检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

新型雀替式黏弹性阻尼器试验与力学性能分析

自然灾害学报 2024年第5期33卷 210-217页

作者：彭国威陶忠徐荣荣戴必辉燕钊昆明理工大学建筑工程学院云南昆明650500 云南省抗震工程技术研究中心云南昆明650500 西南林业大学土木工程学院云南昆明650224

该文提出一种新型雀替式黏弹性阻尼器,为研究其构造形式的合理性和可行性,对5个新型雀替式黏弹性阻尼器进行了变形相关性、频率相关性以及疲劳性能循环加载试验,分析新型雀替式黏弹性阻尼器的耗能系数、等效黏滞阻尼比和骨架曲线等几项... 详细信息

该文提出一种新型雀替式黏弹性阻尼器,为研究其构造形式的合理性和可行性,对5个新型雀替式黏弹性阻尼器进行了变形相关性、频率相关性以及疲劳性能循环加载试验,分析新型雀替式黏弹性阻尼器的耗能系数、等效黏滞阻尼比和骨架曲线等几项性能参数。研究结果表明:5个新型雀替式黏弹性阻尼器滞回曲线饱满,滞回性能较好,耗能能力较强,橡胶硬度为65°的试件累计耗能为2.343 kN·m;变形幅值对阻尼器的影响明显,随着变形量的增加,阻尼器的最大阻尼力和周期耗能逐渐增大,能量耗散系数和等效刚度逐渐减小;不同橡胶材料的新型雀替式黏弹性阻尼器试件的滞回曲线、等效黏滞阻尼比和骨架曲线形状基本一致;不同加载频率下,耗能系数和等效黏滞阻尼比分别在0.03962~0.04016和0.1260~0.1320之间,2个性能指标变化均较小,频率相关性较弱;疲劳加载后新型黏弹性阻尼器耗能系数衰减24.8%,等效黏滞阻尼比衰减25.4%,具有良好的疲劳性能,无明显的滞回曲线面积衰减和低周疲劳现象。

关键词：木结构加固新型雀替式黏弹性阻尼器变形相关性频率相关性疲劳性能滞回耗能

Identification and robust limit-cycle-oscillation analysis of uncertain aeroelastic system

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2011年第7期54卷 1841-1848页

作者： dai YuTing WU ZhiGang YANG Chao School of Aeronautic Science and Engineering Beijing University of Aeronautics and AstronauticsBeijing 100191China

Model uncertainty directly affects the accuracy of robust flutter and limit-cycle-oscillation (LCO) analysis. Using a data-based method, the bounds of an uncertain block-oriented aeroelastic system with nonlinearity are obtained in the time domain. Then robust LCO analysis of the identified model set is performed. First, the proper orthonormal basis is constructed based on the on-line dynamic poles of the aeroelastic system. Accordingly, the identification problem of uncertain model is converted to a nonlinear optimization of the upper and lower bounds for uncertain parameters estimation. By replacing the identified memoryless nonlinear operators by its related sinusoidal-input describing function, the Linear Fractional Transformation (LFT) technique is applied to the modeling process. Finally, the structured singular value(μ) method is applied to robust LCO analysis. An example of a two-degree wing section is carded out to validate the framework above. Results indicate that the dynamic characteristics and model uncertainties of the aeroelastic system can be depicted by the identified uncertain model set. The robust LCO magnitude of pitch angle for the identified uncertain model is lower than that of the nominal model at the same velocity. This method can be applied to robust flutter and LCO prediction.

关键词： aeroelasticity robust identification uncertainty structured singular value p limlt-cycle-oscillation

粪肥源雌激素在农田土壤-作物中污染特征、转运规律及毒理风险

在线全文

学校读者我要写书评

暂无评论

环境化学 2024年第7期43卷 2214-2223页

作者：陈健琴代思媛张碟李舜尧孙凯安徽农业大学资源与环境学院农田生态保育与污染防控安徽省重点实验室合肥230036 安徽大学湿地生态保护与修复安徽省重点实验室合肥230601

雌酮(E1)、17β-雌二醇(E2)、雌三醇(E3)、17α-炔雌醇(EE2)和双酚A(BPA)等作为畜禽粪污中雌激素活性较强的环境内分泌干扰物,可在农田土壤-作物系统内输运和累积,并对野生物种的生殖发育、遗传代谢,以及农产品的质量和安全构成巨大威胁... 详细信息

雌酮(E1)、17β-雌二醇(E2)、雌三醇(E3)、17α-炔雌醇(EE2)和双酚A(BPA)等作为畜禽粪污中雌激素活性较强的环境内分泌干扰物,可在农田土壤-作物系统内输运和累积,并对野生物种的生殖发育、遗传代谢,以及农产品的质量和安全构成巨大威胁.目前,国际上关于粪肥源雌激素在农田土壤-作物中污染特征、转运规律及毒理风险的报道仍较少.本文综述了5种代表性粪肥源雌激素在农田生态系统中的污染特征和时空分布规律,归纳了雌激素在农田土壤-作物中的迁移转化、吸收积累和代谢机理,系统地评估了农田生态系统中雌激素生物毒性效应及其风险模型,旨在为规避农田土壤-作物雌激素污染风险、生产绿色农产品和保障人民健康等奠定理论基础.

