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弹塑性多孔介质流固耦合新理论:混合耦合理论

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计算力学学报 2024年第1期41卷 129-138页

作者：徐丽阳王锴丁智徐日庆陈晓辉浙江大学滨海和城市岩土工程研究中心杭州310058 浙江省城市地下空间开发工程技术研究中心杭州310058 浙大城市学院土木工程系杭州310015 浙江省城市盾构隧道安全建造与智能养护重点实验室杭州310015 北京师范大学水科学研究院北京100875 利兹大学土木工程系英国利兹LS29JT

在全球气候变化和双碳政策的大背景下,多孔介质中固体的变形和流体的输运问题变得尤为重要。然而,在多孔介质中建立流固耦合模型仍面临的挑战之一是需要考虑跨越宏观尺度到纳米尺度的耦合作用。本文利用基于非平衡热力学的混合耦合理论... 详细信息

在全球气候变化和双碳政策的大背景下,多孔介质中固体的变形和流体的输运问题变得尤为重要。然而,在多孔介质中建立流固耦合模型仍面临的挑战之一是需要考虑跨越宏观尺度到纳米尺度的耦合作用。本文利用基于非平衡热力学的混合耦合理论,提出了一个弹塑性多孔介质流固耦合新模型,在同一个理论框架内研究了弹性变形、塑性变形和液体渗流之间跨尺度的耦合,考虑了耗散过程中的熵产,并利用Helmholtz自由能连接宏观尺度上的力学变形和纳米尺度上的液体输运之间的相互作用。在应力-应变关系中采用了弹塑性刚度系数以反映塑性的影响。同时,经典的达西定律扩展为可考虑固体的塑性变形。通过与文献中模型的比较,验证了该模型的有效性。最后,数值分析表明在多孔介质的流固耦合中塑性变形具有比较显著的影响。

关键词：混合耦合理论塑性流固耦合多孔介质跨尺度

维普期刊数据库博看期刊

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不同黄腐酸结构组成及其对小麦生长的影响

土壤通报 2024年第1期55卷 102-112页

作者：朱启明王亚男郑重曾希柏许立阳张洋李雨欣中国农业科学院农业环境与可持续发展研究所北京100081 国家农业环境岳阳观测实验站湖南岳阳414000

【目的】为了找出秸秆源黄腐酸(Stalk fulvic acid,SFA)可以作为矿源黄腐酸(Fulvic acid,FA)和生化源黄腐酸(Biochemical fulvic acid,BFA)替代物的原因,探讨不同黄腐酸结构组成及其对小麦生长的影响。【方法】利用紫外-可见光谱、傅里... 详细信息

【目的】为了找出秸秆源黄腐酸(Stalk fulvic acid,SFA)可以作为矿源黄腐酸(Fulvic acid,FA)和生化源黄腐酸(Biochemical fulvic acid,BFA)替代物的原因,探讨不同黄腐酸结构组成及其对小麦生长的影响。【方法】利用紫外-可见光谱、傅里叶红外光谱和13C核磁共振碳谱技术分析不同黄腐酸的结构组成。以冬小麦GY18204为材料,通过小麦根长、苗长、苗干重、根鲜重以及根活力等相关指标明确不同黄腐酸对小麦种子发芽和苗期生长的影响。【结果】通过结构分析发现SFA与BFA结构类似,与FA化学结构组成存在一定的差异:SFA和BFA具有更多糖类物质和连氧芳香碳等不稳定和功能化基团,FA具有更多羧基等稳定和功能化较少基团。不同黄腐酸对小麦发芽期均有促进效果,FA可促进小麦发芽的浓度范围更大,BFA和SFA只有施加20和40 mg L^(−1)的较低浓度可以促进小麦发芽,高浓度表现出抑制效果。适当降低氮、磷钾肥的用量后配施黄腐酸可显著促进小麦苗期生长,SFA可使根长和苗长提高20~50%,使苗干重和根鲜重提高80~150%,使根活力提高200~240%。FA可使根长和苗长增加50~80%,苗干重和根鲜重提高90~160%,根活力提高220~250%。由此可知,当黄腐酸浓度控制在适宜范围,其对小麦的生长有明显促进作用。【结论】不同来源黄腐酸物理化学性质不同,具有更多不稳定和功能化基团的SFA和BFA在较低的浓度下促进小麦生长,而具有更多稳定和功能化较少基团的FA需要较高的浓度来促进小麦生长。研究结果为秸秆资源开发利用制备黄腐酸及新型生物肥料提供了科学参考。

