福清核电厂基于堆外核仪表系统中间量程测量的动态刻棒试验

通过分析堆外核仪表系统的功率量程和中间量程的性能，使用堆外核仪表中间量程的测量信号进行动态刻棒试验数据验证。验证结果表明，基于堆外核仪表系统中间量程的动态刻棒试验可作为传统动态刻棒试验的一种手段，其测量误差在验收准则允许范围内，且无需进行本底电流测量即可减少动态刻棒测量时间。      

Tailorable Dynamics in Nonlinear Optical Metasurfaces

Controlling light with light is essential for all-optical switching, data processing in optical communications and computing. Until now, all-optical control of light has relied almost exclusively on nonlinear optical interactions in materials. Achieving giant nonlinearities under low light intensity is essential for weak-light nonlinear optics. In the past decades, such weak-light nonlinear phenomena have been demonstrated in photorefractive and photochromic materials. However, their bulky size and slow speed have hindered practical applications. Metasurfaces, which enhance light–matter interactions at the nanoscale, provide a new framework with tailorable nonlinearities for weak-light nonlinear dynamics. Current advances in nonlinear metasurfaces are introduced, with a special emphasis on all-optical light controls. The tuning of the nonlinearity values using metasurfaces, including enhancement and sign reversal is presented. The tailoring of the transient behaviors of nonlinearities in metasurfaces to achieve femtosecond switching speed is also discussed. Furthermore, the impact of quantum effects from the metasurface on the nonlinearities is introduced. Finally, an outlook on the future development of this energetic field is offered.     

Regulating the Interfacial Electronic Coupling of Fe2N via Orbital Steering for Hydrogen Evolution Catalysis

The capability of manipulating the interfacial electronic coupling is the key to achieving on-demand functionalities of catalysts. Herein, it is demonstrated that the electronic coupling of Fe₂N can be effectively regulated for hydrogen evolution reaction (HER) catalysis by vacancy-mediated orbital steering. Ex situ refined structural analysis reveals that the electronic and coordination states of Fe₂N can be well manipulated by nitrogen vacancies, which impressively exhibit strong correlation with the catalytic activities. Theoretical studies further indicate that the nitrogen vacancy can uniquely steer the orbital orientation of the active sites to tailor the electronic coupling and thus benefit the surface adsorption capability. This work sheds light on the understanding of the catalytic mechanism in real systems and could contribute to revolutionizing the current catalyst design for HER and beyond.     

High-performance oxygen transport membrane reactors integrated with IGCC for carbon capture

Precombustion carbon capture is an effective strategy to reduce large-scale CO₂ emissions, which is mainly used in the area of integrated gasification combined cycle (IGCC) power plants. Oxygen transport membranes (OTMs) were suggested as the air separation unit to produce high purity oxygen for the gasifier. However, the improvement in efficiency was limited. Here, a new IGCC process is reported based on a robust OTM reactor, where the OTM reactor is used behind the coal gasifier. This IGCC-OTM process fulfills syngas oxidation, H₂ production, and carbon capture in one unit, thus a significant decrease of the energy penalty is expectable. The membrane reactor does not use noble metal components, and exhibits high hydrogen production rates, high hydrogen separation factor (10³–10⁴), and stable performance in a gas mixture mimicking real syngas compositions from a coal gasifier with H₂S concentrations up to 1,000 ppm.     

From bulk to porous structures: Tailoring monoclinic SrAl2Si2O8 ceramic by geopolymer precursor technique

In this paper, monoclinic SrAl₂Si₂O₈ ceramics with porous structures were prepared based on ion-exchanged geopolymer precursor technique. Micron-level pores with a homogeneous pore-size distribution were introduced into the inorganic framework using foaming agents. The results demonstrated that the apparent density, pore-size distribution and specific surface area of porous geopolymer precursors can be well-engineered via tailoring the category and concentration of the foaming agent. After being treated at 900°C, hexagonal SrAl₂Si₂O₈ first-crystallized from the amorphous geopolymer matrix and then gradually converted into monoclinic SrAl₂Si₂O₈ between 1100°C and 1200°C. The resulting monoclinic SrAl₂Si₂O₈ ceramics maintained the porous structures during high-temperature treatments and exhibited high porosity, specific surface area, and compressive strength. The aforementioned strategy not only achieves monoclinic SrAl₂Si₂O₈ ceramics with well-defined and robust microstructures, but also provides an alternative route to prepare other porous ceramics, with potential applications in fields of high-temperature filters, adsorbents, and heterogeneous catalysis.     

