Positive solutions to a system of second-order nonlocal boundary value problems

In this paper we study the existence of positive solutions to a system of second-order nonlocal boundary value problems by using fixed point index theory in a cone. Our hypotheses imposed on nonlinearities are those which characterize systems of nonlocal boundary value problems, and our boundary value conditions are expressed in terms of possibly nonlinear functions of Riemann–Stieltjes integrals, thus generalizing and unifying the boundary value conditions in the literature. Therefore our results cannot be routinely deduced from the ones for single nonlocal problem in the literature.     

Game theoretic models for climate change negotiations

Negotiations to reduce greenhouse gas accumulation in the atmosphere are modeled as extensive games of perfect information. Various solution concepts, such as Nash equilibrium, reaction function equilibrium, correlated equilibrium and bargaining solutions are applied, analyzed and computed. Special reduction techniques are used when the size of the game tree becomes excessive. A new solution concept, the tree-correlated equilibrium is also introduced. Main features of an Excel add-in designed to compute various solutions are briefly described and a sample policy analysis for a special negotiating scenario is discussed.     

The super-hydrophobic IR-reflectivity TiO2 coated hollow glass microspheres synthesized by soft-chemistry method

The super-hydrophobic and IR-reflectivity hollow glass microspheres (HGM) was synthesized by being coated with anatase TiO₂ and a super-hydrophobic material. The super-hydrophobic self-cleaning property prolong the life time of the IR reflectivity. TBT and PFOTES were firstly applied and hydrolyzed on HGM and then underwent hydrothermal reaction to synthesis anatase TiO₂ film. For comparison, the PFOTES/TiO₂ mutual-coated HGM (MCHGM), PFOTES single-coated HGM (F-SCHGM) and TiO₂ single-coated HGM (Ti-SCHGM) were synthesized as well. The MCHGM had bigger contact angle (153°) but smaller sliding angle (16°) than F-SCHGM (contact angle: 141.2°; sliding angle: 67°). Ti-SCHGM and MCHGM both showed similar IR reflectivity with ca. 5.8% increase compared with original HGM and F-SCHGM. For the thermal conductivity, coefficients of F-SCHGM (0.0479 W/(m K)) was basically equal to that of the original HGM (0.0475 W/(m K)). Negligible difference was found between the thermal conductivity coefficients of MCHGM-coated HGM (0.0543 W/(m K)) and Ti-SCHGM (0.0546 W/(m K)).     

Stability and regeneration of metal catalytic sites with different sizes in Fenton-like system

Metal-based catalysts with different site sizes (e.g., metal nanoparticles (NPs) and single atom catalysts (SACs)) demonstrated outstanding catalytic activities in versatile Fenton-like reactions. However, the surface/structural instability is a critical issue, which will result in rapid passivation in Fenton-like reaction and fail in long-term operation. The catalytic stability of the catalysts with different metal sizes considering versatile peroxides (H₂O₂, peroxymonosulfate (PMS), and peroxodisulfate (PDS)) should be analyzed. In addition, strategies for catalyst regeneration and recyclability improvement are also important to realize the metal-based catalysts for practical applications. In this review, catalytic stability of catalysts with different metal sizes in the backgrounds of versatile peroxides and water matrixes in Fenton-like reactions were first evaluated. Regeneration of metal catalytic sites with different methods were also reviewed. Finally, major challenges and development of methods concerning the stability and regeneration of metal catalytic sites with different sizes were discussed to understand the future researches of metal catalytic sites in Fenton-like reactions.     

Designing Solvated Double-Layer Polymer Electrolytes with Molecular Interactions Mediated Stable Interfaces for Sodium Ion Batteries

Unstable cathode-electrolyte and/or anode-electrolyte interface in polymer-based sodium-ion batteries (SIBs) will deteriorate their cycle performance. Herein, a unique solvated double-layer quasi-solid polymer electrolyte (SDL-QSPE) with high Na⁺ ion conductivity is designed to simultaneously improve stability on both cathode and anode sides. Different functional fillers are solvated with plasticizers to improve Na⁺ conductivity and thermal stability. The SDL-QSPE is laminated by cathode- and anode-facing polymer electrolyte to meet the independent interfacial requirements of the two electrodes. The interfacial evolution is elucidated by theoretical calculations and 3D X-ray microtomography analysis. The Na_0.67Mn_2/3Ni_1/3O₂|SDL-QSPE|Na batteries exhibit 80.4 mAh g⁻¹ after 400 cycles at 1 C with the Coulombic efficiency close to 100 %, which significantly outperforms those batteries using the monolayer-structured QSPE.     

