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Reflection and transmission of elastic waves through a couple-stress elastic slab sandwiched between two half-spaces

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Acta Mechanica Sinica 2017年第6期33卷 1022-1039页

作者： Changda Wang xuejun chen Peijun Wei Yueqiu Li Department of Applied Mechanics University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science University of Science and Technology Beijing Beijing 100083 China Department of Mathematics Qiqihar University Qiqihar 161006 China

The reflection and transmission of elastic waves through a couple-stress elastic slab that is sandwiched between two couple-stress elastic half-spaces are studied in this paper. Because of the couple-stress effects, there are three types of elastic waves in the couple-stress elastic solid, two of which are dispersive. The interface conditions between two couple-stress solids involve the surface couple and rotation apart from the surface traction and displacement. The nontraditional interface conditions between the slab and two solid half-spaces are used to obtain the linear algebraic equation sets from which the amplitude ratios of reflection and transmission waves to the incident wave can be determined. Then,the energy fluxes carried by the various reflection and transmission waves are calculated numerically and the normal energy flux conservation is used to validate the numerical results. The special case, couple-stress elastic slab sandwiched by the classical elastic half-spaces, is also studied and compared with the situation that the classical elastic slab sandwiched by the classical elastic half-spaces. Incident longitudinal wave(P wave) and incident transverse wave(SV wave) are both considered. The influences of the couplestress are mainly discussed based on the numerical *** is found that the couple-stress mainly influences the transverse modes of elastic waves.

关键词： Reflection/transmission Sandwiched slab Couple-stress Energy flux Multiple reflection/transmission

LUMPED PARAMETER NONLINEAR ANALYSIS OF PRESSURE DROP OSCILLATION IN TWO-PHASE FLOW IN EVAPORATOR TUBES

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Journal of Hydrodynamics 1998年第2期10卷 14-20页

作者： Zhou, Yunlong cheng, Zhuoming chen, Tingkuanl chen, xuejun Northeast China Inst of Electric Power Engineering Jilin China

The pressure drop oscillation was analyzed by using a lumped parameter nonlinear model. It is concluded that the instability order ordinary differential equation. The effect of operation conditions on pressure drop oscillation was examined by two dimensionless parameters Ε and η. The result obtained with the model agrees qualitatively with experimental results.

关键词： Evaporators Mathematical models Oscillations Pressure drop Stability

Relection of elastic waves at the elastically supported boundary of a couple stress elastic half-space

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Acta Mechanica Solida Sinica 2017年第2期30卷 154-164页

作者： Changda Wang xuejun chen Peijun Wei Yueqiu Li Department of Applied Mechanics Uniuersity of Science and Technology Beijing Beijing 100083 China Belting Key Laboratory for Magneto-Photoelectrical Composite and Interface Science University of Science and Technology Beijing Beijing 100083 China Department of Mathematics Qiqihar Uniuersity Qiqihar 161006 China

The relection elastic waves at the elastically supported boundary of a couple stress elastic half-space are studied in this paper. Different from the classical elastic solid, there are three kinds of elastic waves in the couple stress elastic solid, and two of them are dispersive. The boundary conditions of a couple stress elastic half-space include the couple stress vector and the rotation vector which disappear in the classical elastic solids. These boundary conditions are used to obtain a linear algebraic equation set, from which the amplitude ratios of relection waves to the incident wave can be determined. Then, the relection coeficients in terms of energy lux ratios are calculated numerically, and the normal energy lux conservation is used to validate the numerical results. Based on these numerical results,the inluences of the boundary parameters, which relect the mechanical behavior of elastic support, on the relection energy partition are discussed. Both the incident longitudinal wave（the P wave） and incident transverse wave（the SV wave） are considered.

关键词： Relection Elastic support Couple stress Dispersive waves Energy lux

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

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Asian Journal of Pharmaceutical Sciences 2024年第2期19卷 38-51页

作者： xuejun chen Ziqing Li Chunrong Yang Degong Yang Department of Pharmacy Shantou University Medical CollegeShantou 515041China Guangdong Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology Shantou University Medical CollegeShantou 515041China

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

关键词： Transdermal drug delivery system Ionic liquid Quantitative structure-activity relationship Intermolecular interaction

Economic Critical Resources for the Industrial Exploitation of Natural Gas Hydrate

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Acta Geologica Sinica(English Edition) 2022年第2期96卷 663-673页

