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Intrinsically stretchable light‐emitting polymer semiconductors are essential building blocks for bioelectronics and display textiles. Stretchability is challenging for rigid conjugated polymers unless sacrificing charge mobility by introducing amorphous domains. High‐performance light‐emitting properties designed with twisted angle are undesirable for conductive materials. Hence, the concurrent strategies hardly satisfy the balance of stretchability, light‐emitting and mobility. Herein, a morphology engineering is proposed by controlling micro‐crystalline and limiting aggregation, that four intrinsically stretchable emissive polymers with good charge mobility based on indacenodithiophene (IDT) are obtained. Polymers reveal good emission properties with high photoluminescence quantum yields (PLQY) of about 20%, while stretchable modulus and charge mobility are tunable by backbone and weight. Specifically emphasizing, IDT‐2T‐H retains high performance of charge mobility and PLQY even at 100% strain. Therefore, organic light emitting diodes are fabricated based on it and showing the luminance of 176.2 cd cm−2, which verifies the potential of technique to reconcile integration of stretchability, light‐emitting, and mobility. This is the first attempt to integrate balanced mechanical, optical, and electrical properties through micro‐crystalline aggregation‐limited morphology in one polymer, offering a feasible approach to advanced integrated circuit and multi‐functional electronics in the future. [ABSTRACT FROM AUTHOR]

In order to study the evolution characteristics of the pore structure of medium and high rank coals, the low-temperature nitrogen adsorption method and the FHH fractal theory model were used to explore the regularity of pore structure characteristics and fractal characteristics of different rank coals. The results show that as the coal rank increases, the BET specific surface area of the coal increases first and then decreases, the BJH pore volume gradually decreases. As for the coal pore size distribution, the number of micro-pores decreases first and then increases, and the number of small and mesopores increases first and then decreases; the value of the FHH fractal dimension D1 can quantify the roughness of the coal surface, which increases with the increase of coal rank. The change of D1 value of the gas-fat coal and lean coal is small, and anthracite stage increases more, the range is 2.256 2 to 2.461 3; the D2 value can quantify the complexity of the pore structure of coal. The D2 value decreases first and then increases with the increase of coal rank, ranging from 2.459 1 to 2.806 5.

A measurement system of gear dynamic transmission error based on optical encoder is built.The system first measures the rotation angles of the input and output shafts of a gear pair by two optical encoders. The collected pulse signals are then counted and interpolated to obtain angle sequences based on uniform time sampling. Finally,the dynamic transmission error of the gear pair can be obtained by comparing the angle sequences of two shafts. The nonlinear dynamics model of a gear system is built and it’s solved based on fourth-order Runge-Kutta method. The simulation results（ rotation angles） are sampled by simulating the optical encoder and data acquisition card and the influence of the resolution of the optical encoder and the time resolution of the data acquisition card on the measurement accuracy is studied. The simulation results show that in order to ensure the measurement accuracy for a gear system with a maximum speed of 1 500 r/min,the resolution of an optical encoder should be not less than 200 pulses per revolution and the time resolution of a data acquisition card should be not lower than 3. 3 × 10-9 s. The gear transmission bench test also shows that the dynamic transmission error obtained by the measurement system has good repeatability,and its values are consistent with the noise phenomenon induced by the bench.