High-performance narrow spectrum green phosphorescent top-emitting organic light-emitting devices with external quantum efficiency up to 38%

In this work, we have experimentally demonstrated the efficacy of micro-cavity effect in realizing high-performance top-emitting organic light-emitting diodes (TEOLEDs). By optimizing the thickness of top Yb/Ag electrode and cavity length, highly efficient green TEOLED with external quantum efficiency as high as 38% was achieved. A strong dependence of electroluminescent (EL) performances and spectrum on cavity length was observed, and there was also a significant angle dependence of EL spectrum. Ultimately, ultra-high current efficiency up to 161.17 cd/A (3.2 V) was obtained by the device with emission peak at 552 nm, which is 35 nm longer than the intrinsic emission peak (517 nm) of utilized green emitter. Interestingly, this device displayed narrow emission with full-width at half-maximum (FWHM) of less than 20 nm, which was obtained by increasing the Ag layer thickness.

Optical Fiber Interferometers Based on Arc-Induced Long Period Gratings at INESC TEC

In this work, we review the most important achievements of an INESC TEC long-period-grating-based fiber optic Michelson and Mach–Zehnder configuration modal interferometer with coherence addressing and heterodyne interrogation as a sensing structure for measuring environmental refractive index and temperature. The theory for Long Period Grating (LPG) interferometers and coherence addressing and heterodyne interrogation is presented. To increase the sensitivity to external refractive index and temperature, several LPG interferometers parameters are studied, including order of cladding mode, a reduction of the fiber diameter, different type of fiber, cavity length and the antisymmetric nature of cladding modes.

A High-Speed Demodulation Technology of Fiber Optic Extrinsic Fabry-Perot Interferometric Sensor Based on Coarse Spectrum

A fast real-time demodulation method based on the coarsely sampled spectrum is proposed for transient signals of fiber optic extrinsic Fabry-Perot interferometers (EFPI) sensors. The feasibility of phase demodulation using a coarse spectrum is theoretically analyzed. Based on the coarse spectrum, fast Fourier transform (FFT) algorithm is used to roughly estimate the cavity length. According to the rough estimation, the maximum likelihood estimation (MLE) algorithm is applied to calculate the cavity length accurately. The dense wavelength division multiplexer (DWDM) is used to split the broadband spectrum into the coarse spectrum, and the high-speed synchronous ADC collects the spectrum. The experimental results show that the system can achieve a real-time dynamic demodulation speed of 50 kHz, a static measurement root mean square error (RMSE) of 0.184 nm, and a maximum absolute and relative error distribution of 15 nm and 0.005% of the measurement cavity length compared with optical spectrum analyzers (OSA).

Investigation of the Jet Characteristics and Pulse Mechanism of Self-Excited Oscillating Pulsed Jet Nozzle

Self-excited oscillation pulse jet technology is widely used to clean sediment from oil storage tanks. Its successful application is dependent on jet performance. As the cleaning requirements of the oil industry increase, it is necessary to optimise the structure of self-excited oscillation pulsed jet nozzles (SOPJNs) to optimise cleaning and energy efficiencies. In this study, the jet performance of a SOPJN is modelled and analysed based on computational fluid dynamics with consideration of a large eddy simulation and homogeneous cavitation. The modelling results are highly consistent with experimental results. The effects of the SOPJN’s inlet diameter, cavity diameter, cavity length, wall reflection angle, and inlet pressure on the jet’s peak velocity, oscillation frequency, and cavitation number were analysed. The results show that the oscillation frequency decreases with the increase of the inlet diameter d1, cavity diameter D, cavity length L and reflection angle of wall α. Optimisation of the SOPJN inlet diameter, cavity length, and wall reflection angle produced a jet with a high peak velocity and strong cavitation. The optimal nozzle cavity diameter strengthens cavitation, while the peak velocity fluctuates as the cavity diameter increases. The peak velocity increases with the inlet pressure, while the increasing rate of the peak velocity decreases. The results of this study can be used in the design and optimisation of similar nozzle structures for improved pulse jet cleaning.