关键词：畜禽粪便农业生态环境雌激素污染转运途径健康风险

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

新时代标准化推动商业航天高质量发展的思考

航天标准化 2024年第1期 1-4页

作者：田露许冬彦代健中国航天标准化与产品保证研究院北京100071

在国家政策的鼓励下,商业航天发展呈现产业规模持续增长、民企发展迅速、商业模式不断革新的态势。标准化在推动商业航天产业升级、加强行业监管和企业管理、助推技术创新等方面发挥着重要的作用。文章从标准化推动商业航天高质量融合... 详细信息

在国家政策的鼓励下,商业航天发展呈现产业规模持续增长、民企发展迅速、商业模式不断革新的态势。标准化在推动商业航天产业升级、加强行业监管和企业管理、助推技术创新等方面发挥着重要的作用。文章从标准化推动商业航天高质量融合创新发展的角度,提出当前面临的主要任务包括:加强商业航天标准化顶层策划,构建高质量发展的标准体系以及政府与市场共同发挥作用的供给体系;加快行业治理和企业管理标准化建设,建立健全商业航天企业质量管理和产品保证标准规范体系;推动标准化与航天科技创新互动发展,建立重大科技项目与标准化工作联动机制;推动航天基础资源统筹和综合利用,发挥国家战略资源的作用;提升商业航天标准化对外开放水平,实现商业航天产品、技术和服务“走出去”。

关键词：商业航天标准化高质量发展

Dynamic Behaviour of a Caisson Quaywall Under Strong Earthquake

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 1999年第1期14卷 47-62页

作者： Liu, HL dai, HC Iai, S Hohai Univ Geotech Engn Res Inst Nanjing 210098 Peoples R China China Yangtze Three Gorges Project Dev Corp Yichang 443002 Peoples R China Minist Transport Port & Harbour Res Inst Nagase 239 Japan

Effective stress analysis is performed to evaluate the residual displacement of a caisson quaywall during 1994 Hokkaido- Toho- Oki Earthquake and 1993 Kushiro- Oki Earthquake. The constitutive model used in this study is a multiple shear mechanism type defined in strain space and can take into account the effect of rotation of principal stress axis. The earthquake accelerations recorded at the outcropping rock during the earthquake are used as input bedrock motion. The results of finite element analysis are in good agreement with the observed behaviour of the quaywall. The analysis also indicates that liquefaction and high excess porewater pressure have a significant effect on the deformation of the caisson. Soil improvement is speculated as the most reliable measures against liquefaction. The influence of soil improvement and the reasonable improved area are discussed in the paper.

关键词： caisson quaywall effective stress analysis lique faction residual deformation

在线全文

学校读者我要写书评

暂无评论

1STC1在乳腺癌中的作用研究进展

河北医药 2024年第2期46卷 284-288页

作者：戴泽华侯净倪青贵州医科大学研究生院贵阳市550004 贵州省人民医院乳腺外科

乳腺癌是目前全球女性恶性肿瘤发病率最高的一种疾病,是一种高度异质性疾病,可根据其不同分子指标表达分为4种分子亚型,具有不同的组织学、临床行为和预后特征。锡钙素-1(STC1)是一种分泌型糖蛋白激素,目前已被证实可调节钙和磷酸盐的稳... 详细信息

乳腺癌是目前全球女性恶性肿瘤发病率最高的一种疾病,是一种高度异质性疾病,可根据其不同分子指标表达分为4种分子亚型,具有不同的组织学、临床行为和预后特征。锡钙素-1(STC1)是一种分泌型糖蛋白激素,目前已被证实可调节钙和磷酸盐的稳态,STC1在哺乳动物的各种组织中表达,并参与多种生理和病理生理过程。同时越来越多的证据表明STC1在多种不同类型的肿瘤中起致癌作用。为了进一步理清STC1与乳腺癌之间的关系,通过大量文献阅读及总结,总结分析了STC1与乳腺癌现有的研究数据,探索STC1与乳腺癌发生、发展、治疗预后等一系列的相关证据,并讨论其在乳腺癌各亚型中的潜在作用,为今后的研究找寻方向。

关键词：乳腺癌锡钙素-1 乳腺癌化疗耐药乳腺癌预后

维普期刊数据库博看期刊

Study on the Durability of Recycled Powder Concrete against Sulfate Attack under Partial Immersion Condition

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2022年第11期10卷 3059-3078页

作者： Hualei Bai Ying Li Dahu dai School of Civil Engineering Qinghai UniversityXining810016China Qinghai Provincial Key Laboratory of Energy Saving Building Materials and Engineering Safety Xining810016China

