Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta Function and Modified Eddington, and second-order approximation methods with reference to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(F-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the Disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of approximation of the phase function of the RTE leads to a better precision in flux calculations. However, this approach may be limited to a certain order that has not been studied in this paper.

重大疫情下医院空间资源弹性应急转换策略:以上海市级综合医院向临时定点医院的功能转换为例

以新型冠状病毒肺炎(以下简称“新冠肺炎”)疫情期间,上海6家市级综合医院向临时新冠肺炎定点医院的快速功能转换为例,总结分析其在时间和空间资源有限的情况下,在建筑空间、医疗设备、人力资源等方面应急转换的实践经验及存在的不足。提出基于弹性理念的医院空间应急转换框架,表明从综合医院向定点医院的平疫功能转换应以空间资源的弹性转换为前提,同步在医疗设备、人力资源、物资储备管理等方面做好弹性配置,以提升时间上的转换速度和空间上的利用效率。建议优化医院空间规划、加强应急队伍建设以及完善物资储备体系,以更加有力地应对未来可能发生的突发公共卫生事件。

具有多重时滞的中立型反馈系统的稳定性

本文结合Ｌｙａｐｕｎｏｖ泛函和差分算子稳定性的结果，采用常数变易法，给出了一类具有多重时滞的中立型反馈系统一致渐近稳定的充分条件．

Exploring human rhythmic gait movement in the role of cerebral cortex signal

The rhythmic movement is a spontaneous behavior due to the central pattern generator （CPG）. At present, the CPG model only shows the spontaneous behavior, but does not refer to the instruction regulation role of the cerebral cortex. In this paper, a modified model based on the Matsuoka neural oscillator theory is presented to better show the regulation role of the cerebral cortex signal to the CPG neuronal network. The complex interaction between the input signal and other parameters in the CPG network is established, making all parameters of the CPG vary with the input signal. In this way, the effect of the input signal to the CPG network is enhanced so that the CPG network can express the self-regulation movement state instead of being limited to the spontaneous behavior, and thus the regulation role of the cerebral cortex signal can be reflected. Numerical simulation shows that the modified model can generate various movement forms with different modes, frequencies, and interchanges between them. It is revealed in theories that the cerebral cortex signal can regulate the mode and frequency of the gait in the ~ourse of the gait movement.

Estimation method of glottal vocal efficiency based on conversion function of voice source

This investigation was designed to approach a novel estimation method of glottal vocal efficiency (GVE) based on conversion function of voice source. The conversion function of voice source was defined the ratio of supra-glottal acoustic voice source signal to the glottal air volume flow velocity waveform in frequency domain. A carefully designed in vivo canine larynx experiment and several human experiments including different vowels, pressed, falsetto, breath and typical laryngeal diseases were adopted to demonstrate this alternative GVE method. Compared with other vocal efficiency, it is shown that this method could eliminate the contribution from the super vocal tract transmission and resonance to GVE, and reflect the differences of phonation modes. The average magnitude of this conversion function in frequency domain represents GVE, and the variation of the magnitude in fundamental frequency is identical to AC/DC value.

Organic functional materials based buffer layers for efficient perovskite solar cells

In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.

Waste to wealth:Defect-rich Ni-incorporated spent LiFePO_(4)for efficient oxygen evolution reaction

The development of efficient strategies to recycle lithium-ion battery(LIB)electrode materials is an important yet challenging goal for the sustainable management of battery waste.This work reports a facile and economically efficient method to convert spent cathode material,LiFePO_(4),into a high-performance NiFe oxy/hydroxide catalyst for the oxygen evolution reaction(OER).Herein,Ni-LiFePO_(4)is synthesized via the wetness impregnation method and further evolves into defect-rich NiFe oxy/hydroxide nanosheets during the OER.The introduction of the Ni promoter together with in situ evolution strengthens the electronic interactions among the metal sites and creates an abundance of defects.Experimentally,the evolved Ni-LiFePO_(4)delivers a low overpotential of 285 mV at 10 mA cm-^(2)and a small Tafel slope of 45 mV dec^(-1),outperforming pristine LiFePO_(4)and is even superior to the benchmark catalyst RuO_(2).Density functional theory(DFT)calculations reveal that the introduction of Ni effectively activates Fe sites by optimizing the free energy of the*OOH intermediate and that the abundance of oxygen defects facilitates the oxygen desorption step,synergistically enhancing the OER performance of LiFePO_(4).As a green and versatile method,this is a new opportunity for the scalable fabrication of excellent electrocatalysts based on spent cathode materials.

A New Kinetic Method of Processing TA Data

A new method of investigating the kinetic parameters and mechanism functions of a solid phase reaction is pre-sented. This method is to analyze the data based on the use of these data at the same temperature and the same de-gree of conversion on a series of TA curves with different heating rates, so that the kinetic tripletthe activation energy E, the pre-exponential factor A and the analytical form of the function of conversion f(a) can be obtained. The main advantage of this method is that the values of E and f(a) are obtained respectively, and the determination of f(a) is not under the influence of the value of E and the calculation of the value of E is not influenced by the f(a) either.

Dynamic Modeling and Closed-loop Control of Hybrid Grid-connected Renewable Energy System with Multi-input Multi-output Controller

In this study, a novel approach for dynamic modeling and closed-loop control of hybrid grid-connected renewable energy system with multi-input multi-output(MIMO) controller is proposed. The studied converter includes two parallel DC-DC boost converters, which are connected into the power grid through a single-phase H-bridge inverter. The proposed MIMO controller is developed for maximum power point tracking of photovoltaic(PV)/fuel-cell(FC) input power sources and output power control of the grid-connected DC-AC inverter. Considering circuit topology of the system, a unique MIMO model is proposed for the analysis of the entire system. A unique model of the system includes all of the circuit state variables in DCDC and DC-AC converters. In fact, from the viewpoint of closed-loop controller design, the hybrid grid-connected energy system is an MIMO system. The control inputs of the system are duty cycles of the DC-DC boost converters and the amplitude modulation index of DC-AC inverters. Furthermore, the control outputs are the output power of the PV/FC input power sources as well as AC power injected into the power grid. After the development of the unique model for the entire system, a decoupling network is introduced for system input-output linearization due to inherent connection of the control outputs with all of the system inputs. Considering the decoupled model and small signal linearization, the required linear controllers are designed to adjust the outputs. Finally, to evaluate the accuracy and effectiveness of the designed controllers, the PV/FC based grid-connected system is simulated using the MATLAB/Simulink toolbox.