Research on Quality Management Measures of Green Building Construction

Urbanization has led to the rapid development of the construction industry.However,this has also led to higher requirements for the construction engineering management.Other than the quality monitoring of engineering construction,the energy-saving properties of the building should also be considered.Therefore,a scientific management approach should be adopted to improve green building management.This paper primarily examines the importance of quality management in green building construction,along with the factors influencing it.It also identifies the quality issues present in current green building construction.Finally,it proposes measures for quality management in the green building construction process to facilitate the industry’s healthy development.

基于熵值法的南昌市农业品牌化发展评价

农业品牌化是现代农业的重要形态,也是推进农村经济发展、实施乡村振兴战略的重要途径之一。以江西省南昌市为研究对象,在全面考察南昌市农业品牌化发展环境和基础条件基础上,运用熵值分析法评价了南昌市农业品牌化发展水平。研究结果表明,南昌市农业品牌化发展水平呈逐年上升的态势(从2017年的0.263 5上升至2020年的0.721 2),但综合得分总体偏低。其中产业基础得分最低,需要从夯实产业基础、提升产业化水平、积极开展品牌建设和提高品牌带动能力等方面加以改善。

Quick and Accurate Counting of Rapeseed Seedling with Improved YOLOv5s and Deep-Sort Method

The statistics of the number of rapeseed seedlings are very important for breeders and planters to conduct seed quality testing,field crop management and yield estimation.Calculating the number of seedlings is inefficient and cumbersome in the traditional method.In this study,a method was proposed for efficient detection and calculation of rapeseed seedling number based on improved you only look once version 5(YOLOv5)to identify objects and deep-sort to perform object tracking for rapeseed seedling video.Coordinated attention(CA)mechanism was added to the trunk of the improved YOLOv5s,which made the model more effective in identifying shaded,dense and small rapeseed seedlings.Also,the use of the GSConv module replaced the standard convolution at the neck,reduced model parameters and enabled it better able to be equipped for mobile devices.The accuracy and recall rate of using improved YOLOv5s on the test set by 1.9%and 3.7%compared to 96.2%and 93.7%of YOLOv5s,respectively.The experimental results showed that the average error of monitoring the number of seedlings by unmanned aerial vehicles(UAV)video of rapeseed seedlings based on improved YOLOv5s combined with depth-sort method was 4.3%.The presented approach can realize rapid statistics of the number of rapeseed seedlings in the field based on UAV remote sensing,provide a reference for variety selection and precise management of rapeseed.

论疫情之下我国应急财政投入的路径选择

部分中小企业在新冠肺炎暴发期间命悬一线,虽然中央和地方政府迅速进行了应急财政管理,然而效果却不尽如人意。文章综合运用危机管理和灾害经济学分析了目前货币政策和部分应急财政政策的不适用性,以及疫情期间市场对于直接财政投入的需求,本研究认为现金流才是现阶段中小企业的救命稻草,并通过对比历史上发达国家应急财政管理的基本状况,阐述了我国应急财政投入的现状以及存在的问题。基于此,从投入方向、投入速度、投入力度、投入效果四个方面,提出了拓宽应急资金来源渠道、完善应急财政运作体系、规范支出管理体制、加大动态监督力度、定向投入应急资金的建议。

石嘴山地区梯牧草花粉及大籽蒿与过敏性鼻炎相关性研究

目的 探讨石嘴山地区梯牧草及大籽蒿花粉与过敏性鼻炎的相关性研究。方法 选取201例过敏性鼻炎患者,以梯牧草和大籽蒿为过敏原的过敏性鼻炎患者为研究对象,并与同期花粉浓度进行比较。结果 梯牧草致过敏性鼻炎患者发病时间为6~8个月,共计76例。其中单纯梯牧草过敏12例,男性5例,女性7例;梯牧草合并大籽蒿过敏64例,男性30例,女性34例。梯牧草过敏检测阳性与梯牧草过敏检测阴性患者比较,性别差异无统计学意义(P>0.05),年龄差异呈正相关性(P<0.05),主要集中在18~50岁。经过皮肤点刺试验后,分为单纯梯牧草过敏与梯牧草合并大籽蒿过敏2组,患者并发症差异无统计学意义(P<0.05)。结论 梯牧草是我国北方地区一种较少的花粉过敏原,同时其花粉季节与大籽蒿重叠,梯牧草花粉与大籽蒿花粉之间的交叉反应更容易诱发过敏性哮喘、过敏性结膜炎以及过敏性咳嗽。

