A nonlinear wake model of a wind turbine considering the yaw wake steering

Duo to fluctuations in atmospheric turbulence and yaw control strategies,wind turbines are often in a yaw state.To predict the far wake velocity field of wind turbines quickly and accurately,a wake velocity model was derived based on the method of momentum conservation considering the wake steering of the wind turbine under yaw conditions.To consider the shear effect of the vertical incoming wind direction,a two-dimensional Gaussian distribution function was introduced to model the velocity loss at different axial positions in the far wake region based on the assumption of nonlinear wake expansion.This work also developed a“prediction-correction”method to solve the wake velocity field,and the accuracy of the model results was verified in wake experiments on the Garrad Hassan wind turbine.Moreover,a 33-kW two-blade horizontal axis wind turbine was simulated using this method,and the results were compared with the classical wake model under the same parameters and the computational fluid dynamics(CFD)simulation results.The results show that the nonlinear wake model well reflected the influence of incoming flow shear and yaw wake steering in the wake velocity field.Finally,computation of the wake flow for the Horns Rev offshore wind farm with 80 wind turbines showed an error within 8%compared to the experimental values.The established wake model is less computationally intensive than other methods,has a faster calculation speed,and can be used for engineering calculations of the wake velocity in the far wakefield of wind turbines.

Assessment of scale interactions associated with wake meandering using bispectral analysis methodologies

Large atmospheric boundary layer fluctuations and smaller turbine-scale vorticity dynamics are separately hypothesized to initiate the wind turbine wake meandering phenomenon,a coherent,dynamic,turbine-scale oscillation of the far wake.Triadic interactions,the mechanism of energy transfers between scales,manifest as triples of wavenumbers or frequencies and can be characterized through bispectral analyses.The bispectrum,which correlates the two frequencies to their sum,is calculated by two recently developed multi-dimensional modal decomposition methods:scale-specific energy transfer method and bispectral mode decomposition.Large-eddy simulation of a utility-scale wind turbine in an atmospheric boundary layer with a broad range of large length-scales is used to acquire instantaneous velocity snapshots.The bispectrum from both methods identifies prominent upwind and wake meandering interactions that create a broad range of energy scales including the wake meandering scale.The coherent kinetic energy associated with the interactions shows strong correlation between upwind scales and wake meandering.

Chronic Hepatitis B in Indian Americans: Lack of Screening and Poor Linkage to Care

Background: Chronic hepatitis B (CHB) is a major cause of liver-related morbidity and mortality in the United States (US) and globally. CHB disproportionately affects Asian Americans and many other immigrant minority populations, primarily owing to the high prevalence of CHB in their countries of origin. India is a country with a medium-to-high prevalence of hepatitis B (HB) (>2%) and has over 40 million people infected with hepatitis B virus (HBV), with more than 115,000 deaths annually from HBV-related complications. Indian Americans are one of the largest immigrant populations in the US but remain underdiagnosed and poorly linked to clinical care. We, therefore, assessed the HBV prevalence and evaluated the linkage-to-care (LTC) among Indian Americans to develop strategic plans to reduce the impact of HBV in the US. Methods: Between April 2022 and January 2024, serologic screening and surveys were provided to 328 Indian American adults (age 20 - 80) in New York City. All participants were tested for a triple panel consisting of hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), and hepatitis B core IgG antibody (anti-HBc). A survey was conducted on the subjects chronically infected with HBV regarding their histories of infection. Self-administered questionnaires were employed to evaluate demographic and epidemiologic characteristics. Results: Of 328 screened and evaluated (246 males and 82 females), 10 (3.0%) were HBV-infected, 222 (67.7%) were susceptible to HBV, and 96 (29.3%) were immune. The prevalence of chronic HBV varied between the age groups: 4.6% (age 20 - 40), 3.4% (age 41 - 60), and 1.7% (age 61 - 80). Of 10 chronically infected, only two subjects had been previously diagnosed but were not engaged in care. Conclusion: HBV disproportionately affects Asian Americans, primarily owing to immigration from parts of the world where the disease is endemic. Indian Americans belong to an intermediate-risk group, with an HBV prevalence of >2%, but remain underdiagnosed and poorly linked to care. Our pilot study on Indian American populations, the first of its kind, demonstrates a 3% prevalence of CHB, none of whom are linked to care. In addition, this population has a high percentage of unimmune subjects, creating a large reservoir for future infection. With the growing population of Indian Americans, our findings can be used to develop community-based strategies for HBV screenings and LTC that target high-risk groups.

