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1,386 results on '"Lu, Haifeng"'

157. Partition Variable Frequency and EPS Hybrid Control to Achieve Full Load Range ZVS for Dual Active Bridge Converters

Author

Fan, Zhihua, Lu, Haifeng, Chai, Jianyun, Li, Yaowang, and Sun, Xudong

Abstract

Zero -voltage switching (ZVS) is of great importance for high-efficiency dc/dc converters. In the dual active bridge (DAB) converter with the extended phase shift (EPS) control, however, due to the junction capacitance of switches, the ZVS region splits into two separated parts according to its load degree. It has been found that applying the variable frequency modulation (VFM) simply to the EPS can move rather than fill the gap between the ZVS areas. In this article, a partition VFM is proposed, which increases the switching frequency at heavy loads and decreases it at light loads. The partition VFM extends the ZVS regions of EPS toward each other and connects them finally. A hybrid control law combining the partition VFM and EPS has been developed. The minimum rms current optimization is carried out to determine the relationship between duty cycle and phase shift. Some frequency-dependent characteristics are analyzed to establish loss model. Minimum switching frequency is calculated to obtain high efficiency while ensuring ZVS. Finally, the effectiveness of the proposed control method is experimentally verified on a 100–300-kHz, 1-kW DAB prototype.

Published
2024
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168. Progress in microalgae cultivation photobioreactors and applications in wastewater treatment: A review

Author

Lu Haifeng, Ma Shanshan, Yuanhui Zhang, Liu Zhidan, and Duan Na

Subjects
microalgae cultivation, wastewater treatment, photobioreactor (PBR), review, Agriculture (General), S1-972, Biotechnology, TP248.13-248.65
Abstract

Using microalgae to treat wastewater has received growing attention in the world because it is regarded as a novel means for wastewater treatment. It is commonly recognized that large-scale cultivation and commercial application of microalgae are limited by the development of photobioreactor (PBR). Although there are a lot of PBRs for microalgae pure cultivation which used culture medium, specialized PBRs designed for wastewater treatment are rare. The composition of wastewater is quite complicated; this might cause a very different photosynthetic effect of microalgae compared to those grown in a pure cultivation medium. Therefore, PBRs for wastewater treatment need to be redesigned and improved based on the existing PBRs that are used for microalgae pure cultivation. In this review, different PBRs for microalgae cultivation and wastewater treatment are summarized. PBR configurations, PBR design parameters and types of wastewater are presented. In addition, the wastewater treatment efficiency and biomass productivity were also compared among each type of PBRs. Moreover, some other promising PBRs are introduced in this review, and a two-stage cultivation mode which combines both closed and open system is discussed as well. Ultimately, this article focuses on current problems and gives an outlook for this field, aiming at providing a primary reference for microalgae cultivation by using wastewater.

Published
2017
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170. Oral Fungal Alterations in Patients with COVID‐19 and Recovered Patients

Author

Hu, Xiaobo, primary, Wang, Haiyu, additional, Yu, Bo, additional, Yu, Jia, additional, Lu, Haifeng, additional, Sun, Junyi, additional, Sun, Ying, additional, Zou, Yawen, additional, Luo, Hong, additional, Zeng, Zhaohai, additional, Liu, Shanshuo, additional, Jiang, Yan, additional, Wu, Zhongwen, additional, and Ren, Zhigang, additional

Published
2023
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171. Alterations in the intestinal microbiome and metabolic profile of patients with cirrhosis supplemented with lactulose, Clostridium butyricum, and Bifidobacterium longum infantis: a randomized placebo-controlled trial

Author

Lu, Haifeng, primary, Zhu, Xiaofei, additional, Wu, Lingyun, additional, Lou, Xiaobin, additional, Pan, Xiaxia, additional, Liu, Bowen, additional, Zhang, Hua, additional, Zhu, Lingxiao, additional, Li, Lanjuan, additional, and Wu, Zhongwen, additional

Published
2023
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179. Unsaturated seepage and stability of double-layer slope under rainfall infiltration

Author

Zhang Yuan and Lu Haifeng

Subjects
Environmental sciences, GE1-350
Abstract

Taking a homogeneous double-layer soil slope as an example, the SEEP/W module and SLOPE/W module in the finite element analysis software GeoStudio were used in this paper. Then, the changes of pore water pressure and stability under different rainfall patterns and soil parameters were studied. Finally, the variation curves of pore water pressure and slope safety factor with rainfall time were obtained. The results show that: Soil parameters a and m are directly proportional to the slope safety factor, while n is inversely proportional to the slope safety factor. Under the condition of continuous rainfall, the decreasing rate of slope safety factor is directly proportional to the rainfall intensity.Under different rainfall patterns, the continuous rainfall in the advanced and normal rainfall patterns will cause the slope stability to decline and then gradually recover, while delayed and averaged rainfall patterns rainfall will cause the slope stability to decline continuously.In addition, there is a lag period in the change of slope safety factor, and the whole lag period lasts about 6 hours. During the lag period, the pore water pressure inside the soil began to decrease, while the slope safety factor continued to decrease. The safety factor starts to recover after the lag period ends.

Published
2021
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180. EPIC: Emotion Perception by Spatio-Temporal Interaction Context of Gait

Author

Lu, Haifeng, Xu, Shihao, Zhao, Shipeng, Hu, Xiping, Ma, Rong, and Hu, Bin

Abstract

Recently, psychophysiological computing has received considerable attention. Due to easy acquisition at a distance and less conscious initiation, gait-based emotion recognition is considered as a valuable research branch in the field of psychophysiological computing. However, most existing methods rarely explore the spatio-temporal context of gait, which limits the ability to capture the higher-order relationship between emotion and gait. In this paper, we utilize a range of research, including psychophysiological computing and artificial intelligence, to propose an integrated emotion perception framework called EPIC, which can find novel joint topology and generate thousands of synthetic gaits by spatio-temporal interaction context. First, we analyze the joint coupling among non-adjacent joints by calculating Phase Lag Index (PLI), which can discover the latent connection among body joints. Second, to synthesize more sophisticated and accurate gait sequences, we explore the effect of spatio-temporal constraints, and propose a new loss function that utilizes the Dynamic Time Warping (DTW) algorithm and pseudo-velocity curve to constrain the output of Gated Recurrent Units (GRU). Finally, Spatial Temporal Graph Convolution Networks (ST-GCN) is used to classify emotions using the generation and the real data. Experimental results demonstrate our approach achieves the accuracy of 89.66%, and outperforms the state-of-the-art methods on Emotion-Gait dataset.

Published
2024
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