An approximate bundle method for solving nonsmooth equilibrium problems

We present an approximate bundle method for solving nonsmooth equilibrium problems. An inexact cutting-plane linearization of the objective function is established at each iteration, which is actually an approximation produced by an oracle that gives inaccurate values for the functions and subgradients. The errors in function and subgradient evaluations are bounded and they need not vanish in the limit. A descent criterion adapting the setting of inexact oracles is put forward to measure the current descent behavior. The sequence generated by the algorithm converges to the approximately critical points of the equilibrium problem under proper assumptions. As a special illustration, the proposed algorithm is utilized to solve generalized variational inequality problems. The numerical experiments show that the algorithm is effective in solving nonsmooth equilibrium problems.     

Isobaric heat capacities of R245fa and R236fa in liquid phase at temperatures from (315 to 365) K and pressures up to 5.5 MPa

Isobaric heat capacities of compressed liquid 1,1,1,3,3-pentafluoropropane (R245fa) and 1,1,1,3,3,3-hexafluoropropane (R236fa) were measured by scanning calorimetry. The experimental system basically consists of a calvet calorimeter (Setaram C80) and a pressure balance unit. A total of 55 data points for liquid R245fa and 52 data points for liquid R236fa were obtained at temperatures from (315 to 365) K and pressures up to 5.5 MPa. The uncertainties for the heat capacity of R245fa and R236fa were estimated to be (1.8 and 1.6)%, respectively. The experimental data was correlated to an empirical equation, the form of which was decided by stepwise fit method. The average absolute percentage deviations between the data points and the equation were (0.23 and 0.10)% for R245fa and R236fa.     

Atomically Dispersed Nickel(I) on an Alloy-Encapsulated Nitrogen-Doped Carbon Nanotube Array for High-Performance Electrochemical CO2 Reduction Reaction

Single-atom catalysts (SACs) show great promise for electrochemical CO₂ reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single-atom electrode greatly limit their performance. Herein, we prepared a nickel single-atom electrode consisting of isolated, high-density and low-valent nickel(I) sites anchored on a self-standing N-doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon-fiber paper. The combination of single-atom nickel(I) sites and self-standing array structure gives rise to an excellent electrocatalytic CO₂ reduction performance. The introduction of copper tunes the d-band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single-nickel-atom electrode exhibits a specific current density of −32.87 mA cm⁻² and turnover frequency of 1962 h⁻¹ at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency.     

SEISMIC PERFORMANCE OF STEEL STRUCTURES WITH REDUCED BEAM SECTION CONNECTIONS

采用有限元方法对翼缘削弱型节点钢结构的抗震性能进行了研究,通过模态分析和动力时程分析,详细分析了框架的周期、结构动内力、动应力以及塑性变形区的发展规律等,并和普通节点框架的计算结果进行对比. 研究结果表明：在小震下,翼缘削弱型节点的抗震性能并不理想,但在大震下,表现出了良好的抗震性能,塑性变形出现在梁端削弱处,塑性应变增加,柱底剪力和顶层位移均比普通节点框架的小,建议在强震区推广使用翼缘削弱型节点.     

GAUSS PRINCIPLE OF LEAST CONSTRAINT IN GENERALIZED COORDINATES AND ITS GENERALIZATION

当采用广义坐标描述系统的运动时,相比质点形式的高斯最小拘束原理,通过广义坐标形式的高斯最小拘束原理来建立动力学优化模型,计算效率更高. 从高斯原理的变分形式出发推导了广义坐标形式的高斯最小拘束原理,并研究了非理想约束、单边约束及刚体碰撞情形下的高斯最小拘束原理的形式. 研究认为:对刚体碰撞情形下,高斯最小拘束原理不能取代碰撞恢复定律,碰撞恢复定律以碰撞后广义速度的约束方程形式起作用.