下鼻道填充术对下鼻甲继发性缺失患者鼻腔容积影响的对照研究

目的 基于CT的3D建模方法探讨下鼻甲缺失患者行下鼻道填充术(IMAP)手术前后鼻腔容积相关物理量的变化。方法 回顾性收集20例伴有特殊症状的下鼻甲继发性缺失(SITL)患者的空鼻症6项量表(ENS6Q)评分及CT影像,通过3D建模的方式估算鼻腔容积及鼻腔黏膜表面积,计算其鼻腔下部容积比,与ENS6Q评分进行相关性分析;通过SITL患者手术前后的CT影像计算鼻腔容积及鼻腔黏膜表面积,并进行对比分析,将接受IMAP患者术前估算鼻腔下部容积减去术中填充物体积计算推测鼻腔下部容积及容积比,并与20例无鼻窦疾病的对照组进行对比,据此尝试对术中填充物的体积给出建议。结果 SITL且伴有特殊症状患者在IMAP术后的ENS6Q总分显著下降,且均低于11分(P=0.003),但仍显著高于对照组。在容积方面,IMAP显著降低了SITL且伴有特殊症状患者的估算鼻腔下部分容积比(P=0.021),IMAP术后的SITL且伴有特殊症状患者与对照组无明显差异。在黏膜表面积方面,IMAP术后的SITL且伴有特殊症状患者的估算鼻腔下部分黏膜表面积显著降低(P=0.021),但其黏膜表面积大小与对照组比较具有显著差异,且该差异与术前差异相仿。估算的鼻腔下部容积比与实际术后的鼻腔下部容积比存在一定相关性。结论 (1)SITL且伴有特殊症状患者的鼻腔容积与其ENS6Q评分有显著相关性;(2)IMAP对鼻腔的作用不仅仅在于缩窄容积,更在于重新恢复了鼻腔黏膜的功能;(3)应用下鼻甲部分鼻腔容积的容积比来估算术后鼻腔的情况或许可以进一步改进IMAP手术。

鼻内镜Messerklinger中鼻甲成形术与鼻内镜中鼻甲部分切除术治疗CRSwNP的效果

目的探讨鼻内镜Messerklinger中鼻甲成形术与鼻内镜中鼻甲部分切除术治疗慢性鼻-鼻窦炎伴鼻息肉(CRSwNP)的效果。方法选取2019年1月—2021年1月在我院拟行鼻内镜手术治疗的CRSwNP患者94例,随机分为鼻甲成形组和鼻甲部分切除组,每组47例。鼻甲成形组选择鼻内镜Messerklinger中鼻甲成形术治疗,鼻甲部分切除组选择鼻内镜中鼻甲部分切除术治疗,评估两组临床疗效,并对比两组术前、术后1周及术后3个月的鼻功能和粘膜组织炎症生化指标含量[人软骨糖蛋白-39(YKL-40)、白介素细胞-6(IL-6)、MUC5AC阳性表达面积百分率]变化,记录两组术后并发症和术后随访1年的复发率。结果与鼻甲部分切除组比较,鼻甲成形组的临床总有效率显著性提升(93.62%vs 76.60%,P<0.05);观察各项鼻功能指标和粘膜组织炎症生化指标发现,两组进行组间、时间点及组间·时间点的交互效应时,差异均有统计学意义(P<0.05),其中两组术后1周及3个月后的鼻粘膜纤毛输送速率相比术前有显著性提高,鼻气道阻力、内镜Lund-Kennedy、嗅觉功能评分和粘膜组织YKL-40、IL-6含量及MUC5AC阳性表达面积百分率相比术前显著降低(均P<0.05),上述指标两组间比较差异均有统计学意义(P<0.05);两组患者术后并发症总发生率差异无统计学意义(P>0.05);鼻甲成形组随访1年的复发率均显著低于鼻甲部分切除组(P<0.05)。结论CRSwNP患者选择鼻内镜Messerklinger中鼻甲成形术治疗,能提升临床疗效,促使患者的鼻功能、鼻粘膜炎症改善,效果比鼻内镜中鼻甲部分切除术更好,且并未增加术后并发症,患者术后复发率也更低。

