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空化噪声量测结构的声学性能研究

水动力学研究与进展（A辑） 1991年第1期6卷 52-59页

作者：吴建华柴恭纯王河生南京水利科学研究院

本文从理论上分析了在水流空化声测研究中空化噪声量测结构的声学性能。提出了判断空化噪声传声窗声学性能的两个条件,第一,工作液体和传声窗特性阻抗匹配条件:ρ_1C_1=ρ_2C_2;第二,空化噪声谱频域的最大频率f_(max)(或最小波长λ_(mi... 详细信息

本文从理论上分析了在水流空化声测研究中空化噪声量测结构的声学性能。提出了判断空化噪声传声窗声学性能的两个条件,第一,工作液体和传声窗特性阻抗匹配条件:ρ_1C_1=ρ_2C_2;第二,空化噪声谱频域的最大频率f_(max)(或最小波长λ_(min))条件:f_(max)≤C/(60D)(或λ_(min)/D≥60)。若传声窗满足其中任一条件,就可以获得较好的声测效果。同时,对此结果进行了试验验证,试验结果和理论分析结果吻合很好。根据这两个条件,本文对目前常规使用的有机玻璃传声窗的声学性能进行了分析。结果表明:对于清水空化的声测研究而言,其阻抗比r_(21)=2.18,不满足ρ_1C_1=ρ_2C_2条件,而且实际空化噪声谱频域很难满足f_(max)≤V/(60D)条件。因此,有机玻璃材料传声窗的传声效果并不理想,其声学性能不如聚乙烯材料更好。

关键词：空化噪声传声窗特性阻抗

Genetic Diversity of Chinese Soybean mosaic virus Strains and Their Relationships with Other Plant Potyviruses Based on P3 Gene Sequences

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Journal of Integrative Agriculture 2014年第10期13卷 2184-2195页

作者： yang Qing-hua LI Kai ZHI Hai-jian GAI Jun-yi Soybean research institute Nanjing Agricultural University/National Center for Soybean Improvement/National Key Laboratory of Crop Genetics and Germplasm Enhancement Ministry of Science and Technology

Soybean mosaic virus （SMV）, a member of the genus Potyvirus, is a major pathogen of soybean plants in china, and 16 SMV strains have been identified nationwide based on a former detailed SMV classification system. As the P3 gene is thought to be involved in viral replication, systemic infection, pathogenicity, and overcoming resistance, knowledge of the P3 gene sequences of SMV and other potyviruses would be useful in efforts to know the genetic relationships among them and control the disease. P3 gene sequences were obtained from representative isolates of the above-mentioned 16 SMV strains and were compared with other SMV strains and 16 Potyvirus species from the National Center for Biotechnology GenBank database. The P3 genes from the 16 SMV isolates are composed of 1041 nucleotides, encoding 347 amino acids, and share 90.7-100% nucleotide （NT） sequence identities and 95.1-100% amino acid （AA） sequence identities. The P3 coding regions of the 16 SMV isolates share high identities （92.4-98.9% NT and 96.0-100% AA） with the reported Korean isolates, followed by the USA isolates （88.5-97.9% NT and 91.4-98.6% AA）, and share low identities （80.5-85.2% NT and 82.1-84.7% AA） with the reported HZ 1 and P isolates from Pinellia ternata. The sequence identities of the P3 genes between SMV and the 16 potyviruses varied from 44.4 to 81.9% in the NT sequences and from 21.4 to 85.3% in the AA sequences, respectively. Among them, SMV was closely related to Watermelon mosaic virus （WMV）, with 76.0-81.9% NT and 77.5-85.3% AA identities. In addition, the SMV isolates and potyvirus species were clustered into six distinct groups. All the SMV strains isolated from soybean were clustered in Group I, and the remaining species were clustered in other groups. A multiple sequence alignment analysis of the C-terminal regions indicated that the P3 genes within a species were highly conserved, whereas those among species were relatively variable.

关键词： Soybean mosaic virus Potyvirus P3 gene homology analysis phylogenetic tree multiple sequence alignment

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风荷载作用下滨海地区水闸结构受力特性研究

人民珠江 2024年第5期45卷 132-142页

作者：张建阳佳林杨杰珠海市规划设计研究院广东珠海519000 广东省滨海地区防灾减灾工程技术研究中心广东珠海519000 南京水利科学研究院江苏南京210029 南京水科院瑞迪科技集团有限公司江苏南京210029

以广东省珠海市金湾区滨海商务区机场东路东侧主渠水闸为例,针对水闸结构所受风荷载,对比研究中英美日设计规范的计算方法,分析各国方法的差异;基于计算流体动力学数值模拟,对不同风向、规范风压及极端台风天气下水闸结构所受风荷载的... 详细信息

