The effect of TiN deposition time on the field-emission performance coated on ZnO nanorod arrays

ZnO nanorod arrays (NRs) with a large number of sharp tips and uniform shapes were grown on the carbon cloth (CC) by a simple hydrothermal method. Titanium nitride (TiN) nanoparticles with various thicknesses were deposited on the ZnO NRs by magnetron sputtering to obtain ZnO/TiN core-shell arrays. Field emission (FE) performance of ZnO NRs show close dependence on TiN coating thickness. The turn-on field first decreases and then increases with increasing TiN coating thickness from 60 nm to 300 nm. The arrays with a design architecture can strike a balance between increased emission sites and limited field shielding effects. ZnO/TiN240 core-shell NRs have the lower turn-on electric field at 0.79 V/μm and the higher current densities at 9.39 mA/cm². The field enhancement factor (β) of ZnO/TiN240 is about 3.2 times that of the bare ZnO NRs. On the other hand, the electrochemical properties were improved due to the formation of core-shell heterojunction on the ZnO/TiN interface and porous structure, which makes the ion and charge transport more convenient. Hence, this work not only revealed that the ZnO/TiN core-shell structure exhibited excellent improvement in both FE and supercapacitors applications, but also that growing arrays on CC was expected to achieve flexible display.     

Influence of temperature on acoustic emission source location accuracy in underground structure

An acoustic emission (AE) experiment was carried out to explore the AE location accuracy influenced by temperature. A hollow hemispherical specimen was used to simulate common underground structures. In the process of heating with the flame, the pulse signal of constant frequency was stimulated as an AE source. Then AE signals received by each sensor were collected and used for comparing localization accuracy at different temperatures. Results show that location errors of AE keep the same phenomenon in the early and middle heating stages. In the later stage of heating, location errors of AE increase sharply due to the appearance of cracks. This provides some beneficial suggestions on decreasing location errors of structural cracks caused by temperature and improves the ability of underground structure disaster prevention and control.     

Optimization of sensitizer concentration for upconversion photoluminescence of Yb3+/Er3+: La10W22O81 nanophosphor rods

Yb³⁺/Er³⁺codoped La₁₀W₂₂O₈₁ (LWO) nanophosphor rods have been successfully synthesized by a facile hydrothermal assisted solid state reaction method, and their upconversion photoluminescence properties were systematically studied. X-ray diffraction patterns revealed that the nanophosphors have an orthorhombic structure with space group Pbcn (60). A microflowers-like morphology with irregular hexagonal nanorods was observed using field emission scanning electron microscopy for the Yb³⁺(2 mol%)/Er³⁺(2 mol%):LWO nanophosphor. The shape and size of the nanophosphor and the elements along with their ionic states in the material were confirmed by TEM and XPS studies, respectively. A green upconversion emission was observed in the Er³⁺: LWO nanophosphors under 980 nm laser excitation. A significant improvement in upconversion emission has been observed in the Er³⁺: LWO nanophosphors by increasing the Er³⁺ ion concentration. A decrease in the upconversion emission occurred due to concentration quenching when the doping concentration of Er³⁺ ions was greater than 2 mol%. An optimized Er³⁺(2 mol%): LWO nanophosphor exhibited a strong near infrared emission at 1.53 μm by 980 nm excitation. The green upconversion emission of Er³⁺(2 mol%): LWO was remarkably enhanced by co-doping with Yb³⁺ ions under 980 nm excitation because of energy transfer from Yb³⁺ to Er³⁺. The naked eye observed this upconversion emission when co-doping with 2 mol% Yb³⁺. In order to obtain the high upconversion green emission, the optimized sensitizer concentration of Yb³⁺ ions was found to be 2 mol%. The upconversion emission trends were studied as a function of stimulating laser power for an optimized sample. Moreover, the NIR emission intensity has also been enhanced by co-doping with Yb³⁺ ions due to energy transfer from Yb³⁺ to Er³⁺. The energy transfer dynamics were systematically elucidated by energy level scheme. Colorimetric coordinates were determined for Er³⁺ and Yb³⁺/Er³⁺: LWO nanophosphors. The energy transfer mechanism was well explained and substantiated by several fluorescence dynamics of upconversion emission spectra and CIE coordinates. The results demonstrated that the co-doped Yb³⁺(2 mol%)/Er³⁺(2 mol%): LWO nanophosphor material is found to be a suitable candidate for the novel upconversion photonic devices.     

