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Zhifang Zhao,Yang Yang,Hui Ma,Haixu Wang,Hongxu Tian,Chenyi Han 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1
Assembly errors may change contact state of gear pairs, then induce failure and vibration. To reveal the effects of assembly errors and tooth modification on the meshing characteristics, the loaded tooth contact analysis (LTCA) is conducted through an improved algorithm. The time-varying meshing stiffness (TVMS), static transmission error (STE) and contact stress (CS) are calculated considering assembly errors and tooth modification. Then, sensitivity of meshing characteristics to coupling assembly errors are investigated based on the design of orthogonal experiment (DOE). The meshing characteristic analysis results show that assembly errors have a significant effect on mesh characteristics of the gear pair. The results of sensitivity analysis indicate that the meshing characteristic is the most sensitive to axial deviation for the model used in this paper.
Dan, Danhui,Sun, Limin,Yang, Zhifang,Xie, Daqi Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.2
In this paper, a fuzzy inference system and an analytical hierarchy process-based online evaluation technique is developed to monitor the condition of the 32-km Donghai Bridge in Shanghai. The system has 478 sensors distributed along eight segments selected from the whole bridge. An online evaluation subsystem is realized, which uses raw data and extracted features or indices to give a set of hierarchically organized condition evaluations. The thresholds of each index were set to an initial value obtained from a structure damage and performance evolution analysis of the bridge. After one year of baseline monitoring, the initial threshold system was updated from the collected data. The results show that the techniques described are valid and reliable. The online method fulfills long-term infrastructure health monitoring requirements for the Donghai Bridge.
Danhui Dan,Limin Sun,Zhifang Yang,Daqi Xie 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.2
In this paper, a fuzzy inference system and an analytical hierarchy process-based online evaluation technique is developed to monitor the condition of the 32-km Donghai Bridge in Shanghai. The system has 478 sensors distributed along eight segments selected from the whole bridge. An online evaluation subsystem is realized, which uses raw data and extracted features or indices to give a set of hierarchically organized condition evaluations. The thresholds of each index were set to an initial value obtained from a structure damage and performance evolution analysis of the bridge. After one year of baseline monitoring, the initial threshold system was updated from the collected data. The results show that the techniques described are valid and reliable. The online method fulfills long-term infrastructure health monitoring requirements for the Donghai Bridge.
Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter
Chu, Enhui,Bao, Jianqun,Song, Qi,Zhang, Yang,Xie, Haolin,Chen, Zhifang,Zhou, Yue The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.
Zero-Voltage and Zero-Current Switching Interleaved Two-Switch Forward Converter
Enhui Chu,Jianqun Bao,Qi Song,Yang Zhang,Haolin Xie,Zhifang Chen,Yue Zhou 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.
Xi, Dongmei,Wanapat, Metha,Deng, Weidong,He, Tianbao,Yang, Zhifang,Mao, Huaming Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.8
Three male Gayal, two years of age and with a mean live weight of $203{\pm}26$ kg, and three adult Yunnan Yellow Cattle, with a mean live weight of $338{\pm}18$ kg were fed a ration of pelleted lucerne hay and used to collect rumen fluid for in vitro measurements of digestibilities and gas production from fermentation of a range of forages. The forages were: bamboo stems, bamboo twigs, bamboo leaves, rice straw, barley straw, annual ryegrass hay, smooth vetch hay and pelleted lucerne hay. There were significant (p<0.05) effects of the source of rumen fluid on in vitro dry matter digestibility (IVDMD) and gas production during fermentation of forage. For the roughage of lowest quality (bamboo stems and rice straw), gas production during fermentation was higher (p<0.05) in the presence of rumen fluid from Gayal than Yunnan Yellow Cattle. Differences for these parameters were found for the better quality roughages with gas production being enhanced in the presence of rumen fluid from Yunnan Yellow Cattle. Moreover, the IVDMD of investigated roughages was significantly higher (p<0.05) in Gayal than Yunnan Yellow Cattle. The results offer an explanation for the positive live weight gains recorded for Gayal foraging in their natural environment where the normal diet consists of poor quality roughages.