Analysis on Bicultural Identities of Chinese Americans Based on Acculturation Theory

In the context of globalization,the communication between countries is gradually enhanced and the immigration is increasing.Chinese Americans,as a unique ethnic group,are easy to fall into the difficult problem of self-identity construction when facing the bicultural identity conflict between Chinese and American.This paper selects the film The Farewell created by a Chinese American director as the research object,analyzes the cultural identity crisis of Chinese Americans,introduces the cultural adaption strategy adopted by Chinese Americans from the perspective of Acculturation Theory,and provides reference for Chinese Americans about how to realize the bicultural identities in the cultural diaspora.

A Study on the Infiltration Methods of British and American Literature in High School English Reading Teaching

Reading is the key content of high school English teaching,which can improve students’mastery of words,grammar,and other knowledge,and can expand their horizons.British and American literature is the essence of British and American culture,and its application in high school English reading teaching can help improve students’English proficiency.This paper outlines the problems of high school English teaching,analyzes the role of British and American literature in high school English reading teaching,and explores the infiltration methods of British and American literature in high school English reading teaching,in order to provide references for teachers.

A Corpus Study of Acupuncture from the Perspective of Mass Media Based on the Corpus of Contemporary American English

Based on the Corpus of Contemporary American English(COCA),this study examines acupuncture from the perspective of mass media.Acupuncture has been circulating throughout the Chinese Cultural Circle since the Qin and Han Dynasties,and has since spread directly or indirectly to the rest of the world.The United States boasts the world’s second-largest acupuncture market,with its laws,regulations,industry growth,research,and education all positively influencing the development of acupuncture in other nations.This study uses COCA to analyze the form and content of acupuncture’s dissemination in eight different types of media.The findings show that acupuncture appears in COCA a total of 1,788 times,with the highest frequency in magazines,followed by blogs,and the lowest frequency in fiction.These findings reveal the popularity of acupuncture in mass media in the United States and provide empirical data and insights for the future dissemination and development of acupuncture in the United States.

Three-dimensional dynamics of a single bubble rising near a vertical wall:Paths and wakes

In order to clarify the migration mechanism and wake behavior of a single bubble rising near a vertical wall,three-dimensional direct numerical simulations are implemented based on the open-source soft-ware Basilisk and various types of migration paths like linear,zigzag and spiral are investigated.The volume of fluid(VOF)method is used to capture the bubble interface at a small scale,while the gas-liquid interface and high-velocity-gradient regions in the flow field are encrypted with the adaptive mesh refinement technology.The results show that the vertical wall has an obstructive effect on the diffusion of the vortex boundary layer on the surface of the bubble migrating in a straight line,and the resulting reaction force tends to push the bubbles away from the wall surface.For the zigzag or spiral movement of a bubble in the x-y plane,the perpendicular wall is an unstable factor,but on the contrary,the motion in the z-y plane is stabilized.

Linear logistic regression with weight thresholding for flow regime classification of a stratified wake

A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and the strongly stratified turbulence regimes based on information available in a full Reynolds stress model.First,we generate a direct numerical simulation database with Reynolds numbers from 10,000 to 50,000 and Froude numbers from 2 to 50.Order(100)independent realizations of temporally evolving wakes are computed to get converged statistics.Second,we train a linear logistic regression classifier with weight thresholding for automated flow regime classification.The classifier is designed to identify the physics critical to classification.Trained against data at one flow condition,the classifier is found to generalize well to other Reynolds and Froude numbers.The results show that the physics governing wake evolution is universal,and that the classifier captures that physics.