Techno-economic analysis of a hybrid energy system for CCHP and hydrogen production based on solar energy

A typical problem in Northeast China is that a large amount of surplus electricity has arisen owing to the serious photovoltaic power curtailment phenomenon. To effectively utilize the excess photovoltaic power, a hybrid energy system is proposed that uses surplus electricity to produce hydrogen in this paper. It combines solar energy, hydrogen production system, and Combined Cooling Heating and Power (CCHP) system to realize cooling, heating, power, and hydrogen generation. The system supplies energy for three public buildings in Dalian City, Liaoning Province, China, and the system configuration with the lowest unit energy cost (0.0615$/kWh) was obtained via optimization. Two comparison strategies were used to evaluate the hybrid energy system in terms of unit energy cost, annual total cost, fossil energy consumption, and carbon dioxide emissions. Subsequently, the annual total energy supply, typical daily loads, and cost of the optimized system were analyzed. In conclusion, the system is feasible for small area public buildings, and provides a solution to solve the phenomenon of photovoltaic power curtailment.     

Experimental evaluation of the luminescence performance of fired clay brick coated with SrAl2O4:Eu/Dy phosphor

This study evaluates the luminescence performance of fired clay bricks coated with SrAl₂O₄:Eu/Dy phosphor. To do so, SrAl₂O₄:Eu/Dy phosphor was first produced using the traditional solid-state reaction synthesis technique. The prepared phosphor was then used for coating fired clay bricks to analyze the luminescence performance via spectral analysis, decay characteristics, and microstructure of the bricks. The results reveal that excitation and emission spectra of the phosphor coated bricks range from 200 to 480 nm and 455 to 650 nm, respectively, suggesting that the phosphor coated bricks have the capacity of absorbing light with a wide range of wavelengths. The peak wavelength projected at 511 nm in the emission spectrum is achieved, which indicates 4f⁶5 d¹-4f⁷ transition of Europium (Eu²⁺). The repeated excitation and deexcitation of Eu²⁺ by using hole traps and trap levels offered by Dysprosium (Dy³⁺), exist between the ground and the excited state of Eu²⁺ leads to luminescent phenomenon. Moreover, the decay characteristics has revealed that phosphor coated bricks can emit light for a considerable amount of time (>8.5 min) upon the removal of the excitation source. The results reveal that phosphor coated bricks has the potential of increasing energy efficiency of residential and commercial buildings.     

Development and quality evaluation of a cereal-based breakfast product from yellow maize (Zea mays), sesame (Sesamum indicum) and mushroom (Pleurotus ostreatus) flour blends

Composite flours were prepared from blends of yellow maize (Zea mays), sesame seed (Sesamum indicum) and oyster mushroom (Pleurotus ostreatus) powder in the ratio of 80:20:0; 75:20:5; 70:20:10; 65:20:15 and 60:20:20, respectively to produce the cereal-based breakfast product coded as YSB, SMB, TMB, PMB and OMB with YSB as the control. The breakfast cereals were produced by hydration and toasting of yellow maize and sesame to 160°C for 25 min and blended together with oven-dried and packaged oyster mushroom. The developed products were analysed for proximate, vitamins, minerals and sensory properties. The proximate composition (%) of different blends ranged as moisture (4.07–7.08), ash (3.09–2.28), crude fat (16.04–12.83), crude fibre (4.30–8.22), protein (16.14–22.54), carbohydrate (56.34–47.04) and energy (434.34–393.83 Kcal). Vitamin A (7.99–5.98 mg/100 g), vitamin B₁ (0.08–0.42 mg/100 g), vitamin B₂ (0.06–0.15 mg/100 g), vitamin B₃ (1.91–4.52 mg/100 g) and vitamin C (3.55–3.32 mg/100 g) were u while minerals (mg/100 g) were calcium (75.31–58.02), potassium (0.65–4.01), magnesium (12.25–12.62), iron (1.21–4.15) and zinc (0.40–1.32). Sensory scores revealed that the cereal-based breakfast product were acceptable to the panellist with oyster mushroom supplementation up to 10%.     

