Mesh stiffness analysis of beveloid gears for the rotating vector transmission

Yucheng Huang,Xuesong Du,Caichao Zhu,Gaoxiang Ni,Najeeb Ullah,Hao Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8

This paper investigates the meshing stiffness of beveloid gears in the beveloid rotate vector (BRV) transmission. It is a new kind of transmission evolved from rotate vector (RV) reducer. In the BRV transmission, the beveloid gear is a kind of involute gear with a bevel angle. The BRV transmission have high power density, large transmission ratio and high precision in geared coupled systems. However, there is rare systematic research conducted on the meshing stiffness analysis of the BRV transmission at present. Based on the loaded contact finite element analysis principle, a meshing stiffness analysis model for beveloid gears is established. The influence of different factors such as pitch cone angle, addendum coefficient, load and rim structure parameters of external gear on meshing stiffness are studied. The results show that the pitch cone angle and addendum coefficient have little effect on the shape of the meshing stiffness curve, but they have a significant influence on the amplitude of meshing stiffness. In contrast, the load can affect both the shape and the amplitude of the meshing stiffness curve obviously. Also, the size of scallop-hole and rim thickness have a great impact on the amplitude of the meshing stiffness. The prescribed piece of study can provide a better understanding for gear researchers in order to understand the influence of different parameters on dynamic characteristics analysis of the BRV transmission systems.

Study of co-excited green emission of Tb3+, Ce3+ and Gd3+ in yttrium aluminum garnet

Fei Huang,Limin Dong,Hao Wang,Weimin Wang,Yucheng Wang,Zhengyi Fu 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

YAG : Tb3+, Ce3+, Gd3+ nano-phosphors derived from a sol-gel chemistry have been successfully synthesized and characterized by TG/DTA, XRD, SEM, and spectrometer. The results show that the phosphors have a uniform particle size distribution ranging 30-50 nm. The value of the lattice constant increased with an increase of the Gd3+ content. Tb3+ →Ce3+, Ce3+ →Tb3+ and Gd3+ →Ce3+ energy transfer existed in the co-excited system. The luminescence intensity was controlled by the concentration and ratio of the co-dopants. A small quantity of Gd3+ and Ce3+ evidently increased the green emission (5D4→7F5) of Tb3+. YAG : Tb3+, Ce3+, Gd3+ nano-phosphors derived from a sol-gel chemistry have been successfully synthesized and characterized by TG/DTA, XRD, SEM, and spectrometer. The results show that the phosphors have a uniform particle size distribution ranging 30-50 nm. The value of the lattice constant increased with an increase of the Gd3+ content. Tb3+ →Ce3+, Ce3+ →Tb3+ and Gd3+ →Ce3+ energy transfer existed in the co-excited system. The luminescence intensity was controlled by the concentration and ratio of the co-dopants. A small quantity of Gd3+ and Ce3+ evidently increased the green emission (5D4→7F5) of Tb3+.

Effects of the Microstructure of Copper Through-Silicon Vias on their Thermally Induced Linear Elastic Mechanical Behavior

ZhiYong Wu,Zhiheng Huang,Yucheng Ma,Hua Xiong,Paul P. Conway 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

Through-silicon vias (TSVs) have been investigated extensively in recent years. However, the physical mechanisms behind some of the common problems associated with TSVs, such as the protrusion of Cu vias, are still unknown. In addition, since the dimensions of TSVs have been shrunk to microscopic levels, the sizes of the microstructural features of TSVs are no longer small compared to the dimensions of the vias. Therefore, the role and importance of the microstructural features of TSVs need to be studied to enable more accurate reliability predictions. This study focused on the effects the microstructural features of TSVs, i.e., the Cu grains and their [111] texture, grain size distribution, and morphology, have on the thermally induced linear elastic behavior of the vias. The results of the study indicate that stress distribution in the model that takes into account the Cu grains, whose Young’s moduli and Poisson’s ratios are set according to their crystallographic orientations, is more heterogeneous than that in a reference model in which the bulk properties of Cu are used. Stresses as high as 250 MPa are observed in the via of the model that takes into consideration the Cu grains, while stresses in the via of the reference model are all lower than 150 MPa. In addition, smaller Cu grains in the vias result in higher stresses; however, the variation in stress owning to changes in the grain size is within 20 MPa. The frequency of the stresses ranging from 80 MPa to 100 MPa was the highest in the stress distribution of the vias, depending on boundary conditions. The stress level in the vias decreases with the decrease in the number of grains with the [111] texture. Finally, the stress level is lower in the model in which the grain structure is generated using a phase field model and is closer to that of the microstructures present in real materials.