Excitation and power spectrum analysis of electromagnetic radiation for the plasma wake of reentry vehicles

The plasma wake of reentry vehicles has the advantages of extensive space range and long traceability,which provides new possibilities for the detection and monitoring of reentry vehicles.Based on the Zakharov model,this work investigates the excitation and power spectrum characteristics of electromagnetic radiation for the plasma wake of a typical reentry vehicle.With the aid of parametric decay instability,the excitation condition of electromagnetic radiation for a typical plasma wake is evaluated first.The power spectrum characteristics of electromagnetic radiation,including the effects of both the flight parameters and incident wave parameters are analyzed in detail.The results show that when the phenomenon of excited electromagnetic radiation occurs,plasma wakes closer to the bottom of the vehicle and with faster speeds require higher incident frequencies and thresholds of the electric field.As the frequency of the incident wave increases,peaks appear in the power spectra of plasma wakes,and their magnitudes increase gradually.The frequency shifts of the secondary peaks are equal,whereas,the peaks of the downshifted spectral lines are generally larger than those of the upshifted spectral lines.The work in this paper provides a new idea and method for the tracking of reentry vehicles,which has potential application value in the field of reentry vehicle detection.

On the structure of the turbulent/non-turbulent interface in a fully developed spatially evolving axisymmetric wake

In this work,we numerically study the structure of the turbulent/nonturbulent(T/NT)interface in a fully developed spatially evolving axisymmetric wake by means of direct numerical simulations.There is a continuous and contorted pure shear layer(PSL)adjacent to the outer edge of the T/NT interface.The local thickness of the PSLδ_(PSL)exhibits a wide range of scales(from the Kolmogorov scale to the Taylor microscale)and the conditional mean thickness<δ_(PSL)>I/η_(c)≈6 withη_(c)being the centerline Kolmogorov scale is the same as the viscous superlayer.In the viscous superlayer,the pure shear motions without rotation are overwhelmingly dominant.It is also demonstrated that the physics of the turbulent sublayer is closely related to the PSL with a large thickness.Another significant finding is that the time averaged area of the rotational regionA R,and the pure shear region<A_(S)>at different streamwise locations scale with the square of the wake-width b_(U)^(2).This study opens an avenue for a better understanding of the structures of the T/NT interface.

Gender differences of lower urinary tract symptoms in older Chinese Americans

Objective To describe whether or not there are gender differences in lower urinary tract symptoms(LUTS)prevalence and risk factors in community-dwelling older Chinese Americans.Methods We performed a secondary analysis of a prospective cross-sectional population-based survey of Chinese Americans aged 60 years and older between January 2011 and December 2013 in English,Mandarin,Cantonese,Taishanese,or Teochew.A clinical review of systems was used to assess LUTS,which included urinary frequency,urgency,burning and/or pain,blood in urine,and urinary incontinence.Results Of the total 3157 people queried,42%were men and 58%were women.More men reported LUTS compared to women(32.9%vs.28.6%,p=0.01).In a multivariable analysis,female gender(adjusted odds ratio[aOR]0.60,95%confidence interval[CI]0.49-0.73),being married(aOR 0.79,95%CI 0.65-0.97),and smoking(aOR 0.66,95%CI 0.49-0.88)were found to be protective,while traditional Chinese medicine use(aOR 1.51,95%CI 1.28-1.78),heart disease(aOR 1.54,95%CI 1.24-1.91),and anxiety(aOR 1.69,95%CI 1.25-2.28)were most strongly associated with increased odds of LUTS.When examining genders separately,being married was found to be protective only in women.Meanwhile,unique factors found in men were hypertension,heart disease,and practice of Tai Chi.Conclusion In this large population-based study,LUTS were more prevalent in older Chinese American men than women.We also found gender-specific factors that influenced the odds of reporting LUTS;however,traditional Chinese medicine use was the only factor that was shared by both genders.Future longitudinal investigations are needed to elucidate these underlying mechanisms to provide evidence-based and culture-specific guidelines for this rapidly growing population.