Chinese Hα Solar Explorer(CHASE)——a complementary space mission to the ASO-S

The Chinese HαSolar Explorer(CHASE)is designed to test a newly developed satellite platform and conduct solar observations.The scientific payload of the satellite is an Hαimaging spectrograph(HIS),which can,for the first time,acquire full-disk spectroscopic solar observations in the Hαwaveband.This paper briefly introduces CHASE/HIS including its scientific objectives,technical parameters,scientific application system,etc.The CHASE mission is scheduled to launch in 2021.It will complement the observations by on-orbit solar spacecraft(such as SDO,IRIS,STEREO and PSP),as well as future solar missions of the Solar Orbiter and Advanced Space-based Solar Observatory(ASO-S).

The Lyman-alpha Solar Telescope(LST) for the ASO-S mission——Ⅲ. data and potential diagnostics

The Lyman-alpha Solar Telescope(LST)is one of the three payloads onboard the Advanced Space-based Solar Observatory(ASO-S)mission.It aims at imaging the Sun from the disk center up to 2.5 R⊙targeting solar eruptions,particularly coronal mass ejections(CMEs),solar flares,prominences/filaments and related phenomena,as well as the fast and slow solar wind.The most prominent speciality of LST is the simultaneous observation of the solar atmosphere in both Lyαand white light(WL)with high temporospatial resolution both on the solar disk and the inner corona.New observations in the Lyαline together with traditional WL observations will provide us with many new insights into solar eruptions and solar wind.LST consists of a Solar Corona Imager(SCI)with a field of view(FOV)of 1.1–2.5 R⊙,a Solar Disk Imager(SDI)and a full-disk White-light Solar Telescope(WST)with an identical FOV up to 1.2 R⊙.SCI has a dual waveband in Lyα(121.6±10 nm)and in WL(700±40 nm),while SDI works in the Lyαwaveband of 121.6±7.5 nm and WST works in the violet narrow-band continuum of 360±2.0 nm.To produce high quality science data,careful ground and in-flight calibrations are required.We present our methods for different calibrations including dark field correction,flat field correction,radiometry,instrumental polarization and optical geometry.Based on the data calibration,definitions of the data levels and processing procedures for the defined levels from raw data are described.Plasma physical diagnostics offer key ingredients to understand ejecta and plasma flows in the inner corona,as well as different features on the solar disk including flares,filaments,etc.Therefore,we are making efforts to develop various tools to detect the different features observed by LST,and then to derive their physical parameters,for example,the electron density and temperature of CMEs,the outflow velocity of the solar wind,and the hydrogen density and mass flows of prominences.Coordinated observations and data analyses with the coronagraphs onboard Solar Orbiter,PROBA-3,and Aditya are also briefly discussed.

Prevalence of heterophoria in a population of school children in central China:the Anyang Childhood Eye Study