低温等离子射频消融联合下鼻甲骨折外移术治疗阻塞性睡眠呼吸暂停低通气综合征的疗效观察

目的探讨阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者接受低温等离子射频消融联合下鼻甲骨折外移术后睡眠及经鼻持续气道正压通气(nasal continuous positive airway pressure,nCPAP)治疗耐受性的改善情况。方法选择40例OSAHS合并双侧下鼻甲肥大的患者作为研究对象,均在局麻下接受下鼻甲低温等离子射频消融联合骨折外移术。术前及术后2周分别采用多导睡眠监测(PSG)、鼻阻力仪、autoCPAP呼吸机及视觉模拟量表(VAS)测定睡眠呼吸暂停低通气指数(AHI)、最低血氧饱和度(lowest oxygen saturation,LSaO_(2))、鼻气道阻力及nCPAP治疗耐受性。结果与术前比较,术后2周时患者AHI降低至(35.17±9.72)次/h,LSaO_(2)提高至(83.21±6.58)%,鼻气道阻力降低至(0.55±0.09)kPa·s/cm^(3),VAS评分升高至8.32±1.17,差异比较均有统计学意义(P均<0.05)。结论低温等离子射频消融联合下鼻甲骨折外移术能有效降低OSAHS患者的鼻阻力,提高nCPAP治疗的耐受性,改善OSAHS患者的睡眠情况。

鼻内镜修正性手术联合中鼻甲部分黏膜切除治疗难治性鼻-鼻窦炎的临床效果

目的探讨鼻内镜修正性手术联合中鼻甲部分黏膜切除治疗难治性鼻-鼻窦炎的临床效果。方法100例难治性鼻-鼻窦炎患者随机分为两组,对照组行鼻内镜修正性手术治疗,研究组行鼻内镜修正性手术联合中鼻甲部分黏膜切除治疗,比较两组的临床效果、鼻腔功能、并发症以及复发情况。结果研究组的治疗总有效率高于对照组,复发率低于对照组(P<0.05)。术后6个月,研究组的DCAN小于对照组,NMCA、NCV均大于对照组(P<0.05)。结论鼻内镜修正性手术联合中鼻甲部分黏膜切除治疗难治性鼻-鼻窦炎的临床效果显著,可改善患者的鼻腔功能,降低复发风险。

鼻内镜手术联合低温等离子鼻甲射频消融术治疗慢性鼻窦炎患者的效果及对术后鼻通气功能及变态反应的影响

目的探讨鼻内镜手术联合低温等离子鼻甲射频消融术治疗慢性鼻窦炎患者的效果。方法选取2020年1月至2022年1月我院收治的80例慢性鼻窦炎患者为研究对象,按手术方式的差异将其分为对照组和观察组,各40例。对照组采用鼻内镜手术,观察组采用鼻内镜手术联合低温等离子鼻甲射频消融术。比较两组的治疗效果。结果观察组的治疗总有效率高于对照组(P<0.05)。术后1 d,观察组的鼻腔容积大于对照组,鼻阻力小于对照组(P<0.05)。术后1 d,观察组的总免疫球蛋白E(TIgE)、嗜酸性粒细胞阳离子蛋白(ECP)水平均低于对照组(P<0.05)。术后3个月,观察组的糖精清除时间短于对照组,黏液纤毛清除率高于对照组,黏液纤毛清除速度大于对照组(P<0.05)。两组的并发症总发生率无显著差异(P>0.05)。结论鼻内镜手术联合低温等离子鼻甲射频消融术治疗慢性鼻窦炎的效果显著,可促进术后鼻通气功能及鼻腔黏液纤毛清除功能改善,减轻变态反应,且安全性高,值得推广。

