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INVESTIGATION OF RATTLING THRESHOLD IN GEAR SYSTEM

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Chinese Journal of Mechanical Engineering 2005年第4期18卷 571-574页

作者： Dong Haijun Shen Yunwen liu mengjun Wang Sanmin School of Mechatronic Engineering Northwestern Polytechnical University Xi＇an 710072 China

A lumped mass gear-rattling model with backlash is established by considering the time varying mesh stiffness, composite transmission error and the torque fluctuation. Based on the principle that no separation will occur if the response amplitude is not larger than the static response, the threshold is obtained by theoretical derivation. The validity of the theoretical derivation is verified by the numerical method. The results show that the time-varying mesh stiffness has little effect on the threshold. When the exciting frequency is less than the system natural frequency, the theoretical agrees well with the numerical one. The higher the exciting frequency or the smaller the average input torque is, the easier the separation will occur. When the exciting frequency is larger than the natural frequency by a certain value, the theoretical threshold does not agree with the numerical results. The numerical results show that the motion state will change from the meshing state to the separating state directly. The phenomenon that the gear pair sometimes separates and sometimes meshes occurs only when the exciting frequency is smaller.

关键词： Rattling Gear Backlash Threshold Reynolds equation

Privacy-preserving Distributed Location Proof Generating System

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China Communications 2016年第3期13卷 203-218页

作者： liu mengjun liu Shubo ZHANG Rui Li Yongkai WANG Jun CAO Hui Key Laboratory of Aerospace Information security and trusted computing Ministry of Education Wuhan University School of computer Wuhan University Department of Electronic Engineering University of Hawaii

The rapid development of location-based service(LBS) drives one special kind of LBS, in which the service provider verifies user location before providing services. In distributed location proof generating schemes, preventing users from colluding with each other to create fake location proofs and protecting user's location privacy at the same time, are the main technical challenges to bring this kind of LBS into practical. Existing solutions tackle these challenges with low collusion-detecting efficiency and defected collusion-detecting method. We proposed two novel location proof generating schemes, which inversely utilized a secure secret-sharing scheme and a pseudonym scheme to settle these shortcomings. Our proposed solution resists and detects user collusion attacks in a more efficient and correct way. Meanwhile, we achieve a higher level of location privacy than that of previous work. The correctness and efficiency of our proposed solution is testified by intensive security analysis, performance analysis, as well as experiments and simulation results.

关键词： computer software and theory location proof secret-sharing location privacy

Global behavior of gear system using mixed cell mapping

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Science China(Physics,Mechanics & Astronomy) 2004年第Z1期47卷 113-119页

作者： SHEN Yunwen liu mengjun DONG Haijun Northwestern Polytechnical University Xi'an 710072 China Northwestern Polytechnical University Xi'an 710072 China Northwestern Polytechnical University Xi'an 710072 China

In some mechanical nonlinear systems, the transient motion will be undergoing a very long process and the attractor-basin boundaries are so complicated that some difficulties occur in analyzing the system global behavior. To solve this problem a mixed cell mapping method based on the point mapping and the principle of simple cell mapping is developed. The algorithm of the mixed cell mapping is studied. A dynamic model of a gear pair is established with the backlash, damping, transmission error and the time-varying stiffness taken into consideration. The global behaviors of this system are analyzed. The coexistence of the system attractors and the respective attractor-basin of each attractor with different parameters are obtained, thus laying a theoretical basis for improvement of the dynamic behaviors of gear system.

关键词： mixed cell mapping, global analysis, attractor-basin, gear pair, nonlinear dynamic system.

Liquid crystal-based optical aptasensor for the sensitive and selective detection of Gram-negative bacteria

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Science China Chemistry 2022年第10期65卷 2023-2030页

作者： mengjun liu Minmin Zhang Jiamei Chen Ruizhi Yang Zhaofan Huang Zhenping liu Na Li Lingling Shui Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices School of Information and Optoelectronic Science and EngineeringSouth China Normal UniversityGuangzhou 510006China Joint Laboratory of Optofluidic Technology and Systems National Center for International Research on Green OptoelectronicsSouth China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou 510006China

The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical ***,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(***),a model of Gram-negative *** nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to *** schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper *** specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of *** optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an *** the prominent affinity and specificity of the aptamer,the established sensitive and selective *** assay shows an ultralow detection limit of 27 cfu/*** prepared aptasensor can also be applied for the sensitive and selective determination of *** in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.

