Optimal control of an SIQRS epidemic model with three measures on networks

Nonlinear Dynamics - At present, the main measures for disease control are vaccination, quarantine and treatment. Taking the three measures into consideration, time-varying optimal control problems...     

基于电化学老化衰退模型的锂离子动力电池外特性

当前锂离子动力电池电化学模型存在模型复杂、建模难度大、计算效率低、老化评估效果差的问题,本文提出一种考虑电池衰退老化的机理模型(ADME).本文首先通过有限差分法对伪二维(P2D)电化学模型进行离散降阶处理,得到简化伪二维(SP2D)模型.在SP2D模型的基础上,基于阴阳两极发生的副反应导致的衰退老化现象,提出一种考虑电池衰退老化的机理模型.其次,使用多变量偏差补偿最小二乘法实现模型参数辨识.最后通过动力电池衰退老化性能循环实验,对比分析了恒流、脉冲工况下SP2D模型和ADME模型的终端电压输出.结果表明:ADME模型较为简单、计算效率和估算精度高,可以有效评估电池容量老化衰退,得到理想的锂离子动力电池外特性曲线.     

A self-penetrating and chemically stable zinc (ii)-organic framework as multi-responsive chemo-sensor to detect pesticide and antibiotics in water

Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)_0.5(bimb)]·H₂O}_n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {8⁶} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium.     

Nanoscale detection of faint machinery vibration using the NV center in diamond

We propose a novel method for detection of the faint machinery vibration at the nanometer resolution based on the spin magnetic resonant effect. A suspension magnet acts as a vibration sensor to transfer the vibration signals as the magnetic field fluctuation to excite the spin magnetic resonance. Due to the high sensitivity of the magnetic field of the nitrogen-vacancy center in diamond, the theoretical detection limit of mechanical vibration is as high as 5.7 nm, and the actual measurement resolution reached 12.8 nm, and proved the potential for further improvement to ∼pm resolution. The feasibility of this method is verified by dynamic tests. This method provides a novel approach for the detection of micro-mechanical vibrations.     

Effects of Ionic Liquids on the Thermodynamics of Hydrogen Activation by Frustrated Lewis Pairs: A Density Functional Theory Study**

Nowadays, hydrogen activation by frustrated Lewis pairs (FLPs) and their applications are one of the emerging research topics in the field of catalysis. Previous studies have shown that the thermodynamics of this reaction is determined by electronic structures of FLPs and solvents. Herein, we investigated systems consisting of typical FLPs and ionic liquids (ILs), which are well known by their large number of types and excellent solvent effects. The density functional theory (DFT) calculations were performed to study the thermodynamics for H₂ activation by both inter- and intra-molecular FLPs, as well as the individual components. The results show that the computed overall Gibbs free energies in ILs are more negative than that computed in toluene. Through the thermodynamics partitioning, we find that ILs favor the H−H cleavage elemental step over the elemental steps of proton attachment, hydride attachment and zwitterionic stabilization. Moreover, the results show that these effects are strongly dependent on the type of FLPs, where intra-molecular FLPs are more affected compared to the inter-molecular FLPs.     

可用于连续识别Cu^2+和阴离子、中性分子荧光探针的研究进展

铜(Cu)含量的高低直接影响着生命体的正常运转和自然体系的平衡.检测铜离子的方法多种多样,其中具有较高敏感度和选择性的荧光化学传感器应用更加广泛.综述了以Cu^2+为基的荧光化学传感器通过"替换"法实现了对阴离子S^2-, CN^-, H2PO4^-, PPi和I^-以及中性分子ATP、ADP和生物硫醇等的连续识别的研究进展.     