In order to make full use of waste recycled fine powder(RFP)in concrete and achieve the goal of carbon neutrality in the concrete industry,the durability of sulfate resistance is an important aspect of evaluating the performance of recycled powder concrete(RPC).Therefore,the durability of RPC under partial sulfate immersion was studied to provide theoretical guidance for understanding the erosion mechanism of *** compressive strength,mass loss,and microstructure change patterns of RPC under partial immersion of 5%Na2SO4 and MgSO4 solutions were analyzed by cubic compressive strength,mass loss rate,SEM-EDS,and *** results showed that the surface crystalline matter of concrete in Na2SO4 solution was mainly white powders,and that of concrete in MgSO4 solution was mainly transparent paste,both of which had a little spalling on the outer surface of the *** compressive strength and mass loss rate of concrete with 20%RFP was relatively good,indicating that concrete with 20%RFP had better durability against *** compressive strength of the lower part of the concrete partially immersed in Na2SO4 solution was higher than that of the upper part and the strength of the lower part of RPC-2 was 3.11%higher than the upper part at 180 d;The pattern was reversed in the MgSO4 solution,where the strength of the lower part of RPC-2 was 19.74%lower than the upper part at 180 *** analysis showed that the hydration products of RPC were mainly gypsum and ettringite,while the RPC produced more hydration products with the promotion of magnesium ion in the MgSO4 *** higher the replacement rate of RFP,the more frequent the gypsum-type failures in the concrete.

关键词： Recycled powder concrete recycled fine powder sulfate resistance compressive strength

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

大型沉井下沉过程拉应力影响因素分析

长安大学学报（自然科学版） 2024年第1期44卷 47-57页

作者：王正振戴康乐苏天涛龚维明郭辉兰州理工大学土木工程学院甘肃兰州730050 东南大学土木工程学院江苏南京210000 中国铁道科学研究院铁道建筑研究所北京100081

为研究大型沉井下沉过程中的拉应力影响因素,以五峰山长江大桥北锚碇沉井为工程背景,利用ABAQUS有限元软件建立足尺首次下沉沉井数值模型,在利用现场实测数据验证数值模型准确性的基础上,通过控制变量法分别分析初始下沉高度、开挖方式... 详细信息

为研究大型沉井下沉过程中的拉应力影响因素,以五峰山长江大桥北锚碇沉井为工程背景,利用ABAQUS有限元软件建立足尺首次下沉沉井数值模型,在利用现场实测数据验证数值模型准确性的基础上,通过控制变量法分别分析初始下沉高度、开挖方式、沉井平面尺寸等因素对沉井基础混凝土拉应力的影响,并据此提出相应的拉裂防控措施。研究结果表明:在大型沉井初始下沉过程中,宽度方向混凝土拉应力往往大于其长度方向,且沉井长宽比越大,宽度方向与长度方向的拉应力比越大,故宽度方向拉应力是工程监控的重点;沉井隔墙拉应力可通过梁的相关理论近似分析,但需考虑隔墙在交点处的相互作用;初始下沉高度、开挖方式及荷载对沉井混凝土拉应力均有较大影响;沉井最大拉应力随着外荷载的增大而线性增大,八区开挖方式比大锅底开挖混凝土最大拉应力减小近90%,增大初始下沉高度可使混凝土最大拉应力减小近50%;增大初始下沉高度和调整开挖方式仅通过改变施工工序即可实现,是较为经济合理的控制井身拉应力的方法;井身混凝土强度、隔墙宽度、井壁宽度等对井身拉应力的影响较小,在沉井下沉过程中无需重点考虑。

关键词：桥梁工程大型沉井有限元内力分析影响因素防控措施下沉

Electrospun composites of PHBV/pearl powder for bone repairing

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2015年第4期25卷 327-333页

作者： Jingjing Bai Jiamu dai Guang Li College of Material Science and Engineering Donghua University

Electrospun fi ber has highly structural similarity with natural bone extracelluar matrix(ECM). Many researches about fabricating organic–inorganic composite materials have been carried out in order to mimic the natural composition of bone and enhance the biocompatibility of materials. In this work, pearl powder was added to the poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) and the composite nano fi ber scaffold was prepared by electrospinning. Mineralization ability of the composite scaffolds can be evaluated by analyzing hydroxyapatite(HA)formation on the surface of nano fi ber scaffolds. The obtained composite nano fi ber scaffolds showed an enhanced mineralization capacity due to incorporation of pearl powder. The HA formed amount of the composite scaffolds was raised as the increase of pearl powder in composite scaffolds. Therefore, the prepared PHBV/pearl composite nano fi ber scaffolds would be a promising candidate as an osteoconductive composite material for bone repairing.

关键词： Hydroxyapatite Pearl PHBV Mineralization Composite nano fi bers scaffolds