以广东省珠海市金湾区滨海商务区机场东路东侧主渠水闸为例,针对水闸结构所受风荷载,对比研究中英美日设计规范的计算方法,分析各国方法的差异;基于计算流体动力学数值模拟,对不同风向、规范风压及极端台风天气下水闸结构所受风荷载的分布情况进行研究;采用结构有限元分析不同风荷载工况下,水闸结构的受力特性,为滨海地区水闸结构的抗风设计提供一定的借鉴意义。研究结果表明:中国规范考虑风振系数后的风荷载值与英美日3国规范基本相当;水闸风向系数为0.75~1.03,风荷载可根据水闸朝向与主导风向的夹角乘以一定的风向折减系数;水闸背风面风荷载体型系数大于常规建筑物,建议水闸结构按照风敏感建筑进行风荷载计算;台风极端天气作用下,水闸结构风荷载在考虑风振系数的基础上再乘以一定的放大系数,并适当增加水闸结构的刚度以满足正常使用要求;考虑外海潮位及风暴增水的叠加影响,水闸结构地基承载力建议乘以不小于1.15的安全系数。

关键词：风荷载台风极端天气水闸结构计算流体动力学受力特性

Adaptive sampling algorithm for detection of superpoints

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Science in china(Series F) 2008年第11期51卷 1804-1821页

作者： CHENG Guang GONG jian DING Wei wu hua QIANG ShiQiang Key Lab of jiangsu Computer Network School of Computer Science and Engineering Southeast University Nanjing 210096 China

The superpoints are the sources （or the destinations） that connect with a great deal of destinations （or sources） during a measurement time interval, so detecting the superpoints in real time is very important to network security and management. Previous algorithms are not able to control the usage of the memory and to deliver the desired accuracy, so it is hard to detect the superpoints on a high speed link in real time. In this paper, we propose an adaptive sampling algorithm to detect the superpoints in real time, which uses a flow sample and hold module to reduce the detection of the non-superpoints and to improve the measurement accuracy of the superpoints. We also design a data stream structure to maintain the flow records, which compensates for the flow Hash collisions statistically. An adaptive process based on different sampling probabilities is used to maintain the recorded IP addresses in the limited memory. This algorithm is compared with the other algorithms by analyzing the real network trace data. Experiment results and mathematic analysis show that this algorithm has the advantages of both the limited memory requirement and high measurement accuracy.

关键词： superpoints detection adaptive process flow sample and hold collision compensation

research on shape optimization of CSG dams

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Water Science and Engineering 2011年第4期4卷 445-454页

作者： Xin CAI Ying-li wu jian-gang YI Yu ming College of Mechanics and Materials Hohai University Naijing 210098 P R. China College of Water Conservancy and Hydropower Engineering Hohai University Naijing 210098 P. R. China Geotechnical Engineering Department Nanjing Hydraulic Research Institute Nanjing 210024 P. R. China

The multi-objective optimization method was used for shape optimization of cement sand and gravel （CSG） dams in this study. The economic efficiency, the sensitivities of maximum horizontal displacement and maximum settlement of the dam to water level changes, the overall stability, and the overall strength security were taken into account during the optimization process. Three weight coefficient selection schemes were adopted to conduct shape optimization of a dam, and the case studies lead to the conclusion that both the upstream-and downstream dam slope ratios for the optimal cross-section equal 1：0.7, which is consistent with the empirically observed range of 1：0.6 to 1;0.8 for the upstream and downstream dam slope ratios of CSG dams. Therefore, the present study is of certain reference value for designing CSG dams.

关键词： CSG dam shape optimization sensitivity analysis

Fabrication of AI foam without thickening process through melt-foaming method

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Journal of Iron and Steel research International 2018年第1期25卷 90-98页

作者： Dong-hui yang jian-qing Chen Lei Wang Jing-hua jiang Ai-bin Ma College of Mechanics and Materials Hohai UniversityNanjing 210098 Jiangsu China Suqian research institute of Hohai University Suqian 223814 Jiangsu China

By using calcium carbonate （CaCO3） powder as the blowing agent, Al foams with porosities of - 60 to 85% and pore size of - 1.5 mm were fabricated via melt-foaming method. Instead of adding a thickening agent to increase Al melt viscosity, a small amount of Mg ingot （5.0 wt%） was added first, and then A1 melt was foamed by adding calcium carbonate via the impellor stirring. The effect of Mg addition on the gas release behavior of calcium carbonate in the Al melt was investigated. The compression behavior of fabricated Al foams was examined. The results show that the blowing gas is possibly from the reaction between Mg and calcium carbonate, and this reaction can produce solid oxides with micrometer level size, which leads to increasing the Al melt viscosity and is beneficial for inhibiting pores coarsening. Besides, the micrometer level cracks in the cell walls make the strength of Al foam decrease.

