performance of fingerprinting based indoor localization. Our proposal is a two-step procedure in which severe variation in the received signal strength is minimized during the first step via convex optimization, and distance metric learning is then used to estimate a more accurate location. Numerical results show that our proposal outperforms existing techniques in terms of accuracy and reliability. 相似文献
119.
分析了确定参考信号接收功率(RSRP)边缘覆盖电平需要考虑的各种因素,包括边缘覆盖概率、阴影衰落余量、快衰落余量、干扰余量等,并根据TD-LTE的技术特点给出了取值建议。最后给出了RSRP在不同覆盖概率目标值时的建议值,同时对确定边缘覆盖电平一些需要注意的问题进行了说明。 相似文献
120.
Fe‐TiO2 photocatalysts with different ratios of Fe to Ti were prepared by a sol‐gel process using tetra‐n‐butyl titanium and iron(III) nitrate as Ti and Fe sources, respectively. The photocatalytic function of the prepared composites was examined for the decomposition of low‐concentration(0.1 ppm) airborne benzene, toluene, ethyl benzene, and o‐xylene(BTEX). The Fe‐TiO2 composites were characterized by energy dispersive X‐ray spectroscopy, X‐ray diffraction, UV‐visible spectroscopy, and Fourier transform infrared spectroscopy. The time‐series ratios of outlet to inlet concentrations of toluene, ethyl benzene, and o‐xylene target chemicals, as determined by the Fe‐TiO2 composites under visible light exposure, were lower than or similar to those of the reference TiO2 photocatalyst. Moreover, the time‐series ratios of outlet to inlet concentrations of the three compounds, as determined for the Fe‐TiO2 composites, increased as the ratio of Fe to Ti increased from 0.001 to 0.010. In contrast, under UV exposure, the time‐series ratios of outlet to inlet concentrations of BTEX, determined for the Fe‐TiO2 composites, were similar to or higher than those obtained from the reference TiO2 photocatalyst. Fe‐TiO2 composites with an optimal Fe to Ti ratio could effectively be applied for the purification of low‐concentration aromatic organic pollutants. 相似文献