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Tingting Han,Xinyi Guo,Botao Zhou,Xin Hao 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.2
Northern Central China (NC China) is a seriously arid region. Precipitation variations are vital for environmental protection and socio-economical development. This study investigates the recent changes in summer heavy precipitation (HP) events over NC China and associated atmospheric circulation anomalies. Compared with the period of 1986–2002, the HP amount and frequency both significantly increase during 2003–2016, contributing to the shift to increase in total summer precipitation amount. After the early 2000s, the Northwest Pacific subtropical high becomes intensified and shifts westward and northward, leading to significant moisture convergence anomalies over NC China and divergence anomalies over Northwest Pacific. Therefore, the net moisture budget dramatically increases since the early 2000s. Further results show that the strengthened net moisture influx across the southern boundary contributes dominantly to the increased net moisture budget, especially at the lower level. Despite a relatively small magnitude, the intensified westerly current across western boundary makes a dominant contribution at middle and upper layers. Additionally, the strengthened westerly and easterly anomalies occupy northern and southern China, respectively, along with the eastward expansion of westerly jet stream region. Thus, the lower-level convergence and upper-level divergence both intensify, and further trigger enhanced ascending movement. These conditions jointly contribute to the inter-decadal change in HP events over NC China after the early 2000s.
Outage Probability Analysis of the VAF Relaying M2M Networks
Lingwei Xu,Hao Zhang,Tingting Lu,T. Aaron Gulliver 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5
Based on variable-gain amplify-and-forward (VAF) relaying scheme, the lower bound on outage probability (OP) of the mobile-relay-based mobile-to-mobile (M2M) networks over N-Nakagami fading channels is investigated in this paper. By the method of the harmonic mean of positive random variables, the exact closed form expression of the lower bound on OP is derived. Then the OP performance under different conditions is evaluated through numerical simulations. The numerical simulation results coincide with the theoretical results well, and the accuracy of the analytical results is verified. The simulation results showed that: the fading coefficient, the number of cascaded components, the relative geometrical gain, and the power-allocation parameter have an important influence on the OP performance.
User Bias Drift Social Recommendation Algorithm based on Metric Learning
Jianli Zhao,Tingting Li,Shangcheng Yang,Hao Li,Baobao Chai 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.12
Social recommendation algorithm can alleviate data sparsity and cold start problems in recommendation system by integrated social information. Among them, matrix-based decomposition algorithms are the most widely used and studied. Such algorithms use dot product operations to calculate the similarity between users and items, which ignores user’s potential preferences, reduces algorithms’ recommendation accuracy. This deficiency can be avoided by a metric learning-based social recommendation algorithm, which learns the distance between user embedding vectors and item embedding vectors instead of vector dot-product operations. However, previous works provide no theoretical explanation for its plausibility. Moreover, most works focus on the indirect impact of social friends on user’s preferences, ignoring the direct impact on user’s rating preferences, which is the influence of user rating preferences. To solve these problems, this study proposes a user bias drift social recommendation algorithm based on metric learning (BDML). The main work of this paper is as follows: (1) the process of introducing metric learning in the social recommendation scenario is introduced in the form of equations, and explained the reason why metric learning can replace the click operation; (2) a new user bias is constructed to simultaneously model the impact of social relationships on user’s ratings preferences and user’s preferences; Experimental results on two datasets show that the BDML algorithm proposed in this study has better recommendation accuracy compared with other comparison algorithms, and will be able to guarantee the recommendation effect in a more sparse dataset.
Performance Analysis of the M2M Network over Keyhole Nakagami Fading Channels
Lingwei Xu,Hao Zhang,Tingting Lu,Zengfeng Wang,T. Aaron Gulliver 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.7
The performance of the mobile-to-mobile (M2M) network over keyhole Nakagami fading channels is investigated in this paper. Using the method of the probability density function (PDF) of the signal-to-noise ratio (SNR), the exact and approximate closed-form average symbol error probability (ASEP) expressions are derived for pulse-amplitude modulation (PAM), phase shift keying (PSK),and frequency shift keying modulation (FSK). The exact closed-form expressions for channel capacity are also presented. Then the ASEP and channel capacity performance under different conditions is evaluated through numerical simulations to verify the analysis. The simulation results showed that the performance of the M2M network is improved with the transmitting/receiving antennas and the fading coefficient increased.
Performance Analysis of the Home M2M Cooperative Networks
Lingwei Xu,Hao Zhang,Tingting Lu,T A Gulliver 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.4
Based on decode-and-forward (DF) relaying scheme, the exact closed-form expression of the outage probability (OP) for the home mobile-to-mobile (M2M) cooperative networks over N-Nakagami fading channels is derived in this paper. Then the OP performance under different conditions is evaluated through numerical simulations. The numerical simulation results coincide with the theoretical results well, and the accuracy of the theoretical results is verified. The simulation results showed that: the fading coefficient, the number of cascaded components, the relative geometrical gain, and the power-allocation parameter have an important influence on the OP performance.
Hu, Xiaodong,Hao, Wei,Wang, Huili,Ning, Tingting,Zheng, Mingli,Xu, Chuncheng Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.4
The objective of this study was to assess the use of peach pomace in total mixed ration (TMR) silages and clarify the differences in aerobic stability between TMR and TMR silages caused by lactic acid bacteria (LAB). The TMR were prepared using peach pomace, alfalfa hay or Leymus chinensis hay, maize meal, soybean meal, cotton meal, limestone, a vitamin-mineral supplement, and salt in a ratio of 6.0:34.0:44.4:7.0:5.0:2.5:1.0:0.1 on a dry matter (DM) basis. Fermentation quality, microbial composition, and the predominant LAB were examined during ensiling and aerobic deterioration. The results indicated that the TMR silages with peach pomace were well fermented, with low pH and high lactic acid concentrations. The aerobic stability of TMR silages were significantly higher than that of TMR. Compared with TMR silages with alfalfa hay, TMR silage with Leymus chinensis hay was much more prone to deterioration. Although the dominant LAB were not identical in TMR, the same dominant species, Lactobacillus buchneri and Pediococcus acidilactici, were found in both types of TMR silages after 56 d of ensiling, and they may play an important role in the aerobic stability of TMR silages.