Search

Utilizing panel data pertaining to green building across 333 prefecture-level administrative units in China (excluding Hong Kong, Macao, and Taiwan) during the period spanning 2008–2020, an exhaustive examination of the evolution of China's spatial pattern in green building is conducted employing the nearest neighbor index method, spatial autocorrelation analysis method, and kernel density analysis method. Furthermore, geographic probes are employed to scrutinize the determinants influencing China's spatial configuration of green buildings. The findings reveal that: (1) An alteration in the density distribution from a "unipolar nucleus and double sub-nuclei" configuration to a "triple polar nuclei and multiple sub-nuclei" manifestation has been discerned in the spatial agglomeration of green buildings in China, exhibiting annual growth. Additionally, the center of green building development has shifted from the northwest to the southwest. (2) Pronounced agglomerations are predominantly situated in the eastern, central, and western regions of the country. High-high agglomerations have gradually dissipated over time in the central provincial capitals of China, the Yangtze River Delta, the Pearl River Delta, and the city clusters of Beijing-Tianjin-Hebei along the eastern seaboard. The western regions manifest a concentration of low-low and low-high aggregates, with high-low agglomeration primarily observed in the provincial capitals of the western regions. (3) The spatial differentiation of green buildings in China is attributable to a multitude of variables encompassing the environment, economy, society, and policies. Among these factors, economic, social, and innovative elements exert the most significant influence on the explicable degree of spatial differentiation. [ABSTRACT FROM AUTHOR]

Self-excited oscillations of flags attached at the leading edge of aerofoils have been investigated at post-stall angles of attack at a chord Reynolds number of 100 000. Significant increases in the time-averaged lift coefficient and stall angle have been observed for three aerofoils: one symmetric, one cambered and one with a sharp leading edge. The aerodynamic improvement is due to the periodic formation of vortices caused by the flag oscillations. When the flag is near the aerofoil surface, it is lifted upwards by the induced velocity of the growing vortex. As the flag moves up, the vortex grows in strength and reaches maximum circulation when the flag is furthest from the aerofoil surface and subsequently sheds. Flags with large stiffness exhibit better spatial and temporal coherence of flag oscillations than the compliant flags, resulting in a larger maximum lift coefficient and higher stall angle. For all aerofoils tested, the best lift enhancement with respect to the clean aerofoils is found when the angle of attack is 6° to 10° above the stall angle of the clean aerofoil. High lift is observed when the flags are locked in with the wake instability in a narrow frequency band, depending on the flag mass ratio and length. [ABSTRACT FROM AUTHOR]

Hand, foot and mouth disease (HFMD) is a susceptible viral infectious disease to infants and children, which led to millions of cases and hundreds of deaths annually in China. Existing predictive methods commonly learn the development patterns from historical observations. However, almost all these methods are neglect the immediate impact of exogenous factors on HFMD transmission. To solve the limitation, we consider the approximately unidirectional influences from temperature to confirmed cases and then propose a transfer one-step-ahead learning (Tr-OSH) method to establish their association. The Tr-OSH method first extract the unidirectional representation from temperature observations, and subsequently transfer the obtained representation for HFMD cases prediction. Moreover, we notice the independent correlation of each time step and period, and generate the independent representation by the relevance to upcoming values. Intensive experiments on real-world HFMD datasets demonstrate that our Tr-OSH method much efficaciously improves prediction accuracy. [ABSTRACT FROM AUTHOR]

During the flight mission of hypersonic aircraft, severe aerodynamic heating will occur on the surface, so thermal protection system (TPS) is required to protect the load-bearing structure of the aircraft. The present paper develops an engineering software for automatic optimization of the thickness of tile-type TPS for reusable aircraft. For requirements on TPS of reusable aircraft in the reentry stage, the method of heat flow-time curve enveloping, automatic material selection, and one-dimensional unsteady heat transfer calculation for multilayer plates under thermal load conditions had been researched, an interactive engineering software had been developed. The software improves the calculation accuracy and calculation efficiency of TPS thickness optimization, and it is suitable for rapid design in the conceptual design stage of the aircraft. Finally, by an example, the function of the software is verified. [ABSTRACT FROM AUTHOR]

A folded core is a three-dimensional configuration formed by folding a flat sheet of paper. Similar to foam and honeycomb, folded cores are widely used in aerospace as the cores for sandwich structures due to their excellent mechanical properties and light structural weight. In general, the core's configuration is heterogeneous and anisotropic, while from a macroscopic point of view it is considered homogeneous. Analytical solutions of equivalent mechanical properties are generally obtained by equivalent methods and modified by numerical simulations due to the complexity of the configuration. We can find the best combination of a core's parameters by using analytical solutions. The faceted regular folded configuration (RFC), consisting of repetitive identical cells, can be expanded to a plane. According to the principle of equivalent load-deformation, this article investigates the equivalent mechanical properties of the V-type folded core (VFC). The analytical solutions of Ez—equivalent elastic modulus in Direction z, equivalent shear modulus in Plane xz—Gxz, and equivalent shear modulus in Plane yz—Gyz have been obtained and verified by numerical simulations. In addition, the reliability of the equivalent mechanical properties is further demonstrated by the case study. By applying the analytical solutions, the optimization process of VFC can be simplified and sped up, which is of great engineering significance to the aircraft design process. [ABSTRACT FROM AUTHOR]

The effects of unsteady trailing-edge blowing on delta wing aerodynamics were investigated experimentally to understand the aerodynamics--propulsion interaction for dynamic thrust vectoring. Two models with sweep angles of [LAMBDA] = 50 and 65 deg, representing nonslender and slender delta wings, respectively, were tested in a water tunnel. Flow visualization and velocity and force measurements were conducted at stall and poststall incidences. For the periodic blowing, it was found that the dynamic response of leading-edge vortex breakdown and wing normal force coefficient exhibit phase lags for both nonslender and slender delta wings. The estimated time constants are larger than those reported in the literature for unsteady wings undergoing pitching or plunging. In the case of transient blowing, the time delay for the decelerating jet is significantly larger than that for the accelerating jet. The variation of the circulation and the reattachment process near the wing surface were studied by means of velocity measurements. The range of the estimated time constants is similar at the stall and poststall incidences for both the slender and nonslender wings. DOI: 10.2514/1.45890