Abstract. Self-organizing maps (SOMs; a feature-extracting technique based on an unsupervised machine learning algorithm) are used to classify atmospheric boundary layer (ABL) meteorology over Beijing through detecting topological relationships among the 5-year (2013-2017) radiosondebased virtual potential temperature profiles. The classified ABL types are then examined in relation to near-surface pollutant concentrations to understand the modulation effects of the changing ABL meteorology on Beijing's air quality. Nine ABL types (i.e., SOM nodes) are obtained through the SOM classification technique, and each is characterized by distinct dynamic and thermodynamic conditions. In general, the selforganized ABL types are able to distinguish between high and low loadings of near-surface pollutants. The average concentrations of PM 2.5 , NO 2 and CO dramatically increased from the near neutral (i.e., Node 1) to strong stable conditions (i.e., Node 9) during all seasons except for summer. Since extremely strong stability can isolate the near-surface observations from the influence of elevated SO 2 pollution layers, the highest average SO 2 concentrations are typically observed in Node 3 (a layer with strong stability in the upper ABL) rather than Node 9. In contrast, near-surface O 3 shows an opposite dependence on atmospheric stability, with the lowest average concentration in Node 9. Analysis of three typical pollution months (i.e., January 2013, December 2015 and December 2016 suggests that the ABL types are the primary drivers of day-to-day variations in Beijing's air quality. Assuming a fixed relationship between ABL type and PM 2.5 loading for different years, the relative (absolute) contributions of the ABL anomaly to elevated PM 2.5 levels are estimated to be

The service time of a single bus line is divided into some time periods according to passenger flow intensity; it is supposed that passengers arrive evenly at the stop and bus runs are set evenly in each time period. The bus timetable setting problem is to determine bus run assignments in each time period to minimise the total waiting time of passengers on platforms if the number of total runs is known. This is a typical time-continuous multi-stage decision problem, and the dynamic programming method is appropriate to solve it. Global optimisation procedures using dynamic programming are developed to solve such a multi-stage decision problem. A numerical example is given to demonstrate the efficiency of the proposed method.

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16Self-organizing maps (SOMs; a feather-extracting technique based on an unsupervised machine learning 17 algorithm) are used to classify the atmospheric boundary layer (ABL) types over Beijing by detecting topological 18 relationships among the 4-yr (2013-2016) radiosonde profiles. The resulting ABL types are then examined in 19 relation to air quality, including surface pollutant concentrations and columnar aerosol properties, to understand 20 the regulating effects of different ABL structures on Beijing's air quality. The SOM provides nine ABL types (i.e., 21 SOM nodes), and each type is characterized by distinct dynamic and thermodynamic conditions. On average, SO 2, 22 NO 2 , CO, PM 10 and PM 2.5 increase 120-220 % from a near neutral (i.e., node 1) to strong stable condition (i.e., 23 node 9). The ABL controls on diurnal cycles of pollutants are as follows: (1) elevated inversion enhances the 24 afternoon baseline; and (2) surface inversion improves the evening increment. Comparing the CO/SO 2 ratios for 25 the different ABL types demonstrates that the local contribution increases with enhanced static stability near the 26 ground, and it is the stable ABL stratification rather than weak surface wind that confines the regional contribution.

In the current period when the highway industry is accelerating the improvement of infrastructure construction and implementing new development concepts, the construction of green service area is an important part of promoting the high-quality development of highway transportation infrastructure. Based on the study of the connotation of the green service area, in order to provide experience and reference for its construction and transformation, this article put forward the content of the construction of green service area, and further combined the comprehensive survey of service areas of a certain province in central China, analysed and summarized current situation of green construction technologies from aspects of location and land use, buildings, environmental protection facilities, and renewable energy utilization.

The selection of wastewater treatment technology in service area should be adapted to the features of the wastewater quality and quantity. Also, the construction investment, the operating energy consumption, and the system simplicity should be considered as the demands of highway service area construction and maintenance. Based on investigations, this article analyzed the limitations of conventional treatment processes currently represented by contact oxidation. Evaluation and discussion for typical applicable processes were conducted from aspects of low energy consumption, treatment and discharge in cold regions, and reclaim water reuse.

In view of the lack of coordination or guidance of green road concept and relevant evaluation to encourage sustainability, we redefined the concept of green road and its characteristics, and then reviewed some cross-sector targets of various departments related to green development. The history of green road related policies and studies were reviewed, and a green road evaluation indices system were established with 2 broad categories-compulsory and selective. The compulsory category contains 8 indices; and the selective category includes 76 indices, which are divided into 7 categories and 31 subcategories, covering design, construction and operation. In order to improve the evaluation continually, rating principles, grading methods and main reference literature were given. Then we selected 30 indices and design in a questionnaire to trial evaluation, and 11 projects of Hubei province were collected and used for analysis. Finally, based on the longterm and complexity of the evaluation system, we suggest some key improving strategies of green road evaluation in China. The establishment of the green road system is an attempt to bridge the requirements of different departments, and to stimulate the progressing technology to meet various challenges., 0 Web of Conferences https://doi.org/10.

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