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采用拉缝板连接的现浇框架填充墙抗震性能试验研究

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世界地震工程 2024年第3期40卷 131-141页

作者：朱源杰赖正聪缪易辰苏何先李凯昆明理工大学公共安全与应急管理学院云南昆明650500 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

为研究拉缝板连接的现浇PVC管空心填充墙对结构抗震性能的影响。试验设计了6榀足尺单层单跨混凝土框架试件,其中:2榀空框架,2榀无拉缝板刚性连接的PVC管空心填充墙框架和2榀有拉缝板柔性连接的PVC管空心填充墙框架,通过对各试件进行低... 详细信息

为研究拉缝板连接的现浇PVC管空心填充墙对结构抗震性能的影响。试验设计了6榀足尺单层单跨混凝土框架试件,其中:2榀空框架,2榀无拉缝板刚性连接的PVC管空心填充墙框架和2榀有拉缝板柔性连接的PVC管空心填充墙框架,通过对各试件进行低周反复荷载试验,研究了拉缝板连接的现浇填充墙框架的破坏特征、滞回曲线、骨架曲线、耗能比和刚度退化等抗震性能指标。同时对拉缝板进行抗压承载力试验和材料拉伸试验。结果表明:加入PVC空心填充墙能提升框架的初始刚度和承载力;有PVC结构拉缝板的试件组的抗震性能介于空框架与无PVC结构拉缝板的试件组之间,加入PVC结构拉缝板能一定程度提高框架的耗能能力,减缓整体框架刚度退化。

关键词： PVC结构拉缝板现浇PVC管空心填充墙框架拟静力试验连接构造抗震性能

Changes in cesarean section rates and its indications among primiparous women during each implementation phase of Chinese two-child policy:a retrospective study

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Chinese Medical Journal 2022年第18期135卷 2264-2266页

作者： Yumei cheng Shaofei su Shaowen Wu Department of Perinatal Medicine Beijing Obstetrics and Gynecology HospitalCapital Medical UniversityBeijing Maternal and Child Health Care HospitalBeijing 100026China Department of Central Laboratory Beijing Obstetrics and Gynecology HospitalCapital Medical UniversityBeijing Maternal and Child Health Care HospitalBeijing 100026China

To the Editor:Cesarean section(CS)is among the most important and safe procedures in *** medically indicated,CS can be a life-saving *** the Chinese one-child policy,couples tended to choose CS for various *** 2010,the CS rate in China rose to among the world’s highest.^([1])Yet,CS can also have various adverse maternal and neonatal *** mortality and maternal and infant complications are higher with CS compared with vaginal delivery.[2]Over the past several decades,CS rates have increased sharply worldwide,and controlling these rates has become among the most prominent obstetric issues.

关键词： section policy among

基于光响应非均匀性的WhatsApp压缩视频来源识别

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应用光学 2024年第2期45卷 337-345页

作者：陈懿辉田妮莉潘晴苏开清广东工业大学信息工程学院广东广州510006

光响应非均匀噪声(photo response nonuniformity,PRNU)是光学成像传感器成像时引入的一种独特噪声,可有效识别压缩视频的来源。针对现有算法提取压缩视频的PRNU效果并不显著的问题,论文提出了一种改进PRNU提取算法。首先,去除视频编解... 详细信息

光响应非均匀噪声(photo response nonuniformity,PRNU)是光学成像传感器成像时引入的一种独特噪声,可有效识别压缩视频的来源。针对现有算法提取压缩视频的PRNU效果并不显著的问题,论文提出了一种改进PRNU提取算法。首先,去除视频编解码的环路滤波器,对视频帧使用双密度双树复小波变换进行分解;然后对高频子带使用基于贝叶斯阈值估计的双变量收缩算法进行估计,再使用自适应加窗维纳滤波进行二次估计,得到噪声残差;最后用基于量化参数值加权的最大似然估计法聚合噪声残差,再与视频帧估计得到PRNU。实验结果表明:该文提出的方法在20 s时WhatsApp视频的识别率为75%。

关键词：光响应非均匀性源相机识别压缩视频双密度双树复小波变换双变量收缩

MHD Flow Control of Oblique Shock Waves Around Ramps in Low-temperature supersonic Flows

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Chinese Journal of Aeronautics 2010年第1期23卷 22-32页

作者： su Changbing,Li Yinghong,cheng Bangqin,Wang Jian,Cao Jun,Li Yiwen Engineering College,Air Force Engineering University,Xi’an 710038,China [a] Engineering College Air Force Engineering University Xi'an 710038 China