作者： chen xuejun LU Hailong ZHANG Jiecheng YE Jianliang XIE Wenwei College of Engineering Peking UniversityBeijing 100871China Institute of Ocean Research Peking UniversityBeijing 100871China Beijing International Center for Gas Hydrate School of Earth and Space SciencesPeking UniversityBeijing 100871China Institute for Marine Science and Technology Shenzhen Graduate SchoolPeking UniversityShenzhen 518055China Guangzhou Marine Geological Survey Guangzhou 510075China

Since the implementation of several pilot production tests were in natural gas hydrate(NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for industrial exploitation. Prior to the industrial exploitation of any given NGH reservoir, the economic feasibility should be examined. The first step of economic evaluation of a NGH reservoir is to know whether its resource amount meets the requirement for industrial exploitation. Unfortunately, few relevant studies have been conducted in this regard. In this study, the net present value(NPV) method is employed to estimate the economic critical resources required for the industrial exploitation of NGHs under different production scenarios. Sensitivity analysis is also performed in order to specify the effects of key factors, such as the number of production wells, gas price, technological improvement and tax incentive, on the economic critical resources. The results indicate that China requires the lowest economic critical resource for a NGH reservoir to be industrially exploited, ranging from 3.62 to 24.02 billion m3 methane. Changes in gas price and tax incentives also play significant roles in affecting the threshold and timeline for the industrial exploitation of NGH.

关键词： natural gas hydrate industrial exploitation economic critical resource net present value recovery factor

Phase distribution in horizontal gas-liquid two-phase bubbly flow

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Nuclear Science and Techniques 1999年第3期10卷 184-189页

作者： SUN Kexia ZHANG Mingyuan chen xuejun (Xi’an Jiaotong University, Xi’an, 710049) Xi'an Jiaotong University Xi'an 710049

An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity *** variations of phase distribution with variations of gas and liquid volumetric fluxes were analyzed and the present data were compared with some of other researcher’s data and existing models. It was found there exists more complicated phase distribution pattern in horizontal flow system than in vertical flow. The radial local void fraction profiles are similar at the same measurement angle with various gas and liquid flow rates. However, an asymmetric profile can be observed at a given slice of the pipe cross-section.

关键词：气-液二相液起泡流相分布

Monitoring Study of Long-Term Land Subsidence during Subway Operation in High-Density Urban Areas Based on DInSAR-GPS-GIS Technology and Numerical Simulation

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Computer Modeling in Engineering & Sciences 2023年第2期134卷 1021-1039页

作者： Yu Song xuejun chen Baoping Zou Jundong Mu Rusheng Hu Siqi cheng Shengli Zhao College of Civil and Architecture Engineering Guilin University of TechnologyGuilin541004China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou310023China Hangzhou Metro Group Co. Ltd.Hangzhou310003China China Railway Tunnel Bureau Group Co. Ltd.Guangzhou511458China General Supervision Station of Construction Engineering Quality and Safety of Hangzhou Hangzhou310005China

During subway operation,various factors will cause long-term land subsidence,such as the vibration subsidence of foundation soil caused by train vibration load,incomplete consolidation deformation of foundation soil during tunnel construction,dense buildings and structures in the vicinity of the tunnel,and changes in water level in the stratum where the tunnel is *** monitoring of long-term land subsidence during subway operation in high-density urban areas differs from that in low-density urban construction *** former is the gathering point of the entire urban *** are many complex buildings around the project,busy road traffic,high pedestrian flow,and less vegetation *** existing items ***,monitoring distance is long,and providing early warning is *** study uses the 2.8 km operation line between Wulin Square station and Ding’an Road station of Hangzhou Subway Line 1 as an example to propose the integrated method of DInSAR-GPS-GIS technology and the key algorithm for long-term land subsidence ***,it selects multiscene image data to analyze long-termland subsidence of high-density urban areas during subway *** show that long-term land subsidence caused by the operation of Wulin Square station to Ding’an Road station of Hangzhou Subway Line 1 is small,with maximumsubsidence of 30.64 mm,and minimumsubsidence of 11.45 mm,and average subsidence ranging from 19.27 to 21.33 *** FLAC3D software was used to verify the monitoring situation,using the geological conditions of the soil in the study area and the tunnel profile to simulate the settlement under vehicle load,and the simulation results tended to be consistent with the monitoring situation.