纽曼健康系统模式护理对鼻甲肥大术后患者睡眠质量及康复进程的影响

目的:探讨纽曼健康系统模式护理对鼻甲肥大术后患者睡眠质量及康复进程的应用效果.方法:选取2021年5月至2022年5月本院收治的115例鼻甲肥大术后患者为研究对象.采用随机抽签法将其分为实验组(n=58,采用纽曼健康系统模式护理)和对照组(n=57,给予常规模式护理).对两组睡眠质量[匹兹堡睡眠质量指数(PSQI)],康复进程(鼻痛消失时间、呼吸障碍缓解时间、吞咽障碍消失时间),疼痛程度[疼痛数字评分法(NRS)],以及并发症发生率进行统计学分析.结果:采取不同护理模式干预后,实验组NRS、PSQI评分,均低于对照组,差异均有统计学意义(P<0.05);实验组鼻痛消失、呼吸障碍缓解、吞咽障碍消失时间,均显著短于对照组,差异均有统计学意义(P<0.05);实验组并发症发生率(1.72%),显著低于对照组(14.04%),差异亦有统计学意义(P<0.05).结论:采取纽曼健康系统模式护理,能提升鼻甲肥大术后患者睡眠质量,降低并发症发生率,加快其康复进程.

鼻内镜修正性手术联合中鼻甲切除治疗难治性鼻-鼻窦炎的近期效果

目的探讨鼻内镜修正性手术联合中鼻甲切除治疗难治性鼻-鼻窦炎(DTRS)的近期效果。方法回顾性分析2020-02—2022-02于扶沟县人民医院耳鼻喉科行鼻内镜修正性手术联合中鼻甲切除治疗的70例DTRS患者的临床资料。男39例,女31例;年龄(41.68±7.35)岁(范围:25~58岁)。病情严重程度:Ⅰ级19例、Ⅱ级28例、Ⅲ级16例、Ⅳ级7例。BMI(25.73±2.14)kg/m 2(范围:21~31 kg/m 2)。病程(7.43±2.54)a(范围:1~13 a)。均于术前和术后1周时评价患者的临床症状,检测鼻阻力和糖精清除时间。术后随访6个月,统计并发症发生率、治疗总有效率和复发率。结果术后1周时,患者的临床症状各项评分、鼻阻力和糖精清除时间均较术前显著改善,差异均有统计学意义(P<0.05)。术后发生眶周青紫2例、鼻腔粘连1例、窦口闭锁2例,并发症总发生率为7.14%(5/70)。均经对症处理后痊愈。术后随访6个月期间,治愈28例、有效36例、无效6例,总有效率为91.43%(64/70)。末次随访,治愈中的1例和有效中的2例患者复发,复发率为4.69%(3/64)。结论鼻内镜修正性手术联合中鼻甲切除治疗DTRS,能有效改善患者的临床症状,减轻鼻阻力,缩短糖精清除时间,并可减少并发症发生率,提升治疗总有效率和降低复发率。

Reheat effect on the improvement in efficiency of the turbine driven by pulse detonation

Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine efficiency.Considering that the flow losses are dissipated into the gas as heat energy,some of them can be recycled during the expansion process in subsequent stages by the reheat effect,which should be helpful to improve the detonationdriven turbine efficiency.Taking this into account,this paper developed a numerical model of the detonation chamber coupled with a two-stage axial turbine,and a stoichiometric hydrogen-air mixture was used.The improvement in turbine efficiency attributable to the reheat effect was calculated by comparing the average efficiency of the stages with the efficiency of the two-stage turbine.The research indicated that the first stage was critical in suppressing the flow unsteadiness caused by pulse detonation,which stabilized the intake condition of the second stage and consequently allowed much of the flow losses from the first stage to be recycled,so that the efficiency of the two-stage turbine was improved.At a 95%confidence level,the efficiency improvement was stable at 4.5%—5.3%,demonstrating that the reheat effect is significant in improving the efficiency of the detonation-driven turbine.

Optimization of a Pipeline-Type Savonius Hydraulic Turbine

This study focuses on a DN50 pipeline-type Savonius hydraulic turbine.The torque variation of the turbine in a rotation cycle is analyzed theoretically in the framework of the plane potential flow theory.Related numerical simulations show that the change in turbine torque is consistent with the theoretical analysis,with the main power zone and the secondary power zone exhibiting a positive torque.In contrast,the primary resistance zone and the secondary resistance zone are characterized by a negative torque.Analytical relationships between the turbine’s internal flow angleθ,the deflector’s inclination angleα0,and the coverage angleαof the power zone are introduced,and a method for calculating the optimal number of blades is proposed to maximize the power zone.Results are presented about performance tests conducted on five groups of hydraulic turbines with the blade number ranging from 3 to 7.Such results indicate that both the turbine’s recovery power and efficiency attain the highest values when the blade number is 4,which is in agreement with the number of blades calculated by the proposed method.Additionally,the study examines the effects of the flow rate on turbine parameters and the projected energy generation and cost savings for a specific pipeline configuration.

