Corrective matrix that is derived to restore consistency of discretization schemes can significantly enhance accuracy for the inside particles in the Moving Particle Semi‐implicit method. In this situation, the error due to free surface and wall boundaries becomes dominant. Based on the recent study on Neumann boundary condition (Matsunaga et al, CMAME, 2020), the corrective matrix schemes in MPS are generalized to straightforwardly and accurately impose Neumann boundary condition. However, the new schemes can still easily trigger instability at free surface because of the biased error caused by the incomplete/biased neighbor support. Therefore, the existing stable schemes based on virtual particles and conservative gradient models are applied to free surface and nearby particles to produce a stable transitional layer at free surface. The new corrective matrix schemes are only applied to the particles under the stable transitional layer for improving the wall boundary conditions. Three numerical examples of free surface flows demonstrate that the proposed method can help to reduce the pressure/velocity fluctuations and hence enhance accuracy further. 相似文献
Micro‐structure patterned substrates attract our attention due to the special and programmable wettabilities. The interaction between the liquid and micro/nano structures gives rise to controllable spreading and thus evaporation. For exploration of the application versatility, the introduction of nanoparticles in liquid droplet results in interaction among particles, liquid and microstructures. In addition, temperature of the substrates strongly affects the spreading of the contact line and the evaporative property. The evaporation of sessile droplets of nanofluids on a micro‐grooved solid surface is investigated in terms of liquid and surface properties. The patterned nickel surface used in the experiments is designed and fabricated with circular and rectangular shaped pillars whose size ratios between interval and pillars is fixed at 5. The behavior is firstly compared between nanofluid and pure liquid on substrates at room temperature. For pure water droplet, the drying time is relatively longer due to the receding of contact line which slows down the liquid evaporation. Higher concentrations of nanoparticles tend to increase the total evaporation time. With varying concentrations of graphite at nano scale from 0.02% to 0.18% with an interval at 0.04% in water droplets and the heating temperature from 22 to 85°C, the wetting and evaporation of the sessile droplets are systematically studied with discussion on the impact parameters and the resulted liquid dynamics as well as the stain. The interaction among the phases together with the heating strongly affects the internal circulation inside the droplet, the evaporative rate and the pattern of particles deposition. 相似文献
A new synthetic application of N-sulfonyl-1,2,3-triazoles acting as a 1-aza-[4C] synthon via the 1,2-shift reaction of an α-imine rhodium carbene was developed for the synthesis of fused pyrimidine derivatives. The high reactivity of the strained three-membered 2H-azirine ring facilitated the unusual cyclization of electron-deficient dienes with electron-deficient dienophiles. The compatibility was good with common functionalities tolerated. Excellent chemoselectivity was observed, and no reactions occurred between the rhodium carbene and 2H-azirine. The products could be converted into seven-membered multi-functionalized 1H-1,4-diazepine derivatives, illustrating the potential application of the protocol in medium-sized N-heterocycle synthesis. 相似文献
The anode oxygen evolution reaction (OER) is known to largely limit the efficiency of electrolyzers owing to its sluggish kinetics. While crystalline metal oxides are promising as OER catalysts, their amorphous phases also show high activities. Efforts to produce amorphous metal oxides have progressed slowly, and how an amorphous structure benefits the catalytic performances remains elusive. Now the first scalable synthesis of amorphous NiFeMo oxide (up to 515 g in one batch) is presented with homogeneous elemental distribution via a facile supersaturated co‐precipitation method. In contrast to its crystalline counterpart, amorphous NiFeMo oxide undergoes a faster surface self‐reconstruction process during OER, forming a metal oxy(hydroxide) active layer with rich oxygen vacancies, leading to superior OER activity (280 mV overpotential at 10 mA cm?2 in 0.1 m KOH). This opens up the potential of fast, facile, and scale‐up production of amorphous metal oxides for high‐performance OER catalysts. 相似文献
Phase estimation and compensation is one of the enabling functionalities in continous-variable quantum key distribution (CVQKD). Recently, a novel CVQKD scheme has been independently proposed to combat the local oscillator (LO) side channel attacks. Furthermore, we have carried out a proof-of-principle experimental study on the feasibility of the CVQKD without sending a LO. However, this scheme contains a serious weakness: The phase noise caused by the two different lasers between the sender and the receiver would severely destroy the quantum signal and finally reduce the secure distance. In this paper, we investigate the optical phase noise and explore the optimal approach to estimate and compensate such kind of noise with appropriate data overhead. Numerical simulations show that our scheme can successfully reconstruct the phase drifts even at low signal-to-noise ratio conditions. We also suggest that a higher accuracy of phase estimation could be achieved by using the frequency division multiplexing scheme. This opens an opportunity to employ advanced pilot-aided phase estimation techniques in quantum communication system.
Cycloparaphenylene (CPP) shows modulated photophysical and electronic properties due to its strained structure and radially oriented π-electron system. Incorporation of CPP into metal-organic frameworks (MOFs) could transfer its extensive properties in solution to porous solids. Moreover, with the unique arrangement of the macrocycles and their interactions with the framework, emerging characteristics are anticipated. As an example of “robust dynamics”, we synthesized the first MOF structure (FDM-1001) with CPP precisely anchored to the ordered framework by employing a [8]CPP-containing linear dicarboxylate linker. Metric relationship between the dynamic macrocycles and the robust backbone creates ideal π-π interactions between them, which leads to an essentially directional arrangement of [8]CPP in the three-dimensional space. Furthermore, the MOF with [8]CPP could be successfully oxidized to generate an infinite array of radicals that show enhanced air stability compared to its molecular analogue. 相似文献
Modifying the position and numbers of lateral fluorine substituent is a common method to design and adjust the mesophase of liquid crystal compounds. Here, a series of 2-(2,2?-difluoro-4?-alkoxy-1,1?-biphenyl-4-yl)-5-substituted benzoxazole with both non-polar (H, CH3) and polar (NO2) groups (coded as nPF(2)PF(2)Bx) is synthesised and characterised. All of the compounds show a conspicuous inter-ring twist angle of 38° compared with corresponding reference compounds I and II which are calculated by density functional theory method, and it is interesting to note that the final compounds nPF(2)PF(2)Bx show only nematic mesophase during heating or cooling. Meanwhile, the UV-vis absorption bands and photoluminescence emission peaks both display remarkable blue-shifted. The aforementioned results reveal that lateral difluoro substituents play a key role to stable the nematic mesophase by increasing the dihedral angle of biphenyl. 相似文献