This paper investigates the random responses of a TDOF structure with strongly nonlinear coupling and parametric vibration. With the nonlinear cou- pling of inertia in the equations of motion of the system being remov...This paper investigates the random responses of a TDOF structure with strongly nonlinear coupling and parametric vibration. With the nonlinear cou- pling of inertia in the equations of motion of the system being removed by successive elimination, the non-Gaussian moment equation method (NGM) is applied and 69 moment equations are integrated with central cumulative truncation technique. The stochastic central difference-cum-statistical linearization method(SCD-SL) and the digital simulation method(DSM) are also used. A comparison of results by different methods are given and the SCD-SL method is the most efficient method.展开更多
Background：Human immunodeficiency virus （HIV） is spreading rapidly among men who have sex with men （MSM） in China.Anonymous questionnaires or direct interviews have been frequently used to study their behavior.Th...Background：Human immunodeficiency virus （HIV） is spreading rapidly among men who have sex with men （MSM） in China.Anonymous questionnaires or direct interviews have been frequently used to study their behavior.The aim of the study was to describe the behavioral risk profile of the MSM in Beijing using the randomized response techniques （RRTs）.Methods：A cross-sectional survey of sexual behavior among a sample of MSM was conducted in two HIV counseling and testing clinics in Beijing.The survey was carried out with an anonymous questionnaire containing sensitive questions on sexual behavior.To obtain the honest responses to the sensitive questions,three distinctive RRTs were used in the questionnaire：（1） Additive randomized response model for quantitative questions,（2） randomized response model for multiple choice questions,and （3） Simmons randomized response model for binomial questions.Formulae for the point estimate,variance,and confidence interval （CI） were provided for each specific model.Results：Using RRTs in a sample of 659 participants,the mean age at first homosexual encounter was estimated to be 21.7 years （95% CI：21.2-22.2）,and each had sex with about three （2.9,95% CI：2.4-3.4） male partners on average in the past month.The estimated rate for consistent condom use was 56.4% （95% CI：50.1-62.8%）.In addition,condom was estimated to be used among 80.0% （95% CI：74.1-85.9%） of the population during last anal sex with a male partner.Conclusions：Our study employed RRTs in a survey containing questions on sexual behavior among MSM,and the results showed that RRT might be a useful tool to obtain truthful feedback on sensitive information such as sexual behavior from the respondents,especially in traditional Chinese cultural settings.展开更多
Obtaining correct responses to sensitive questions in social and behavioural researches is an ancient problem in survey research with respondents misreporting on sensitive behaviours or giving false response to protec...Obtaining correct responses to sensitive questions in social and behavioural researches is an ancient problem in survey research with respondents misreporting on sensitive behaviours or giving false response to protect themselves.This paper develops an alternative unbiased estimator by modifying the dichotomous randomized response technique model to tackle this problem.The proposed estimatorwas compared numerically with conventional ones by considering different practicable and suitable design choices.Proposed model was also considered when sampling with unequal probabilities with or without replacement.It was observed that the proposed estimator performs efficiently than the conventional ones.As the proposed model captures progressively more people involved in the sensitive attribute,the model outperforms other models considered.Therefore,social and behavioural researchers can now obtain correct and valid responses from sensitive behavioural researches with ease in order to make informed and reliable decisions.展开更多
Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-respon...Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-response.In this paper,we extend their idea to the simultaneous estimation of two means by making use of the forced quantitative randomized response model of Gjestvang and Singh(Metrika 66(2):243-257,2007)but then re-scrambling the scrambled scores.This idea of re-scrambling already scrambled responses seems completely new in the field of randomized response sampling.The performance of the proposed forced quantitative randomized response model has been investigated analytically as well as empirically.展开更多
In view of the feature of flight flutter test data with atmospheric turbulence excitation, a method which combines wavelet transformation with random decrement technique for identifying flight flutter modal parameters...In view of the feature of flight flutter test data with atmospheric turbulence excitation, a method which combines wavelet transformation with random decrement technique for identifying flight flutter modal parameters is presented. This approach firstly uses random decrement technique to gain free decays corresponding to the acceleration response of the structure to some non-zero initial conditions. Then the continuous Morlet wavelet transformation of the free decays is performed; and the Parseval formula and residue theorem are used to simplify the transformation. The maximal wavelet transformation coefficients in different scales are searched out by means of band-filtering characteristic of Morlet wavelet, and then the modal parameters are identified according to the relationships with maximal modulus and angle of the wavelet transform. In addition, the condition of modal uncoupling is discussed according to variation trend of flight flutter modal parameters in the flight flutter state. The analysis results of simulation and flight flutter test data show that this approach is not only simple, effective and feasible, but also having good noise immunity.展开更多
基金The project supported by National Natural Science Foundation of China
文摘This paper investigates the random responses of a TDOF structure with strongly nonlinear coupling and parametric vibration. With the nonlinear cou- pling of inertia in the equations of motion of the system being removed by successive elimination, the non-Gaussian moment equation method (NGM) is applied and 69 moment equations are integrated with central cumulative truncation technique. The stochastic central difference-cum-statistical linearization method(SCD-SL) and the digital simulation method(DSM) are also used. A comparison of results by different methods are given and the SCD-SL method is the most efficient method.