Mitigation of Antisymmetric Mode and Drag with Base Cavities

Experiments were carried out to examine the impact of base cavities on the base pressure fluctuations and total drag of a cylindrical afterbody for freestream Mach numbers 0.6-1.5. Significant improvement in the base pressure and a substantial reduction in the afterbody drag was noticed in the presence of a base cavity at subsonic Mach numbers. However, on increasing the cavity length beyond a certain value its performance deteriorates. At supersonic Mach numbers their effectiveness drops drastically. Tones in the spectra can be classified into two types depending on the dominant azimuthal mode which is either 0 or 1 and are referred to as symmetric and an antisymmetric mode, respectively. Spectra at subsonic Mach numbers exhibit tones which are related either to mode 0 or 1. However, at supersonic Mach numbers only tones related to mode 0 exist. The base cavity either, effectively suppress the antisymmetric mode or modify it into a symmetric mode resulting in mitigation of the tones related to antisymmetric mode.

A new species of a rare genus, Truxonchus quangi sp. n. (Mononchida, Anatonchidae) from bat xat nature reserve in Lao Cai Province, Vietnam

Truxonchus quangi sp. n. is described and illustrated from Vietnam. Females of the new species are characterized by large body size (L = 4.8-5.8 mm); barrel shaped buccal cavity of large size (105-113 x 66-73 µm) with one dorsal tooth and two subventral teeth posteriorly directed, of equal shape, size and apex position; dorsal tooth apex located 36-39% of buccal cavity length from its base; reproductive system didelphic-amphidelphic, vagina long, 39-45% of corresponding body width, with distinct par refringens vaginae, sclerotized pieces rounded in optical section; tail long, filiform, ventrally arcuate, with three small caudal glands in tandem and prominent subventral spinneret. The new species is close to T. dolichurus but differs by the larger buccal cavity, more anterior position of the dorsal tooth apex, more anterior vulval position and presence of advulval pores.

Research on Resonance Mechanism and Collaborative Optimization of Double-cavity Self-Excited Oscillating Pulse Cavitation Jet Nozzle

The peak value and pulsation amplitude of the self-excited oscillating pulse cavitation jet nozzle are important indexes to evaluate the jet performance. It is of great significance in theory and engineering practice to predict the peak value of the self-excited oscillating pulse cavitation jet nozzle accurately. In order to investigate the evolution mechanism of the inner and outer flow field of a double-cavity self-excited oscillation pulse cavitation jet nozzle, a simulation model of the jet impact test of the nozzle was established. Before entrance rounded corners, former cavity cavity diameter, cavity cavity length, before the cavity under the nozzle diameter, cavity, the cavity cavity after entry the rounded, lumen diameter, cavity length and cavity after cavity under the nozzle diameter as design variables, and strike force to combat force peak pulse amplitude as the target variable, the orthogonal experiment method, back propagation neural network combined with non dominated sorting genetic algorithm, The collaborative optimization design method of self-excited oscillating pulse cavitation jet nozzle was determined. Based on the collaborative optimization results, the 3D printing technology was used to manufacture the visualization test model of the flow field of the self-excited oscillating pulse cavitation jet nozzle, and the experimental verification was carried out. The results show that when the inlet pressure is 2MPa, the main and secondary order of the influences of various factors on the jet performance of the nozzle is the nozzle diameter under the front cavity, the diameter of the back cavity, the diameter of the front cavity, the length of the front cavity, the nozzle diameter under the back cavity, the cavity distance, the fillet of the back cavity, the fillet of the front cavity and the length of the back cavity. Compared with the optimal result of orthogonal test, the amplitude of impact pulsation and the peak value of impact force are increased by 14.61% and 2.42% respectively. The optimal structure of the nozzle determined by collaborative optimization can produce obvious pulse cavitation jet, and the cavitation region of the nozzle cavity contracts periodically with time. The higher the inlet pressure, the higher the cavitation intensity and the higher the content of hollow bubble. This study can promote the development of jet performance calculation of self-excited oscillation pulse cavitation jet nozzles, and provide support for the design of self-excited oscillation pulse cavitation jet nozzles.