Numerical method for the inverse heat transfer problem in composite materials with Stefan-Boltzmann conditions

In this paper, one specific kind of heat transfer problem with nonlinear Stefan-Boltzmann conditions are considered in a three dimensional multi-layer domain. Theoretical results for forward and inverse problems are presented. Numerical simulations of specific models from applications are provided to demonstrate the heat transfer process in the composite materials of forward problem. One reconstruction method is proposed to find the corrosion part, and the numerical examples show that the reconstruction algorithm is effective.     

On Pseudo-Holomorphic Curves from Two-Spheres into a Complex Grassmannian G（2, 5）

Let s ： S2 → G（2, 5） be a linearly full totally unramified pseudo-holomorphic curve with constant Gaussian curvature K in a complex Grassmann manifold G（2, 5）. It is prove that K is either 1 4 1 or 4/5 if s is non-±holomorphic. Furthermore, K = 1/3 if and only if s is totally real. We also prove that the Gaussian curvature K is either 1 or -4/3 if s is a non-degenerate holomorphic curve under some conditions.     

A class of nonlinear integrodifferential impulsive periodic systems of mixed type and optimal controls on Banach space

A class of nonlinear integrodifferential impulsive periodic systems of mixed type on Banach space is considered. Existence of periodic PC-mild solutions is proved. Existence of periodic optimal pairs of systems governed by nonlinear impulsive integrodifferential equations of mixed type is also presented. An example is given for demonstration.     

Carbon cloth supported lithiophilic carbon nanotubes@Ag skeleton for lithium anode via ultrafast Joule heating method

Journal of Solid State Electrochemistry - Regulating lithium deposition and stripping behavior during cycles is critical for constructing high-performance and stable lithium metal anodes (LMAs)....     

Activating Bi p-orbitals in Dispersed Clusters of Amorphous BiOx for Electrocatalytic Nitrogen Reduction

Catalytic strategies based on main group metals are significantly less advanced than those of transition metal catalysis, leaving untapped areas of potentially fruitful research. We here demonstrate an effective approach for the modulation of Bi 6p energy levels during the construction of atomically dispersed clusters of amorphous BiO_x. Bi oxidation state is proposed to strongly affects the nitrogen fixation activity, with the half-occupied p_z orbitals of the Bi²⁺ ions being highly efficient toward electron injection into the inert N₂ molecule. With sufficient catalytic sites to adsorb and activate N₂, the bonding between N₂ and catalyst is able to be in situ identified. The catalyst shows an outstanding Faraday efficiency (≈30 %) and high yield (≈113 μg h⁻¹ mg⁻¹_cat) in NH₃ production, outperforming most of the existing catalysts in aqueous solution. These results lay the basis for developing the potential of p-block elements for catalysis of multi-electron reactions.     

Correlating Polysulfide Solvation Structure with Electrode Kinetics towards Long-Cycling Lithium–Sulfur Batteries

Lithium–sulfur (Li−S) batteries are promising due to ultrahigh theoretical energy density. However, their cycling lifespan is crucially affected by the electrode kinetics of lithium polysulfides. Herein, the polysulfide solvation structure is correlated with polysulfide electrode kinetics towards long-cycling Li−S batteries. The solvation structure derived from strong solvating power electrolyte induces fast anode kinetics and rapid anode failure, while that derived from weak solvating power electrolyte causes sluggish cathode kinetics and rapid capacity loss. By contrast, the solvation structure derived from medium solvating power electrolyte balances cathode and anode kinetics and improves the cycling performance of Li−S batteries. Li−S coin cells with ultra-thin Li anodes and high-S-loading cathodes deliver 146 cycles and a 338 Wh kg⁻¹ pouch cell undergoes stable 30 cycles. This work clarifies the relationship between polysulfide solvation structure and electrode kinetics and inspires rational electrolyte design for long-cycling Li−S batteries.     

Symmetry-Broken Intermolecular Charge Separation of Cationic Radicals

A quadrupolar compound Pyr-BA with two pyrrole-type nitrogen atoms doped externally was prepared in this work. In high contrast with other π ionic radicals, its cationic radical Pyr-BA ⋅ ⁺ undergoes unusual symmetry-broken charge separation (SB-CS), generating the mixed valence complex of Pyr-BA^+1−q ⋅⋅⋅ Pyr-BA^+1+q , where q is the degree of charge transfer. Variable-temperature (VT) single-crystal analysis, absorption and EPR experiments all confirmed that aggregation and lower temperature would help to facilitate this SB-CS process. Gibbs energy calculations and gauge-including magnetically induced current simulation both validate that, for Pyr-BA ⋅ ⁺ , SB-CS behavior is more favorable than the conventional dimerization mode. To the best of our knowledge, this is the first study that shows solid single-crystal evidence for spontaneous SB-CS between identical ionic radicals. Such a unique phenomenon is of great significance both in terms of fundamental aspects and uncharted material science.     

Spin-Distribution-Directed Regioselective Substitution Strategy for Highly Stable Olympicenyl Radicals

The synthesis of bench-stable conjugated π-radicals is challenging owing to the lack of modular approaches, which greatly hampers their practical material screens and applications. Here, we demonstrate a spin-distribution-directed regioselective substitution strategy to introduce substituents into the specific positions of an olympicenyl radical in a stepwise manner, resulting in a series of highly stable radical species. The substituents can also adjust the crystal packing by means of steric and electronic factors, enabling the changing from a π-dimer to a pseudo-one-dimensional chain. The first single crystal organic field-effect transistor device based on a graphenic radical is fabricated in air, showing a hole mobility of up to 0.021 cm² V⁻¹ s⁻¹ and excellent device stability. This approach may be generalized to diverse spin-delocalized open-shell organic radicals.     

State-constrained bipartite tracking of interconnected robotic systems via hierarchical prescribed-performance control

This paper investigates the collaborative design problem aiming to achieve state-constrained bipartite tracking of the interconnected robotic systems (IRSs) with prescribed performance. In practical applications, the physical limitations of the robots are inevitable. Besides, it is difficult to ensure that the target trajectory is known for each robot of the IRSs in advance. Thus, it is important to follow the target trajectory and meanwhile obey the state constraint being generated from the physical limitations and the external environment of the IRSs. To this end, we propose a new hierarchical state-constrained estimator-based control framework with the characteristics of low computation complexity and high task adaptability. With limited accessibility of the target trajectory, we newly present the estimator to observe it at each time interval through the interconnections among the robots. The state constraint is never violated throughout the convergence process by using the presented control algorithm. The theoretical proof and simulation results are presented to validate the feasibility of the control framework.

     

部分相干光学成像系统的光学传递函数和像质评价准则

根据光学成像理论，建立了部分相干成像光学系统的光学传递函数。该函数与非相干成像光学系统传递函数相同，因而部分相干成像和非相干成像两者的光学系统波面像差公差标准也是相同的。这一点解释了显微镜光学系统的光学设计惯用法则：镜头像差公差标准的选择，并不因为采用成像照明方式的不同而有所差异。