Ice-Induced Vibrational Response of Single-Pile Offshore Wind-Turbine Foundations

Important challenges must be addressed to make wind turbines sustainable renewable energy sources.A typical problem concerns the design of the foundation.If the pile diameter is larger than that of the jacket platform,traditional mechanical models cannot be used.In this study,relying on the seabed soil data of an offshore wind farm,the m-method and the equivalent embedded method are used to address the single-pile wind turbine foundation problem for different pile diameters.An approach to determine the equivalent pile length is also proposed accordingly.The results provide evidence for the effectiveness and reliability of the model based on the equivalent embedded method.

Research on the Icing Diagnosis ofWind Turbine Blades Based on FS–XGBoost–EWMA

In winter,wind turbines are susceptible to blade icing,which results in a series of energy losses and safe operation problems.Therefore,blade icing detection has become a top priority.Conventional methods primarily rely on sensor monitoring,which is expensive and has limited applications.Data-driven blade icing detection methods have become feasible with the development of artificial intelligence.However,the data-driven method is plagued by limited training samples and icing samples;therefore,this paper proposes an icing warning strategy based on the combination of feature selection(FS),eXtreme Gradient Boosting(XGBoost)algorithm,and exponentially weighted moving average(EWMA)analysis.In the training phase,FS is performed using correlation analysis to eliminate redundant features,and the XGBoost algorithm is applied to learn the hidden effective information in supervisory control and data acquisition analysis(SCADA)data to build a normal behavior model.In the online monitoring phase,an EWMA analysis is introduced to monitor the abnormal changes in features.A blade icing warning is issued when themonitored features continuously exceed the control limit,and the ambient temperature is below 0℃.This study uses data fromthree icing-affected wind turbines and one normally operating wind turbine for validation.The experimental results reveal that the strategy can promptly predict the icing trend among wind turbines and stably monitor the normally operating wind turbines.

Vibration attenuation performance of wind turbine tower using a prestressed tuned mass damper under seismic excitation

With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cause excessive vibration of the WTT.To investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this study.First,a mathematical model is established based on structural dynamics under seismic excitation.Then,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning optimization.Next,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal acceleration.Finally,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the PTMD.In addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.

Influence of Trailing-Edge Wear on the Vibrational Behavior of Wind Turbine Blades

To study the impact of the trailing-edge wear on the vibrational behavior of wind-turbine blades,unworn blades and trailing-edge worn blades have been assessed through relevant modal tests.According to these experiments,the natural frequencies of trailing-edge worn blades-1,-2,and-3 increase the most in the second to fourth order,thefifth order increases in the middle,and thefirst order increases the least.The damping ratio data indi-cate that,in general,thefirstfive-order damping ratios of trailing-edge worn blades-1 and trailing-edge worn blades-2 are reduced,and thefirstfive-order damping ratios of trailing-edge worn blades-3 are slightly improved.The mode shape diagram shows that the trailing-edge worn blades-1 and-2 have a large swing in the tip and the blade,whereas the second-and third-order vibration shapes of the trailing edge-worn blade-3 tend to be improved.Overall,all these results reveal that the blade’s mass and the wear area are the main fac-tors affecting the vibration characteristics of wind turbine blades.

