Extraction of Strain Characteristic Signals from Wind Turbine Blades Based on EEMD-WT

Analyzing the strain signal of wind turbine blade is the key to studying the load of wind turbine blade,so as to ensure the safe and stable operation of wind turbine in natural environment.The strain signal of the wind turbine blade under continuous crosswind state has typical non-stationary and unsteady characteristics.The strain signal contains a lot of noise,which makes the analysis error.Therefore,it is very important to denoise and extract features of measured signals before signal analysis.In this paper,the joint algorithm of ensemble empirical mode decomposition(EEMD)and wavelet transform(WT)is used for the first time to achieve sufficient noise reduction and effectively extract the feature signals of non-stationary strain signals.The application process of EEMD-WT is optimized.This optimization can avoid the repeated selection of wavelet basis function and the number of decomposition layers due to different crosswind conditions.EEMD adaptively decomposes the strain signal into intrinsic mode functions,to judge the frequency of IMFs,remove the high-frequency noise components,retain the useful components.The useful components are denoised twice by the wavelet transform,the components and residual terms after the secondary denoising are reconstructed to obtain the characteristic signal.The EEMD-WT was applied to process the simulating signals andmeasured the strain signals.The results were compared with the results of the EEMD.The results showed that the EEMD-WTmethod has better noise reduction performance,and can effectively extract the characteristics of strain signals,which lays a solid foundation for accurate analysis of wind turbine blade strain signals under crosswind conditions.

Age Structure and Change Trend of Tobacco Farmers:A Case Study of Shashi Town,Liuyang City,Hunan Province

Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.

The Effects of Turbulence Intensity and Tip Speed Ratio on the Coherent Structure of Horizontal-Axis Wind Turbine Wake:A Wind Tunnel Experiment

The evolution laws of the large-eddy coherent structure of the wind turbine wake have been evaluated via wind tunnel experiments under uniform and turbulent inflow conditions.The spatial correlation coefficients,the turbulence integral scales and power spectrum are obtained at different tip speed ratios(TSRs)based on the time-resolved particle image velocity(TR-PIV)technique.The results indicate that the large-eddy coherent structures are more likely to dissipate with an increase in turbulence intensity and TSR.Furthermore,the spatial correlation of the longitudinal pulsation velocity is greater than its axial counterpart,resulting into a wake turbulence dominated by the longitudinal pulsation.With an increase of turbulence intensity,the integral scale of the axial turbulence increases,meanwhile,its longitudinal counterpart decreases.Owing to an increase in TSR,the integral scale of axial turbulence decreases,whereas,that of the longitudinal turbulence increases.By analyzing the wake power spectrum,it is found that the turbulent pulsation kinetic energy of the wake structure is mainly concentrated in the low-frequency vortex region.The dissipation rate of turbulent kinetic energy increases with an increase of turbulence intensity and the turbulence is transported and dissipated on a smaller scale vortex,thus promoting the recovery of wake.

Study of the Flow Mechanism of Wind Turbine Blades in the Yawed Condition

The computational fluid dynamics method was used to simulate the flow field around a wind turbine at the yaw angles of 0°,15°,30°,and 45°.The angle of attack and the relative velocity of the spanwise sections of the blade were extracted with the reference points method.By analyzing the pressure distribution and the flow characteristics of the blade surface,the flow mechanism of the blade surface in the yawed condition was discussed.The results showed that the variations of the angle of attack and the relative velocity were related to the azimuth angle and the radius in the yawed condition.The larger the yaw angle was,the larger the variation was.The pressure distribution in the spanwise sections was affected by both the angle of attack and the relative velocity.The angle of attack was more influential than the relative velocity.At the same yaw angle,when the angle of attack decreased,the c_(p)∼x/c curve shrunk inward and the lift force decreased.The larger the yaw angle was,the more obvious the shrink was.The effect of the yaw on the blade root region was higher than its effect on the blade tip region.

