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Jun Hu,Can Tao,Aining Yuan,Junjie Bao,Qin Cheng,Gewen Xu,Yiping Huang 한국고분자학회 2019 폴리머 Vol.43 No.2
Series of waterborne polyurethanes (WPUs) containing poly(tetra methylene glycol) (PTMG), 4,4-dicyclohexylmethane diisocyanate (HMDI), 2,2-dimethylolpropionic acid (DMPA), 2,2,4-trimethyl-1,3-pentanediol (TMPD), isosorbide (ISO) and ethylenediamine (EDA) were synthesized. The effects of ISO on the structure and properties of WPUs were studied by gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMTA), X-ray diffraction (XRD), thermogravimetry (TG), mechanical test, chemical resistance and hardness test. The deconvolution analysis of FTIR of WPUs revealed that the hydrogen bond interaction in the WPUs increased with the increase of ISO content. Furthermore, the degree of microphase separation was increased with the increase of hydrogen bond interaction, which was confirmed by DSC, XRD and DMTA test. The results demonstrated that the addition of ISO can increase the hydrogen bond interaction between the hard and hard segments in WPUs, which improved the mechanical properties of the WPU films. The highest tensile strength was obtained of 59.67 MPa when the content of isosorbide was 10.35 wt%. Moreover, the ISO was helpful to improve the chemical resistance and hardness of the coatings by the comprehensive performance analysis.
Jun Hu,Yong Liu,Yuping Li,Kai Yao 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10
In this paper, the construction of a section of Nanjing Metro Line 2, a shallow underground tunnel constructed with an underground mining method, was analysed. Due to the existence of two aquifer soil layers near the tunnel, water and sand inrush occurred during the tunnelling process. This disrupted tunnelling project was covered until the artificial ground freezing technique was used to achieve a waterless environment. After the 40-day active freezing period, the ground temperature conditions satisfied the design requirements, thereby ensuring the construction schedule. The ground freezing technique and other supplementary measurements were introduced in this study, which could be useful for other similar projects.
Yao, Junhu,Tian, Xiaoyan,Xi, Haibo,Han, Jincheng,Xu, Ming,Wu, Xiaobing Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.1
The experiment was conducted to study the effect of choice feeding on growth performance, carcass quality, gastrointestinal development and feed utilization of 22-49 days old broilers. One hundred and forty four 22-day-old broilers were randomly allocated to 3 treatments with 4 replicates per treatment and 12 birds per replicate. Three feeding regimes are complete diet (control), ground corn and protein concentrate (treatment I), and soybean meal and balancer (treatment II). Protein concentrate is the residue part of complete diet without corn, and balancer is the residue part of complete diet without soybean meal. Treatment I and II are designed for the broilers to freely choose the two parts of diet. The results showed that: (1) broilers under choice feeding (treatment I and II) had lower performances compared with the control; (2) gastrointestinal development and the efficiency ratios that broilers converted dietary crude protein and lysine to body weight gain were improved in treatment I (p<0.05); (3) there were no significant differences in the apparent metabolizabilities of dietary dry matter, crude protein and gross energy, and deposition ratios of dietary nitrogen and energy, and carcass quality among three feeding regimes (p>0.05).
Xuejing Zhang,Junhu Yang,Wenkai Bei,Wei Han,Canyang Chen,Le Yang 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2
The efficiency of multiphase twin-screw pump decreases sharply under wet gas conditions (GVF>95%) with severe vibration and thermal problems. Based on the design characteristics of twin-screw pump and screw compressor, a design method of multigradient variable pitch decompression screw pump is to address these problems in this paper. This method keeps the cross section profiles of screw pump unchanged,only changes the pitch of screw. According to the design concept of decompression of screw compressor, the screw rotor is divided into three regions from the inlet to the outlet. The pitch of screw and thread width in these regions are designed separately to increase the volumetric efficiency of the screw pump and reduce the vibration. The effective clearance leakage model of twin-screw pump is simplified and modified. Considering two-phase back flow and combining mechanical model with thermodynamic model, the flow capacity, volumetric efficiency, pressure, and temperature distribution of new and conventional screw pumps are predicted by non-isothermal compression model. The calculations show that the design scheme of multi-gradient variable-pitch decompression screw pump can solve the volumetric efficiency and vibration problems under wet gas conditions fundamentally and can significantly reduce the power consumption of screw pump. However, the problem of temperature rise of screw pump still exists. Cooling system for the screw pump should be designed to continuously cool the screw pump.
