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Objective Cancer Hospital Station on Shenzhen Rail Transit Line 14 adopts a scheme of large-diameter (8.5 m) shield tunnel expansion featuring tunnel-first and station-later. During the connection of the main station structure and auxiliary entrances in underground excavation, the construction of large local openings in tunnel lining is required. To ensure the structural safety during tunnel opening construction, it is necessary to study the mechanical behavior of urban rail transit station structure based on existing shield tunnel interval underground excavation. Method To simulate the station underground excavation process under various working conditions, a multi-ring shell-rigid beam-contact lining calculation model considering the effects of lining structure circumferential and longitudinal joints is adopted. The scenarios include full-opening lining ring control condition (opening condition) and half-opening lining ring control condition (support removal condition). Key design parameters, such as the position of capping block, the forms of internal support, and the dimension of tunnel longitudinal opening, are analyzed for their impact on station structure. Result & Conclusion Based on the stress characteristics of ring beams, it is recommended to use steel or embedded steel components for the upper and lower ring beams in the design. It is recommended that the arrangement of through-joint assembled segments in the opening area should be adopted according to segment stress characteristics, and the capping block of tunnel opening section through-joint assembled segments be designed at the tunnel top for Cancer Hospital Station. The bending moment distribution of opening lining ring segments throughout construction process is closely related to the effective constraint points of internal supports, and the premise of internal supports forming effective constraint is a complete axial force transmission path. The integrity of opening lining ring structure is contingent upon the lateral constraints of circumferential joints during the local tunnel opening construction.

In order to realize the reliable unlocking of solar arrays of a CubeSat under the strict constraints of space and power dissipation, a shape memory alloy(SMA) wire linear actuation unlocking mechanism is developed. Through using a spring-SMA structure, relying on the spring force locking, heating the SMA wire and producing a recovery stress drive pin movement, the solar arrays are unlocked. The mathematical model of the unlocking mechanism is established, and the relationship among stroke, unlocking time, power, alloy wire diameter and working voltage of the SMA unlocking mechanism is obtained through simulation. In order to optimize its overall unlocking time and power, the particle swarm optimization algorithm is used to optimize the diameter and working voltage of the alloy wire. The simulation results show that the SMA unlocking mechanism with the wire whose diameter is 0.5 mm has the best working performance when the driving voltage is 1.2 V. Finally, the experimental study of the design results shows that the unlocking time of the actuation unlocking mechanism is 3.2 s, its power is 3.55 W and that its pin-pulling stroke is 1.8 mm, being consistent with the simulation results. The unlocking mechanism has a high reliability, consistent working performance and good adaptability, therefore having passed various environmental tests and being successfully applied to a CubeSat in orbit.

Influence of nano-strengthening immersion on the properties of recycled aggregate (RA) and recycled aggregate concrete (RAC) and the microstructure of interfacial transition zones (ITZs) between mortar and aggregate were studied in this paper. Results showed that nano-strengthening immersion was helpful to reduce the crushing value and total pore area of RA, to significantly improve the mechanical strength of RAC, and to modify the bond strength between RAC and steel rebar and the structural properties of RAC beams. Mercury intrusion porosimetry (MIP), micro-hardness (MH) and scanning electron microscope (SEM) observation were conducted in order to reveal the enhancement mechanism of nano-strengthening immersion. Results showed that the density and mechanical properties in ITZs were obviously improved by nano-strengthening because the coating and penetration of nano-materials was helpful to block the pores and cracks in ITZs, to avoid the directed gathering of CH crystal, and to accelerate the hydration of cement and mineral additions.

