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This paper focus on optimization operation problem of ecology and power generation considering uncertainty of inflow on the Three Gorges reservoir. A model with constraint violation as objective is proposed to obtain ecological and power generation optimization dispatch rule of the Three Gorges Reservoir using stochastic dynamic programming. In the model, minimization of ecological water shortage and constraint violation and maximization of power generation benefit are taken as objective, simple discrete-time Markov chain and stochastic dynamic programming take into account the uncertainties of inflow. A case study shows that the proposed approach is feasible and efficient to produce a dispatch rule to balance ecological and economic benefits. Some conclusions of the influence of ecology and power generation are finally drawn.

With the reservoir construction gradually completed, joint operation of reservoir groups is an important measure to realize reservoir flood control potential,but when the river basin is large, the flood channel routing and time-lag cannot be simplified, in addition, the curse of dimensionality is very difficult for model solving With the expansion of the number of reservoirs. These factors restrict the application of joint operation of large scale mixed reservoirs.In this study, The DP-POA cyclic iterative algorithm which is based on large scale system decomposed-coordinating method was proposed to solve the optimal problem considering the flood routing and time-lag.The upper Yangtze River is selected as a case study. 6 reservoirs, including the Three Gorges Reservoir(TGR)、Xiangjiaba Reservoir(XJB)、Xiluodu Reservoir (XLD)、 Pubugou Reservoir (PBG)、Goupitan Reservoir (GPT) and Tingzikou Reservoir (TZK)are taken into accounts.Compared with current operation of reservoirs independent,results demonstrate that the method can effectively reduce the maximum operating water level of TGR and flood diversion in the lower reaches of the TGR. Therefore, the safety of the flood control points along the river has been largely improved based on the proposed method.

To realize a fast and high-precision simulation of unsteady flows and water quality process in river networks, a 1-D mathematical modelling system for free-surface flows and water quality process is developed. In the hydrodynamic model, a θ semi-implicit method is used to discretize the free-surface gradient term in the momentum equation while the Eulerian-Lagrangian method is employed to solve the advection term. To achieve good mass conservation, the finite-volume method is used to discretize continuity equation. Moreover, the resulting hydrodynamic model is unconditionally stable with respect to the gravity wave speed and flow advection. In solving the scalar transport equation, the forward difference is used for discretization in time while the centre-difference is in space. A sub-cycling is introduced to divide the computational time step and improve the stability of water quality model. Therefore, large time steps are allowed in both the hydrodynamic and the transport models. The coupling of the branches of the river networks is solved using a predictioncorrection method. Then, a Gaussian pulse test and a rectangular wave test are employed to demonstrate the accuracy and the efficiency of the system, which will also provide powerful supports for ecological operations of cascade reservoirs in drainage basins.

This paper presents a theoretical study on the design of an X-ray fluorescence (XRF) analyzer. The relative geometric positions of the analyzer’s source, detector and specimen are emphasized, which impacts the analyte’s characteristic X-ray fluorescence counts. The theoretical formula for the X-ray fluorescence intensity was derived. The geometric factors (angle and distance) were simulated using Monte Carlo Neutron-Particle Transport Code MCNP5. The Cu’s X-ray characteristic peak counts were calculated. These Monte Carlo model calculations analyzed two types of geometry changes. The best geometric positions for the XRF analyzer had the incident angle for the excitation source (β) equivalent to the exit angle for the specimen’s characteristic X-ray (β). The maximal characteristic X-ray peak counts were obtained when α and β were orthogonal, and the minimum counts were obtained when parallel. To increase the fluorescence counts, the source and detector should be set as close to the specimen as possible. This method and these conclusions can provide technical guidance for designing XRF analyzers.

Lithium sulfide (Li2S) is a promising alternative cathodic material for lithium–sulfur batteries, which can alleviate the volume expansion of sulfur‑based cathodes. As a fully lithiated cathode, Li2S can be paired with Li-free anodes, thereby increasing the selectivity of anodic materials. Nevertheless, Li2S cathode is hindered by its high cost, harsh preparation conditions, and inadequate conductivity, which impose limitations on its practical application. Hence, the crucial factor in enabling the practicality of Li2S cathode is the development of low-cost and facile synthetic methods to produce highly conductive Li2S material. Herein, a high‑conductivity Li2S@C/CNT composite cathode is prepared using low-cost Li2SO4 as a lithium source through a facile spray drying technique combined with carbothermal reduction method. Benefiting from the high-speed three-dimensional pathway for electron transport provided by the in-situ formed botryoidal highly conductive network, the Li2S@C/CNT cathode exhibits ultrahigh initial discharge capacity (1028.5 mA h g− 1@1 C), superior cycle stability (520.6 mA h g− 1 after 200 cycles), and remarkable rate capability (301.8 mA h g− 1@5 C). This work not only presents a simple and feasible approach for the low-cost preparation of high‑performance Li2S cathode, but also proposes an innovative idea for advancing the development of high energy density lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