关键词： Long-term land subsidence subway operation DInSAR-GPS-GIS technology high-density urban areas urban subway numerical simulation

The APETALA2 homolog CaFFN regulates flowering time in pepper

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Horticulture Research 2021年第1期8卷 3158-3171页

作者： Xinjie Yuan Rong Fang Kunhua Zhou Yueqin Huang Gang Lei Xiaowu Wang xuejun chen Institute of Vegetables and Flowers Jiangxi Academy of Agricultural Sciences330200 NanchangChina Institute of Vegetables and Flowers Chinese Academy of Agricultural Sciences100081 BeijingChina

Flowering time is an important agronomic trait that contributes to fitness in ***,the genetic basis of flowering time has not been extensively studied in *** understand the genetics underlying flowering time,we constructed an F 2 population by crossing a spontaneous early flowering mutant and a late-flowering pepper *** bulked segregant RNA-seq,a major locus controlling flowering time in this population was mapped to the end of chromosome *** APETALA2(AP2)homolog(CaFFN)cosegregated with flowering time in 297 individuals of the F 2 population.A comparison between the parents revealed a naturally occurring rare SNP(SNP2T>C)that resulted in the loss of a start codon in CaFFN in the early flowering *** Nicotiana benthamiana plants with high CaFFN expression exhibited a delay in flowering time and floral patterning *** the other hand,pepper plants with CaFFN silencing flowered ***,the CaFFN gene acts as a flowering repressor in *** may function as a transcriptional activator to activate the expression of CaAGL15 and miR156e and as a transcriptional repressor to repress the expression of CaAG,CaAP1,CaSEP3,CaSOC1,and miR172b based on a qRT-PCR *** activation of CaAGL15 by CaFFN was detected using yeast one-hybrid and dual-luciferase reporter assays,consistent with the hypothesis that CaFFN regulates flowering ***,the CaFFN gene association analysis revealed a significant association with flowering time in a natural pepper population,indicating that the CaFFN gene has a broad effect on flowering time in ***,the phylogeny,evolutionary expansion and expression patterns of CaFFN/AP2 homologs were analyzed to provide valuable insight into *** study increases our understanding of the involvement of CaFFN in controlling flowering time in pepper,thus making CaFFN a target gene for breeding early maturing pepper.

关键词： homolog pepper breeding

Unstable Allotetraploid Tobacco Genome due to Frequent Homeologous Recombination, -. Segmental Deletion, and Chromosome Loss

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Molecular Plant 2018年第7期11卷 914-927页

作者： Shumin chen Feihong Ren Lei Zhang Yong Liu xuejun chen Yuanmei Li Liang Zhang Bin Zhu Pan.Zeng Zaiyun Li Robert M. Larkin Hanhui Kuang Key Laboratory of Horticultural Plant Biology Ministry of Education Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region) MOA College of Horticulture and Forestry Sciences Huazhong Agricultural University Wuhan 430070 People's Republic of China Yunan Academy of Tobacco Agricultural Science Kunming Yunnan Province People's Republic of China College of Plant Science Huazhong Agricultural University Wuhan 430070 People's Republic of China These authors contributed equally to this article.

The types of mutations and their corresponding frequencies are difficult to measure in complex genomes. In this study, a high-throughput method was developed to identify spontaneous loss-of-function alleles for the resistance gene N and the transgenic avirulence gene P50 in allotetraploid tobacco. A total of 2134 loss- of-function alleles of the N gene were identified after screening 14 million F1 hybrids. Analysis of these mutants revealed striking evolutionary patterns for genes in polyploids. Only 14 of the loss-of-function mutations were caused by spontaneous point mutations or indels, while the others were caused by home- ologous recombination （with a frequency of 1/12 000） or chromosome loss （1/15 000）. Loss of the chromosome with the PS0 insertion occurred at a similar frequency （1/13 000）, and the frequency of spon- taneous segmental deletion in this chromosome was 1/16 000. Both homeologous recombination and chromosome loss considerably decreased the viability of the mutants. Our data suggest that the high mutation rate in polyploids is probably due to the occurrence of homeologous recombination and the toler- ance of large mutations such as chromosome loss in polyploid genomes. Frequent mutations tend to drive polyploids to extinction unless a novel mutation helps the polyploid to effectively compete with diploids or find a new ecological niche.

关键词： polyploid genome evolution homeologous recombination chromosome loss spontaneous mutation