Analysis of Near-Wake Deflection Characteristics of Horizontal Axis Wind Turbine Tower under Yaw State

The yaw of the horizontal axis wind turbine results in the deflection of the wake flow field of the tower.The reasonable layout of wind farm can reduce the power loss of the downstream wind turbine generators due to the blocking effect of the upstream wake flow and increase the output power of the whole wind farm.However,there is still much space for further research.In this paper,experimental research is conducted on the near-wake deflection characteristics of wind turbine tower under yaw state,expecting the effect of throwing away a brick in order to get a gem.In the low-turbulence wind tunnel test,regarding the most unfavorable position where the rotating blades coincide with the tower,Particle image velocimetry(PIV)technology is used to test the instantaneous velocity field and output power and analyze experimental data at four different yaw angles,different inflow velocities and heights.Meanwhile,in order to quantitatively analyze the laws on wake deflection,the radon transformation is used to analyze the velocity contour for calculating the wake direction angle,and the results show high reliability.The comprehensive experimental results indicate that the near-wake flow field of the tower obviously deflects towards a side in the horizontal plane.With the increase of the yaw angle,the deflection angle of the wake flow field further increases,and the recovery of wake velocity accelerates.The closer to the blade root,the more complex the flow is,and the influence of the blade on the near wake of the tower is gradually weakened.The change laws on the wake direction angle with the yaw angle and the blade spanwise direction are obtained.The experiment in this paper can provide guidance for layout optimization of wind farm,and the obtained data can provide a scientific basis for the research on performance prediction of horizontal axis wind turbine.

Analysis of Employment Trend in Flue-Cured Tobacco Planting

Based on the investigation of the amount of labor used in each production link of flue-cured tobacco planting in Liuyang since 1989,and through the analysis of the changes of labor-related factors,it is concluded that the amount of labor used in tobacco planting in Liuyang experienced a significant increase and relatively stable stage in the early 1990s,and it has been declining continuously since the beginning of the 21st century;the change of flue-cured tobacco planting technology mode,as well as mechanized,large-scale and specialized production are the main factors that affect the change of the amount of labor used in flue-cured tobacco planting in Liuyang.Based on the method of changing the technical model to reduce amount of labor used,the types of labor used for planting of flue-cured tobacco can be divided into the following types:reducing the amount of labor by technical methods;reducing the amount of labor by making use of weather;reducing the amount of labor by using drugs;reducing the amount of labor used at the cost of reducing the technical implementation standards of a certain production link.The change of labor used in flue-cured tobacco planting is not only related to the cost and price factors,but also related to the profound social and economic background.In the future,reducing labor and cost is the trend of flue-cured tobacco production,and mechanization,large-scale and specialized production are the main development direction of flue-cured tobacco production,but under the condition that flue-cured tobacco production is still dominated by manual operation,maintaining a certain amount of labor is still the basis for maintaining high quality of flue-cured tobacco planting at present.

Development of Customized Production Machine for Flue-cured Tobacco Formula Nutritional Soil

On the basis of full investigation and repeated trials,nutritional soil composed of cake fertilizer,mushroom residue,cow dung and calcium magnesium phosphate fertilizer was determined as an alternative for traditional flue-cured tobacco fired ash soil.In accordance with the feed grinding,mixing and processing integrated principle,processing machine for flue-cured tobacco nutritional soil was developed.The clogging problem of mixing box was solved by improving grinding and stirring method of mixing system.Mechanized and large-scale production and commercialized supply of flue-cured tobacco nutritional soil was piloted to simplify the production process and reduce the production cost of nutritional soil for flue-cured tobacco and meet the needs of green development of tobacco production,thereby creating good social and economic benefits.