Analysis on Characteristic of Pressure Fluctuation in Hydraulic Turbine with Guide Vane
FengXia Shi,JunHu Yang,XiaoHui Wang 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.3
An unsteady three-dimensional simulation based on Reynolds time-averaged governing equation and RNG k-ε turbulence model, was presented for pump-as-turbine, the pressure fluctuation characteristic of hydraulic turbine with guide vane was obtained. The results show that the time domains of pressure fluctuation in volute change periodically and have identical cycles. In volute tongue and inlet pressure fluctuations are light, while in dynamic and static coupling interface pressure fluctuations are serious; In impeller blade region the pressure fluctuation of pressure surface are lighter than that of suction surface. The dominant frequencies of pressure fluctuation concentrate in low frequency region, and concentrate within 2 times of the blade passing frequency.
Effect of Different Guide Vane Numbers on Transient Radial Force of Pump as Turbine
FengXia Shi,JunHu Yang,XiaoHui Wang 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.1
Guide vane was added to pump as turbine (PAT), the transient flow characteristics of PAT were calculated and experimented under different guide vane numbers. The results show that after the PAT was added guide vane, the distribution of speed streamline and blade load is more uniform than before, and the unsteady radial force on impeller decreased greatly, which is good for the stability of PAT’s operation. When the guide vane number is equal to 9, both the maximum radial force difference and dominant frequency amplitude of radial force are the minimum. So there is an optimal guide vane number, for the given geometric parameters of PAT.
Li Wang,Xuejing Zhang,JunHu Yang,Chong Ma,Wei Han,Yubing Gong 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2
When GVF in the inlet of the oil-gas mixed transmission twin-screw pump is high, the temperature difference between the inlet and outlet of the screw pump will rise significantly, and rotor expansion jam will occur. To prevent the expansion jam caused by the overheating of the screw pump, the cooling water jacket is designed for gas-liquid mixed screw pump with high GVF to continuously cool. Using the theory of fluid-structure interaction heat transfer, the cooling effect of the cooling water jacket of the equal pitch screw pump and the variable pitch screw pump is numerically calculated, and after comparison with the experiment, it finds that the maximum deviation of the outlet temperature of the variable pitch screw pump does not exceed 4K and the average deviation is about 6 %. When GVF is 96%, the calculation of the cooling water cavity shows that the average temperature drop of the liner after the cooling of the equal pitch screw pump and the variable pitch screw pump is about 4K and 3K, respectively. When GVF rises from 90% to 99%, the average temperature drop is about 3.5K. Cooling water jacket has obvious cooling effect on screw pump with high GVF.
Effect of Different Guide Vane Numbers on Transient Radial Force of Pump as Turbine
Shi, FengXia,Yang, JunHu,Wang, XiaoHui Korean Society for Fluid machinery 2018 International journal of fluid machinery and syste Vol.11 No.1
Guide vane was added to pump as turbine (PAT), the transient flow characteristics of PAT were calculated and experimented under different guide vane numbers. The results show that after the PAT was added guide vane, the distribution of speed streamline and blade load is more uniform than before, and the unsteady radial force on impeller decreased greatly, which is good for the stability of PAT's operation. When the guide vane number is equal to 9, both the maximum radial force difference and dominant frequency amplitude of radial force are the minimum. So there is an optimal guide vane number, for the given geometric parameters of PAT.