A class of complicated 9,9-diarylfluorenes as nonplanar building blocks were synthesized and utilized to prepare a novel H-shaped oligofluorene. High glass transition temperatures and excellent solubility of the obtained oligomers indicated the 9,9-diarylfluorenes would be promising building blocks for the construction of H-shaped optoelectronic materials.

In this work, a new aspect of the utilization and development of the open‐ended coaxial probe technique for EM‐properties measurement of coating materials with a concave surface is studied. It is found from the results of an analysis performed using FDTD modeling that the reflection coefficient is strongly affected, even for large sample radii. In order to satisfy concave‐surface materials measurement, we propose a technique to modify the standard open‐ended coaxial probe to improve measurement accuracy. It is based on adding a ring patch at the end of the extended length of the inner conductor throughout the air gap between the probe and the material under test. The proposed technique is analyzed and verified by experiments. Results of the measured ε* and μ* of the several microwave‐absorbing materials coated on prototype boxes with different radii for shielding are in relative agreement with the published data. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 278–281, 2000.

A novel sliding-mode variable structure(SMVS) control strategy is proposed to reduce the ripples of flux and torque of brushless double-fed machines(BDFM) based on direct torque control system. In order to ensure the constant switching frequency for the inverter, two hysteresis regulators in the conventional direct torque control system system are substituted by the SMVS controllers of flux and torque，nonsingular terminal sliding modes are designed to make the motor power reach the given values in a finite period of time. and the high-order sliding mode method is adopted to estimate the chattering phenomenon of the conventional sliding mode. Meanwhile, to obtain the parameters of High-order terminal sliding mode control, a method of fuzzy neural network is presented. The simulation results show that the nonsingular high-order terminal sliding-mode control can improve the robustness and dynamic response of the system.

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