AIM:To investigate the prevalence of heterophoria and the relationship between heterophoria and refractive error in a school-based study conducted in central China.METHODS:A total of 23637 th-grade children were recruited into the cross-sectional school-based Anyang Childhood Eye Study(ACES)by cluster sampling method.Heterophoria was examined using alternate cover and cover-uncover testing.The Maddox rod and prism test were conducted at 33 cm and 6 m distance fixation.Uncorrected viual acuity(UCVA)and best-corrected viual acuity(BCVA)were recorded as logarithm of the minimum angle of resolution(logM AR)with cycloplegic autorefraction by administrating of Mydrin-P and 1.0%cyclopentolate.Hyperopia was defined as the spherical equivalent(SE)refraction of+0.50 D or greater,and higher hyperopia was defined as+2.00 D or greater.Emmetropia was defined as the SE refraction in the range of-0.49 to+0.49 D,and myopia was in the SE refraction range from-0.50 D to less.RESULTS:Totally 2260 students in grade 7 were examined.Response rate among eligible children was 95.64%.Totally 486 children,22.66%of the population,were diagnosed with heterophoria in which 479 were diagnosed with exophoria at near distance,and 6 with esophoria.Totally 89(4.15%)children were diagnosed with heterophoria in which 82 had exophoria,and 7 had esophoria at far distance.Exophoria was common at near fixation(22.33%).Myopia was examined to be related to exophoria at near distance(OR 3.03,95%CI 2.33-3.95)and far distance fixation(OR 1.90,95%CI 1.09-3.32).CONCLUSION:Exophoria is a predominant heterophoria for 7 th-grade junior school in central China.Significant associations are discovered between heterophoria and refractive error.Hyperopia is associated with esophoria,and myopia is associated with exophoria.

南昌市农业社会化服务推进“三品一标”建设的探索与实践——以江西省绿能农业发展有限公司为例

在分析南昌市农业社会化服务产业发展现状的基础上,以江西省绿能农业发展有限公司为例,实证研究了农业社会化服务在促进品种培优、品质提升、品牌打造和标准化生产方面的经验做法,探索了以农业社会化服务推进“三品一标”建设的必要性和可行性,并有针对性地提出了南昌市推进农业社会化服务高质量发展的优化路径。

Radiative hydrodynamic simulations of the spectral characteristics of solar white-light flares

As one of the most violent activities in the solar atmosphere,white-light flares(WLFs)are generally known for their enhanced white-light(or continuum)emission,which primarily originates in the solar lower atmosphere.However,we know little about how white-light emission is produced.In this study,we aim to investigate the response of the continua at 3600Åand 4250Åand also the Hαand Lyαlines during WLFs modeled using radiative hydrodynamic simulations.We take non-thermal electron beams as the energy source for the WLFs in two different initial atmospheres and vary their parameters.Our results show that the model with non-thermal electron beam heating clearly shows enhancements in the continua at 3600Åand 4250Åas well as in the Hαand Lyαlines.A larger electron beam flux,a smaller spectral index,or an initial penumbral atmosphere leads to a stronger emission increase at 3600Å,4250Åand in the Hαline.The Lyαline,however,is more obviously enhanced in a quiet-Sun initial atmosphere with a larger electron beam spectral index.It is also notable that the continua at 3600Åand 4250Åand the Hαline exhibit a dimming at the start of heating and reach their peak emissions after the peak time of the heating function,while the Lyαline does not show such behaviors.These results can serve as a reference for the analysis of future WLF observations.