关键词：黄腐酸结构组成小麦种子发芽小麦苗期生长

血清CK-MB水平与急性心肌梗死患者病情严重程度的关系分析

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中国现代药物应用 2024年第16期18卷 41-44页

作者：杨叙利卢佩仪广州市白云区第二人民医院检验科 510450

目的研究血清肌酸激酶同工酶(CK-MB)水平与急性心肌梗死(AMI)患者病情严重程度的关系。方法择选98例AMI患者,收集其病例信息作回顾性分析,按照病情严重程度不同将其分为较重组、较轻组,分别为35、63例。对比两组临床资料[年龄、性别、... 详细信息

目的研究血清肌酸激酶同工酶(CK-MB)水平与急性心肌梗死(AMI)患者病情严重程度的关系。方法择选98例AMI患者,收集其病例信息作回顾性分析,按照病情严重程度不同将其分为较重组、较轻组,分别为35、63例。对比两组临床资料[年龄、性别、吸烟史、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、心率(HR)、心肌肌钙蛋白I(cTnI)、心脏型脂肪酸结合蛋白(H-FABP)、CK-MB],并对其做Logistic回归分析,分析AMI患者病情严重程度的影响因素。结果两组在年龄、性别、吸烟史、LDL-C、HDL-C、HR上差异不明显(P>0.05);在cTnI、H-FABP、CK-MB上,较重组分别为(25.62±5.24)、(122.18±20.65)、(64.08±12.17)ng/ml,均高于较轻组的(16.41±4.28)、(56.57±23.12)、(25.94±18.54)ng/ml,差异明显(P0.05),CK-MB是AMI疾病严重程度的独立影响因素(OR=2.186,P<0.05)。结论血清CK-MB水平与AMI患者病情严重程度密切相关,CK-MB过高是AMI病情严重的独立危险因素。

关键词：肌酸激酶同工酶急性心肌梗死病情严重程度关系

Ecological compensation based on willingness to accept for conservation of drinking water sources

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Frontiers of Environmental Science & Engineering 2015年第1期9卷 58-65页

作者： linyu xu Bing YU yang li State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China

Ecological compensation is a powerful environmental economic tool for environmental protection in areas where drinking water sources are located. We established an ecological compensation accounting system based on respondents＇ willingness to accept （WTA）. In this system, stakeholder preferences and the factors that influence them can be gauged effectively using logit and tobit models. We applied this accounting system to ecological compensation for the Miyun Reservoir, Beijing, China. The average WTA value for Miyun Reservoir residents was approximately 1186 CNY per family in 2012, which could be set as a suitable compensation standard, since it is slightly higher than the local protection cost. Thus, the annual total ecological compensation could be 58.73 million CNY. Distance from the reservoir, job types, and attitude to environmental protection were variables with significant effects on WTA. In addition, trends for individual preferences were identified via an analysis of key influential factors. The results suggest some useful information for establishing ecological compensation mechanisms for conservation of drinking water sources. Suggestions include popularizing the concept and meaning of ecological compensation among residents, setting different compensation levels based on distance from the reservoir, considering the requirements of farmers, and taking various in-kind and out-of-kind compensa- tion approaches.

关键词： contingent valuation method questionnaire survey Miyun Reservoir

Investigation and Modeling of Austenite Grain Evolution for a Typical High-strength Low-alloy Steel during Soaking and Deformation Process

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Acta Metallurgica Sinica(English Letters) 2022年第6期35卷 996-1010页

作者： Ming-Jie Zhao liang Huang Chang-Min li Jia-Hui xu xu-yang li Jian-Jun li Peng-Chuan li Chao-Yuan Sun State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China China National Erzhong Group Deyang Wanhang Die Forging Co.LTD Deyang 618000China

The final mechanical properties of components greatly depend on their grain size. It is necessary to study the grain evolution during different thermomechanical processes. In the study, the real-time austenite grain evolution of a high-strength low-alloy(HSLA) steel during the soaking process is investigated by in situ experiments. The effects of different deformation parameters on the dynamic recrystallization(DRX) kinetic behaviors are investigated by hot compression experiments. Based on the observations and statistics of the microstructures at different thermomechanical processes, a unified grain size model is established to evaluate the effects of soaking parameters and deformation parameters on the austenite grain evolution. Also, the DRX kinetic model and critical strain model are established, which can describe the effects of the soaking process on the DRX kinetics process well. The established grain size model and DRX kinetic model are compiled into the numerical simulation software using Fortran language. The austenite grain evolution of the material under different deformation conditions is simulated, which is consistent with the experimental results. It indicates that the established model is reliable, and can be used to simulate and predict the grain size during different thermomechanical processes accurately.