The COVID-19 Pandemic: A Double Threat to Chinese Americans’ Mental Health

Objective:To explore the double psychosocial threats of the COVID-19 pandemic,targeted behavior toward Chinese Americans,and the correlates to their mental health.Methods:A quantitative,cross-sectional,and descriptive design was utilized by using a purposive convenience sample of 301 Chinese Americans over the age of 18 residing in the United States.Online data collection was conducted through the social media platform WeChat from April 8–21,2021.Descriptive statistical analysis was used for the participants’demographic charac-teristics,Multidimensional Scale of Perceived Social Support(MSPSS),Double Threat Situations,COVID-19 Racial Discrimination,and General Anxiety Disorder-7(GAD-7).Stepwise logistic regression was conducted to verify predictors for anxiety levels by GAD-7.Results:In this sample(N=301),127(42.19%)were male and 174(57.81%)were female.The average age was 41.67(SD=5.89).Among MSPSS subscales,social support from family(MSPSS-Fam,79.73%,n=240)and social support from significant others(MSPSS-SO,73.75%,n=222)were high.231(76.74%)reported threats due to their Chinese ethnic background during the COVID-19 outbreak.Predictors for the high anxiety level by GAD-7 were COVID-19 racial discrimination from the local community(OR=0.47,95%CI=0.39–0.71,p<0.001),media/online(OR=0.36,95%CI=0.26–0.53,p<0.001),the perceived threat from the COVID-19 virus(OR=0.33,95%CI=0.23–0.51,p<0.001)and Perceived racism threat from Chinese back-ground related to COVID-19(OR=0.31,95%CI=0.21–0.49,p<0.001).Conclusions:COVID-19 double-threats(The virus and racial discrimination)situations are significantly related to the high level of anxiety among Chinese Americans.The sense of belonging and social perceptions of Chinese immigrants is closely related to public health problems in Western societies and needs to be addressed at all levels.Ourfindings call for the attention of health-care workers to specific racism double-threatened situations and high mental health risks,as well as direct and indirect ethnic discrimination that Chinese Americans are experiencing during this pandemic,the long-term influ-ences and effective coping ways related to this issue should be explored in further research.

Wake Effects on A Hybrid Semi-Submersible Floating Wind Farm with Multiple Hub Heights

Wind farms generally consist of a single turbine installed with the same hub height. As the scale of turbines increases,wake interference between turbines becomes increasingly significant, especially for floating wind turbines(FWT).Some researchers find that wind farms with multiple hub heights could increase the annual energy production(AEP),while previous studies also indicate that wake meandering could increase fatigue loading. This study investigates the wake interaction within a hybrid floating wind farm with multiple hub heights. In this study, FAST.Farm is employed to simulate a hybrid wind farm which consists of four semi-submersible FWTs(5MW and 15MW) with two different hub heights. Three typical wind speeds(below-rated, rated, and over-rated) are considered in this paper to investigate the wake meandering effects on the dynamics of two FWTs. Damage equivalent loads(DEL) of the turbine critical components are computed and analyzed for several arrangements determined by the different spacing of the four turbines. The result shows that the dynamic wake meandering significantly affects downstream turbines’ global loadings and load effects. Differences in DEL show that blade-root flapwise bending moments and mooring fairlead tensions are sensitive to the spacing of the turbines.

Status Quo and Application of North American Wisteria in Shijiazhuang

The introduction and planting of three cultivars of North American wisteria in Shijiazhuang were observed.By comparing the inflorescences of Chinese wisteria,Japanese wisteria and North American wisteria,it is concluded that North American wisteria has compact inflorescence,rich color and late flowering period,and can prolong the ornamental time of wisteria when collocating with Chinese wisteria and Japanese wisteria in landscape application.The application of North American wisteria in Chinese gardens can not only enrich the species diversity of the region,but also have positive significance for improving the landscape effect of the whole city.

In Her Mother’s House:Mother-Daughter Dissonance in Post-1990s Chinese American Fiction

This paper attempts to examine the trope of“home”and the depiction of mother-daughter dissonance“in her mother’s house”in post-1990s Chinese American fiction.The research selects four novels in the case study and focuses on how mother-daughter dissonance“in her mother’s house”is presented,what cultural connotations the trope of“home”carries and how they are affected by such extra-contextual factors as racism,sexism and classism.In comparison with two representative mother-daughter narrative works in pre-1990s period,the new characteristics and connotations of“home”in mother-daughter dissonance in post-1990s Chinese American fiction are revealed.