Deng, Weidong,Wanapat, Metha,Ma, Songcheng,Chen, Jing,Xi, Dongmei,He, Tianbao,Yang, Zhifang,Mao, Huaming Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.7
Six male Gayal (Bos frontalis), approximately two years of age and with a mean live weight of $203{\pm}17$ kg ($mean{\pm}standard\;deviation$), were housed indoors in metabolism cages and fed bamboo (Sinarundinaria) leaves and twigs. After an adjustment period of 24 days of feeding the diet, samples of rumen liquor were obtained for analyses of bacteria in the liquor. The diversity of rumen bacteria was investigated by constructing a 16S rDNA clone library. A total of 147 clones, comprising nearly full length sequences (with a mean length of 1.5 kb) were sequenced and submitted to an on-line similarity search and phylogenetic analysis. Using the criterion of 97% or greater similarity with the sequences of known bacteria, 17 clones were identified as Ruminococcus albus, Butyrivibrio fibrosolvens, Quinella ovalis, Clostridium symbiosium, Succiniclasticum ruminis, Selenomonas ruminantium and Allisonella histaminiformans, respectively. A further 22 clones shared similarity ranging from 90-97% with known bacteria but the similarity in sequences for the remaining 109 clones was less than 90% of those of known bacteria. Using a phylogenetic analysis it was found that the majority of the clones identified (57.1%) were located in the low G+C subdivision, with most of the remainder (42.2% of clones) located in the Cytophage-Flexibacter-Bacteroides (CFB) phylum and one clone (0.7%) was identified as a Spirochaete. It was apparent that Gayal have a large and diverse range of bacteria in the rumen liquor which differ from those of cattle and other ruminants. This may explain the greater live weights of Gayal, compared to cattle, grazing in the harsh natural environments in which Gayal are located naturally.
Deng, Weidong,Wang, Liping,Ma, Songcheng,Jin, Bo,He, Tianbao,Yang, Zhifang,Mao, Huaming,Wanapat, Metha Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.6
Three male Gayal (Bos frontalis) and three male Yunnan Yellow cattle (Bos taurus) were fed pelleted lucerne and measurements made of digestibility, nitrogen utilisation, rumen fermentation and microbial population and key plasma metabolites. Total actual dry matter intake was similar but when expressed in terms of live weight or metabolic live weight feed intakes were significantly higher (p<0.05) for Gayal than cattle. Apparent digestibilities of dry matter, organic matter, fibre and dietary nitrogen were similar for both Gayal and cattle. Rumen ammonia nitrogen and total volatile fatty acids were significantly higher (p<0.05) for Gayal than cattle and total numbers of viable rumen bacteria, cellulolytic and amylolytic bacteria, but not proteolytic bacteria nor protozoa, were significantly greater (p<0.05) for Gayal than cattle. Although Gayal have a different rumen ecology to cattle, similar digestive parameters were exhibited. Further research is required to establish relationship between rumen ecology and digestive parameters.
A Bayesian Network Approach to Launch Vehicle Software Failure Prediction
Tinggui Yan,Xiaoqian Chen,Shipeng Li,Li Ma,Jian Bai,Zhifang Yang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.11
Launch Vehicle software has played an important role in Launch Vehicle system. However, the reliability assessment of Launch Vehicle software is still a hard problem due to the complexity of Launch Vehicle software. Failure prediction can be an effective approach of Launch Vehicle reliability evaluation, whereas failure prediction of software has not yet been fully explored. In this paper, a Markov Bayesian Network model for Launch Vehicle software failure prediction (MBNG) is proposed. In MBNG, unique features of Launch Vehicle software is considered as an important part in the modeling process, which improves the effectiveness of this novel model. Experiments are conducted to verify the effectiveness of MBNG model and compare its performance with classic models.