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ON THE(CO)HOMOLOGY OF(QUOTIENTS OF)MOMENT-ANGLE MANIFOLDS OVER POLYGONS

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Acta Mathematica Scientia 2022年第6期42卷 2204-2222页

作者： zhi lv Song ZHANG School of Mathematical Sciences Fudan UniversityShanghai 200433China

The purpose of this paper is to represent the cohomology ring of a moment-angle manifold over an m-gon explicitly in terms of the quotient of an exterior algebra,and to count the Betti numbers of the cohomology groups... 详细信息

关键词： moment-angle manifold spectral sequence cohomology ring Betti number

An Improved FastSLAM Algorithm Based on Revised Genetic Resampling and SR-UPF

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International Journal of Automation and computing 2018年第3期15卷 325-334页

作者： Tai-zhi lv Chun-Xia Zhao Hao-Feng Zhang School of Computer Science and Technology Nanjing University of Science and Technology

FastSLAM is a popular framework which uses a Rao-Blackwellized particle filter to solve the simultaneous localization and mapping problem（SLAM）. However, in this framework there are two important potential limitations, the particle depletion problem and the linear approximations of the nonlinear functions. To overcome these two drawbacks, this paper proposes a new FastSLAM algorithm based on revised genetic resampling and square root unscented particle filter（SR-UPF）. Double roulette wheels as the selection operator, and fast Metropolis-Hastings（MH） as the mutation operator and traditional crossover are combined to form a new resampling method. Amending the particle degeneracy and keeping the particle diversity are both taken into considerations in this method. As SR-UPF propagates the sigma points through the true nonlinearity, it decreases the linearization errors. By directly transferring the square root of the state covariance matrix, SR-UPF has better numerical stability. Both simulation and experimental results demonstrate that the proposed algorithm can improve the diversity of particles, and perform well on estimation accuracy and consistency.

关键词： Simultaneous localization and mapping (SLAM) genetic algorithm square root unscented particle filter (SR-UPF) fastMetropolis-Hastings (MH) double roulette wheels.

Release characteristics of different diameter ultrafine fibers as antibacterial materials

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Journal of Innovative Optical Health Sciences 2021年第2期4卷 1-10页

作者： zhiqiang Wei Erniao Liu Hao Li zhimei Wei zhi lv Department of Orthopaedics Shanxi Medical University Second Hospital Taiyuan 030001P.R.China Institute of Materials Science and Technology Sichuan University Chengdu 610065P.R.China

Although the electrospinning technique has been devoted to promoting therapeutic purposes as a drug carrier,however,there are still many fundamental problems in this *** work focuses on a comparison of various diameter polyethersulfone(PES)electrospun ultrafine fibers as an-timicrobial *** fibrous morphology,antimicrobial agent distribution,thermally property,and biocompatibility evaluation of PES-based ultrafine fibers were systematically *** results demonstrated that the PES-based ultrafine fibers were suitable as anti-microbial ***,the drug release behavior and mechanism were studied through total *** release mechanism was confirmed to Fickian *** was revealed that the drug max release amount(71.5%)and release rate(7.71)are the highest for the smallest diameter ultrafine ***,the antimicrobial activity of PES ultrafine fibers is also inversely correlated with the diameter of *** electrospun PES fibers would control their release behavior through the diameter and have a potential application in the wound dressings,such as chronic osteomyelitis and exposure injury.

关键词： Electrospinning polyethersulfone ultrafine fibers drug release antimicrobial activity

High-gain and low-distortion Brillouin amplification based on pump multi-frequency intensity modulation

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Chinese Physics B 2019年第2期28卷 277-282页

作者： Li-Wen Sheng De-Xin Ba zhi-Wei lv National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology

Using a pump with a multi-line spectrum to broaden the Brillouin gain bandwidth is an effective way to achieve lowdistortion amplification with high gain. Here, we theoretically and experimentally investigate the generation of a broadband Brillouin gain spectrum based on multi-frequency intensity modulation in an optical fiber. The arbitrary bandwidth of the Brillouin gain spectrum of stimulated Brillouin scattering(SBS) can be obtained as expected. In our experiment, a broadband Brillouin gain spectrum with a bandwidth of about 200 MHz is demonstrated. We also achieve a low-distortion amplification of a weak signal, whose maximum magnification is 65 d B for a-68-dBm input power signal.