A Comparative Study of British Gentleman Culture and American Cowboy Culture

This paper makes a comparative analysis by selecting British gentleman culture and American cowboy culture,the two distinctive cultures,to trace their roots,explore their connotations,and search for their similarities and differences,so as to better understand the respective characteristics of British and American cultures.The result shows that although the two cultures have different styles,which can interpret two different ethnic cultures,they are related by blood and have certain commonalities.

Discourse Construction of the Belt and Road Initiative in British and American Media:The Perspective of Proximization Theory

This study takes the reports on China’s“One Belt,One Road”in the British and American media as the object of study,mainly by collecting more than 10,000 words from the relevant reports published in the British media The Times,The Daily Telegraph and The Guardian from 2019-2022,to create a British corpus.A number of US media outlets,such as the New York Times,Los Angeles Times and Washington Post,were also collected to extract over 10,000 words of relevant corpus to create a US corpus.The BFSU Qualitative Coder 1.1,AntConc 3.5.7 and the LLX2 chi-square test were used to analyse the perceptions of the British and American corpora on China’s“One Belt,One Road”initiative,and to explore the temporal,spatial and value convergence of speakers and addressees in the corpus in the context of convergence theory.In this paper,we explore the specific distribution and pragmatic functions of the convergence of speakers and addressees in the corpus,in order to explore and reveal the different features of the application of convergence strategies in the British and American corpora in relation to China’s“One Belt,One Road”initiative.

Theoretical and Practical Exploration of Ideology and Politics in British and American Literature Curriculum

British and American literature is the essence of culture and civilization created in the long historical development process and a bright pearl in the treasure house of world literature.Different types of civilization history,ideological history,and values can better help students understand the literary quality and ideology in various periods of Western civilization.Studying British and American literature aids students in using cross-cultural perspectives to distinguish Chinese and foreign literature and culture.Therefore,the ideological and political tasks of the curriculum are particularly prominent.This research takes a fragment of selected British and American literature as an example to analyze the paths and methods of ideological and political coordination between British and American literature and curriculum,and to explore new ways of educating students in colleges and universities using British and American literature in the new era.

The dry and hot American Southwest under the present and future climates

由于正在持续的特大干旱,更频繁的洪水,热浪以及导致空气污染的山火,美国西南部目前正在经历气候危机.这些气候危机主要与水文气候过程相关,尤其是气候系统各圈层之间的水汽通量.本研究主要讨论目前一些水文系统的科学基站以及物理驱动因素,比如北美夏季风以及太平洋北美遥相关.本研究指出降水以及气温对于干旱的相对作用的理论和工具.确定内部变率和外部强迫对于美国西南部水文气候系统的相对作用尤为重要.展望未来,需要研究高分辨率模拟系统,加强降水以及温度对于水文气候系统相对作用的理解,外部强迫的作用以及通过科学家以及其他利益相关者之间的合作.

区块链产业发展:经济特性与中美路径差异

区块链具有去中心化、可追溯性两大核心特征和不可篡改、去信任化、信息透明、可匿名性四大衍生特征,并进一步引致出能够作用于经济领域的五大经济特性:减少信息不对称、降低组织的集中度、提供可置信的承诺、生成新的价值标的、减少交易成本。区块链是否能与产业良好融合是其能否有效发挥上述重要经济特性的一个重要因素。本文通过对中美区块链行业的对比分析发现,中国对于区块链的应用领域态度更为审慎,同时也具有更强的政策导向,主要应用领域为实体经济;而美国虽然对区块链的政策导向不如中国明显,但其在技术、人才培养等方面都具有显著优势,区块链应用规模在全球范围内处于绝对领先地位。总的来看,中国区块链产业发展面临审慎的金融政策与区块链特征不匹配、结合区块链与实体经济的配套设施相对缺失、区块链适用领域有待细化、区块链技术有待提升等问题。为进一步推动中国区块链产业发展,需要推动央行数字货币发展、加强数字化基础设施建设、针对性推动区块链行业发展、加强区块链技术基础研究。