基本型间歇性外斜视眼位控制力相关因素的临床研究

目的探讨基本型间歇性外斜视(IXT)患者控制力的影响因素。方法收集2021年3月至2023年9月首都医科大学附属北京同仁医院眼科中心的434例(868只眼)基本型IXT患者的病例资料。其中,男性215例(430只眼),女性219例(438只眼);年龄4~20岁,年龄中位数为9.83(8.23,11.63)岁。使用纽卡斯尔(NCS)控制力评分法评估患者眼位控制力。根据NCS评分结果分为控制力良好组和控制力不佳组。检查所有患者的屈光状态、斜视度、立体视觉、调节功能及集合功能。年龄、屈光状态、斜视度、近立体视、调节功能及集合功能等经正态性检验不服从正态分布,以中位数(下四分位数,上四分位数)表示,组间比较采用秩和检验。远立体视保存率以百分比表示,组间比较采用χ2检验。采用Logistic回归分析IXT控制力的影响因素。结果控制力良好组患者主视眼的等效球镜屈光度(SE)、非主视眼SE、看近斜视度、看远斜视度及近立体视分别为-1.25(-2.75,0.50)D、-1.38(-2.78,0.75)D、-30(-40,-25)PD、-25(-35,-20)PD及2.30(2.15,2.90)Log弧秒;控制力不佳组患者分别为-0.00(-1.75,0.88)D、-0.25(-1.88,1.00)D、-50(-60,-40)PD、-50(-60,-35)PD及2.60(2.15,3.20)Log弧秒。两组比较,控制力良好组患者主视眼和非主视眼的近视屈光度均更大、看近和看远斜视度均更小而近立体视更好,其差异均有统计学意义(Z=-3.314,-3.047,-11.803,-12.328,-2.785;P<0.05)。控制力良好组和控制力不佳组患者的远立体视保存率分别为65.58%和36.79%。两组比较,控制力良好组患者远立体视保存率更高,差异具有统计学意义(χ2=33.079;P<0.05)。控制力良好组患者主视眼、非主视眼及双眼调节灵活度分别为9.00(6.63,11.00)cpm、8.50(6.50,11.00)cpm及7.75(6.00,10.00)cpm;控制力不佳组患者分别为7.50(6.00,10.00)cpm、7.50(6.00,9.25)cpm及7.00(5.00,9.00)cpm。控制力良好组患者主视眼、非主视眼及双眼调节灵活度均优于控制力不佳组,其差异具有统计学意义(Z=-4.065,-3.666,-2.690;P<0.05)。控制力良好组患者看远总集合幅度、看近总集合幅度、看远融像储备率、看近融像储备率、AC/A、看远集合储备及看近集合储备分别为50.50(35.75,59.00)、55.00(47.50,65.00)、0.76(0.51,1.16)、0.77(0.51,1.11)、2.00(1.00,4.00)、22.00(16.00,27.00)及24.00(18.00,30.00);控制力不佳组患者分别为65.00(55.25,77.00)、70.00(58.50,84.00)、0.50(0.31,0.72)、0.51(0.34,0.65)、2.33(1.00,4.00)、22.00(16.00,28.00)及24.00(18.00,30.00)。两组比较,控制力良好组患者看远总集合幅度和看近总集合幅度均更小、看远融像储备率和看近融像储备率均更大,其差异具有统计学意义(Z=-7.439,-6.435,-5.709,-6.254;P<0.05);而AC/A、看远集合储备及看近集合储备的差异无统计学意义(Z=-0.845,-0.469,-0.798;P>0.05)。多因素Logistic回归分析发现影响IXT患者眼位控制力的因素中,非主视眼SE、远立体视、看近集合幅度及看近融像储备率具有统计学意义(OR=1.220,95%CI:1.044~1.427,P<0.05)、(OR=0.399,95%CI:0.203~0.785,P<0.05)、(OR=1.050,95%CI:1.027~1.074,P<0.05)及(OR=0.149,95%CI:0.054~0.412,P<0.05)。结论基本型IXT的控制力主要由集合功能而非调节功能影响;基本型IXT的控制力可能主要通过看近的集合功能来驱动。

Vibration control on shells through theoretical and numerical analysis

A theoretical and numerical study has been performed on an air film dumper attached to a plate structure. Combined with the analysis by Fox and Whittorg a damping model of the air fiim damper has been developed. A complex stiffness was introduced to represent the air pressure in the damper cavity. The stain energy and dissipated energy were integrated from the real part and imaginary part of the complex stiffness to determine the stiffness and damping. The response of the plate with the air film damper was considered by treating the air film as multiple discrete damping-stiffness elements using ANSYS.