基金the National Natural Science Foundation of China，the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions
文摘Background：Human immunodeficiency virus （HIV） is spreading rapidly among men who have sex with men （MSM） in China.Anonymous questionnaires or direct interviews have been frequently used to study their behavior.The aim of the study was to describe the behavioral risk profile of the MSM in Beijing using the randomized response techniques （RRTs）.Methods：A cross-sectional survey of sexual behavior among a sample of MSM was conducted in two HIV counseling and testing clinics in Beijing.The survey was carried out with an anonymous questionnaire containing sensitive questions on sexual behavior.To obtain the honest responses to the sensitive questions,three distinctive RRTs were used in the questionnaire：（1） Additive randomized response model for quantitative questions,（2） randomized response model for multiple choice questions,and （3） Simmons randomized response model for binomial questions.Formulae for the point estimate,variance,and confidence interval （CI） were provided for each specific model.Results：Using RRTs in a sample of 659 participants,the mean age at first homosexual encounter was estimated to be 21.7 years （95% CI：21.2-22.2）,and each had sex with about three （2.9,95% CI：2.4-3.4） male partners on average in the past month.The estimated rate for consistent condom use was 56.4% （95% CI：50.1-62.8%）.In addition,condom was estimated to be used among 80.0% （95% CI：74.1-85.9%） of the population during last anal sex with a male partner.Conclusions：Our study employed RRTs in a survey containing questions on sexual behavior among MSM,and the results showed that RRT might be a useful tool to obtain truthful feedback on sensitive information such as sexual behavior from the respondents,especially in traditional Chinese cultural settings.
文摘Obtaining correct responses to sensitive questions in social and behavioural researches is an ancient problem in survey research with respondents misreporting on sensitive behaviours or giving false response to protect themselves.This paper develops an alternative unbiased estimator by modifying the dichotomous randomized response technique model to tackle this problem.The proposed estimatorwas compared numerically with conventional ones by considering different practicable and suitable design choices.Proposed model was also considered when sampling with unequal probabilities with or without replacement.It was observed that the proposed estimator performs efficiently than the conventional ones.As the proposed model captures progressively more people involved in the sensitive attribute,the model outperforms other models considered.Therefore,social and behavioural researchers can now obtain correct and valid responses from sensitive behavioural researches with ease in order to make informed and reliable decisions.
文摘Recently,Ahmed et al.(Commun Stat Theory Methods 47(2):324-343,2018)have introduced the idea of simultaneously estimating means of two sensitive variables by collecting one scrambled response and another pseudo-response.In this paper,we extend their idea to the simultaneous estimation of two means by making use of the forced quantitative randomized response model of Gjestvang and Singh(Metrika 66(2):243-257,2007)but then re-scrambling the scrambled scores.This idea of re-scrambling already scrambled responses seems completely new in the field of randomized response sampling.The performance of the proposed forced quantitative randomized response model has been investigated analytically as well as empirically.
基金National Natural Science Foundation of China(60134010)
文摘In view of the feature of flight flutter test data with atmospheric turbulence excitation, a method which combines wavelet transformation with random decrement technique for identifying flight flutter modal parameters is presented. This approach firstly uses random decrement technique to gain free decays corresponding to the acceleration response of the structure to some non-zero initial conditions. Then the continuous Morlet wavelet transformation of the free decays is performed; and the Parseval formula and residue theorem are used to simplify the transformation. The maximal wavelet transformation coefficients in different scales are searched out by means of band-filtering characteristic of Morlet wavelet, and then the modal parameters are identified according to the relationships with maximal modulus and angle of the wavelet transform. In addition, the condition of modal uncoupling is discussed according to variation trend of flight flutter modal parameters in the flight flutter state. The analysis results of simulation and flight flutter test data show that this approach is not only simple, effective and feasible, but also having good noise immunity.
