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Controllability of an underactuated spacecraft with one thruster under disturbance

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Acta Mechanica Sinica 2012年第3期28卷 838-847页

作者： Dong-xia Wang Ying-Hong Jia Lei Jin Hai-Chao Gui Shi-Jie Xu Department of Guidance Navigation and ControlSchool of AstronauticsBeihang University100191 BeijingChina

For an underactuated spacecraft using only one thruster, the attitude controllability with respect to the or- bit frame is studied in the presence of periodical oscillation disturbance, which provides a preconditional guide on de- signing control law for underactuated attitude control sys- tem. Firstly, attitude dynamic model was established for an underactuated spacecraft, and attitude motion was described using the special orthogonal group （SO （3））. Secondly, Liou- ville theorem was used to confirm that the flow generated by the drift vector of the underactuated attitude control system is volume-preserving. Furthermore, according to Poincar6＇s re- currence theorem, we draw conclusions that this drift field is weakly positively poisson stable （WPPS）. Thirdly, the suffi- cient and necessary condition of controllability was obtained on the basis of lie algebra rank condition （LARC）. Finally, the controllable conditions were analyzed and simulated in different cases of inertia matrix with the installed position of thruster.

关键词： Underactuated spacecraft Periodical oscilla-tion disturbance. Controllability. Weakly positively poissonstable ~ Lie algebra

Incentive mechanism for sharing distributed energy resources

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Journal of Modern Power Systems and Clean energy 2019年第4期7卷 837-850页

作者： Jianxiao WANG Haiwang ZHONG Junjie QIN Wenyuan TANG Ram RAJAGOPAL Qing xia Chongqing KANG Department of Electrical engineering Tsinghua UniversityBeijing 100084China Department of Electrical engineering and Computer Sciences University of CaliforniaBerkeleyCA 94720-1776USA Department of Electrical and Computer engineering North Carolina State UniversityRaleighNC 27695USA Department of Civil and environmental engineering Stanford UniversityStanfordCA 94305USA

To improve the controllability and utilization of distributed energy resources(DERs),distribution-level electricity markets based on consumers’bidding and offers have been ***,the transaction costs will dramatically increase with the rapid development of ***,in this paper,we develop an energy sharing scheme that allows users to share DERs with neighbors,and design a novel incentive mechanism for benefit allocation without users’bidding on electricity *** the energy sharing scheme,an aggregator organizes a number of electricity users,and trades with the connected power *** aggregator is aimed at minimizing the total costs by matching the surplus energy from DERs and electrical loads.A novel index,termed as sharing contribution rate(SCR),is presented to evaluate different users’contributions to the energy ***,based on users’SCRs,an efficient benefit allocation mechanism is implemented to determine the aggregator’s payment to users that incentivize their participation in energy *** avoid users’bidding,we propose a decentralized framework for the energy sharing and incentive *** studies based on real-world datasets demonstrate that the aggregator and users can benefit from the energy sharing scheme,and the incentive mechanism allocates the benefits according to users’contributions.

关键词： Distributed energy resource(DER) energy sharing Incentive mechanism Nash bargaining

Estimating Photometric Redshifts with Artificial Neural Networks and Multi-Parameters

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 448-456页

作者： Li-Li Li Yan-xia Zhang Yong-Heng Zhao Da-Wei Yang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 College of Physics Science and Information engineering Hebei Normal University Shijiazhuang 050016

We calculate photometric redshifts from the Sloan Digital Sky Survey Data Release 2 （SDSS DR2） Galaxy Sample using artificial neural networks （ANNs）. Different input sets based on various parameters （e.g. magnitude, color index, flux information） are explored. Mainly, parameters from broadband photometry are utilized and their performances in redshift prediction are compared. While any parameter may be easily incorporated in the input, our results indicate that using the dereddened magnitudes often produces more accurate photometric redshifts than using the Petrosian magnitudes or model magnitudes as input, but the model magnitudes are superior to the Petrosian magnitudes. Also, better performance resuits when more effective parameters are used in the training set. The method is tested on a sample of 79 346 galaxies from the SDSS DR2. When using 19 parameters based on the dereddened magnitudes, the rms error in redshift estimation is σz = 0.020184. The ANN is highly competitive tool compared to the traditional template-fitting methods when a large and representative training set is available.

关键词： galaxies fundamental parameters - techniques photometric - method dataanalysis

Efficient and Practical Syntheses of enantiomerically Pure (S)-(−)-Norcryptostyline Ⅰ, (S)-(−)-Norcryptostyline Ⅱ, (R)-(+)-Salsolidine and (S)-(−)-Norlaudanosine via a Resolution-Racemization Method

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Chinese Journal of Chemistry 2014年第10期32卷 1039-1048页

作者： Ruiheng Zhu Zhangli Xu Wei Ding Shiling Liu xiaoxin Shi xia Lu Department of Pharmaceutical engineering School of PharmacyEast China University of Science and Technology130 Mei-Long RoadShanghai 200237China

Four racemic tetrahydroisoquinolines(RS)-(±)-1-4 were prepared from homoveratrylamine via amidation,Bischler-Napieralski reaction and the subsequent *** enantiomerically pure tetrahydroisoquinolines(S)-(−)-norcryptostyline Ⅰ[(S)-(−)-1],(S)-(−)-norcryptostyline Ⅱ[(S)-(−)-2],(R)-(+)-salsolidine[(R)-(+)-3]and(S)-(−)-norlaudanosine[(S)-(−)-4]were then obtained in 45%,40%,41%and 38%yields,respectively,via resolution of the racemic compounds(RS)-(±)-1-4 with half equivalent of chiral *** addition,the enantiomerically enriched compounds(R)-(+)-1,(R)-(+)-2,(S)-(−)-3 and(R)-(+)-4 from the mother liquors were efficiently racemized via a one-pot redox method in almost quantitative yields.