This article is devoted to experimental study on the control of the oblique shock wave around the ramp in a low-temperature supersonic flow by means of the magnetohydrodynamic （MHD） flow control technique. The purpose of the experiments is to take advantage of MHD interaction to weaken the oblique shock wave strength by changing the boundary flow characteristics around the ramp. Plasma columns are generated by pulsed direct current （ DC ） discharge, the magnetic fields are generated by Nd-Fe-B rare-earth permanent magnets and the oblique shock waves in supersonic flow are generated by the ramp. The Lorentz body force effect of MHD interaction on the plasma-induced airflow velocity is verified through particle image velocimetry（PIV）measurements. The experimental results from the supersonic wind tunnel indicate that the MHD flow control can drastically change the flow characteristics of the airflow around the ramp and decrease the ratio of the Pitot pressure after shock wave to that before it by up to 19.66% ,which leads to the decline in oblique shock wave strength. The oblique shock waves in front of the ramp move upstream by the action of the Lorentz body force. The discharge characteristics are analyzed and the MHD interaction time and consumed energy are determined with the help of the pulsed DC discharge images. The interaction parameter corresponding to the boundary layer velocity can reach 1.3 from the momentum conservation equation. The velocity of the plasma column in the magnetic field is much faster than that in the absence of magnetic field force. The plasma can strike the neutral gas molecules to transfer momentum and accelerate the flow around the ramp.

关键词： aerospace propulsion system magnetohydrodynamic flow control plasma shock wave

Identification of Nonstructural Protein 8 as the N-Terminus of the RNA-Dependent RNA Polymerase of Porcine Reproductive and Respiratory Syndrome Virus

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Virologica Sinica 2018年第5期33卷 429-439页

作者： Yuanyuan Liu Yunhao Hu yue Chai Liping Liu Jiangwei Song Shaochuan Zhou Jia su Lei Zhou Xinna Ge Xin Guo Jun Han Hanchun Yang Key Laboratory of Animal Epidemiology of the Ministry of Agriculture College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology China Agricultural University

Porcine reproductive and respiratory syndrome virus (PRRSV) is a member within the family Arteriviridae of the order Nidovirales. Replication of this positive-stranded RNA virus within the host cell involves expression of viral replicase proteins encoded by two ORFs, namely ORF1 a and ORF1 b. In particular, translation of ORF1 b depends on a-1-ribosomal frameshift strategy. Thus, nonstructural protein 9 (nsp9), the first protein within ORF1 b that specifies the function of the viral RNA-dependent RNA polymerase, is expressed as the C-terminal extension of nsp8, a small nsp that is encoded by ORF1 a. However, it has remained unclear whether the mature form of nsp9 in virus-infected cells still retains nsp8,addressing which is clearly critical to understand the biological function of nsp9. By taking advantage of specific antibodies to both nsp8 and nsp9, we report the following findings. (1) In infected cells, PRRSV nsp9 was identified as a major product with a size between 72 and 95 k Da (72–95 KDa form), which exhibited the similar mobility on the gel to the in vitro expressed nsp8–9 ORF1 b, but not the ORF1 b-coded portion (nsp9 ORF1 b). (2) The antibodies to nsp8, but not to nsp7 or nsp10, could detect a major product that had the similar mobility to the 72–95 KDa form of nsp9. Moreover, nsp9 could be co-immunoprecipitated by antibodies to nsp8, and vice versa. (3) Neither nsp4 nor nsp2 PLP2 was able to cleave nsp8–nsp9 in vitro. Together, our studies provide experimental evidence to suggest that nsp8 is an N-terminal extension of *** findings here paves way for further charactering the biological function of PRRSV nsp9.

关键词： Porcine reproductive and respiratory syndrome virus (PRRSV) Nsp8 Nsp9

FAST宁静区生态系统服务时空分异特征及权衡/协同关系分析

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中国环境科学 2024年第9期44卷 5145-5159页

作者：权小丫苏维词勾容黄贤凤重庆师范大学地理与旅游学院重庆401331 贵州省山地研究所贵州贵阳550001

基于InVEST与光能利用率模型(CASA)对2000-2020年间500m口径球面射电望远镜(FAST)宁静区植被净初级生产力(NPP),水源涵养,土壤保持,生境质量四项生态系统服务进行计算,分析其在不同尺度上的时空变化特征,识别其生态系统服务热点区域,采... 详细信息