Experimental studies on the energy dissipation of bolted structures with frictional interfaces:A review

Bolted joints play a more and more important role in the structure with lighter weight and heavier load.This paper aims to provide an overview of different experimental approaches for the dynamic behavior of structures in the presence of bolted joints,especially the energy dissipation or damping at frictional interfaces.The comprehension of energy dissipation mechanisms due to friction is provided first,while the key parameters and the measurement techniques,such as the excitation force,the preload of the bolt,or the pressure at the interfaces,are briefly introduced.Secondly,the round-robin systems aim to measure the hysteresis parameters of the frictional joints under tangential loads are reviewed,summarizing the basic theory and the strategies to apply the excitation force or acquire the response in different testing systems.Followed by parameter identification strategies for bolted structures,the test rigs with one or more simplified bolted joints are summarized to give an insight into the understanding of typical characteristics of bolted structures,which are affected by the presence of friction.More complex test rigs hosting real-like or actual engineering structures with bolted lap or flange joints are also introduced to show the identification process of the dynamic characteristics of bolted connections employed in specific applications.Based on the review paper,researchers can get the basic knowledge about the experimental systems of the bolted structures,especially several classical round robin systems,such as the Gaul resonator and widely used Brake-Reußbeam system.Readers can take advantage of this background for more creative and effective future studies,make more progress on the study of assembled structures and understand the influence of bolting frictional connections on the dynamic response better.

Resolving the geometric structure of trastuzumab by mobility capillary electrophoresis and native mass spectrometry

Available online Immunoglobulins G(IgGs)are Y-shaped globular proteins,however,their high flexibility and heterogeneity pose great challenges to their structure and conformation determinations.Geometric structure of IgG closely correlates to its biofunctions,such as the antibody escape of human immunodeficiency virus(HIV)could attribute to the distance mismatch between the ends of two Fab arms(antigen-binding sites)and envelope glycoprotein spikes on virion surface.Herein,we report the first use of mobility capillary electrophoresis(MCE)and native mass spectrometry(nMS)to resolve the internal geometric structure and conformation of an IgG(trastuzumab)in solution phase.After proteolysis,the ellipsoid dimensions of IgG and its subunits were measured by MCE-nMS experiments.IgG was then reconstructed,in which the sizes and relative positions of these three subunits in three-dimensional space were characterized.It was found that the two Fab arms have an angle of~102.1°and a distance of~11.0 nm between the two antigen-binding sites under native condition,and the Fc arm was tilted~16.0°towards one of the Fab arms.Fc was not on the plane of Fab-Fab,but has an angle of no larger than 103.1°.Under acidic environment(pH 3.0),each subunit of the IgG would unfold into larger dimensions,and the angles between these subunits also change.With great potential for tumor imaging and therapy,the structure of F(ab')_(2)fragments was also measured and validated by molecular dynamic simulation.It was found that the electrostatic force among these three subunits and steric hindrance stemming from Fc help maintaining the angle between two Fab arms.

屈光参差性弱视儿童双眼视觉状态

目的:分析屈光参差性弱视儿童的屈光状态、矫正视力情况及其与双眼视觉功能的关系。方法:横断面研究。收集2015年11月至2016年9月就诊于北京9家医院(分布于8个区县)的屈光参差性弱视儿童患者106例(106眼),年龄(6.2±5.4)岁。根据屈光参差危险因素将所有患者分为远视性屈光参差组(67例)、近视性屈光参差组(5例)、散光性屈光参差组(12例)、远视合并散光性屈光参差组(20例)及近视合并散光性屈光参差组(2例)。对所有患者行裸眼视力(UCVA)、矫正视力(BCVA)、屈光状态、远近立体视等检查。采用Pearson相关性分析双眼屈光参差的差值程度与高度屈光不正眼UCVA、BCVA及双眼视觉间的相关性,并分析双眼矫正视力差值程度与双眼视觉的相关性。采用单因素方差分析比较5组高度屈光不正眼BCVA及远近立体视情况。结果:屈光参差的差值程度与高度屈光不正眼UCVA和BCVA、远立体视、近立体视(即随机点立体视,包括立体视锐度、交叉立体视、非交叉立体视)均呈负相关(均P<0.05);双眼矫正视力差值与远立体视、近立体视均呈负相关(均P<0.05)。5组间在高度屈光不正眼BCVA、远立体视、近立体视方面总体差异均有统计学意义(F=6.221、5.271、3.622、3.647、3.464,P<0.05),进一步两两比较显示高度屈光不正眼BCVA在近视性屈光参差组最好,然后依次为远视性屈光参差组、散光性屈光参差组、近视合并散光性屈光参差组以及远视合并散光性屈光参差组,组间差异均有统计学意义(均P<0.05);远立体视在远视性屈光参差组最好,然后依次为近视性屈光参差组、散光性屈光参差组,组间差异均有统计学意义(均P<0.05),但远视合并散光性屈光参差组与近视合并散光性屈光参差组的远立体视差异无统计学意义;近立体视在近视性屈光参差组最好,然后依次为远视性屈光参差组、散光性屈光参差组、远视合并散光性屈光参差组以及近视合并散光性屈光参差组,组间差异均有统计学意义(均P<0.05)。结论:屈光参差性弱视儿童的屈光参差程度与视力、立体视功能相关,且立体视功能和双眼矫正视力差值也有相关性。不同类型屈光参差儿童立体视损害有所差异。

