RESUMEN
In the work, four new Sb-based phosphates, K4 (SbO2 )5 (PO4 )3 , Rb(SbO2 )2 PO4 , Rb3 (SbO2 )3 (PO4 )2 and Cs3 (SbO2 )3 (PO4 )2 (H2 O)1.32 , were successfully synthesized by a high-temperature melt method. Among them, Rb(SbO2 )2 PO4 and Rb3 (SbO2 )3 (PO4 )2 are the first reported examples of Rb-containing alkali metal Sb-based phosphates. They show three-dimensional (3D) frameworks composed of [Sb8 P4 O30 ]∞ layer for K4 (SbO2 )5 (PO4 )3 and [Sb6 P2 O20 ]∞ layer for Rb(SbO2 )2 PO4 , and 2D lamellar structure composed of [Sb3 P2 O10 ]∞ for Rb3 (SbO2 )3 (PO4 )2 and Cs3 (SbO2 )3 (PO4 )2 (H2 O)1.32 . A detailed structural comparison shows that the structure dimensions for them transfer from 1D to complex 3D framework with the increase of (Sb+P)/O ratio, which affects performances of the compounds. Optical property and energy band structure calculations were also carried out based on the density functional theory (DFT). The present study enriches the diversity of Sb-based phosphates and paves the way for further explore their optical properties in the future.
RESUMEN
When there is not enough scientific knowledge to assume a particular regression model, sufficient dimension reduction is a flexible yet parsimonious nonparametric framework to study how covariates are associated with an outcome. We propose a novel estimator of low-dimensional composite scores, which can summarize the contribution of covariates on a right-censored survival outcome. The proposed estimator determines the degree of dimension reduction adaptively from data; it estimates the structural dimension, the central subspace and a rate-optimal smoothing bandwidth parameter simultaneously from a single criterion. The methodology is formulated in a counting process framework. Further, the estimation is free of the inverse probability weighting employed in existing methods, which often leads to instability in small samples. We derive the large sample properties for the estimated central subspace with data-adaptive structural dimension and bandwidth. The estimation can be easily implemented by a forward selection algorithm, and this implementation is justified by asymptotic convexity of the criterion in working dimensions. Numerical simulations and two real examples are given to illustrate the proposed method.
RESUMEN
How to raise the bridge barrier with a concrete base height of only 51 cm to SS level of protection is not yet studied. In order to effectively retrofit an existing concrete barrier design to meet new crash testing criteria, the structural dimensions and concrete strength of the existing bridge barrier were investigated, and finite element simulation analysis was carried out, and simulation suggested the existing barrier was insufficient. Based on the structural dimension design principles of bridge barriers, the existing structure of bridge barrier was designed after adding lightweight and high-strength B750HL material crossbeams and posts on top of the concrete base, and the bearing capacity of the bridge barrier was calculated based on the yield line theory. Then, a finite element simulation analysis model was established to study and analyze the blocking, guiding, and cushioning functions of the improved design of bridge barrier. Finally, full-scale-vehicle crash tests were conducted with the SS-level small car, bus, and tractor-van trailer for this bridge barrier design scheme. This paper is the world's first to use B750HL steel as the material for the crossbeam and post of a bridge barrier with a concrete base height of only 51 cm. According to the research results, the B750HL bridge barrier, which was designed based on the calculation of structural dimension design and yield line theory, effectively reduces the increased constant load on the bridge deck caused by the extra crossbeams and posts. At the same time, it can reduce material costs and save engineering costs. After being verified by finite element simulation crash tests and full-scale-vehicle crash tests, the protective capacity of the B750HL bridge barrier was proven to meet the SS-level evaluation requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). The research findings of this paper is that the finite element simulation crash tests can effectively simulate full-scale-vehicle crash test, and the finite element simulation crash tests is reliable. If the safety performance of the barrier in the finite element simulation crash tests meets the requirements, the probability of passing the full-scale-vehicle crash test is higher. Therefore, a design scheme is proposed for the B750HL bridge barrier to improve hybrid bridge barriers at a height of 51 cm or more based on various design methods.