Abstract. The Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme is an international collaborative project focusing on understanding the sources, processes and health effects of air pollution in the Beijing megacity. APHH-Beijing brings together leading China and UK research groups, state-of-the-art infrastructure and air quality models to work on four research themes: (1) sources and emissions of air pollutants; (2) atmospheric processes affecting urban air pollution; (3) air pollution exposure and health impacts; and (4) interventions and solutions. Themes 1 and 2 are closely integrated and support Theme 3, while Themes 1–3 provide scientific data for Theme 4 to develop cost-effective air pollution mitigation solutions. This paper provides an introduction to (i) the rationale of the APHH-Beijing programme and (ii) the measurement and modelling activities performed as part of it. In addition, this paper introduces the meteorology and air quality conditions during two joint intensive field campaigns – a core integration activity in APHH-Beijing. The coordinated campaigns provided observations of the atmospheric chemistry and physics at two sites: (i) the Institute of Atmospheric Physics in central Beijing and (ii) Pinggu in rural Beijing during 10 November–10 December 2016 (winter) and 21 May–22 June 2017 (summer). The campaigns were complemented by numerical modelling and automatic air quality and low-cost sensor observations in the Beijing megacity. In summary, the paper provides background information on the APHH-Beijing programme and sets the scene for more focused papers addressing specific aspects, processes and effects of air pollution in Beijing.

No abstract

Three kinds of nozzles normally used in industrial production are numerically simulated, and the structure of nozzle with the best jetting performance out of the three nozzles is optimized. TheR90 nozzle displays the most optimal jetting properties, including the smooth transition of the nozzle’s inner surface. Simulation results of all sample nozzles in this study show that the helix nozzle ultimately displays the best jetting performance. Jetting velocity magnitude alongYandZcoordinates is not symmetrical for the helix nozzle. Compared to simply changing the jetting angle, revolving the jet issued from the helix nozzle creates a grinding wheel on the cleaning surface, which makes not only an impact effect but also a shearing action on the cleaning object. This particular shearing action improves the cleaning process overall and forms a wider, effective cleaning range, thus obtaining a broader jet width.

Community detection (CD) has become an important research direction for data mining in complex networks. Evolutionary algorithm-based (EA-based) approaches, among many other existing community detection methods, are widely used. However, EA-based approaches are prone to population degradation and local convergence. Developing more efficient evolutionary algorithms thus becomes necessary. In 2013, Cuevas et al. proposed a new differential evolution (DE) hybrid meta-heuristic algorithm based on the simulated cooperative behavior of spiders, known as social spider optimization (SSO). On the basis of improving the SSO algorithm, this paper proposes a community detection algorithm based on differential evolution using social spider optimization (DESSO/CD). In this algorithm, the CD detection process is done by simulating the spider cooperative operators, marriage, and operator selection. The similarity of nodes is defined as local fitness function; the community quality increment is used as a screening criterion for evolutionary operators. Populations are sorted according to their contribution and diversity, making evolution even more different. In the entire process, a random cloud crossover model strategy is used to maintain population diversity. Each generation of the mating radius of the SSO algorithm will be adjusted appropriately according to the iterative times and fitness values. This strategy not only ensures the search space of operators, but also reduces the blindness of exploration. On the other hand, the multi-level, multi-granularity strategy of DESSO/CD can be used to further compensate for resolution limitations and extreme degradation defects based on modular optimization methods. The experimental results demonstrate that the DESSO/CD method could detect the community structure with higher partition accuracy and lower computational cost when compared with existing methods. Since the application of the SSO algorithm in CD research is just beginning, the study is competitive and promising.

Compared with traditional water dyeing, supercritical carbon dioxide (scCO2) dyeing is more environmentally benign. scCO2 is widely used as a green solvent in dyeing synthetic fibers. However, studies involving dyeing natural fibers in scCO2 are scarce. The commonly used methods result in corrosion of the dyeing equipment. Thus, the development of new special dyes suitable for scCO2 dyeing is necessary; in addition, insight into the dyeing mechanism is important in promoting the design and synthesis of dyes for wool fibers in scCO2. On the basis of our previous work, a possible dyeing mechanism in which the dyes exhibit hydrophobic interaction with keratins is proposed. The NN bond twisting in azo dyes promotes the dyes embedding into the spaces of the alpha helices in proteins. According to the proposed mechanism, two new azo disperse dyes (azo thiazole-N­(CH3)2 and azo thiazole-OCH3 ) were synthesized; these dyes enable the dyeing of wool fibers in scCO2. Meanwhile, the introduction of a succinimidyl ester group results in the fixation rate of the new reactive disperse dyes azo thiazole-NHS and azo-NHS reaching 100%. The byproduct of azo thiazole-NHS and azo-NHS reacting with the amino group of wool keratin is not corrosive to the dyeing equipment, thus enabling an eco-friendly dyeing process for wool fibers. Our strategy of introducing a succinimidyl ester reactive group will promote the development of new functional disperse dyes suitable for dyeing wool fibers in scCO2.

The effects of polytetrafluoroethylene (PTFE) on the tensile and tribological properties of carbon fiber-reinforced poly(methyl methacrylate) (PMMA) composites were studied. Tribological tests were conducted on an Amsler friction and wear tester using a block-on-ring arrangement. It was observed that the PTFE played a main role in the tensile-resistant and wear-resistant properties of the PMMA composites. The tensile properties were ruled by the fiber-matrix adhesion. And the excellent tribological performance of the PTFE fillers improved the tribological properties of PMMA composites.

No abstract

No abstract