Behavioral Risk Profile of Men Who Have Sex with Men in Beijing, China： Results from a Cross-sectional Survey with Randomized Response Techniques

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.

Effects of single lance configuration on coal combustion process in tuyere from viewpoint of coal plume

Pulverized coal utilization in the blast furnace is decided by the particle flow and combustion behaviors in the raceway.Under a specific operating condition,these behaviors are directly related to the lance configuration in the upstream tuyere zone.Focusing on single straight lance,six types of single lance configurations were designed by assembling four parameters in different ways.These four parameters are the lance diameter,lance insertion angle,and the horizontal and vertical distances from the lance tip to the tuyere tip.With different lance configuration schemes applied,the pulverized coal combustion process in the lance-blowpipe-tuyere zone was simulated.The simulation results regarding particle diffusion and combustion behaviors were characterized by three indicators from the viewpoint of a coal plume.They are the plume diffusion angle,diffusion uniformity,and the average plume temperature at the tuyere outlet.To promote coal utilization,the values of these indicators under different configurations were analyzed,yielding two optimal configurations.The first one is to reduce the lance length immersed in the blowpipe-tuyere by 100 mm.The other is to increase the horizontal distance from the lance tip to the tuyere outlet by 50 mm,and the insertion angle to 11° with the lance tip located at the tuyere centerline.The findings can enhance the understanding of the influence mechanism of lance con-figuration on the coal utilization and provide guidelines for the design of new lance configurations.