关键词： tetrahydroisoquinolines norcryptostyline salsolidine norlaudanosine resolution racemization

Efficient strategies for changing the diapause character of silkworm eggs and for the germline transformation of diapause silkworm strains

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Insect Science 2012年第2期19卷 172-182页

作者： Ai-Chun Zhao Ding-Pei Long San-Yuan Ma Long-xia Xu Mei-Rong Zhang Fang-Yin Dai Qing-You xia Cheng Lu Zhong-Huai xiang The Key Sericultural Laboratory of Agricultural Ministry Institute of Sericulture and Systems BiologySouthwest UniversityChongqingChina

To overcome the disadvantages of current silkworm Bombyx mori transgenic technology, such as costly and time-consuming to maintain non-diapause transgenic silkworms, we report here on the development of treatments for the germline transformation of diapause silkworm strains. Our results showed that HC1 treatment within 3 h of oviposition was able to prevent the diapause of eggs from Japanese lineage diapause silkworm strains and was also suitable for germline transformation of the same strains. By incu- bating developing mother eggs from Chinese lineage diapause silkworm strains at 15℃ （15℃-IME）, we were able to prevent the diapause of their daughter eggs; a similar strategy （15℃-IMES） for the germline transformation of the same strains was that the mother eggs were incubated at 15℃, and the daughter eggs were then microinjected according to the conventional microinjection methods used for non-diapause eggs. By combining tempera- ture and light controls, the improved 15℃-IMES strategy prevented diapause in daughter eggs, and also enabled the germline transformation of both Japanese and Chinese lineage diapause silkworm strains. Although each of the strategies developed here has advantages and disadvantages, we suggest that the 15℃-IMES strategy is a good reference for the establishment of germline transformation technologies of other egg diapause insects. These new strategies for the efficient germline transformation of diapause silkworm strains are likely to improve the practical use of silkworm transgenic lines in sericulture and also highlight silkworm functional genomics research and its modeling.

关键词： Bombyx mori diapause functional genomics gerrnline transformation insect piggyBac

Experimental Research on Boundary Shear Stress in Typical Meandering Channel

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China Ocean engineering 2018年第3期32卷 365-373页

作者： CHen Kai-hua xia Yun-feng ZHANG Shi-zhao Wen Yun-cheng XU Hua Nanjing Hydraulic Research Institute Nanjing 210029China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China The State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Nanjing 210098China Key Laboratory of Port Waterway and Sedimentation Engineering of Ministry of TransportNanjing 210024China

A novel instrument named Micro-Electro-Mechanical System(MEMS) flexible hot-film shear stress sensor was used to study the boundary shear stress distribution in the generalized natural meandering open channel, and the mean sidewall shear stress distribution along the meandering channel, and the lateral boundary shear stress distribution in the typical cross-section of the meandering channel was analysed. Based on the measurement of the boundary shear stress, a semi-empirical semi-theoretical computing approach of the boundary shear stress was derived including the effects of the secondary flow, sidewall roughness factor, eddy viscosity and the additional Reynolds stress, and more importantly, for the first time, it combined the effects of the cross-section central angle and the Reynolds number into the expressions. Afterwards, a comparison between the previous research and this study was developed. Following the result, we found that the semi-empirical semi-theoretical boundary shear stress distribution algorithm can predict the boundary shear stress distribution precisely. Finally, a single factor analysis was conducted on the relationship between the average sidewall shear stress on the convex and concave bank and the flow rate, water depth, slope ratio,or the cross-section central angle of the open channel bend. The functional relationship with each of the above factors was established, and then the distance from the location of the extreme sidewall shear stress to the bottom of the open channel was deduced based on the statistical theory.