Dynamic Analysis of a 10 MW Floating Offshore Wind Turbine Considering the Tower and Platform Flexibility

Recently,semisubmersible floating offshore wind turbine technologies have received considerable attention.For the coupled simulation of semisubmersible floating offshore wind energy,the platform is usually considered a rigid model,which could affect the calculation accuracy of the dynamic responses.The dynamic responses of a TripleSpar floating offshore wind turbine equipped with a 10 MW offshore wind turbine are discussed herein.The simulation of a floating offshore wind turbine under regular waves,white noise waves,and combined wind-wave conditions is conducted.The effects of the tower and platform flexibility on the motion and force responses of the TripleSpar semisubmersible floating offshore wind turbine are investigated.The results show that the flexibility of the tower and platform can influence the dynamic responses of a TripleSpar semisubmersible floating offshore wind turbine.Considering the flexibility of the tower and platform,the tower and platform pitch motions markedly increased compared with the fully rigid model.Moreover,the force responses,particularly for tower base loads,are considerably influenced by the flexibility of the tower and platform.Thus,the flexibility of the tower and platform for the coupled simulation of floating offshore wind turbines must be appropriately examined.

Preparation and property of seal coating for gas turbine compressor

Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block.Bond coating was prepared by atmospheric plasma spraying and top coating was prepared by flame spraying.The microstructure,mechanical properties and abradability of the coating were characterized by scanning elec-tron microscope(SEM),hardness tester,universal testing machine,thermal shock testing machine and abradability testing machine.The res-ults show that the overall spraying structure of the seal coating is uniform,the nickel metal phase is the skeleton supporting the entire coat-ing,and the coating is well bonded without separation.The seal coating has a bonding strength of not less than 7.7 MPa,excellent thermal stability,and thermal shock resistance cycle numbers at 500℃more than 50;the scratch length,deepest invasion depth and wear amount of the coating increase with rise of test temperature,with almost no coating adhesion,indicating that the seal coating has excellent abradability.

Turbine Passage Secondary Flow Dynamics and Endwall Heat Transfer Under Different Inflow Turbulence

This study presents endwall hydrodynamics and heat transfer in a linear turbine cascade at Re 5×105 at low and high intensities of turbulence.Results are numerically predicted using the standard SST model and Reθ-γtransition model as well as using the high-resolution LES separately.The major secondary flow components,comprising the horseshoe,corner,and passage vortices are recognized and the impact on heat or mass transfer is investigated.The complicated behavior of turbine passage secondary flow generation and establishment are impacted by the perspective of boundary layer attributes and inflow turbulence.The passage vortex concerning the latest big leading-edge vane is generated by the enlargement of the circulation developed at the first instance adjacent to the pressure side becomes powerful and mixes with other vortex systems during its migration towards the suction side.The study conclusions reveal that substantial enhancements are attained on the endwall surface,for the entire spanwise blade extension on the pressure surface,and in the highly 3-D region close to the endwall on the suction surface.The forecasted suction surface thermal exchange depicts great conformity with the measurement values and precisely reproduces the enhanced thermal exchange owing to the development and lateral distribution of the secondary flows along the midspan of the blade passage downstream.The impacts of the different secondary flow structures on the endwall thermal exchange are described in depth.

Novel Method for Evaluating the Aging of Aviation Turbine Engine Oils via High-Temperature Bearing Deposit Tests

Aviation turbine engine oils require excellent thermal-oxidative stability because of their high-temperature environments.High-temperature bearing deposit testing is a mandatory method for measuring the thermal-oxidative performance of aviation lubricant oils,and the relevant apparatus was improved in the present study.Two different commercial aviation turbine engine oils were tested,one with standard performance(known as the SL oil)and the other with high thermal stability,and their thermal-oxidative stability characteristics were evaluated.After 100 h of high-temperature bearing testing,the SL oil was analyzed by using various analytical techniques to investigate its thermal-oxidative process in the bearing test,with its thermal-oxidative degradation mechanism also being discussed.The results indicate that the developed high-temperature bearing apparatus easily meets the test requirements of method 3410.1 in standard FED-STD-791D.The viscosity and total acid number(TAN)of the SL oil increased with the bearing test time,and various deposits were produced in the bearing test,with the micro-particles of the carbon deposits being sphere-like,rod-like,and sheet-like in appearance.The antioxidant additives in the oil were consumed very rapidly in the first 30 h of the bearing test,with N-phenyl-1-naphthylamine being consumed faster than dioctyldiphenylamine.Overall,the oil thermal-oxidative process involves very complex physical and chemical mechanisms.