间歇性外斜视患者知觉眼位和主观斜视角的比较

目的:通过和同视机主观斜视角比较,了解间歇性外斜视患者知觉眼位的情况和意义。方法:系列病例研究。对2017年2-8月在北京同仁医院的间歇性外斜视患者分别用同视机检测其主观斜视角和用基于计算机平台的视感知觉检查方法检测其知觉眼位,将同时具备以上2项检测结果的患者作为研究对象。对二者水平方向眼位进行线性相关分析;统计同视机主观斜视角在垂直方向眼位偏斜的检出率,对同视机主观斜视角未检出垂直偏斜者分析其垂直知觉眼位的分布情况;对水平和垂直知觉眼位进行线性相关和回归分析。结果:共有120例间歇性外斜视患者被纳入研究。在水平方向,主观斜视角为(-8.1±5.3)°,知觉眼位偏移值为(332±233)像素,同视机主观斜视角越向外偏移,水平方向的知觉眼位偏移越大(r=-0.383,P<0.001)。在垂直方向,3例(2.5%)同视机检测到眼位偏斜,117例未检测出垂直眼位偏斜者中有113例(94.2%)可检测出不同程度的知觉眼位偏差,为(22±29)像素,其中67.5%(81/120)≤26像素(垂直眼位偏斜在0.5°以内),有82.5%(99/120)≤53像素(垂直眼位偏斜在1°以内)。120例患者垂直方向知觉眼位偏移为(24±32)像素,它与水平方向知觉眼位偏移呈线性相关关系(r=0.373,P<0.001),线性回归方程为垂直知觉眼位偏移=6.403+0.052×水平知觉眼位偏移(F=19.093,P<0.001)。结论:同视机主观斜视角与知觉眼位偏移均能反映间歇性外斜视患者双眼分视状态下水平方向的眼位偏斜状态;知觉眼位检查在垂直方向的眼位偏斜检出率明显高于同视机;垂直方向的知觉眼位偏斜随着水平方向知觉眼位偏斜的增加而增大。

Nonlinear interval analysis of rotor response with joints under uncertainties

The dynamic influence of joints in aero-engine rotor systems is investigated in this paper.Firstly,the tangential stiffness and loss factor are obtained from an isolated lap joint setup with dynamic excitation experiments.Also,the influence of the normal contact pressure and the excitation level are examined,which revel the uncertainty in joints.Then,the updated Thin Layer Elements(TLEs)method with fitted parameters based on the experiments is established to simulate the dynamic properties of joints on the interface.The response of the rotor subjected to unbalance excitation is calculated,and the results illustrate the effectiveness of the proposed method.Meanwhile,using the Chebyshev inclusion function and a direct iteration algorithm,a nonlinear interval analysis method is established to consider the uncertainty of parameters in joints.The accuracy is proved by comparison with results obtained using the Monte-Carlo method.Combined with the updated TLEs,the nonlinear Chebyshev method is successfully applied on a finite model of a rotor.The study shows that substantial attention should be paid to the dynamical design for the joint in rotor systems,the dynamic properties of joints under complex loading and the corresponding interval analysis method need to be intensively studied.