关键词： High-strength steel Grain growth Dynamic recrystallization Grain size model Numerical simulation

Effects of arsenic on seed germination and physiological activities of wheat seedlings

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Journal of Environmental Sciences 2007年第6期19卷 725-732页

作者： li Chun-xi FENG Shu-li SHAO Yun JIANG li-na LU xu-yang HOU Xiao-li College of life Sciences Henan Normal University Xinxiang 453007 China

The effects of arsenic （As） were investigated on seed germination, root and shoot length and their biomass and some other factors to elucidate the toxicity of As. The results showed low concentrations of As （0-1 mg/kg） stimulated seed germination and the growth of root and shoot, however, these factors all decreased gradually at high concentrations of As （5-20 mg/kg）. The contents of O2^-, MDA, soluble protein and peroxidase （POD） activity all increased with increasing As concentrations. Soluble sugar content, ascorbate peroxidase （APX）, and superoxide dismutase （SOD） activities decreased at low concentrations of As, and increased at high concentrations of As. While acetylsalicylic acid （ASA） and chlorophyll contents, catalase （CAT） activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg, and then decreasing trend. By polyacrylamide gel electrophoresis （PAGE）, As induced the expression of POD isozymes of wheat seedlings. As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg. However, As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg. The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.

关键词： arsenic wheat germination physiological activities

Effect of Skeleton Grain Size on the Saturation of Gas Hydrate in Natural Sediments

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Journal of Ocean University of China 2024年第3期23卷 676-682页

作者： xu Zhenqiang li yang College of Marine Sciences Ocean University of ChinaQingdao 266100China China Petroleum&Chemical Corporation Beijing 100728China

Natural gas hydrate is prospected as a new and promising,highly clean energy resource that mainly occurs in perma-frost or at continental *** formation is subject to many soil conditions,such as grain size,matrix materials,pore morphology,and *** this study,we propose that grain size is the most decisive parameter that affects the saturation of gas hydrate in sediments based on data from Ocean Drilling Program Leg 164 and Mallik 5L-38,which represent marine sediments and terrestrial sediments,*** study reveals that high gas hydrate saturation generally occurs in coarse-grained sand,regardless of whether sediment formation is homogeneous or inhomogeneous,and the sorting of sediments may affect the hydrate saturation to a certain *** grain size and sorting of sediments may be the most intuitive proxy method for a rough estimation of hydrate *** study is necessary to fully understand the relationship between hydrate morphology and sediment grain size,even though massive hydrates are typically found in fine clayey-rich sediments.

关键词： grain size saturation gas hydrates ODP Leg 164 Mallik 5L-38

Random projection method for ultra wideband signal acquisition

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 14-21页

作者： liN Jie SHI Guang-ming CHEN xu-yang ZHANG li School of Electronic Engineering Xidian University Xi＇an 710071 China

High-speed high-resolution analog-to-digital （A/D） conversion demanded by ultra wideband （UWB） signal processing is a very challenging problem. This paper proposes a parallel random projection method for UWB signal acquisition. The proposed method can achieve high sampling rate, high resolution and technical feasibility of hardware implementation. In the proposed method, an analog UWB signal is projected over a set of random sign functions. Then the low-rate high-resolution analog-to-digital convertors （ADCs） are used to sample the projection coefficients. The signal can be reconstructed by simple linear calculation with the sampling matrix, without complying with optimization algorithm and prior knowledge. In other aspects, unlike other approaches that need to utilize an accurate time-shift at extremely high frequency, or design a hybrid filter bank, or generate specific basis functions or work for signals with prior knowledge, the proposed method is a universal sampling approach and easy to apply. The simulation results of signal to noise ratio （SNR） and spurious-free dynamic range （SFDR） validate the efficiency of the proposed method for UWB signal acquisition.

关键词： random projection high speed high resolution data acquisition UWB signal

Development and Research on the Internet Resources Aggregation Platform

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Wuhan University Journal of Natural Sciences 2007年第2期12卷 243-248页

作者： xu Youwei TANG Shengqun yang Yan xu yang li ling State Key Laboratory of Software Engineering Wuhan University Wuhan 430072 Hubei China

We proposed an Intemet resource aggregation platform based on semantic web. The platform includes an Web Ontology Language（OWL） ontology design toolkit（VO-Editor） and a selective inference algorithm engine so that it can visually editing ontology and using novel selective reasoning for information aggregation. We introduce the VO-Editor and the principle of selective inference algorithm. At last a case of budget travel system is used to interpret the approach of Internet resources aggregation by this platform.

关键词： semantic web ontology information aggregation inference Web Ontology Language