Search

Polystyrene particles (EPS) were used as the doping material, which were hydrophilic modified by different surfactants. On this basis, polystyrene particles were added to foam concrete, and the effects of hydro¬philic modified polystyrene particles on the mechanical properties and thermal insulation performance of concrete were studied. The results showed that unmodified polystyrene belongs to hydrophobic materials with a contact angle of 112°. After modification with triethanolamine, the contact angle decreased to 31°, indicating ex¬cellent hydrophilicity. Foam concrete had porous characteristics, and the pore size distribution was 20-230 µm. The setting time decreased with the increase of polystyrene particle doping, the fluidity first increased and then decreased, the solidification time of EPS-0.9% was 90 minutes, and the highest fluidity was 17.9 mm. With the increase of EPS particles, the compressive strength of foam concrete continued decreasing, the flexural strength first decreased and then slightly increased, the thermal conductivity and dry density first decreased and then increased, and the carbonation resistance continued decreasing. At 28 d of age, the compressive strength of the EPS-1.2% sample reached the minimum value of 5.2 MPa, and the carbonization depth reached the maximum value of 2.13 mm. The flexural strength of the EPS-0.6% sample reached a maximum value of 0.57 MPa. The dry density and thermal conductivity of the EPS-0.9% sample reached the lowest values, which were 357 kg/m³ and 0.069 W/(m • K), respectively, indicating the best insulation performance. [ABSTRACT FROM AUTHOR]

Large‐sized transparent scintillators with a high photoluminescent quantum yield (PLQY) and self‐absorption‐free properties are highly desired to achieve high spatial resolution X‐ray imaging. In this research, a transparent 0D organic–inorganic (ETP)2SbCl5 (ETP = Ethyl triphenylphosphine) amorphous wafer is developed by melting the ETPCl and SbCl3 mixture and then undergoing a quenching process. The obtained amorphous wafer exhibits a high light transmittance of 86% in the range of 450–800 nm. It also shows a light emission peak at 624 nm, a Stokes shift of 259 nm, and PLQY approaching unity (99.3%). These properties enable it to produce X‐ray images with a high spatial resolution of 19.0 lp mm−1 at a modulation transfer function (MTF) value of 0.2, among the best values reported. Additionally, it also shows remarkable stability under continuous X‐ray illumination. Its unique optical properties and ability to be processed in large sizes make the organic–inorganic metal halide transparent wafer a promising scintillator. This also demonstrates the potential application of the melt‐quenching method in fabricating highly luminescent, low‐electronic‐dimensional metal halide wafers. [ABSTRACT FROM AUTHOR]

Two control strategies of DFIG under grid distortion are firstly summarized, namely, the control strategy of PI-R current controller based on dq reference frame and the control strategy of PI current controller based on the multiple rotating dq reference frame, and their advantages and disadvantages are analysed. On the basis of dynamic modelling of DFIG under grid distortion, in view of the defect that DFIG coupling is not considered in the control strategy of PI-R current controller based on dq reference frame, an improved control strategy considering motor coupling is proposed. In the end, the modelling and simulation of the unimproved and improved control strategies of PI-R current controller based on dq reference frame are carried out, and the simulation results verified the effectiveness of the improved control strategy.

It is important to achieve stability of bus voltage in control of DC microgrids. In the DC microgrid, the traditional droop control method is usually adopted to stabilize the bus voltage for its high reliability and cost-effectiveness. However, line resistance will reduce the voltage quality of the DC bus in actual situations. In order to improve the voltage quality of the DC bus, a novel bus voltage control strategy based on modified droop characteristic is proposed. Finally, the simulation model of the off-grid DC microgrid with improved droop control strategy is built on PSCAD/EMTDC platform, and the results verify the effectiveness and feasibility of the proposed control strategy.

Nowadays, distributed generation technology is of great help to the efficient utilization of new energy. If the distributed power supply is connected to the DC micro-grid, it will be more secure and reliable. Therefore, it is necessary to control the voltage stability of the DC bus and ensure the balance of the source charge power of system to ensure the power supply quality and safety of the DC micro-grid. There are two operation modes of DC micro-grid: connected operation and isolated operation, and isolated operation control is the foundation and key of system-level control of DC micro-grid. To solve the problem of bus voltage fluctuation in isolated dc micro-grid, this study proposes a voltage hierarchical-droop control strategy for DC micro-grid, which can effectively improve the stability of the DC bus voltage. Last, this study builds the simulation model of DC micro-grid in the MATLAB/Simulink platform to verify the validity and feasibility of the proposed control strategy.

Summary: Polypyrrole is successfully introduced to enhance the reaction stability and ionic conductivity of LiNi1/3Co1/3Mn1/3O2 material through an ultrasound dispersion method and applied as cathode materials for lithium‐ion batteries. This polymer can significantly advance the electrochemical properties. Expectedly, the 8 wt.% LiNi1/3Co1/3Mn1/3O2/polypyrrole composite has lower mixing degree of Li+/Ni2+, higher c/a value, which delivers the first discharge capacity of 199.2 mAh g−1, which abate to 121.3 mAh g−1 in the 300th cycle at 0.2 C between 2.5 and 4.5 V. Even at 3 C, it continues to reveal a reversible capacity of 86.4 mAh g−1 after 100 cycles. All the consequences implied that the 8 wt.% LiNi1/3Co1/3Mn1/3O2/polypyrrole verified a minor charge transfer resistance and better Li+ diffusion ability, hence establishing preferable rate and cycling performance compared with the primordial LiNi1/3Co1/3Mn1/3O2. [ABSTRACT FROM AUTHOR]

In this paper, we reported a simple and effective strategy to synthesize core-shell dummy template magnetic molecularly imprinted polymers (FeO@DMIPs) using ethyl paraoxon as a template for the recognition and selective extraction of organophosphorus pesticide. Initially, monodisperse FeO nanoparticles were synthesized directly through a facile one-pot hydrothermal method. Then, the imprinted layer was synthesized directly on the surface of the magnetic core by means of a one-pot sol-gel copolymerization which avoided further modification of the external part of the magnetic core. The structure and morphology of the materials (FeO@DMIPs) were characterized by SEM, TEM, FTIR, XRD, and VSM. It was observed that FeO@DMIPs showed regular morphology, good dispersibility, and superparamagnetism. The synthesis conditions for the formation of FeO@DMIPs were systematically investigated. It was found that the morphology and monodispersity of FeO@DMIPs were highly influenced by the ratio of the mixture solvent of methanol and water and the volume ratio of functional monomer (APTES) and cross-linker (TEOS). The binding performance of the imprinted polymers was investigated through a series of adsorption experiments, which indicated that the FeO@DMIPs had a fast adsorption rate (15 min) and high adsorption capacity (195.7 mg g) to methyl parathion and phoxim. Meanwhile, real wine sample tests demonstrated a good extraction effect. This study provides a possibility for the selective extraction of organophosphorus pesticide residue in a complex matrix. [ABSTRACT FROM AUTHOR]