All-solid-state lithium–sulfur batteries are considered one of the most promising candidates for energy storage devices due to their high energy density and safety. However, the poor electron transport of sulfur-based cathodes significantly reduces their reaction kinetics, resulting in low utilization efficiency and subpar rate performance. Herein, leveraging the similar chemical properties of sulfur and selenium, we uniformly deposit SexS1−x (x = 0–0.3) solid solutions with different selenium content on the surface of active carbon via a facile melt-diffusion method to achieve SexS1−x@AC (x = 0–0.3) composite materials. The introduction of selenium effectively enhances the lithium-ion diffusion coefficient of the SexS1−x@AC (x = 0–0.3) cathodes, and improves the stability of the cathode/solid electrolyte interface. With the increase in selenium content, the reaction kinetics of the SexS1−x@AC (x = 0–0.3) cathodes are altered. Specifically, the average lithium-ion diffusion coefficients for the S@AC and Se0.2S0.8@AC cathodes are 6.11 × 10−14 and 1.65 × 10−13 cm2 s−1, respectively, showing a twofold increase. Concurrently, the Se0.2S0.8@AC cathode exhibits higher discharge capacity (698.8 mA h g−1) than that of the S@AC cathode (501.3 mA h g−1) at 1 A g−1. Surprisingly, even when the mass loading increases to 8.85 mg cm−2, the Se0.2S0.8@AC cathode still shows superior cycling stability, which is attributed to the fast ionic/electronic transport pathways within the cathode. Moreover, the Se0.2S0.8@AC cathode maintains good physical contact at the cathode/SE interface after cycling. In all-solid-state lithium–sulfur batteries, the introduction of selenium in the sulfur cathode enhances reaction kinetics (1.65 × 10−13 cm2 s−1), provides additional reactive sites, and significantly improves the electrochemical performance of Se0.2S0.8@AC even with high mass loading (8.85 mg cm−2). [ABSTRACT FROM AUTHOR]

In order to establish an accurate and comprehensive sensory evaluation method for heated cigarette products, 10 representative products were selected for sensory evaluation. Based on taste, sensory descriptors were proposed and screened, and then each index and weight were calculated by Analytic Hierarchy Process. The results indicated that 10 descriptors including smoke amount, flavor, burning sensation, aftertaste, harmony, impurity, strength, concentration, puff-by-puff releasing homogeneity, and irritancy were obtained through evaluation and screening, which could be used for sensory evaluation of heated cigarette products. After the combination and selection of these descriptors based on traditional cigarette inducators, it was finally determined that flavor, motion state of aerosol, strength, irritancy, aftertaste, and puff-by-puff releasing homogeneity were the top 6 indexes affecting the sensory evaluation of heated tobacco products, with weights of 25%, 30%, 10%, 10%, 15%, and 10%, respectively. The establishment of the sensory evaluation indexes and weights of the heated cigarette is helpful to rationally, comprehensively, and intuitively evaluate the sensory quality of each heated cigarette product. [ABSTRACT FROM AUTHOR]

With non-toxic nature, wide bandgap, and thermal stability, Sn-based perovskite materials have become a hot topic in the field of perovskite solar cell research. In this paper, the SCAPS-1D software was used to construct the FTO/TiO2/CH3NH3SnI3/Spiro-OMeTAD/ Ag perovskite solar cells and the performances of the constructed cells were calculated. The effects of the thickness of absorption and hole buffer layer, the surface defects between hole buffer layer and absorption layer, and the operating temperature on the device performance were studied, then the device performance was optimized. The photoelectric conversion efficiency of the optimized perovskite solar cell is 30. 955%. The theoretical analysis suggests a new approach for enhancing the photoelectric conversion efficiency of perovskite solar cells. [ABSTRACT FROM AUTHOR]