Simulation of interaction between high-temperature process and heat emission from electricity system in summer

During the hot summer season, using electricity systems increases the local anthropogenic heat emission, further increasing the temperature. Regarding anthropogenic heat sources, electric energy consumption, heat generation, indoor and outdoor heat transfer, and exchange in buildings play a critical role in the change in the urban thermal environment. Therefore, the Weather Research and Forecasting (WRF) Model was applied in this study to investigate the heat generation from an indoor electricity system and its influence on the outdoor thermal environment. Through the building effect parameterization (BEP) of a multistorey urban canopy scheme, a building energy model (BEM) to increase the influence of indoor air conditioning on the electricity consumption system was proposed. In other words, the BEP+BEM urban canopy parameterization scheme was set. High temperatures and a summer heat wave were simulated as the background weather. The results show that using the BEP+BEM parameterization scheme of indoor and outdoor energy exchange in the WRF model can better simulate the air temperature near the surface layer on a sunny summer. During the day, the turning on the air conditioning and other electrical systems have no obvious effect on the air temperature near the surface layer in the city, whereas at night, the air temperature generally increases by 0.6 ℃, especially in densely populated areas, with a maximum temperature rise of approximately 1.2 ℃ from 22:00 to 23:00. When the indoor air conditioning target temperature is adjusted to 25–27 ℃, the total energy release of the air conditioning system is reduced by 12.66%, and the temperature drops the most from 13:00 to 16:00, with an average of approximately 1 ℃. Further, the denser the building is, the greater the temperature drop.     

Powder sintering and gel casting methods in making glass foam using waste glass: A review on parameters,performance, and challenges

The application of insulation materials in buildings and energy storage facilities is gaining global attention to reduce energy consumption, heat loss, and CO₂ emissions. Given the high insulation performance, glass foam is gaining popularity replacing combustible, high energy-consuming, and costly conventional insulation materials. The industrial process of glass foam manufacturing is an energy-consuming and non-ecofriendly process which requires the annealing of glass around its melting temperature. Therefore, researchers have developed powder sintering and gel casting methods to sinter glass foam mix at a temperature slightly above its glass transition point. However, research findings on these two methods are scattered because of the different parameters being used by researchers. The properties and performances of glass foam depend on the processing parameters, especially on the materials design and sintering conditions. Therefore, this study aimed to provide a comprehensive review on the key parameters for material selection and sintering of glass foams and provide necessary guidelines for the best practice and a direction for future research. Moreover, this review covers the current strategies and challenges associated with the powder sintering and gel casting methods including their sustainability and environmental performance.     

基于改进SOA-VMD的磁声发射信号去噪算法

磁声发射（MAE）是铁磁性材料磁化过程中产生的声发射信号，在构件应力检测和微观损伤检测中有着广泛的应用。针对MAE信号非稳态、复杂性、衰减性等特点，提出海鸥算法结合变分模态分解（SOA-VMD）的去噪方法，为克服海鸥算法求解过程中易陷入局部最优解问题，利用柯西变异算子产生随机迭代过程，使改进算法即柯西变异海欧算法（CVSOA）跳出早熟收敛。采用以幅值谱熵为适应度函数，优化VMD算法中分解模态个数K和二次惩戒因子α两个参数，将含噪声的MAE信号进行VMD分解重构。经仿真信号和实际检测信号分析表明，改进后的CVSOA-VMD算法全局寻优能力和去噪性能优于传统的SOA-VMD算法，降噪后的MAE信号特征值对于不同应力下均方根、偏斜度特征值的重复性更好，可靠性更高。     

Enhanced luminescence and energy transfer performance of double perovskite structure Gd2MgTiO6:Bi3+, Mn4+ phosphor for indoor plant growth LED lighting

Deep-red light emitting phosphors are widely used in LEDs for indoor plant growth because of the critical role played by red light in plant growth. The luminescence properties of deep-red phosphors are still not well understood at present. An energy transfer strategy is a common and effective method to improve luminescence properties. In principle, the energy transfer process may occur when the sensitizer's emission spectra overlap with the activator's excitation spectra. In this work, Bi³⁺ and Mn⁴⁺ were incorporated into the matrix of Gd₂MgTiO₆ as sensitisers and activators, respectively. Mn⁴⁺ ions tend to occupy the [TiO₆] octahedral site and the Bi³⁺ ions are expected to substituted in the site of Gd³⁺. The energy transfer process from Bi³⁺ to Mn⁴⁺ was realised and the photoluminescence (PL) intensity of Mn⁴⁺ increased with the doping content of Bi³⁺. Upon excitation at 375 nm, the PL intensity of Mn⁴⁺ increased to 116.4% when the doping concentration of Bi³⁺ reached 0.3%. Finally, the pc-LED devices were prepared by a Gd₂MgTiO₆:Bi³⁺, Mn⁴⁺ phosphor. The high red luminescence indicated that this phosphor has potential applications in indoor LED lighting.