关键词： Brillouin gain spectrum bandwidth intensity modulation low distortion amplification

Mechanical synergistic interaction between adjacent corrosion defects and its effect on pipeline failure

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Petroleum Science 2023年第4期20卷 2452-2467页

作者： Wei Wang Yi Zhang Jian Shuai Yi Shuai Lei Shi zhi-Yang lv College of Safety and Ocean Engineering China University of PetroleumBeijing102249China Key Laboratory of Oil and Gas Safety and Emergency Technology Ministry of Emergency ManagementBeijing102249China Sinopec(Dalian)Research Institute of Petroleum and Petrochemicals Co. LtdDalianLiaoning116014China

This work provides a new comprehensive assessment method to determine the complex mechanical interaction of adjacent corrosion ***,a three-dimensional(3D)finite element model of pipelines containing adjacent defects(involving longitudinally aligned,circumferentially aligned,and diagonally aligned defects)was developed and validated by full-scale burst ***,the synergistic stress interaction between adjacent defects was analyzed,and the relationship between the burst position of the pipeline and defect spacing was *** last,the applicability of several commonly used critical spacing rules for identifying the interaction between adjacent defects was compared and discussed in *** results show that the failure position of the pipeline containing adjacent defects is related to the relative position of *** longitudinally aligned corrosion defects,the stronger the interaction between defects(i.e.,the shorter the distance between two defects),the closer the failure position of the pipeline to the center of the defect *** circumferentially aligned corrosion defects,the failure position of the pipe tends to move from the defect edge to the geometric center of the defect with increasing defect *** diagonally aligned defects,the failure position is generally located on the path connecting the defect and the *** currently available evaluation criteria for identifying circumferentially interacting defects display the most accuracy,and the identification effect of diagonally aligned defects is the *** addition,the critical spacing rule proposed by Li presents the highest precision in identifying the interacting *** results are expected to provide a stress synergistic failure assessment method for pipelines containing cluster corrosion defects in engineering.

关键词： Pipelines Adjacent defects Interaction Failure position Finite element model

Adsorption of Au(Ⅲ) ions on xanthated crosslinked chitosan resin in hydrochloric acid medium

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Rare Metals 2021年第3期40卷 743-748页

作者： Miao Zeng Ting-An Zhang Guo-zhi lv zhi-He Dou Yan Liu Ying Zhang Key Laboratory of Ecological Utilization of Multi-metal Intergrown Ores of Ministry of Education School of Materials and MetallurgyNortheastern UniversityShenyang 110819China

Xanthated crosslinked chitosan(XCCS) resin prepared under microwave irradiation were used for adsorbing Au(Ⅲ) ions in hydrochloric acid *** influence of pH and temperature on the adsorption capacity of XCCS was *** original XCCS and the loaded XCCS were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD),*** results indicate that the XCCS has ability to adsorb Au(Ⅲ) ions and the maximum adsorption capacity of Au(Ⅲ) ions on XCCS is observed at pH 1 and 20℃.The data of batch adsorption tests are fitted to kinetic models and isotherm models,*** kinetics of adsorption process is found to follow pseudo-second-order kinetic rate model,and equilibrium data agree very well with the Langmuir *** calculation of the Au(Ⅲ) ions adsorption process indicates that the adsorption process is spontaneous and endothermic.

关键词： Xanthated crosslinked chitosan Adsorption Au(Ⅲ)ions

Study on Melting and Recrystallization of Poly(butylene succinate) Lamellar Crystals via Step Heating Differential Scanning Calorimetry

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Chinese Journal of Polymer Science 2017年第12期35卷 1552-1560页

作者： zhi-yu lv Michael C.Zhang Yang Zhang Bao-hua Guo 徐军 Key Laboratory of Advanced Materials (Ministry of Education) Department of Chemical Engineering Tsinghua University

Differential scanning calorimetry（DSC） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhibits a broad endothermic peak or even multiple endotherms, which may result from changes of metastability via recrystallization process. Sometimes, the recrystallization exotherm cannot be observed due to its overlapping with the melting endotherm. In this work, we employed a step heating procedure consisting of successive heating and temperature holding stages to measure the metastability of isothermally crystallized poly（butylene succinate）（PBS） crystals. With this approach we could gain the fraction of crystals melted at different temperature ranges and quantitatively detect the melting-recrystallization behavior. The melting-recrystallization behavior depends on the polymer chain structure and the crystallization temperature. For instance, PBS block copolymer hardly shows recrystallization behavior while PBS oligomer and high molecular weight PBS homopolymer demonstrate remarkable melting-recrystallization phenomenon. High molecular weight PBS isothermally crystallized in the low temperature range shows multiple melting-recrystallization while those isothermally crystallized at elevated temperatures do not exhibit observable recrystallization behavior. Furthermore, the melting endotherms were fitted via the melting kinetics equations. The original isothermally crystallized lamellae demonstrate quite different melting kinetics from the recrystallized lamellar crystals that melt at the highest temperature range, which is attributed to the different degrees of stabilization. Finally, the mechanism of melting-recrystallization is briefly discussed. We propose that apparent meltrecrystallization phenomenon be observed when melting of preformed lamellar crystals and recrystallization of thicker lamellae have similar free energy barrier.