Lanthanum elicitation on hypocrellin A production in mycelium cultures of Shiraia bambusicola is mediated by ROS generation

Rare earth elements(REEs)have been widely applied as efficient elicitors to improve production of biologically important secondary metabolites in plants.However,their effects on microbial secondary metabolites were seldom reported.In this study,lanthanum(LaCl3)was used as an elicitor in mycelium cultures of Shiraia bambusicola to stimulate the production of hypocrellin A(HA),a promising photosensitizer for anticancer photodynamic therapy.La^3+at 1.0 g/L not only increases HA content by 2.50-fold in mycelia,but stimulates HA exudation to the medium with the highest production(225.05 mg/L)on day 6.Further analysis shows that La^3+can induce the intracellular ROS(reactive oxygen species)accumulation with 2.33-fold higher contents of H2O2 in mycelium.HA production induced by La^3+treatment can be suppressed by ROS scavengers.Further analysis reveals that the elicitation of La^3+on HA accumulation is mediated by ROS generation to enhance expression of HA biosynthetical genes.The expression of ATP-binding cassette transporter gene(SbABC)for HA exudation is also regulated partially via ROS generated by NADPH oxidase.These results indicate that the enhanced HA production by La^3+might be mediated by ROS signaling pathway.Our results provide a basis for understanding REE elicitation on fungal metabolites and a practical biotechnological process for enhanced production of HA.

Spatial patterns of net primary productivity and its driving forces:a multi-scale analysis in the transnational area of the Tumen River

Analyzing the spatial patterns of net primary productivity(NPP)and its driving forces in transnational areas provides a solid basis for understanding regional ecological processes and ecosystem services.However,the spatial patterns of NPP and its driving forces have been poorly understood on multiple scales in transnational areas.In this study,the spatial patterns of NPP in the transnational area of the Tumen River(TATR)in 2016 were simulated using the Carnegie Ames Stanford Approach(CASA)model,and its driving forces were analyzed using a stepwise multiple linear regression model.We found that the total amount of NPP in the TATR in 2016 was approximately 14.53 TgC.The amount of NPP on the Chinese side(6.23 TgC)was larger than those on the other two sides,accounting for 42.88%of the total volume of the entire region.Among different land-use and land-cover(LULC)types,the amount of NPP of the broadleaf forest was the largest(11.22 TgC),while the amount of NPP of the bare land was the smallest.The NPP per unit area was about 603.21 gC/(m2 yr)across the entire region,while the NPP per unit area on the Chinese side was the largest,followed by the Russian side and the DPRK's side.The spatial patterns of NPP were influenced by climate,topography,soil texture,and human activities.In addition,the driving forces of the spatial patterns of NPP in the TATR had an obvious scaling effect,which was mainly caused by the spatial heterogeneity of climate,topography,soil texture,and human activities.We suggest that effective land management policies with cooperation among China,the DPRK,and Russia are needed to maintain NPP and improve environmental sustainability in the TATR.

Lanthanum:A novel inducer for enhancement of fungal laccase production by Shiraia bambusicola

Fungal laccases are industrially important inducible enzymes extensively used in the delignification of lignocellulosics,detoxification of environmental wastes and decolorization of textile dyes.The discovery of new inducers is crucial for laccase productivity by filamentous fungi.In this study,a novel laccase-producing strain S8 from a bambusicolous fungus Shiraia bambusicola was identified by using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)as laccase secretion indicator and native polyacrylamide gel electrophoresis.The corresponding full-length cDNA of laccase was cloned and characterized.The effect of lanthanum(LaCl_(3))on extracellular laccase activity was tested at the concentration from 0.2 to 2.0 g/L and at different addition time(day 1-4)in the mycelium culture.In the presence of 1.0 g/L La^(3+) at the beginning of the mycelium cultures,the highest laccase activity(2.7×10^(4) U/L)is reached after 10 days of cultivation,about tenfold higher compared with non-induced cultures.La^(3+) is shown to be a very strong inducer for fungal laccase activity with no inhibitory effect on fungal growth at the optimized concentration.In vivo,La^(3+) added to the mycelium culture not only promotes a continuous and high expression of laccase gene(lcc1),but also induces a rapid generation of signaling molecules including reactive oxygen species(ROS)and nitric oxygen(NO).Both the NO donor sodium nitroprusside(SNP)and exogenous hydrogen peroxide(H_(2)O_(2))potentiate La^(3+)-induced laccase activity and increase membrane permeability of hyphal cells.Moreover,the scavengers such as 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(cPTIO)for NO and vitamin C for ROS suppress the induction.These results suggest that these signals can mediate La^(3+)-induced laccase biosynthesis and its secretion.Our study provides a basis for understanding the induction mechanism of La^(3+) on laccase and a practical strategy for enhanced fungal laccase production.