关键词： Al foam Thickening agent Calcium carbonate Blowing gas Compression

Fluid Mud Measurement and Siltation Analysis in A Trial Excavated Channel in the Approach Channel of the Xiangshan Port

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china Ocean Engineering 2020年第3期34卷 421-431页

作者： DING jian HU Guo-dong WANG Zhen-xiang SHI jian wu De-an Key Laboratory of Coastal Disasters and Defence Ministry of EducationHohai UniversityNanjing 210098China yangtze River Estuary Investigation Bureau of Hydrology and Water Resource Shanghai 200136China

In order to clarify the distribution and variation of silt and fluid mud in the Waiganmen shallow section of the 50000-ton intake channel of the Xiangshan Port,and to understand the influence of the channel excavation on the surrounding flow conditions and the strength of the backsilting,especially the impact of typhoon on the sudden silting of the channel,so as to demonstrate the feasibility and stability of the channel *** fluid mud,hydraulic,sediment and topographic measurements were carried out in the study area,and the thickness of the fluid mud layers,tidal current,sediment and topographic data were ***-frequency sounder,gamma-ray densitometer and SILAS navigational fluid mud measurement system were used to monitor the fluid mud,and the results were compared and *** adaptability and accuracy of the three methods were *** SILAS navigational continuous density measurement system and gamma-ray fixed-point fluid mud measurement are used to detect the density,thickness and variation of the fluid mud *** on the hydrological observation data,the process of erosion and deposition in excavation channel and its influence mechanism are analyzed,and the distribution characteristics and evolution law of siltation in engineering area are given in the form of empirical *** research shows that the super typhoon can produce large siltation,which results in sudden siltation of the *** tidal current is the main dynamic factor of the change of erosion and siltation of the excavation *** the influence of reciprocating tidal current and excavation topography,the trial excavation trench is silted on the *** is fluid mud in the monitoring area of the trench,and the distribution of fluid mud is different in *** thickness of the fluid mud at the bottom of the trench is generally larger than that outside the trench and the slope of the trench,and the siltation of the trench tends to be *** re

关键词： excavation trench fluid mud backsilting measurement tidal current dynamic mechanism

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垂直汇流中空化长度的脉动

水动力学研究与进展（A辑） 1989年第4期4卷 96-104页

作者：吴建华柴恭纯郭子中南京水利科学研究院河海大学

超空穴的重要特征之一是其空化长度的脉动。本文用摄影法,对垂直汇流旋涡空化模型,在流速为16.2m/s、21.4m/s、24.4m/s和28.8m/s四个流速下,随机地记录了约1200个空化长度。应用Kolmogolov方法系统地分析了该模型超空穴空化长度的统计... 详细信息

超空穴的重要特征之一是其空化长度的脉动。本文用摄影法,对垂直汇流旋涡空化模型,在流速为16.2m/s、21.4m/s、24.4m/s和28.8m/s四个流速下,随机地记录了约1200个空化长度。应用Kolmogolov方法系统地分析了该模型超空穴空化长度的统计特征和分布规律,主要有:表征空化长度的均值,表征空化脉动的均方差和空化长度的概率分布规律。同时,本文还分析了控制超空穴空化长度主要的水力参数。对超空穴及其空蚀的研究有参考作用。

关键词：汇流空化长度脉动超空穴

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滑动轴承微动磨损引发不稳定振动研究

汽轮机技术 2024年第1期66卷 45-47,62页

作者：高峰杨华汤红权段旺权张万福杨建刚国电长源汉川发电有限公司汉川431614 上海理工大学上海200093 东南大学南京210096

从轴承支架微动磨损角度开展某超超临界汽轮机高压转子不稳定振动故障机理研究。基于Archard方程,建立轴承在实际装配和载荷条件下微动磨损分析模型。结果表明:轴承瓦枕与支架之间采用球面配合方式,在该区域内出现局部应力集中。在不平... 详细信息

从轴承支架微动磨损角度开展某超超临界汽轮机高压转子不稳定振动故障机理研究。基于Archard方程,建立轴承在实际装配和载荷条件下微动磨损分析模型。结果表明:轴承瓦枕与支架之间采用球面配合方式,在该区域内出现局部应力集中。在不平衡力激励下,激振力通过油膜传递到轴瓦。长时间运行后,瓦枕和支架之间出现微动磨损。轴承防跳间隙和插销间隙增大后,轴承失去稳定性,导致带负荷过程中轴颈中心位移较大,振动出现波动。结合某汽轮机上发生的不稳定振动现象进行了分析,根据轴颈中心位置变化特征可评估轴承状态。

关键词：振动轴承微动磨损汽轮机