Light Load Efficiency Improvement Method for GaN-Based DAB Converter with Hybrid Discontinuous Current Mode

Bo Long,Wei Wang,Xin Lu,YuFei Dai,LiJun Huang,YuCheng Qian,Yong Chen,FuSheng Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Conventional phase-shift controlled dual active bridge (DAB) converters which operate in discontinuous current mode (DCM) are hard to realize the zero-voltage switching (ZVS) due to the light load. This paper proposed an efficiency improvement method for the DAB converter with fix-frequency hybrid discontinue current mode (HDCM). By adopting the HDCM control method, synchronous rectification and wide load range ZVS of switching devices are realized simultaneously without changing the components of the conventional DAB power stage in DCM. Besides, to further improve the conversion ratio and efficiency, the voltage-doubled rectification (VDR) is adopted. The HDCM implementation method with a digital signal processor (DSP) is proposed. A 200W laboratory prototype is designed to validate the correctness of HDCM. Compared to the conventional DAB converter which operates in DCM, experimental results demonstrate that the efficiency was increased 1.2% at 10% rated load.

Feasibility of Free-Breathing, Non-ECG-Gated, Black-Blood Cine Magnetic Resonance Images With Multitasking in Measuring Left Ventricular Function Indices

Peng Pengfei,Yue Xun,Tang Lu,Wu Xi,Deng Qiao,Wu Tao,Cai Lei,Liu Qi,Xu Jian,Huang Xiaoqi,Chen Yucheng,Diao Kaiyue,Sun Jiayu 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.12

Objective: To clinically validate the feasibility and accuracy of cine images acquired through the multitasking method, with no electrocardiogram gating and free-breathing, in measuring left ventricular (LV) function indices by comparing them with those acquired through the balanced steady-state free precession (bSSFP) method, with multiple breath-holds and electrocardiogram gating. Materials and Methods: Forty-three healthy volunteers (female:male, 30:13; mean age, 23.1 ± 2.3 years) and 36 patients requiring an assessment of LV function for various clinical indications (female:male, 22:14; 57.8 ± 11.3 years) were enrolled in this prospective study. Each participant underwent cardiac magnetic resonance imaging (MRI) using the multiple breath-hold bSSFP method and free-breathing multitasking method. LV function parameters were measured for both MRI methods. Image quality was assessed through subjective image quality scores (1 to 5) and calculation of the contrast-to-noise ratio (CNR) between the myocardium and blood pool. Differences between the two MRI methods were analyzed using the Bland–Altman plot, paired t-test, or Wilcoxon signed-rank test, as appropriate. Results: LV ejection fraction (LVEF) was not significantly different between the two MRI methods (P = 0.222 in healthy volunteers and P = 0.343 in patients). LV end-diastolic mass was slightly overestimated with multitasking in both healthy volunteers (multitasking vs. bSSFP, 60.5 ± 10.7 g vs. 58.0 ± 10.4 g, respectively; P < 0.001) and patients (69.4 ± 18.1 g vs. 66.8 ± 18.0 g, respectively; P = 0.003). Acceptable and comparable image quality was achieved for both MRI methods (multitasking vs. bSSFP, 4.5 ± 0.7 vs. 4.6 ± 0.6, respectively; P = 0.203). The CNR between the myocardium and blood pool showed no significant differences between the two MRI methods (18.89 ± 6.65 vs. 18.19 ± 5.83, respectively; P = 0.480). Conclusion: Multitasking-derived cine images obtained without electrocardiogram gating and breath-holding achieved similar image quality and accurate quantification of LVEF in healthy volunteers and patients.