Mechanism of water savings and pollution reduction in paddy fields of three typical areas in southern China

Field irrigation and drainage regulation and fertilization application could affect water utilization and pollution transportation in a paddy field.In this study,representative rice-producing areas of Zhejiang Province in southern China were selected to study the effects of different field water level control(conventional irrigation and drainage W0,controlled irrigation and drainage W1 and W2)and different fertilization methods(2 times of fertilization F2 and three times of fertilization F3)on water irrigation quantity and consumption of rice,rice growth,water utilization,and pollution reduction.Results showed that field water level control had a great effect on irrigation quota in growing period rather than that in soaking period,and irrigation quota for W0 was 37.0%-71.7%higher than that for W1 and W2 in the whole growth period of rice.Although the upper limit of rain storage was greatly increased by W1 and W2,on the contrary,the yield under W1 and W2 was 0.4%-2.1%higher than that under W0.Water consumption,water leakage,and evapotranspiration were 16.63%-34.4%,39.97%-60.8%,and 9.40%-31.53%lower under W1 and W2 than those under W0,respectively,while it showed no significant changes under W1 and W2.Rainfall use rate and WUEI(water use efficiency of irrigation)under W1 and W2 had been significantly improved by 8.20%-129.58%and 31.58%-201.61%compared to W0.The contribution of nitrogen and phosphorus loss from surface water accounted for 90%and the total pollution load of total nitrogen(TN),NO_(3)^(-)-N,NH_(4)^(+)-N and chemical oxygen demand(COD)were 20.0%-63.4%,21.8%-66.3%,21.5%-63.8%,and 21.4%-46.5%lower for W1 and W2 than that for W0,respectively.Meanwhile,compared to F2,dispersed fertilization(F3)was beneficial to increase the yield and decrease pollutant load.Additionally,the path of IRA→NH_(4)^(+)-N→COD and IRA→WCA→WUE_(I) presented partial remediation effect,and the effect size was 23.6%and 38.1%,respectively,the path of IRA→WUE_(I)→WUE_(ET) presented a full remediation effect,and the path of IRA→WCA→WUE_(ET) presented suppression effect.

Sudden Cardiac Death Due to Long QT Syndrome

Identification of sudden cardiac death(SCD)with a structurally normal heart remains an important challenge in forensic pathology.Long QT syndrome(LQTS)is known as an inherited or acquired channelopathy,which is characterized with prolonged QT interval,and is likely to cause SCD in young adults.In this circumstance,no specific pathological change in the heart can be found anatomically or histologically in the LQTS victims.Thus,postmortem LQTS diagnosis is mainly based on clinical manifestations and genetic testing.Here,we reported a 26‑year‑old woman who was found dead at home with a history of unexplained syncope.Her clinical records and an electrocardiograph(ECG)obtained 3 months before her death showed a QTc interval of 539 ms which implicates the diagnosis of LQTS.Although the autopsy and pathological examination findings lacked specificity,we noticed enhanced lipofuscin accumulation in cardiomyocytes,which might be related to LQTS.After excluding potential diseases and injuries,we made the postmortem diagnosis as LQTS according to ECG,clinical history,and forensic postmortem findings.In conclusion,we provided clinical and pathological features of an SCD case due to LQTS,which might enrich the understanding of forensic postmortem SCD diagnosis with nonstructural cardiac diseases.