基于InVEST与光能利用率模型(CASA)对2000-2020年间500m口径球面射电望远镜(FAST)宁静区植被净初级生产力(NPP),水源涵养,土壤保持,生境质量四项生态系统服务进行计算,分析其在不同尺度上的时空变化特征,识别其生态系统服务热点区域,采用权衡-协同指数和随机森林模型揭示四项生态系统服务间的权衡/协同作用关系和强度及其与驱动因子的关系.结果表明:(1)2000-2020年,FAST宁静区四项生态系统服务整体上呈增加趋势,其中NPP增加730.544gC/m^(2),水源涵养量增加5.925mm,生境质量得分上升0.007,土壤保持量增加0.295t/km^(2).(2)圈层差异明显,其中核心区增加最快,服务功能最优;其次是边远区,生态有明显好转;最后是中间区,生态修复相对较慢.(3)土地利用类型中,林地和草地对研究区生态系统服务量的促进作用最大.(4)生态系统服务热点整体上由Ⅰ类和Ⅱ类热点区向非热点区,Ⅲ类热点区及Ⅳ类热点区转变.(5)区内的四项生态系统服务间关系整体以协同为主,且协同作用逐渐增强,在空间上水源涵养与土壤保持和NPP在部分地区呈权衡作用.(6)FAST宁静区四项生态系统服务间权衡/协同关系作用强度的主要驱动因子是降水,蒸散发,石漠化敏感性,坡度和人类活动强度.

关键词：生态系统服务圈层差异时空演变权衡协同 InVEST模型 500m口径球面射电望远镜宁静区

New approach for improving throughput in multi-channel packet radio systems

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Journal of Systems Engineering and Electronics 2010年第2期21卷 180-185页

作者： su Pan Shengmei Liu College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 P. R. China

A new approach for improving the throughputs of multi- channel packet radio systems is proposed. Based on the charac- teristics of multi-code CDMA technology, the scheme factitiously improves the transmission bit rate of a terminal by compressing the packet transmission time and thereby increases the number of the orthogonal spreading codes used by the terminal. By this means, the average interference level of the system is reduced and the system capacity is improved. Simulation results show that the proposed scheme exhibits larger throughput compared with the traditional multi-code CDMA slotted Aloha systems.

关键词： packet radio multi-channel throughput MAC

改进自适应遗传算法优化的船用增压锅炉上锅筒水位滑模控制方法

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中国舰船研究 2024年第2期19卷 181-186页

作者：丁志龙王鹏王永刚苏博群中国人民解放军海军士官学校机电系安徽蚌埠233000 哈尔滨船舶锅炉涡轮机研究所黑龙江哈尔滨150078

[目的]船用增压锅炉的上锅筒水位由于航行中负荷的频繁变化,难以获得理想的控制效果。为了保证上锅筒水位的稳定,对大负荷扰动下的上锅筒水位控制方法进行研究。提出一种基于改进自适应遗传算法优化的增压锅炉上锅筒水位滑模控制方法。... 详细信息

[目的]船用增压锅炉的上锅筒水位由于航行中负荷的频繁变化,难以获得理想的控制效果。为了保证上锅筒水位的稳定,对大负荷扰动下的上锅筒水位控制方法进行研究。提出一种基于改进自适应遗传算法优化的增压锅炉上锅筒水位滑模控制方法。[方法]将上锅筒水位偏差的速度和速度变化率引入S函数来设计滑模控制器,采用李雅普诺夫稳定性原理证明其稳定性。在此基础上,利用改进的自适应遗传算法优化滑模控制器。[结果]将改进的自适应遗传算法优化的增压锅炉上锅筒水位滑模控制方法与传统的PID控制方法进行了对比分析。在响应斜坡扰动信号和阶跃扰动信号时,改进自适应遗传算法优化的滑模控制器均能够无差跟踪输入信号,其稳定时间比PID缩短5 s,超调量也小于PID。[结论]仿真结果表明,改进自适应遗传算法优化的滑模控制方法具有更优的控制效果。

关键词：增压锅炉水位控制滑模控制自适应遗传算法

Self-consistent parabolized stability equation(PSE) method for compressible boundary layer

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Applied Mathematics and Mechanics(English Edition) 2015年第7期36卷 835-846页

作者： Yongming ZHANG Caihong su Department of Mechanics Tianjin University Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin University

The parabolized stability equation （PSE） method has been proven to be a useful and convenient tool for the investigation of the stability and transition problems of boundary layers. However, in its original formulation, for nonlinear problems, the complex wave number of each Fourier mode is determined by the so-called phase-locked rule, which results in non-self-consistency in the wave numbers. In this paper, a modification is proposed to make it self-consistent. The main idea is that, instead of allowing wave numbers to be complex, all wave numbers are kept real, and the growth or decay of each mode is simply manifested in the growth or decay of the modulus of its shape function. The validity of the new formulation is illustrated by comparing the results with those from the corresponding direct numerical simulation （DNS） as applied to a problem of compressible boundary layer with Mach number 6.

关键词： parabolized stability equation (PSE) boundary layer direct numericalsimulation (DNS) self-consistent