Deformation analysis of the main components in a single Screw compressor

The single screw compressor is used in many fields such as air compression, chemical industry and refrigeration. During operation, different gas pressures and temperatures applied on the components can cause different degrees of deformation, which leads to a difference between the thermally induced clearance and the designed clearance. However, limited research about clearance design is reported. In this paper, a temperature measurement instrument and a convective heat transfer model were described and used to establish the temperature of a single screw air compressor’s casing, screw rotor and star wheel. 3-D models of these three main components were built. The gas force deformation, thermal-structure deformation and thermal-force coupling deformation were carried out by using a finite element simulation method. Results show that the clearance between the bottom of the groove and the top of star wheel is reduced by 0.066mm, the clearance between the side of groove and the star wheel is reduced by 0.015mm, and the clearance between the cylinder and the rotor is reduced by 0.01mm. It is suggested that these deformations should be taken into account during the design of these clearances

MnTTS: An Open-Source Mongolian Text-to-Speech Synthesis Dataset and Accompanied Baseline

This paper introduces a high-quality open-source text-to-speech (TTS) synthesis dataset for Mongolian, a low-resource language spoken by over 10 million people worldwide. The dataset, named MnTTS, consists of about 8 hours of transcribed audio recordings spoken by a 22-year-old professional female Mongolian announcer. It is the first publicly available dataset developed to promote Mongolian TTS applications in both academia and industry. In this paper, we share our experience by describing the dataset development procedures and faced challenges. To demonstrate the reliability of our dataset, we built a powerful non-autoregressive baseline system based on FastSpeech2 model and HiFi-GAN vocoder, and evaluated it using the subjective mean opinion score (MOS) and real time factor (RTF) metrics. Evaluation results show that the powerful baseline system trained on our dataset achieves MOS above 4 and RTF about $3.30\times10^{-1}$, which makes it applicable for practical use. The dataset, training recipe, and pretrained TTS models are freely available \footnote{\label{github}\url{https://github.com/walker-hyf/MnTTS}}.Comment: Accepted at the 2022 International Conference on Asian Language Processing (IALP2022

Experimental Studies of The Multi-cylinders Compound Profile Meshing Pair

In order to improve the wear resistance of the meshing pair in Single Screw Compressor, our team developed the multi-cylinders compound profile which could be used in the meshing pair instead of the traditional profile. In this paper, the reliability and utility of the new profile was verified by an experiment. In this experiment, a designed multi-cylinders compound profile meshing pair was applied in an oil-flooded single screw air compressor as the experimental prototype, then the prototype ran 2000 hours continuously in the experimental platform. and the displacement was detected with changing discharge pressure and rotating speed. It is shown that the prototype has a steady displacement, and the energy efficiency grade is very close to the best grade. The displacement is slightly reduced with the discharge pressure arising, but the reduction is far less than the original single line profile meshing pair machine. These prove that the new pair has good sealing performance. A comparative observation on the star wheel profile is conducted at the end of test, and the results demonstrate that the nodular cast iron star wheel new designed has high wear resistant property and good hydrodynamic lubrication characteristic. Thus, the nodular cast iron can be used to make star wheel to reduce the cost of the single screw instead of the expensive PEEK material

The Upconversion Luminescence of Ca3Sc2Si3O12:Yb3+,Er3+ and Its Application in Thermometry

To develop novel luminescent materials for optical temperature measurement, a series of Yb3+- and Er3+-doped Ca3Sc2Si3O12 (CSS) upconversion (UC) phosphors were synthesized by the sol– gel combustion method. The crystal structure, phase purity, and element distribution of the samples were characterized by powder X-ray diffraction and a transmission electron microscope (TEM). The detailed study of the photoluminescence emission spectra of the samples shows that the addition of Yb3+ can greatly enhance the emission of Er3+ by effective energy transfer. The prepared Yb3+ and Er3+ co-doped CSS phosphors exhibit green emission bands near 522 and 555 nm and red emission bands near 658 nm, which correspond to the 2H11/2→4 I15/2, 4S3/2→4 I15/2, and 4F9/2→4 I15/2 transitions of Er3+, respectively. The temperature-dependent behavior of the CSS:0.2Yb3+,0.02Er3+ sample was carefully studied by the fluorescence intensity ratio (FIR) technique. The results indicate the excellent sensitivity of the sample, with a maximum absolute sensitivity of 0.67% K−1 at 500 K and a relative sensitivity of 1.34% K−1 at 300 K. We demonstrate here that the temperature measurement performance of FIR technology using the CSS:Yb3+,Er3+ phosphor is not inferior to that of infrared thermal imaging thermometers. Therefore, CSS:Yb3+,Er3+ phosphors have great potential applications in the field of optical thermometry