关键词： liquid crystal molecular arrangement optical sensor aptamer Gram-negative bacteria

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GST family genes in jujube actively respond to phytoplasma infection

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Horticultural Plant Journal 2024年第1期10卷 77-90页

作者： Qipeng Wang Liman Zhang Chaoling Xue Yao Zhang Xiangrui Meng Zhiguo liu mengjun liu Jin Zhao College of Life Science Hebei Agricultural UniversityBaodingHebei 071000China Hebei Key Laboratory of Plant Physiology and Molecular Pathology Hebei Agricultural UniversityBaodingHebei 071000China Research Center of Chinese Jujube Hebei Agricultural UniversityBaodingHebei 071000China

Jujube witches’broom(JWB)caused by phytoplasma has a severely negative effect on multiple metabolisms in *** GST gene family in plants participates in the regulation of a variety of biotic and abiotic *** study aims to identify and reveal the changes in the jujube GST gene family in response to phytoplasma ***,70 ZjGSTs were identified in the jujube genome and divided into 8 *** them,the Tau-class,including 44 genes,was the *** analysis indicated that Tau-class genes were highly conserved among species,such as Arabidopsis,cotton,chickpea,and *** chromosome location analysis,37.1%of genes were clustered,and 8 of 9 gene clusters were composed of Tau class *** RT-PCR,qRT-PCR and enzyme activity detection,the results showed that the expression of half(20/40)of the tested ZjGSTs was inhibited by phytoplasma infection in field and tissue culture conditions,and GST activity was also significantly *** the resistant and susceptible varieties under phytoplasma infection,ZjGSTU49-ZjGSTU54 in the cluster IV showed opposite expression patterns,which may be due to functional divergence during *** upregulated genes(ZjGSTU45,ZjGSTU49,ZjGSTU59,and ZjGSTU70)might be involved in the process of jujube against *** yeast two-hybrid results showed that all 6 Tauclass proteins tested could form homodimers or ***,the comprehensive analysis of the jujube GST gene family revealed that ZjGSTs responded actively to phytoplasma ***,some screened genes(ZjGSTU24,ZjGSTU49-52,ZjGSTU70,and ZjDHAR10)will contribute to further functional studies of jujube-phytoplasma interactions.

关键词： Chinese jujube GST gene Family Phytoplasma Gene cluster Expression Protein interaction

Expression profiles of genes and enzymes related to ascorbic acid metabolism in fruits of Ziziphus jujuba Mill.‘Jinsixiaozao’

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Frontiers of Agricultural Science and Engineering 2016年第2期3卷 131-136页

作者： Yingying CHEN Zhihui ZHAO Jin ZHAO mengjun liu Research Center of Chinese Jujube Agricultural University of Hebei College of Life Science Agricultural University of Hebei

The fruit of Chinese jujube(Ziziphus jujuba)possesses extremely high concentrations of ascorbic acid(As A).The accumulation of As A,the expression patterns of the nine genes related to As A metabolism as well as the activities of five enzymes involved in As A synthesis,oxidation and recycling were investigated during fruit development in *** Mill.‘Jinsixiaozao'.The results showed that the high level of As A accumulation in jujube fruit is due to a contribution from both As A biosynthesis and As A *** is suggested that L-galactono-1,4-lactone dehydrogenase,ascorbate peroxidase and monodehydro-ascorbate reductase are the crucial genes/enzymes of jujube As A synthesis,oxidization and recycling,*** results provide useful new insights into the regulatory mechanisms of As A accumulation in Chinese jujube.

关键词： Chinese jujube ascorbic acid metabolism gene enzyme

The regulatory pathways of distinct flowering characteristics in Chinese jujube

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Horticulture Research 2020年第1期7卷 1084-1096页

作者： Xianwei Meng Ying Li Ye Yuan Yao Zhang Hongtai Li Jin Zhao mengjun liu Research Center of Chinese Jujube Hebei Agricultural UniversityBaoding 071000China College of Life Science Hebei Agricultural UniversityBaoding 071000China