Comparisons of Wave Force Model Effects on the Structural Responses and Fatigue Loads of a Semi-Submersible Floating Wind Turbine

The selection of wave force models will significantly impact the structural responses of floating wind turbines.In this study,comparisons of wave force model effects on the structural responses and fatigue loads of a semi-submersible floating wind turbine(SFWT)were conducted.Simulations were performed by employing the Morison equation(ME)with linear or second-order wave kinematics and potential flow theory(PFT)with first-or second-order wave forces.A comparison of regular waves,irregular waves,and coupled wind/waves analyses with the experimental data showed that many of the simulation results and experimental data are relatively consistent.However,notable discrepancies are found in the response amplitude operators for platform heave,tower base bending moment,and tension in mooring lines.PFT models give more satisfactory results of heave but more significant discrepan-cies in tower base bending moment than the ME models.In irregular wave analyses,low-frequency resonances were captured by PFT models with second-order difference-frequency terms,and high-frequency resonances were captured by the ME models or PFT models with second-order sum-frequency terms.These force models capture the response frequencies but do not reasonably predict the response amplitudes.The coupled wind/waves analyses showed more satisfactory results than the wave-only analyses.However,an important detail to note is that this satisfactory result is based on the overprediction of wind-induced responses.

Aero-Hydro-Elastic-Servo Modeling and Dynamic Response Analysis of A Monopile Offshore Wind Turbine Under Different Operating Scenarios

This paper constructs a coupled aero-hydro-elastic-servo simulation framework for a monopile offshore wind turbine(OWT).In this framework,a detailed multi-body dynamics model of the monopile OWT including the gearbox,blades,tower and other components(nacelle,hub,bedplate,etc.)has been explicitly established.The effects of pile−soil interaction,controller and operational conditions on the turbine dynamic responses are studied systematically in time domain and frequency domain.The results show that(1)a comprehensive drivetrain model has the capability to provide a more precise representation of the complex dynamic characteristics exhibited by drivetrain components,which can be used as the basis for further study on the dynamic characteristics of the drivetrain.(2)The pile−soil interaction can influence the wind turbine dynamic responses,particularly under the parked condition.(3)The effect of the pile−soil interaction on tower responses is more significant than that on blade responses.(4)The use of the controller can substantially affect the rotor characteristics,which in turn influences the turbine dynamic responses.(5)The tower and blade displacements under the operational condition are much larger than those under the parked condition.The model and methodology presented in this study demonstrate potential for examining complex dynamic behaviors of the monopile OWTs.To ensure accuracy and precision,it is imperative to construct a detailed model of the wind turbine system,while also taking into account simulation efficiency.

Nonlinear Flap-Wise Vibration Characteristics ofWind Turbine Blades Based onMulti-Scale AnalysisMethod

This work presents a novel approach to achieve nonlinear vibration response based on the Hamilton principle.We chose the 5-MW reference wind turbine which was established by the National Renewable Energy Laboratory(NREL),to research the effects of the nonlinear flap-wise vibration characteristics.The turbine wheel is simplified by treating the blade of a wind turbine as an Euler-Bernoulli beam,and the nonlinear flap-wise vibration characteristics of the wind turbine blades are discussed based on the simplification first.Then,the blade’s large-deflection flap-wise vibration governing equation is established by considering the nonlinear term involving the centrifugal force.Lastly,it is truncated by the Galerkin method and analyzed semi-analytically using the multi-scale analysis method,and numerical simulations are carried out to compare the simulation results of finite elements with the numerical simulation results using Campbell diagram analysis of blade vibration.The results indicated that the rotational speed of the impeller has a significant impact on blade vibration.When the wheel speed of 12.1 rpm and excitation amplitude of 1.23 the maximum displacement amplitude of the blade has increased from 0.72 to 3.16.From the amplitude-frequency curve,it can be seen that the multi-peak characteristic of blade amplitude frequency is under centrifugal nonlinearity.Closed phase trajectories in blade nonlinear vibration,exhibiting periodic motion characteristics,are found through phase diagrams and Poincare section diagrams.