关键词： boundary shear stress flume physical model river bend MEMS flexible hot-film shear stress sensor

Contribution of mixed commercial starter cultures to the quality improvement of fish-chili paste,a Chinese traditional fermented condiment

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Food Bioscience 2022年第2期46卷 430-438页

作者： Qian Hua Yingying Sun Yanshun Xu Pei Gao Wenshui xia State Key Laboratory of Food Science and Technology 1800 Lihu AveWuxiJiangsu214122China School of Food Science and Technology Jiangnan University1800 Lihu AveWuxiJiangsu214122China

This study evaluated the effects of commercial starter cultures on the microbial counts,protein degradation,biogenic amines and volatile compounds in fermented fish-chili *** inoculated groups with different starter cultures and one group without inoculation were *** results revealed that the application of mixed starter cultures promoted the growth of lactic acid bacteria and yeast,while effectively inhibited the enterbacteriaceae counts compared with the spontaneously fermented *** inoculation with mixed starter cultures resulted in higher levels of umami-tasting free amino acids(FAAs)in all inoculated *** content of sweet-tasting FAAs was found in group HS(Pichia anomala+Staphylococcus xylosus+Staphylococcus carnosus+Pediococcus pentosaceus+Pediococcus acidilactici),and much lower bitter-tasting components were presented in group HW(Pichia anomala+Staphylococcus xylosus+Staphylococcus carnosus),HS and HV(Pichia anomala+Lactobacillus plantarum).In addition,total levels of biogenic amines detected in all inoculated samples were significantly lower compared with control,especially the content of tyramine(P<0.05).For the volatile compounds,more esters as well as less undesirable odor substances such as aldehydes,were exhibited in four inoculated groups.

关键词： Fish-chili paste Commercial starter cultures Biogenic amines Volatile compounds

Prevention and management of postoperative deep vein thrombosis in lower extremities of patients with gastrointestinal tumor

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World Journal of Gastrointestinal Surgery 2024年第10期16卷 3269-3276页

作者： Liang Shu Cheng-Wei xia Yu-Fan Pang Department of Thyroid Surgery Affiliated Hospital of Southwest Medical UniversityLuzhou 646000Sichuan ProvinceChina

BACKGROUND Deep vein thrombosis(DVT)is a significant postoperative concern,particularly in patients undergoing surgery for gastrointestinal(GI)*** patients often present multiple risk factors,including advanced age and elevated body mass index(BMI),which can increase the likelihood of thromboembolic ***-tive prophylaxis is crucial in this high-risk population to minimize complications such as DVT and pulmonary embolism(PE).This study investigates a compre-hensive DVT prevention protocol,combining mechanical and pharmacological strategies alongside early mobilization,to evaluate its effectiveness and safety in reducing postoperative thrombosis rates among GI cancer surgery *** To evaluate the effectiveness and safety of postoperative DVT prevention strate-gies in patients with GI *** A prospective cohort study was conducted involving 100 patients who underwent surgery for GI tumors between January and December *** patients received a standardized DVT prevention protocol,which included risk assessment,mecha-nical prophylaxis,pharmacological prophylaxis,and early *** primary endpoint was the incidence of DVT within 30 days ***-condary outcomes included the occurrence of PE,bleeding complications,and adherence to the *** The overall incidence of DVT was 7%(7/100 patients).One patient(1%)deve-loped *** adherence rate to the prevention protocol was 92%.Bleeding complications were observed in 3%of *** risk factors for DVT development included advanced age[odds ratio(OR):1.05;95%confidence interval(95%CI):1.01-1.09],higher BMI(OR:1.11;95%CI:1.03-1.19),and longer operative time(OR:1.007;95%CI:1.001-1.013).CONCLUSION Implementing a comprehensive DVT prevention and management protocol for patients undergoing GI tumor surgery resulted in a lower *** adherence and individualized risk assessment are crucial for optimizing outcomes.

关键词： Deep vein thrombosis Gastrointestinal tumors Thromboprophylaxis Postoperative complications Venous thromboembolism

Analysis of the temporal and spatial distribution of water quality in China＇s major river basins, and trends between 2005 and 2010

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Frontiers of Earth Science 2015年第3期9卷 463-472页

作者： Jinjian LI xiaojie MenG Yan ZHANG Juan LI Linlin xia Hongmei ZHenG State Key Joint Laboratory of environment Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China Chinese Research Academy of environmental Sciences Beijing 100012 China

In this study, based on environmental quality monitoring data on 22 pollutants from 490 control sections, we analyzed the spatial distribution and temporal changes of water quality in ten Chinese river basins （watersheds） to reveal the trends from 2005 to 2010. We used a comprehensive water pollution index （WPI） and the proportions of this index accounted for by the three major pollutants to analyze how economic development has influenced water quality. Higher values of the index represent more serious pollution. We found that WPI was much higher for the Hai River Basin （1.83 to 5.60 times the averages in other regions）. In the Yangtze River Basin, WPI increased from upstream to downstream. The indices of some provinces toward the middle of a basin, such as Hebei Province in the Hal River Basin, Shanxi Province in the Yellow River Basin, and Anhui Province in the Huai River Basin, were higher than those of upstream and downstream provinces. In the Songhua, Liao, and South- east river basins, WPI decreased during the study period： in 2010, it decreased by 33.9%, 44.3%, and 67.2%, respectively, compared with the 2005 value. In the Pearl River, Southwest, and Inland river basins, WPI increased by 23.1%, 47.7%, and 38.5% in 2010, compared with 2005. A comparison of WPI with the GDP of each province showed that the water pollution generated by economic development was lightest in northwestern, southwestern, and northeastern China, and highest in central and eastern China, and that the water environment in some coastal regions were improving. However, some provinces （e.g., Shanxi Province） were seriously polluted.

关键词： water environment temporal changes spatial