Facile synthesis of the desired red phosphor Li2Ca2Mg2Si2N6:Eu2+ for high CRI white LEDs and plant growth LED device

The red emission with suitable peak wavelength and narrow band is acutely required for high color rendering index (CRI) white LEDs without at the cost of the luminous efficacy. Herein, the Li₂Ca₂Mg₂Si₂N₆:Eu²⁺ red phosphor was prepared with facile solid-state method using Ca₃N₂, Mg₃N₂, Si₃N₄, Li₃N, and Eu₂O₃ as the safety raw materials under atmospheric pressure for the first time, which shows red emission peaking at 638 nm with full width at half maximum (FWHM) of 62 nm under blue light irradiation and becomes the desired red phosphor to realize the balance between luminous efficacy and high CRI in white LEDs. The morphology, structure, luminescence properties, thermal quenching behavior, and chromaticity stability of the Li₂Ca₂Mg₂Si₂N₆:Eu²⁺ phosphor are investigated in detail. Concentration quenching occurs when the Eu²⁺ content exceeds 1.0 mol%, whereas high-temperature photoluminescent measurements show a 32% drop from the room-temperature efficiency at 423 K. In view of the excellent luminescence performances of Li₂Ca₂Mg₂Si₂N₆:Eu²⁺ phosphor, a white LEDs with CRI of 91 as a proof-of-concept experiment was fabricated by coating the title phosphor with Y₃Al₅O₁₂:Ce³⁺ on a blue LED chip. In addition, the potential application of the title phosphor in plant growth LED device was also demonstrated. All the results indicate that Li₂Ca₂Mg₂Si₂N₆:Eu²⁺ is a promising red-emitting phosphor for blue LED-based high CRI white LEDs and plant growth lighting sources.     

数字花卉植物的全息可视化与交互实现

花卉植物形态、结构与生长过程的数字化和可视化是现代林业科研的重要研究内 容，数字花卉植物在科普、教育、展示等方面都有着广泛的应用与需求。全息影像技术是一种 新兴的前沿技术，其原理源自佩珀尔幻象，通常用于生成立体感强的影像，实现数字幻象与真 实世界的融合，拥有良好的观赏性，用户接受度较高。将全息影像技术与数字花卉植物相关研 究进行结合，可以加强数字花卉植物的可视化效果，从而实现更好的科普、教育、展示效果。 因此在现有的研究基础之上，考虑实现数字花卉植物的全息可视化，并在可视基础上增加了用 户交互实现，设计出一套兼具展示性和交互性的流程，力求总结出一种具有完整可行性的方案， 从而对数字花卉植物的新型表现形式进行深入研究，以期对数字植物研究与应用的进一步发展 提供参考。     

Off-design performance evaluation of Hassi R’Mel ISCC power plant

The paper presents a thermodynamic analysis of an existing ISCC power plant when running at off-design operation conditions. The off-design regime is due to changes in air temperature and DNI. The analysis is based on the results of calculations performed by the flow sheet programme ‘Cycle-Tempo’. For off-design modelling, some reasonable assumptions are adopted in regard to the operations of the turbomachines and heat exchangers. The power plant performance is examined when it is running following the operation strategy ‘saving mode’. The complementarily between the solar field and the duct burners (DBs), and the operation of the power plant, in terms of hourly net electricity output and thermal efficiency, are analysed on two representative days, a summer day and a winter day. The key parameters in the study are essentially the HTF mass flow rate, DB fuel consumption, thermal energies supplied by the solar field, and the DBs.     

Comparison of a district heating system operation based on actual data – Omsk city,Russia, case study*

A district heating (DH) system in the Russian city of Omsk has been considered as a case study. This study is based on the data set of temperature and demand recorded over two-year operation of the DH system. We provide an insight on how the heat demand profile is met by the control framework. The paper quantifies the DH system performance by using heat load curves, maximum, minimum and average values of temperature, paving the way for a modelling approach. Central heating process in Omsk in 2017 was generally smoother than in 2016, while peak values are also lower. In 2017, its supply temperature was about 5°C closer to the control curve. The dispersion of the points was reduced between 2016 and 2017, especially at higher outdoor temperatures. Further lowering annual and peak heat demand, which are respectively 4% and 9% lower in 2017 should be a priority in future.     

An analytical-numerical approach for parameter determination of a five-parameter single-diode model of photovoltaic cells and modules

Parameter extraction of the five-parameter single-diode model of solar cells and modules from experimental data is a challenging problem. These parameters are evaluated from a set of nonlinear equations that cannot be solved analytically. On the other hand, a numerical solution of such equations needs a suitable initial guess to converge to a solution. This paper presents a new set of approximate analytical solutions for the parameters of a five-parameter single-diode model of photovoltaic (PV) cells and modules. The proposed solutions provide a good initial point which guarantees numerical analysis convergence. The proposed technique needs only a few data from the PV current-voltage characteristics, i.e. open circuit voltage V_oc, short circuit current I_sc and maximum power point current and voltage I_m; V_m making it a fast and low cost parameter determination technique. The accuracy of the presented theoretical I–V curves is verified by experimental data.     

Day‐Ahead Global Solar Radiation Forecasting Using Binary Trees and Factor Analysis

A method is proposed for forecasting global solar radiation. The method is based on weather information using binary trees and factor analysis. The feature of this method is that it is possible to use a simple linear forecasting equation. The method has been tested on meteorological and global solar radiation data obtained at several observation sites, and the results show that it is a promising means of maintaining the balance between demand and supply of electric power in power systems of the near future with a large number of photovoltaic systems installed.     

One-step foaming method to functional polyurethane absorbents foam

Traditional preparation of superhydrophobic absorbents relies on solvents or further modification with silane. For environmental reasons, it is ideal to find ways that reduce or completely non-solvent. Herein, we show that superhydrophobic sponges can be obtained without solvents by the foaming process. Rough surface morphology and low surface energy were achieved simultaneously during the formation of superhydrophobic foam without further modification. The time required for oil–water separation was shortened significantly, when combined the sponge with a vacuum system. Importantly, the obtained sponge can retain its high oil absorption capacity after several cycles of oil–water separation. The sponge is easy to be scaled up and we have fabricated foams in large scale (37 cm × 30 cm × 22 cm) for making it an ideal candidate for practical application.     

Stability and stabilisation of a class of networked dynamic systems

We investigate the stability and stabilisation of a linear time invariant networked heterogeneous system with arbitrarily connected subsystems. A new linear matrix inequality based sufficient and necessary condition for the stability is derived, based on which the stabilisation is provided. The obtained conditions efficiently utilise the block-diagonal characteristic of system parameter matrices and the sparseness of subsystem connection matrix. Moreover, a sufficient condition only dependent on each individual subsystem is also presented for the stabilisation of the networked systems with a large scale. Numerical simulations show that these conditions are computationally valid in the analysis and synthesis of a large-scale networked system.     

多堆厂址始发事件分析探讨

多堆厂址一级概率安全评价（PSA）研究中，机组数目的增加使得建模工作量剧增，给整个核电厂的风险评估带来困难。结合已有基础，本文研究了多堆厂址始发事件分析的筛选方法，提出利用堆芯损伤频率（CDF）上下限值评估方法，分析厂址内不同机组数对厂址CDF的影响。结果表明，双机组厂址适合优先进行具体分析。针对双机组核电站，对多堆厂址内各始发事件进行筛选。结果表明，丧失厂外电、丧失热阱等事件适合建模分析，并对其他筛选结果给出后续分析建议，为多堆厂址一级PSA后续事故序列建模工作提供了重要基础。