Flowering is the most important event in higher *** to most fruit tree species,Chinese jujube(Ziziphus jujuba Mill.),the most important member of the large,diverse Rhamnaceae family and a leading dry fruit-producing species,has unique characteristics that include a short juvenile phase and extremely fast flower bud ***,the distinct mechanism of flowering regulation in Chinese jujube is still *** morphological and cytological development period of jujube flowering was first investigated,and the crucial developmental stages were *** bud differentiation in Chinese jujube took only approximately 11–13 days,which is a distinct characteristic of perennial fruit ***,44 genes related to six flowering pathways were identified in the jujube genome and were found to be randomly distributed among 11 of the 12 ***-specific and spatiotemporal expression patterns showed that all these genes were expressed in the ***,photoperiodrelated genes were highly expressed during flower bud *** genes were also positively responsive to photoperiod regulation and phase change processes,indicating that photoperiod-related genes play crucial roles in jujube flower bud *** protected cultivation,ZjPIF4,a temperature-related gene,was expressed in the early stages of flowering and responded to increasing ***,STRING analysis and yeast two-hybrid screening indicated that photoperiod-related(ZjCO)and temperature-related(ZjPIF4)proteins could interact with ZjFT,the key protein involved in the determination of flowering time,indicating crosstalk between photoperiodrelated pathways and ambient temperature-related pathways in *** study is the first report to comprehensively analyze the flowering pathways in Chinese jujube and revealed that photoperiod-related and ambient temperature-related pathways are the main mechanisms regulating the distinct flowering

关键词： characteristics flowers flowering

The regulation of cell wall lignification and lignin biosynthesis during pigmentation of winter jujube

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Horticulture Research 2021年第1期8卷 3257-3270页

作者： Qiong Zhang Lihu Wang Zhongtang Wang Rentang Zhang Ping liu mengjun liu Zhiguo liu Zhihui Zhao Lili Wang Xin Chen Haifeng Xu Shandong Institute of Pomology Tai’anShandong 271000China School of Landscape and Ecological Engineering Hebei University of EngineeringHandanHebei 056038China College of Food Science and Engineering Shandong Agricultural University61 Daizong StreetTai’an 271018 ShandongP.R.China Research Center of Chinese Jujube Hebei Agricultural UniversityBaodingHebei 071000China

Fruit lignification is due to lignin deposition in the cell wall during cell ***,there are few studies on the regulation of cell wall lignification and lignin biosynthesis during fruit *** this study,we investigated the regulation of cell wall lignification and lignin biosynthesis during pigmentation of winter *** cellulose content decreased,while the lignin content increased in the winter jujube pericarp during *** O-fast green staining showed that the cellulose content was higher in the cell wall of winter jujube prior to pigmentation,whereas the lignin in the cell wall increased after *** thickness of the epidermal cells decreased with pericarp pigmentation.A combined metabolomics and transcriptomics analysis showed that guaiacyl-syringyl(G-S)lignin was the main lignin type in the pericarp of winter jujube,and F5H(LOC107424406)and CCR(LOC107420974)were preliminarily identified as the key genes modulating lignin biosynthesis in winter *** MYB and six NAC transcription factors(TFs)with potential regulation of lignin biosynthesis were screened out based on phylogenetic *** MYB and two NAC TFs were selected as candidate genes and further studied in *** ectopic expression and winter jujube pericarp injection of the candidate genes indicated that the MYB activator(LOC107425254)and the MYB repressor(LOC107415078)control lignin biosynthesis by regulating CCR and F5H,while the NAC(LOC107435239)TF promotes F5H expression and positively regulates lignin *** findings revealed the lignin biosynthetic pathway and associated genes during pigmentation of winter jujube pericarp and provide a basis for further research on lignin regulation.

关键词： winter jujube analysis.

Insights into the evolution and spatial chromosome architecture of jujube from an updated gapless genome assembly

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Plant Communications 2023年第6期4卷 221-224页

作者： Meng Yang Lu Han Shufeng Zhang Li Dai Bin Li Shoukun Han Jin Zhao Ping liu Zhihui Zhao mengjun liu College of Horticulture Hebei Agricultural UniversityBaodingHebei 071001China Research Center of Chinese Jujube Hebei Agricultural UniversityBaodingHebei 071001China College of Life Sciences Hebei Agricultural UniversityBaodingHebei 071001China These authors contributed equally to this article.

Dear Editor,Jujube(Ziziphus jujuba Mill.),commonly called Chinese jujube,is a vital member of the Rhamnaceae *** is famous for its tolerance to dry,barren,and saline-alkali soils,and its fruit has important nutritional and medicinal *** fundamental research on jujube has involved assembly of draft genome sequences for the fresh-eating cultivar‘Dongzao’(liu et al.,2014),dry-eating cultivar‘Junzao’(Huang et al.,2016),and wild sour jujube‘Suanzao’(Shen et al.,2021).

关键词： Mill jujube cultivar