关键词： DSC Step heating Poly(butylene succinate) Metastability Melting-recrystallization Melting kinetics

Psychological impacts of the COVID-19 epidemic on Chinese people: Exposure, post-traumatic stress symptom, and emotion regulation

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Asian Pacific Journal of Tropical Medicine 2020年第6期13卷 252-259页

作者： Hong-juan Jiang Jiang Nan zhi-yue lv Juan Yang Department of Psychology The First Affliated HospitalHainan Medical UniversityHaikou 571199China Student Affairs Office Hainan Medical UniversityHaikou 571199China Key Laboratory of Tropical Translational Medicine of Ministry of Education Hainan Medical UniversityHaikou571199China Key Laboratory of Emegency and Trauma of Ministry of Education Key Laboratory of Brain Science Research&Transformation in Tropical Environment of Hainan ProvinceDepartment of PsychologyThe First Affliated HospitalHainan Medical UniversityHaikou 571199China

Objective:To examine the effects of coronavirus disease-2019(COVID-19)exposure,expressive suppression/cognitive reappraisal,and demographic variables on post-traumatic stress symptoms(PTS)among ***:Participants were recruited by social media through We Chat and 6049 Chinese(aged from 17 to 63 years;median=24)from 31 provinces were included in the *** symptoms,expressive suppression,and cognitive reappraisal were assessed after the outbreak of COVID-19.A regression mixture analysis was conducted in Mplus ***:A regression mixture model identified three latent classes that were primarily distinguished by differential effects of COVID-19 exposures on PTS symptoms:(1)Class 1(mildly PTS symptoms,80.9%),(2)Class 2(moderate PTS symptoms,13.0%),and(3)Class 3(high PTS symptoms,6.1%).The results demonstrated that the young,women and people with responsibilities and concerns for others were more vulnerable to PTS symptoms;and they had more expression inhibition and less cognitive reappraisal in three latent ***:The findings suggest that more attention needs to be paid to vulnerable groups such as the young,women and people with responsibilities and concerns for *** to encourage emotional expression and increase cognitive reappraisal may also be helpful for trauma survivors.

关键词： COVID-19 exposures Post-traumatic stress symptoms Expressive suppression Cognitive reappraisal

Posttraumatic stress symptom trajectories of Chinese university students during the first eight months of the COVID-19 pandemic and their association with cognitive reappraisal,expressive suppression,and posttraumatic growth

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Asian Pacific Journal of Tropical Medicine 2022年第10期15卷 451-460页

作者： Hong-juan Jiang Jiang Nan zhi-yue lv Juan Yang The First Affiliated Hospital of Hainan Medical University Haikou 571199China Student Affairs Office Hainan Medical UniversityHaikou 571199China Centre for Research in Psychology and Human Well-Being Faculty of Social Sciences and HumanitiesUniversiti Kebangsaan MalaysiaBangi 43600Malaysia Affiliated Hainan Hospital Key Laboratory of Tropical Translational Medicine of Ministry of EducationHainan Medical UniversityHaikou571199China Zhongshan School of Medicine Sun Yat-Sen UniversityGuangzhou510275China Affiliated Maternal and Child Health Hospital/Affiliated Children's Hospital Hainan Medical UniversityHaikou 571199China Key Laboratory of Brain Science Research&Transformation in Tropical Environment of Hainan Province Hainan Medical UniversityHaikou 571199China

Objective: To identify the moderating effects of cognitive reappraisal(CR) and expressive suppression(ES) on the relationship between posttraumatic stress(PTS) symptoms and posttraumatic growth(PTG) in university students. Methods: The survey included 1 987 Chinese university students who completed questionnaires on PTS symptoms in February 2020, with three follow-up surveys at two-month intervals until August 2020. We assessed CR and ES at February 2020 and PTG at August 2020. Growth mixture modeling was used to classify the PTS symptom trajectories. Multinomial logistic regression was used to recognize the predictors of class membership. The relationships among PTS symptoms, CR, ES, and PTG were examined using multi-group path ***: Sex, SARS-Co V-2 infection of a family member or friend, number of siblings, CR, and ES were significantly associated with PTS symptoms. Three latent classes were identified: ‘Increasing PTS’(n=205, 10.0%) who had rapid deterioration of PTS symptoms, ‘Moderate PTS’(n=149, 8.0%) who had a high level of PTS symptoms at the beginning and slightly increasing, and ‘Persistent Minimal PTS’(n=1 633, 82.0%), who had slow resolution of PTS symptoms over time. Male, SARS-Co V-2 infection of a family member or friend, and having a lower CR and a higher ES, were more likely to have ‘Increasing PTS’. PTS at February 2020 predicted PTG only in ‘Increasing PTS’ class, and both CR and ES had moderating effects on the conversion between ***: Most students recovered from posttraumatic stress of COVID-19 pandemic, but a small proportion expeienced increasing PTS symptoms, and those with this condition may benefit from emotional regulation intervention.

关键词： COVID-19 pandemic Posttraumatic stress symptoms Cognitive reappraisal Expressive suppression Posttraumatic growth Chinese university students