The time-dependent interfacial adhesion between rock and fresh mortar is key for printing concrete linings in mountain tunnels. However, a scientific deficit exists in the time-dependent evolution of the interfacial adhesion, which can cause adhesion failure when printing tunnel lining. Nanoclay has the potential to increase the interfacial adhesion and eliminate the adhesion failure. Before the actual printing of tunnel linings, the time-dependent interfacial adhesion between artificial rock and fresh mortar modified by nanoclay should be understood. This paper studied the time-dependent interfacial adhesion based on fast tack tests, fast shear tests, and isothermal calorimetry tests. With the addition of nanoclay, the maximum tensile stress and the maximum shear stress increased. Compared with a reference series, the maximum interfacial tensile stress in a 0.3% nanoclay series increased by 106% (resting time 1 min) and increased by 209% (resting time 32 min). A two-stage evolution of the interfacial adhesion was found with the addition of nanoclay. In the first stage, the time-dependent interfacial adhesion increased rapidly. A 0.3% NC series showed an increase rate six times higher than that of the reference series. As the matrices aged, the increase rate slowed down and followed a linear pattern of increase, still higher than that of the reference series. The stiffening of fresh matrices resulted in the interface failure mode transition from a ductile failure to a brittle failure. The effect of nanoclay on flocculation and on accelerating the hydration contributed to the time-dependent interfacial adhesion between artificial rock and fresh mortar. [ABSTRACT FROM AUTHOR]

The widespread use of artificial light at night (ALAN) due to urbanization and infrastructure development has raised concerns about its potential impacts on plant physiology. To explore the effects of ALAN with different light intensities on the photosynthesis and respiration of two urban vascular plants, Euonymus japonicus Thunb and Rosa hybrida E.H.L.Krause, under continuous and non-continuous-light conditions, respectively, a field experiment was conducted. Our findings indicate that continuous ALAN significantly inhibited the photosynthesis and respiration of the two plants, disrupting the carbon-balance pattern of their leaves during the day, but this effect is influenced by the intensity of ALAN and plant species. Euonymus japonicus Thunb is more susceptible to continuous ALAN than Rosa hybrida E.H.L.Kraus. Non-continuous ALAN did not significantly affect the photosynthesis and respiration of two species during the day. Furthermore, we observed that high light intensity at night could also impact the value of the net photosynthetic rate (Pn) of Euonymus japonicus Thunb during the night. Turning off light sources at night, reducing the light intensity, and cultivating ALAN-tolerant plants are effective measures to reduce the negative effects of ALAN on plants and maintain plants' normal carbon-balance mode. Future studies should explore the effects of different types of artificial-light sources combined with other environmental conditions on the photosynthesis and respiration of plants at the canopy scale. [ABSTRACT FROM AUTHOR]

Some insects possess corrugated wings, which distinguish from the ordinary airfoils. It is important to research the corrugation effect on the aerodynamic performances. A series of corrugated wing models were designed based on former research in represent study to find out the underlying mechanisms. The effects of the corrugation pattern and inclination angle were studied using computational fluid dynamic (CFD) method during hovering flight at Reynolds numbers in the order of 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided. The findings are as follows: (1) the results of this paper show that patterns of corrugation have different effect on aerodynamic performances. The corrugated wing like Corrug-1 changes the lift and drag very slightly compared with a flat-plate. The corrugation patterns like Corrug-2 and 3 of wing model reduce the lift and drag force. (2) the increase in the inclination angle has limited effect the aerodynamic forces. The inclination angles like corrug-3 and 4 produce almost the same forces.

Air‐stable layered structured cathodes with high voltage and good cycling stability are highly desired for the practical application of Na‐ion batteries. Herein, we report a P2‐Na2/3Ni2/3Te1/3O2 cathode that is stable in ambient air with an average operating voltage of ~3.8 V, demonstrating excellent cycling stability with a capacity retention of more than 92.7% after 500 cycles at 20 mA g−1 and good rate capability with 91.9% capacity utilization at 500 mA g−1 with respect to capacity at 5 mA g−1 between 2.0 and 4.0 V. When the upper cutoff voltage is increased to 4.4 V, P2‐Na2/3Ni2/3Te1/3O2 delivers a reversible capacity of 71.9 mAh g−1 and retains 91.8% of the capacity after 100 cycles at 20 mA g−1. The charge compensation during charge/discharge is mainly due to the redox couple of Ni2+/Ni3+ in the host with a small amount of contribution from oxygen. The stable structure of the material without phase transformation and with small volume change during charge‐discharge allows it to give excellent cycle performance especially when the upper cutoff voltage is not higher than 4.2 V. [ABSTRACT FROM AUTHOR]