Investigation on nonlinear lateral-torsional coupled vibration of a rotor system with substantial unbalance

Substantial unbalance may be caused by fan blade off during the operation period of gas turbine engines,and related dynamic problems are very critical to the safety design of rotor system in aero-engine.This article aims to understand lateral-torsional coupled vibration of the rotor system with substantial unbalance.The governing equation of a modified unbalanced rotor system is established based on Lagrangian approach.Then,a mathematical analytical method is proposed in which a linear approximation is derived and the Floquet theory and Hill’s method are incorporated,from which the modal characteristics of the unbalanced rotor are obtained.The modal characteristics of the unbalanced rotor system are revealed comprehensively for the first time.Furthermore,the relation between the modes and responses of the unbalanced rotor is discussed in detail.The results show that the lateral vibration and torsional vibration of the unbalanced rotor are coupled through the inertial terms in the governing equations.Due to the coupling,veering and lock-in phenomena occur between the frequencies of the forward whirl mode and the torsional mode.Furthermore,lock-in can lead to a kind of principal instability.With regard to the response of the unbalanced rotor,both natural vibration components and enforced vibration components appear in the lateral response,while only natural vibration components appear during torsional vibration.Moreover,natural vibration components play a crucial role in the response within the principal instability region and cause divergence of the vibration amplitudes in the lateral and torsional directions.

Modal characteristics analysis for a flexible rotor with non-smooth constraint due to intermittent rub-impact

Intermittent rub-impact, during which the contact between rotor and stator is characterized by a ‘‘bouncing＂ or intermittent type of behavior, is one of the most common rubbing forms in rotating machinery. When the intermittent rub-impact occurs, the non-smooth constraint, which is the phenomenon that the system stiffness changes with respect to the state of contact and noncontact, will appear. The paper aims at discovering the possible effects of the non-smooth constraint on the flexible rotor＇s modal characteristics by theoretical and experimental methods. The qualitative description for non-smooth constraint is given for the intermittent rub-impact process, and the dynamic modeling for a rotor system with non-smooth constraint is carried out. Meanwhile, the analysis method is developed by Floquet theory and Hill＇s method to obtain the rotor＇s modal characteristics. The results reveal that the non-smooth constraint produced by the intermittent rubimpact will increase the modal frequencies and critical speeds of the rotor system significantly.Due to the time-varying features of the constraint stiffness, the modal frequencies for the intermittent rub-impact rotor present fluctuant changes with the increase of rotation speed, which is different from the general linear rotor system. The non-smooth constraint is possible to lead the rotor＇s instability, and the rotor＇s instable regions can be expanded significantly for the increase of average constraint stiffness, constraint amplitude and contact time ratio. Non-smooth constraint could also expand the resonance speed and resonance sideband of the rotor system, which sometimes results in amplitude jump phenomenon.

Experimental investigation on dynamic response of flat blades with underplatform dampers

One test rig with three blades and two Under-Platform Dampers(UPDs) is established to better understand the dynamical behavior of blades with UPDs. A pre-loaded spring is used to simulate the centrifugal load acting on the damper, thereby achieving continuous adjustment of the pressing load. UPDs with different forms, sizes and materials are carefully designed as experimental control groups. Noncontact measurement via a laser Doppler velocimeter is employed and contact excitation which is performed by an electromagnetic exciter is adopted to directly obtain the magnitude of the excitation load by a force sensor mounted on the excitation rod. Particular attention is paid to the influence of the contact status of the contact surfaces, e.g. the pressure-sensitive paper is used to measure the effective contact area of the UPDs. The experimental variables are selected as the centrifugal force, the amplitude of the excitation force, the damper mass, the effective contact area, and the damper material. The Frequency Response Function(FRF) of the blade under different experimental parameters is obtained by slow frequency sweep under sinusoidal excitation to study the influence of each parameter on the dynamic characteristics of the blade and the mechanism analysis is carried out combined with the experimental results.