ZCuPb20Sn5合金耐磨性能研究

ZCuPb₂₀Sn₅合金作为柱塞泵转子内衬材料，因其含铅量高，而具有良好的减摩耐磨性能，可避免转子在工作中的磨损失效问题. 选用销盘式摩擦磨损试验机，以ZCuPb₂₀Sn₅和45钢为摩擦副，研究了不同PV值和油润滑条件下，ZCuPb₂₀Sn₅合金的摩擦磨损性能. 结果表明:随着PV值的增加，ZCuPb₂₀Sn₅合金的摩擦系数先增加后减小，而磨损率呈增加趋势. 在载荷50 N和线速度2.410 m/s条件下，摩擦系数和磨损率最低，摩擦系数最低能达到0.010，平均摩擦系数达到1个最低峰值点0.063；在载荷250 N、线速度3.610 m/s以及PV值为126 MPa·m/s的条件下，摩擦系数达到另一低峰值0.070，磨损率为2.972×10?7 mm3/(N·m). PV值最大时，摩擦系数和磨损率最大. 载荷小于150 N时，在油润滑的作用下，主要磨损机制为轻微黏着磨损；载荷大于150 N时，在铅和油的协同作用下，以黏着磨损为主，少量磨粒磨损；当载荷大于250 N时，摩擦系数与磨损率均偏高，以磨粒磨损为主，局部有少量氧化磨损.      

近壁声空泡溃灭微射流冲击流固耦合模型及蚀坑反演分析

超声场下液体环境中近壁空泡溃灭会产生强烈的微射流，为探究微射流冲击壁面流固耦合效应，利用流体力学及冲击动力学，考虑了率相关的J-C材料本构模型，建立并分析了微射流冲击壁面流固耦合三维模型，并通过超声空化试验和基于球形压痕试验理论的反演分析进行了验证。结果表明:微射流冲击下材料表面出现微型凹坑，凹坑深度由微射流速度和微射流直径共同决定且随其增大而增大，凹坑直径主要与微射流直径正相关，而凹坑径深比则主要与微射流速度负相关；壁面压强基本呈对称分布且最大压强出现在微射流冲击边缘；超声空化试验验证了微射流冲击下材料表面出现的微型凹坑，反演分析方法表明，在16～18的径深比下，微射流冲击强度为420～500 MPa，对应的微射流速度为310～370 m/s。试验及反演分析结果与理论分析结果相符，验证了流固耦合模型及反演分析方法的合理性及准确性，为后续工程应用中空化强度、微射流速度等的控制提供了理论参考。     

A [001]-Oriented Hittorf's Phosphorus Nanorods/Polymeric Carbon Nitride Heterostructure for Boosting Wide-Spectrum-Responsive Photocatalytic Hydrogen Evolution from Pure Water

Red phosphorus is a promising photocatalyst with wide visible-light absorption up to 700 nm, but the fast charge recombination limits its photocatalytic hydrogen evolution reaction (HER) activity. Now, [001]-oriented Hittorf's phosphorus (HP) nanorods were successfully grown on polymeric carbon nitride (PCN) by a chemical vapor deposition strategy. Compared with the bare PCN and HP, the optimized PCN@HP hybrid exhibited a significantly enhanced photocatalytic activity, with HER rates reaching 33.2 and 17.5 μmol h⁻¹ from pure water under simulated solar light and visible light irradiation, respectively. It was theoretically and experimentally indicated that the strong electronic coupling between PCN and [001]-oriented HP nanorods gave rise to the enhanced visible light absorption and the greatly accelerated photoinduced electron–hole separation and transfer, which benefited the photocatalytic HER performance.     

非单C~*-代数α-比较性的等价刻画

给出非单C~*-代数α-比较性的等价刻画:当每个τ∈QT(■H)均为忠实时,■具有α-比较性,当且仅当对于任意的〈a〉,〈b〉∈Cu(■)且∝,若α·d_τ(a)≤在Cu(■)中成立;一般地,当QT(■H)≠Φ时,■具有α-比较性,当且仅当对于任意的,∈Cu(■),若存在η>0,使得d_τ(α)≤(α~(-1)-η)d_τ(b)(_τ∈QT(■H)),则≤在Cu(■)中成立.