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As classical traffic noise prediction models lack a deeper consideration of the impact of the gradient, the characteristics of longitudinal gradients from multiple roads were collected as data in the mountain city of Chongqing county, which was chosen as the entry point, to study the noise characteristics for a wide range of road gradients and to build a traffic noise prediction model based on artificial neural networks (ANNs). The field data consisted of traffic volumes, heavy-vehicle ratios, average vehicle speeds, road gradients, and corresponding equivalent sound pressure levels. An optimal ANN model was determined and compared with two classical models. The results demonstrated that a one-hidden-layer ANN model was suitable for traffic noise prediction in mountain cities and presented better predictive performance than the conventional models. The best-performing ANN model yielded a determination coefficient of 0.9447 and a mean-squared error of 0.2708 dBA. Moreover, this study confirmed that road gradients were significant for constructing traffic noise prediction models.

Objective: To investigate the status of iron deficiency and the rate of anemia of 3 - 11 year-old children in Chinese cities and countryside and explore the possible related influencing factors., Methods: The multistage stratified cluster random sampling was used to select one kindergarten and one primary school in seven cities (Beijing, Shenyang, Suzhou, Zhengzhou, Chengdu, Lenzhou and Guangzhou) and two countryside randomly in Hebei Province one bottom class, middle class, top class in one kindergarten and one second grade and fifth grade in one primary school were selected randomly. All of the healthful students of these classes were investigated and the element iron and the parameters of red blood cell were detected., Results: 1863 students in 7 cities and 2 countryside were investigated in the research. The incidence of iron deficiency of different ages had statistical significance and with the age increasing, the incidence showed a decreasing trend. The incidences of iron deficiency were 47.1% and 38.2% in 3 -4 year-old children and 4 - 5 year-old children, respectively. The incidence of anemia of different ages had statistical significance. The incidences of anemia of 3 - 4 year-old children and 4 -5 year-old children were significantly higher than those of 5 - 6 year-old children. The incidences of anemia were 4.0% and 7.1% in 3 - 4 year-old children and 4 -5 year-old children, respectively. No statistical significance for different sex of the same age was found for iron deficiency and anemia incidence. The incidence (12%) of anemia of the children in countryside area was significantly higher than those in first-tier cities and second-tier cities., Conclusion: The status of iron deficiency and the rate of anemia of 3 - 11 year-old children in Chinese cities and countryside were improved recently, but still serious. It should be paid more attention to the children with lower serum iron content and the children in rural areas.