Search

In the planning stage of the intercity railway network, the ecological sensitivity evaluation of the planning scheme is not only the key content to explore the ecological environmental rationality of the planning scheme but also a scientific means to promote the sustainable development of intercity railway networks. The purpose of this study is to establish an evaluation method that can quantitatively evaluate the ecological sensitivity of intercity railway network planning to put forwards targeted optimization and adjustment suggestions for the planning scheme. Taking the intercity railway network planning of Guizhou Province as an example, its ecological sensitivity is predicted and evaluated. Six types of ecologically sensitive areas were selected as ecological sensitivity evaluation factors, including protected areas, drinking water sources, geological disaster-prone areas, soil erosion areas, cultivated land resource distribution areas and coal resource distribution areas. Based on the GIS overlay method, the quantitative measurement methods of each evaluation factor are established in turn, and the single factor sensitivity evaluation index is obtained. In addition, the weighted superposition model is used to quantitatively calculate the ecological sensitivity of the planned lines of the intercity railway network in Guizhou Province. Finally, the short board factor of each planned line is obtained, and targeted optimization and adjustment suggestions are put forwards. The research content of this paper can provide a theoretical reference for the practical evaluation of the ecological sensitivity of intercity railway network planning.

A new UHMWPE-based conductive fabric was successfully prepared by radiation-induced graft polymerization and subsequent post-modification, followed by electroless deposition. The chemical structure and composition of modified UHMWPE fabrics were investigated in detail by ATR-FTIR, 29Si NMR, and XPS to confirm grafting and post-modification. After electroless deposition, the morphology, thermal stability, and crystal structure of original and modified fabrics were characterized by SEM, TG, DSC and XRD. Cu-deposited UHMWPE fabric exhibited much better thermal resistance than that of UHMWPE and Cu@UHMWPE-g-PAAc. In order to improve the oxidation resistance of copper-deposited fabric, nickel was processed on copper-coated UHMWPE fabric to protect the copper layer. An electromagnetic shielding effect test showed the nickel–copper coated UHMWPE fabric could shield 94.5% of the electromagnetic wave in the frequency range of 8–12 GHz. This work provides an approach for addressing the issue of poor thermal resistance of metal-coated polymeric materials due to the inherent low melting point of the organic support.

Based on Hamilton’s principle, a nonlinear differential equation considering the effect of dead loads is formulated for box beams. By using Galerkin method, the effect of dead load on the natural frequencies of box beams with various restraint conditions being simply supported, fixed at both ends, cantilevered and fixed at one end and simply supported at the other end is studied. The effects of major physical parameters, including the magnitude of dead load, sectional inertia moment and inertia radius, span length, and restraint conditions are discussed, and the natural frequencies are presented for these box beams, with the nonlinear effect of dead load taken into account. The results show that the deterrent effect of dead loads has significant effect on the increase of the natural frequencies of box beams. It is further observed that this behavior is more apparent at lower-order natural frequencies; the varying deterrent effect of dead loads relates to the stiffness of structures and is more significant for more flexible structures.

Herein, we report on fabrication of a highly durable smart mesh with reversible superhydrophobicity-hydrophilicity, using a two-step surface modification and hydrothermal process for on-demand oil-water separation. This wettability of transformation can be achieved under lower voltage within a few seconds than the reported literatures. Such an on-demand operation could be beneficially applied to automated and remote operation of oil-water separation situations, which would be very useful for the treatment of various effluents, including those with low levels of radioactivity. The reversible wettability not only makes our material applicable in both “oil-removing” and “water-removing” situations, with a separation efficiency of 99%, but also effectively prevents the mesh film from being contaminated with oil. The material developed in this work retained its high separation efficiency after 10 alternate-use cycles, involving oil-removing and water-removing modes, and sonication for 20 min, demonstrating its high durability. Our study provides a new pathway to improve the interface binding force between ZnO nanorod arrays and its support without affecting electrowetting performance, thus potentially making a useful contribution to the design of novel devices based on electrowetting-driven oil-water separation.

Sulfate erosion of concrete is a kind of salt erosion which causes great harm to materials. It is also one of the important factors affecting the degradation of carbon fiber reinforced polymer (CFRP)-concrete interface. In this study, the sulfate environment was simulated by the sulfate dry-wet cycle accelerated erosion test. The bonding properties of CFRP-concrete interface under the dry and wet cycle of sulfate were studied by using 18 double-sided shear specimens. The variation trend of interface failure characteristics and interface characteristic values (interfacial shear stress peak and its corresponding slip amount) with sulfate erosion time were analyzed, and the interface bond-slip relationship curves under different erosion times were obtained. Based on the statistical regression analysis of the experimental results, the relationship between the interface ductility parameters and the interface eigenvalues as a function of sulfate erosion time was obtained. Moreover, a bond-slip degradation model of CFRP-concrete interface under the action of sulfate dry-wet cycle was proposed. The model prediction curve agreed well with the experimental curve. Compared with the experimental data, the prediction model can better reflect the trend of the interface bond-slip curve and the degradation pattern of the interface bond performance with the time of sulfate dry-wet cycles.

The bond-slip performance and constitutive model of the interface between reinforcing steel bars and brick masonry are the basis for seismic performance analysis of reinforced masonry through finite element simulation. In this study, the gradual increase of the vertical load in masonry during construction is simulated using a convenient self-developed test setup that ensures that the specimen is under constant pressure based on the actual stress state of horizontal reinforcing steel bars in reinforced brick masonry. Both the vertical compressive stress and the bond length were considered as variables and were used to form 19 groups of specimens. The bond characteristics of reinforcing steel bars were investigated using pull-out tests. The bond-slip curves of the interface between the horizontal reinforcing steel bar and brick masonry were obtained from test data; then, a five-segment bond-slip model that considered the effect of the vertical compressive stress and the bond length on the bond performance is proposed. This study analysed the variation trend of the bond parameters of each feature point influencing the bond performance in the model. The initial bond stiffness of the micro-slip segment increased with the increase in the vertical compressive stress, and the ultimate bond stress increased significantly. The calculation formulas of the bonding parameters are obtained by regression statistics taking these factors into consideration. The predictions obtained from the model show good agreement with test results.

Overhauser proton magnetometer is a scalar instrument for measuring the total magnetic field intensity. Sensitivity, as one of the important specifications, reflects the ability to measure the change of magnetic field when detecting magnetic anomalies. It is very important to study the sensitivity estimation method for accurately evaluating the sensitivity specification of the magnetometer. In this paper, two methods, synchronous measurement method and gradient measurement method, are proposed to estimate the instrument sensitivity. The experimental results show that the lower the external environmental electromagnetic interference is, the more accurate the sensitivity estimation is. Furthermore, when the synchronization accuracy is about 1.7 milliseconds, the estimation results of the synchronization measurement method and the gradient measurement method are almost equal. Finally, in the environment with low electromagnetic interference, the sensitivity estimation of the JOM-4 magnetometers is 0.042 nT@3s.