建筑固废对GRC 性能影响研究

本文对建筑固废制备GRC进行了研究,通过物理性能、力学性能和抗冻性三方面对再生GRC进行性能表征,同时探讨了建筑固废的取代掺量对再生GRC各项性能的影响。试验结果如下:采用喷射成型工艺,再生GRC的力学性能在废混凝土10%,废尾矿10%和废砖1%取代掺量下达到最优,而后随着掺量的增加力学性能逐渐降低。建筑固废的掺入对再生GRC的物理性能没有明显影响。25次冻融循环后再生GRC没有发现冻融破坏现象,且质量损失在0.2%以下。     

Preloading using fill surcharge and prefabricated vertical drains for an airport

This paper presents the field measurements and analysis of a preloading project with the installation of prefabricated vertical drains (PVDs) in Wenzhou, China. At the site, PVDs were installed to a depth of 22?m from the ground surface with a spacing of 1.5?m in a triangular pattern. The preloading fill thickness was 6?m with a unit weight of approximately 18 kN/m³. After a total elapsed time of 310 days, approximately 3?m thick fill was removed. The measured preloading settlement was approximately 1.5?m. The measurements and analytical results indicated that the soil layer with PVD improvement reached almost 100% primary consolidation when part of the fill was removed. After partial unloading, the PVD-improved zone was in an over-consolidated state. After the runway was opened for traffic, a settlement increment of approximately 7?mm was monitored over a period of 11 months. Analysis indicated that the settlement was mainly due to the consolidation of soil layers below the PVD-improved zone and post-surcharge secondary consolidation of the PVD-improved zone. The values of the parameters related to PVD improvement were back-estimated from the field measurements. These findings can be used to guide the design of PVDs improvement along the east coast of China.     

Flame morphology and self-acceleration of syngas spherically expanding flames

The self-acceleration of spherically expanding flames were investigated using a constant volume combustion chamber for CO/H₂/O₂/N₂ mixtures over a wide range of initial pressure from 0.2 to 0.6 MPa, CO/H₂ ratio from 50/50 to 10/90 and equivalence ratio from 0.4 to 1.5. The adiabatic flame temperature was kept constant by adjusting O₂/N₂ ratio at different equivalence ratios. Schlieren images were recorded to investigate the flame front evolution of spherically expanding flames. Local acceleration exponents were extracted using a proper equation to study the process of flame self-acceleration. Results show that the flame cells develop on the smooth flame fronts and finally reach fractal-like structures due to the hydrodynamic and diffusional-thermal instabilities, resulting in flame self-accelerative propagation. The critical Peclet number corresponding to the onset of self-acceleration, Pe_cr increases nonlinearly with the Markstein length, Ma. The observation further reveals that the onset of self-acceleration is mainly controlled by the diffusional-thermal effect. There exists two distinct flame propagation regimes in the self-acceleration, namely quick transition accelerative and quasi self-similar accelerative regimes. The quick transition regime is controlled by the destabilization effect of hydrodynamic perturbation and stabilization effect of flame stretch. While the quasi self-similar regime is primarily affected by the cascading process of flame front cells controlled by hydrodynamic instability. The self-similar acceleration exponent, α_s varies with the initial pressure and Lewis number, Le. The values of α_s are measured to be 1.1–1.25 (smaller than 1.5), indicating the flame dose not attain self-turbulization.     

Operando Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Sodium–Oxygen Redox Reactions

Lower charge overpotential of sodium–oxygen (Na–O₂) batteries makes them a promising electrical storage technology. However, they have an undesirable discharge product, sodium carbonate (Na₂CO₃), which has widely been found in many previous studies. Whether and how the carbon components in the cathode are involved in the formation of Na₂CO₃ is still not well understood. Herein, an all solid-state Na–O₂ battery was constructed and its charge and discharge cycles were studied using ambient pressure X-ray photoelectron spectroscopy. The operando XPS results clearly demonstrate the formation of Na₂CO₃ on the cathode during the discharge cycle. A fraction of the carbonate formed can be cycled while charging the battery. Transformation of the carbon-based cathode to Na₂CO₃ is a potential cause of capacity fading of the Na–O₂ battery.