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Highlights • Statistics of ridge-valley membrane structures were completed to obtain main structure form and geometric parameters. • Wind tunnel experiments based on the statistics were conducted. • Influences on wind pressure of wind direction, rise-span ratio, eave height, and terrain roughness were analysed. • Wind pressure coefficients of zone for the main wind-force resisting system and the cladding were obtained respectively. • A zoning method for wind pressure based on clustering analysis was tried out and showed its good applicability. Abstract In this study, we aim to investigate the wind pressure acting on ridge-valley tensile membrane structures through wind tunnel experiments. The experimental models were designed according to the statistics of practical engineering projects. Wind tunnel experiments were performed to investigate the effects of wind direction, rise-span ratio, eaves height and terrain roughness. The closed and open structures were both considered. The wind force coefficients were determined experimentally to analyse the mean wind pressure on the entire roof. Subsequently, the mean wind pressure coefficients were obtained to analyse the mean wind pressure distribution. Results show that the mean wind pressure is highly affected by wind direction and rise-span ratio. The terrain roughness exhibits a mild influence on the mean wind pressure, whereas the eaves height exhibits minimal influence. Additionally, the peak wind pressure coefficients were calculated to evaluate the effects of wind direction and rise-span ratio. Clustering analysis was performed to establish a zoning method of wind pressure, which has been proven reliable. Accordingly, the corresponding wind pressure coefficients of zone for the main wind-force resisting system and for the cladding were suggested. The outcomes of the wind pressure analysis, wind pressure coefficient of zone and zoning method for this type of structures are expected to be useful to engineers and researchers. [ABSTRACT FROM AUTHOR]

The magnetic effect on soot properties in ethylene inverse diffusion flames (IDF) was investigated in this study. The investigation involved the use of high-resolution transmission electron microscopy analysis (HRTEM), Raman spectroscopy analysis, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectroscopy (XRD) to examine the nanostructure and graphitization degree of soot collected from flame exhaust gas at various height above burner surface (HAB) under both magnetic and non-magnetic conditions. Increasing the magnetic flux density resulted in modifications to soot properties. When the sampling height was HAB = 4 cm, increasing magnetic flux density resulted in longer fringe lengths, lower fringe tortuosity, less amorphous carbon content and surface oxygen content for the collected soot from flame exhaust gas. These results indicated higher graphitization degrees, which may be attributed to longer residence time and oxidation of soot particle in flames. Moreover, when the sampling height increased from HAB = 4 cm to 6 cm under non-magnetic condition, the nanostructure of soot in the flame exhaust gas was more organized, possible due to the oxidation of soot at the region between HAB = 4 and 6 cm region. However, with the magnetic field on, the crystalline structure of soot in the flame exhaust gas became increasingly disordered as the sampling height increased. This suggested that the soot may also be affected by the magnetic effects in addition to oxidation at the region between HAB = 4 and 6 cm region. The magnetic effect could trigger the transformation of graphitic carbon to amorphous carbon in soot particles as they passed through the magnetic field. With more elaborated magnetic fields, the magnetic effect on soot could contribute to strategies controlling soot emissions and removal. [ABSTRACT FROM AUTHOR]